Author Topic: Cam tower stud replacment  (Read 4906 times)

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Offline Davidov

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Cam tower stud replacment
« on: July 27, 2014, 02:52:09 PM »
I removed all my studs on the cylinder head. The 4 studs for the cam towers.
The last one was being stubborn, so in the process of double-nut removal, the upper threads pulled apart. Grrr.

Studs aren't marked with grade/strength ratings like bolts are, I've only seen the black/hardened bolts (like the exhaust studs) or standard bolt type studs.

I found these full threaded studs at the hardware store, 6mm x 1.0 thread pitch. I measured it against the other studs and cut it to size.

Any reason why I shouldn't use this stud as a replacement?
-David

Offline flybox1

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Re: Cam tower stud replacment
« Reply #1 on: July 27, 2014, 03:13:52 PM »
No real reason to remove those studs, but it's done now. Use an oem one if you can....
Just be sure to use thread sealer, not thread lock, as the ends are exposed to the outside.
If you don't, you'll have oil leaks, eventually.....
'78 750K (F3 engine) PD42b's, Modified airbox w/K&N  filter, 40/110 jets, 1 needle shim, IMS@ 1 turn out. Kerker + Cone 18" QuietCore

Past Bikes
1974 550K0 (stock), 1973 CB350F (stock), 1983 Yamaha XS400K (POS)
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Offline Davidov

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Re: Cam tower stud replacment
« Reply #2 on: July 27, 2014, 03:41:51 PM »
I removed them so I could apply thread sealant
-David

Offline MCRider

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Re: Cam tower stud replacment
« Reply #3 on: July 27, 2014, 04:07:39 PM »
I removed them so I could apply thread sealant
Generally they don't leak if never disturbed. Once removed, for whatever reason, like porting, or such, then you would use the sealer.

AS to your question, IMO, no prob using the replacements, with sealer.
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Ron
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"Sometimes the light's all shining on me, other times I can barely see, lately it appears to me, what a long, strange trip its been."

Offline bjbuchanan

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Re: Cam tower stud replacment
« Reply #4 on: July 27, 2014, 08:46:12 PM »
I bet your replacements would be better than stock, They suck.

Like said use a real sealer not a locker
The dirty girl-1976 cb750k, Ebay 836, Tracy bodykit
Round top carbs w/ 38 pilots, middle needle position, airscrew 7/8ths out, 122 main jet
Stock airbox w/ drop in K&N, Hooker 4-1

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Offline Don R

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Re: Cam tower stud replacment
« Reply #5 on: July 27, 2014, 09:07:11 PM »
I believe the stud diameter may help locate the cam holders, the all thread lacks this tolerance. However I doubt it will cause an issue.
 I had that problem on my drag car, in two locations the threads wore into the part they were holding. My application was entirely different though.
 I wonder if a guy could purchase a bolt the proper length, cut off the head and thread it?  A pair of nuts in a vise would hold the threaded end while you tap the threads. if it rotated you could saw a slot through the nuts, that would pinch down on them.
No matter how many times you paint over a shadow, it's still there.
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Offline bjbuchanan

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Re: Cam tower stud replacment
« Reply #6 on: July 27, 2014, 10:28:17 PM »
I believe the stud diameter may help locate the cam holders, the all thread lacks this tolerance. However I doubt it will cause an issue.
 I had that problem on my drag car, in two locations the threads wore into the part they were holding. My application was entirely different though.
 I wonder if a guy could purchase a bolt the proper length, cut off the head and thread it?  A pair of nuts in a vise would hold the threaded end while you tap the threads. if it rotated you could saw a slot through the nuts, that would pinch down on them.

It would probably take a decent tap but a shouldered bolt is best
The dirty girl-1976 cb750k, Ebay 836, Tracy bodykit
Round top carbs w/ 38 pilots, middle needle position, airscrew 7/8ths out, 122 main jet
Stock airbox w/ drop in K&N, Hooker 4-1

Don't trust me alone with a claw hammer and some pliers

Offline madmtnmotors

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Re: Cam tower stud replacment
« Reply #7 on: July 28, 2014, 03:50:42 AM »
TAMTF...


Wilbur



Projects:
"Evolution": http://forums.sohc4.net/index.php?topic=100352.0
"P.O. Debacle": http://forums.sohc4.net/index.php/topic,126692.msg1441661.html#msg1441661
F2/F3 O-rings: http://forums.sohc4.net/index.php?topic=113672.msg1300721#msg1300721
Cam Tower Studs: https://www.mcmaster.com/#93210a017/=t19sgp
Clean up that nasty harness: http://forums.sohc4.net/index.php?topic=137351.msg1549191#msg1549191
http://forums.sohc4.net/index.php/topic,148188.msg1688494.html#msg1688494
http://forums.sohc4.net/index.php/topic,139544.msg1579364.html#msg1579364
                                          
Charging system diagnosis: http://forums.sohc4.net/index.php?topic=1012.msg8345#msg8345
Get the manuals: http://manuals.sohc4.net/cb750k/
The Dragon: http://forums.sohc4.net/index.php?topic=45183.msg1571675#msg1571675
Headlight Switch: http://forums.sohc4.net/index.php?topic=113986.msg1283236#msg1283236
Branden's leak free top end thread: http://forums.sohc4.net/index.php?topic=107040.0
Engine Lifting Made Easy: http://forums.sohc4.net/index.php/topic,58210.msg1684742.html#msg1684742
                                      http://forums.sohc4.net/index.php/topic,100352.msg1675840.html#msg1675840
Static and Dynamic Timing: http://www.hondachopper.com/garage/carb_info/timing/timing1.html
Airbox Gasket Replacement: http://forums.sohc4.net/index.php/topic,114485.msg1290000.html#msg1290000
"Café" : http://forums.sohc4.net/index.php/topic,84697.msg953814.html#msg953814
PD Carb Choke Linkage: http://forums.sohc4.net/index.php/topic,100352.msg1669248.html#msg1669248
                                    http://forums.sohc4.net/index.php/topic,110931.msg1248354.html#msg1248354
                                    http://forums.sohc4.net/index.php/topic,48858.msg515204.html#msg515204
Follow up on your damn posts: http://forums.sohc4.net/index.php/topic,144305.msg1791605.html#msg1791605
Taiwanese Cam Chain Tensioners:  http://forums.sohc4.net/index.php/topic,155043.msg1774841.html#msg1774841
Gumtwo Seat Cover: http://forums.sohc4.net/index.php/topic,164440.msg1897366.html#msg1897366
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Tank Latch: http://forums.sohc4.net/index.php/topic,165975.msg1919495.html#msg1919495
Shorten your forks: http://vintage-and-classic-honda-s.456789.n3.nabble.com/How-to-shorten-forks-td4042465.html DO NOT CUT THE SPRINGS!
Clutch How To: http://vintage-and-classic-honda-s.456789.n3.nabble.com/How-to-change-and-adjust-a-clutch-SOHC-td4040391.html
Late model K7/K8/F2/F3 front sprocket cover removal: http://forums.sohc4.net/index.php/topic,178428.msg2072279.html#msg2072279
630 to 530 conversion: http://forums.sohc4.net/index.php/topic,180710.msg2094423.html#msg2094423

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Offline 70CB750

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Re: Cam tower stud replacment
« Reply #8 on: July 28, 2014, 04:08:48 AM »
McMaster-Carr:

http://www.mcmaster.com/#98867a270/=t15a10

What Wilbur says, make sure they are made from decent steel, preferably rolled not cut threads.
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Offline MCRider

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Re: Cam tower stud replacment
« Reply #9 on: July 28, 2014, 06:26:32 AM »
DonR:
I think the knock pins do all the locating necessary. I would say that having something shaped like the original would sure feel better to have.
Ride Safe:
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1988 NT650 HawkGT;  1978 CB400 Hawk;  1975 CB750F -Free Bird; 1968 CB77 Super Hawk -Ticker;  Phaedrus 1972 CB750K2- Build Thread
"Sometimes the light's all shining on me, other times I can barely see, lately it appears to me, what a long, strange trip its been."

Offline madmtnmotors

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Re: Cam tower stud replacment
« Reply #10 on: July 28, 2014, 07:02:18 AM »
I think the knock pins do all the locating necessary.

The only knock pins are under the towers. There are no knock pins under the bearing caps. Of course, the bearing caps fit pretty snug front to back, and the shoulder of the bearing cap bolt (opposite the stud) would help prevent any side to side misalignment.
TAMTF...


Wilbur



Projects:
"Evolution": http://forums.sohc4.net/index.php?topic=100352.0
"P.O. Debacle": http://forums.sohc4.net/index.php/topic,126692.msg1441661.html#msg1441661
F2/F3 O-rings: http://forums.sohc4.net/index.php?topic=113672.msg1300721#msg1300721
Cam Tower Studs: https://www.mcmaster.com/#93210a017/=t19sgp
Clean up that nasty harness: http://forums.sohc4.net/index.php?topic=137351.msg1549191#msg1549191
http://forums.sohc4.net/index.php/topic,148188.msg1688494.html#msg1688494
http://forums.sohc4.net/index.php/topic,139544.msg1579364.html#msg1579364
                                          
Charging system diagnosis: http://forums.sohc4.net/index.php?topic=1012.msg8345#msg8345
Get the manuals: http://manuals.sohc4.net/cb750k/
The Dragon: http://forums.sohc4.net/index.php?topic=45183.msg1571675#msg1571675
Headlight Switch: http://forums.sohc4.net/index.php?topic=113986.msg1283236#msg1283236
Branden's leak free top end thread: http://forums.sohc4.net/index.php?topic=107040.0
Engine Lifting Made Easy: http://forums.sohc4.net/index.php/topic,58210.msg1684742.html#msg1684742
                                      http://forums.sohc4.net/index.php/topic,100352.msg1675840.html#msg1675840
Static and Dynamic Timing: http://www.hondachopper.com/garage/carb_info/timing/timing1.html
Airbox Gasket Replacement: http://forums.sohc4.net/index.php/topic,114485.msg1290000.html#msg1290000
"Café" : http://forums.sohc4.net/index.php/topic,84697.msg953814.html#msg953814
PD Carb Choke Linkage: http://forums.sohc4.net/index.php/topic,100352.msg1669248.html#msg1669248
                                    http://forums.sohc4.net/index.php/topic,110931.msg1248354.html#msg1248354
                                    http://forums.sohc4.net/index.php/topic,48858.msg515204.html#msg515204
Follow up on your damn posts: http://forums.sohc4.net/index.php/topic,144305.msg1791605.html#msg1791605
Taiwanese Cam Chain Tensioners:  http://forums.sohc4.net/index.php/topic,155043.msg1774841.html#msg1774841
Gumtwo Seat Cover: http://forums.sohc4.net/index.php/topic,164440.msg1897366.html#msg1897366
Primary Drive: http://forums.sohc4.net/index.php/topic,166063.msg1919278.html#msg1919278
Tank Latch: http://forums.sohc4.net/index.php/topic,165975.msg1919495.html#msg1919495
Shorten your forks: http://vintage-and-classic-honda-s.456789.n3.nabble.com/How-to-shorten-forks-td4042465.html DO NOT CUT THE SPRINGS!
Clutch How To: http://vintage-and-classic-honda-s.456789.n3.nabble.com/How-to-change-and-adjust-a-clutch-SOHC-td4040391.html
Late model K7/K8/F2/F3 front sprocket cover removal: http://forums.sohc4.net/index.php/topic,178428.msg2072279.html#msg2072279
630 to 530 conversion: http://forums.sohc4.net/index.php/topic,180710.msg2094423.html#msg2094423

Sent from my Tandy TRS-80!

Offline MCRider

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Re: Cam tower stud replacment
« Reply #11 on: July 28, 2014, 07:05:22 AM »
I think the knock pins do all the locating necessary.

The only knock pins are under the towers. There are no knock pins under the bearing caps. Of course, the bearing caps fit pretty snug front to back, and the shoulder of the bearing cap bolt (opposite the stud) would help prevent any side to side misalignment.

Good Point.   :D
Ride Safe:
Ron
1988 NT650 HawkGT;  1978 CB400 Hawk;  1975 CB750F -Free Bird; 1968 CB77 Super Hawk -Ticker;  Phaedrus 1972 CB750K2- Build Thread
"Sometimes the light's all shining on me, other times I can barely see, lately it appears to me, what a long, strange trip its been."

Offline Davidov

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Re: Cam tower stud replacment
« Reply #12 on: July 28, 2014, 07:59:40 AM »
I believe the stud diameter may help locate the cam holders, the all thread lacks this tolerance. However I doubt it will cause an issue.
 I had that problem on my drag car, in two locations the threads wore into the part they were holding. My application was entirely different though.
 I wonder if a guy could purchase a bolt the proper length, cut off the head and thread it?  A pair of nuts in a vise would hold the threaded end while you tap the threads. if it rotated you could saw a slot through the nuts, that would pinch down on them.

I did compare the fully threaded stud to one of the good OEM studs.
The towers are locately by the dowels, and there quite a gap between the hole and the factory stud.

I had this thought at first, but it looks like the stud does very little to align/locate the components.

McMaster-Carr:

http://www.mcmaster.com/#98867a270/=t15a10
With those 8.8 grade studs, I would want to use them in all 4 spots.
Is that what you used before, Wilbur?
« Last Edit: July 28, 2014, 08:04:46 AM by Davidov »
-David

Offline madmtnmotors

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Re: Cam tower stud replacment
« Reply #13 on: July 28, 2014, 10:05:22 AM »

McMaster-Carr:
http://www.mcmaster.com/#98867a270/=t15a10

With those 8.8 grade studs, I would want to use them in all 4 spots.
Is that what you used before, Wilbur?

I only needed to replace one, so I only used one. I think I ended up using this one:

http://www.mcmaster.com/#93210a017/=t19sgp

I had a special case where some goob of a P.O. used a tower bolt at one of the bearing cap locations. The tower bolt is a little bit longer than the bearing cap bolt. When used at the bearing cap location it will be too long. This bolt hole (in the head) at the bearing cap is not bottomless (like the stud hole is) unless you use the longer bolt and crank on it until it punches through the head casting. This creates a PROFUSE oil leak because the oil passage for the cam bearing passes through the bore for the bearing bolt (not the stud, but the bolt). This means the bearing cap bolts have oil under pressure behind them. I used a stud at this location as a flag for the next guy who hopefully will see the extra stud (in lieu of the bolt) and say to themselves "Why'd he do that?" since this bolt (now a stud) location now required thread sealer just like the studs do (only more so). I opted for the slightly longer stud because the bolt location also has to reach beyond the knock pin under the cam tower at the bolt location. I also opted for a stud here because I did not want to gob up the bolt with thread sealer and run the risk of packing the oil passage full of thread sealer when inserting the bolt. By using a stud, I could insert the sealed stud before mounting the tower. Now I have one bearing cap with two studs instead of a bolt and a stud.

The Honda fiche calls for a 58mm stud at the stud locations. I would probably use the 57.5mm stud to replace an actual stud, or a slightly longer one could be used and cut to length if necessary. A stud is a stud, I can't imagine any deviation in stud strength between the four studs would cause an issue, unless you spend most of your time hovering around 10,000 rpm...

but then I'm sure other pieces might start coming apart too!  :o
« Last Edit: July 28, 2014, 10:10:52 AM by madmtnmotors »
TAMTF...


Wilbur



Projects:
"Evolution": http://forums.sohc4.net/index.php?topic=100352.0
"P.O. Debacle": http://forums.sohc4.net/index.php/topic,126692.msg1441661.html#msg1441661
F2/F3 O-rings: http://forums.sohc4.net/index.php?topic=113672.msg1300721#msg1300721
Cam Tower Studs: https://www.mcmaster.com/#93210a017/=t19sgp
Clean up that nasty harness: http://forums.sohc4.net/index.php?topic=137351.msg1549191#msg1549191
http://forums.sohc4.net/index.php/topic,148188.msg1688494.html#msg1688494
http://forums.sohc4.net/index.php/topic,139544.msg1579364.html#msg1579364
                                          
Charging system diagnosis: http://forums.sohc4.net/index.php?topic=1012.msg8345#msg8345
Get the manuals: http://manuals.sohc4.net/cb750k/
The Dragon: http://forums.sohc4.net/index.php?topic=45183.msg1571675#msg1571675
Headlight Switch: http://forums.sohc4.net/index.php?topic=113986.msg1283236#msg1283236
Branden's leak free top end thread: http://forums.sohc4.net/index.php?topic=107040.0
Engine Lifting Made Easy: http://forums.sohc4.net/index.php/topic,58210.msg1684742.html#msg1684742
                                      http://forums.sohc4.net/index.php/topic,100352.msg1675840.html#msg1675840
Static and Dynamic Timing: http://www.hondachopper.com/garage/carb_info/timing/timing1.html
Airbox Gasket Replacement: http://forums.sohc4.net/index.php/topic,114485.msg1290000.html#msg1290000
"Café" : http://forums.sohc4.net/index.php/topic,84697.msg953814.html#msg953814
PD Carb Choke Linkage: http://forums.sohc4.net/index.php/topic,100352.msg1669248.html#msg1669248
                                    http://forums.sohc4.net/index.php/topic,110931.msg1248354.html#msg1248354
                                    http://forums.sohc4.net/index.php/topic,48858.msg515204.html#msg515204
Follow up on your damn posts: http://forums.sohc4.net/index.php/topic,144305.msg1791605.html#msg1791605
Taiwanese Cam Chain Tensioners:  http://forums.sohc4.net/index.php/topic,155043.msg1774841.html#msg1774841
Gumtwo Seat Cover: http://forums.sohc4.net/index.php/topic,164440.msg1897366.html#msg1897366
Primary Drive: http://forums.sohc4.net/index.php/topic,166063.msg1919278.html#msg1919278
Tank Latch: http://forums.sohc4.net/index.php/topic,165975.msg1919495.html#msg1919495
Shorten your forks: http://vintage-and-classic-honda-s.456789.n3.nabble.com/How-to-shorten-forks-td4042465.html DO NOT CUT THE SPRINGS!
Clutch How To: http://vintage-and-classic-honda-s.456789.n3.nabble.com/How-to-change-and-adjust-a-clutch-SOHC-td4040391.html
Late model K7/K8/F2/F3 front sprocket cover removal: http://forums.sohc4.net/index.php/topic,178428.msg2072279.html#msg2072279
630 to 530 conversion: http://forums.sohc4.net/index.php/topic,180710.msg2094423.html#msg2094423

Sent from my Tandy TRS-80!

Offline flybox1

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Re: Cam tower stud replacment
« Reply #14 on: July 28, 2014, 10:16:24 AM »
With the cam and timing chain installed (pita), the towers will have  chance to slightly center themselves with any 'play' around the studs and knock pins if there is any. Its then that everything is torqued down.  Be careful to get the cam caps on in the same place and orientation they originally came from....

nice fix, mad....its obvious your PO didnt have access to this awesome forum  ;D
'78 750K (F3 engine) PD42b's, Modified airbox w/K&N  filter, 40/110 jets, 1 needle shim, IMS@ 1 turn out. Kerker + Cone 18" QuietCore

Past Bikes
1974 550K0 (stock), 1973 CB350F (stock), 1983 Yamaha XS400K (POS)
77/78 cool 2 member #3
"Knowledge without mileage equals bullsh!t" - Henry Rollins

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Offline madmtnmotors

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Re: Cam tower stud replacment
« Reply #15 on: July 28, 2014, 10:49:16 AM »
nice fix, mad....

Thanks. I thought I was taking the final exam for the MMI certification (Motorcycle Mechanics Institute). I ended up pulling the motor four times before I figured out where all that damn oil was coming from!  :o

It was a leak from a spot that should not have even been possible. Gotta love them P.O.s!  >:(
TAMTF...


Wilbur



Projects:
"Evolution": http://forums.sohc4.net/index.php?topic=100352.0
"P.O. Debacle": http://forums.sohc4.net/index.php/topic,126692.msg1441661.html#msg1441661
F2/F3 O-rings: http://forums.sohc4.net/index.php?topic=113672.msg1300721#msg1300721
Cam Tower Studs: https://www.mcmaster.com/#93210a017/=t19sgp
Clean up that nasty harness: http://forums.sohc4.net/index.php?topic=137351.msg1549191#msg1549191
http://forums.sohc4.net/index.php/topic,148188.msg1688494.html#msg1688494
http://forums.sohc4.net/index.php/topic,139544.msg1579364.html#msg1579364
                                          
Charging system diagnosis: http://forums.sohc4.net/index.php?topic=1012.msg8345#msg8345
Get the manuals: http://manuals.sohc4.net/cb750k/
The Dragon: http://forums.sohc4.net/index.php?topic=45183.msg1571675#msg1571675
Headlight Switch: http://forums.sohc4.net/index.php?topic=113986.msg1283236#msg1283236
Branden's leak free top end thread: http://forums.sohc4.net/index.php?topic=107040.0
Engine Lifting Made Easy: http://forums.sohc4.net/index.php/topic,58210.msg1684742.html#msg1684742
                                      http://forums.sohc4.net/index.php/topic,100352.msg1675840.html#msg1675840
Static and Dynamic Timing: http://www.hondachopper.com/garage/carb_info/timing/timing1.html
Airbox Gasket Replacement: http://forums.sohc4.net/index.php/topic,114485.msg1290000.html#msg1290000
"Café" : http://forums.sohc4.net/index.php/topic,84697.msg953814.html#msg953814
PD Carb Choke Linkage: http://forums.sohc4.net/index.php/topic,100352.msg1669248.html#msg1669248
                                    http://forums.sohc4.net/index.php/topic,110931.msg1248354.html#msg1248354
                                    http://forums.sohc4.net/index.php/topic,48858.msg515204.html#msg515204
Follow up on your damn posts: http://forums.sohc4.net/index.php/topic,144305.msg1791605.html#msg1791605
Taiwanese Cam Chain Tensioners:  http://forums.sohc4.net/index.php/topic,155043.msg1774841.html#msg1774841
Gumtwo Seat Cover: http://forums.sohc4.net/index.php/topic,164440.msg1897366.html#msg1897366
Primary Drive: http://forums.sohc4.net/index.php/topic,166063.msg1919278.html#msg1919278
Tank Latch: http://forums.sohc4.net/index.php/topic,165975.msg1919495.html#msg1919495
Shorten your forks: http://vintage-and-classic-honda-s.456789.n3.nabble.com/How-to-shorten-forks-td4042465.html DO NOT CUT THE SPRINGS!
Clutch How To: http://vintage-and-classic-honda-s.456789.n3.nabble.com/How-to-change-and-adjust-a-clutch-SOHC-td4040391.html
Late model K7/K8/F2/F3 front sprocket cover removal: http://forums.sohc4.net/index.php/topic,178428.msg2072279.html#msg2072279
630 to 530 conversion: http://forums.sohc4.net/index.php/topic,180710.msg2094423.html#msg2094423

Sent from my Tandy TRS-80!

Offline Davidov

  • Hot Shot
  • ***
  • Posts: 284
  • 1978 CB750 F3
    • My CB750F project log
Re: Cam tower stud replacment
« Reply #16 on: August 03, 2014, 01:22:49 PM »

I had a special case where some goob of a P.O. used a tower bolt at one of the bearing cap locations. The tower bolt is a little bit longer than the bearing cap bolt. When used at the bearing cap location it will be too long. This bolt hole (in the head) at the bearing cap is not bottomless (like the stud hole is) unless you use the longer bolt and crank on it until it punches through the head casting. This creates a PROFUSE oil leak because the oil passage for the cam bearing passes through the bore for the bearing bolt (not the stud, but the bolt). This means the bearing cap bolts have oil under pressure behind them. I used a stud at this location as a flag for the next guy who hopefully will see the extra stud (in lieu of the bolt) and say to themselves "Why'd he do that?" since this bolt (now a stud) location now required thread sealer just like the studs do (only more so). I opted for the slightly longer stud because the bolt location also has to reach beyond the knock pin under the cam tower at the bolt location. I also opted for a stud here because I did not want to gob up the bolt with thread sealer and run the risk of packing the oil passage full of thread sealer when inserting the bolt. By using a stud, I could insert the sealed stud before mounting the tower. Now I have one bearing cap with two studs instead of a bolt and a stud.

The Honda fiche calls for a 58mm stud at the stud locations. I would probably use the 57.5mm stud to replace an actual stud, or a slightly longer one could be used and cut to length if necessary. A stud is a stud, I can't imagine any deviation in stud strength between the four studs would cause an issue, unless you spend most of your time hovering around 10,000 rpm...

but then I'm sure other pieces might start coming apart too!  :o

Holy cheese, your story made me double check the threads on my cyl head, and guess what......TWO of the bolt locations on the camshaft bearing caps (cylinders 2 and 3) were punched through.   :o Cyl 2 was clearly open to atmosphere, and cyl 3 threaded hole was just barely punched through, OI!

So how does some twit end up with 1 extra cam tower bolt?

« Last Edit: August 03, 2014, 04:06:28 PM by Davidov »
-David

Nic

  • Guest
Re: Cam tower stud replacment
« Reply #17 on: August 03, 2014, 03:31:13 PM »
PO's are an amazing bread alright. In my 750 someone had "rebuilt" the top end but the engine had never been fired up luckily. Some 6mm threads in the head were helicoiled but the ones that weren't should have been as well, there were all sorts of different length bolts in the cam area, some Allen heads and one that was an imperial thread because it went in tighter. The tacho drive bolt thread in the head cover was stripped out and the only thing holding the bolt in was the locking tab, I've seen what happens when that bolt falls into the cam.
Recently I've been working on a Kawa900, I'm told that a qualified auto electrician "worked" on the wiring, the usual mongrel connectors were apparent, electrical tape is everywhere, under the tape the real debacle is hiding, there must have been a meltdown because the power wire that goes to the ignition switch had 4" of insulation that was just gone and taped up, also under the tape were wires that had been twisted together, some were soldered but some weren't including the previously mentioned power wire.
The current owner said the bike would cut out momentarily when on left lock, this was done by some tool who was a trained and qualified tradesman, so I'm never surprised when I see what PO's do.
And to be fair, let's not leave out a lot of current owners as well.
« Last Edit: August 03, 2014, 03:34:31 PM by Nic »

Offline madmtnmotors

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  • Really Old Timer ...
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  • Posts: 6,106
  • Sunny Central Florida
Re: Cam tower stud replacment
« Reply #18 on: August 03, 2014, 03:52:22 PM »
Holy cheese, your story made me double check the threads on my cyl head, and guess what......TWO of the bolt locations on the camshaft bearing caps (cylinders 2 and 3) were punched through.   :o Cyl 2 was clearly open to atmosphere, and cyl 3 threaded hole was just barely punched through, OI!

So how does some twit end up with 1 extra longer bolt for the cam towers?

I'm glad I was able to describe the condition so that others could understand. I had to pull this engine four times in order to track down this leak, and I had not intended to pull the engine at all. After pulling the engine for the fourth time, removing the valve cover, cam and cam towers, while staring at the top of the head contemplating removing the head yet again, I noticed three of the four cam bearing bolt holes would fill up with oil. The fourth would not. So I put on my sleuthing cap and was able to "reverse engineer" the process that created this condition as well as why this location leaks so profusely after being compromised. This will be on my "check" list of every subsequent build. The oil leak created by this condition is an oil leak that could not even exist in an undamaged engine.

As for the cam tower bolt that is even longer than the others, the bolts have obviously been further shuffled with other engine bolts. New game of "Where's this bolt go?"!
TAMTF...


Wilbur



Projects:
"Evolution": http://forums.sohc4.net/index.php?topic=100352.0
"P.O. Debacle": http://forums.sohc4.net/index.php/topic,126692.msg1441661.html#msg1441661
F2/F3 O-rings: http://forums.sohc4.net/index.php?topic=113672.msg1300721#msg1300721
Cam Tower Studs: https://www.mcmaster.com/#93210a017/=t19sgp
Clean up that nasty harness: http://forums.sohc4.net/index.php?topic=137351.msg1549191#msg1549191
http://forums.sohc4.net/index.php/topic,148188.msg1688494.html#msg1688494
http://forums.sohc4.net/index.php/topic,139544.msg1579364.html#msg1579364
                                          
Charging system diagnosis: http://forums.sohc4.net/index.php?topic=1012.msg8345#msg8345
Get the manuals: http://manuals.sohc4.net/cb750k/
The Dragon: http://forums.sohc4.net/index.php?topic=45183.msg1571675#msg1571675
Headlight Switch: http://forums.sohc4.net/index.php?topic=113986.msg1283236#msg1283236
Branden's leak free top end thread: http://forums.sohc4.net/index.php?topic=107040.0
Engine Lifting Made Easy: http://forums.sohc4.net/index.php/topic,58210.msg1684742.html#msg1684742
                                      http://forums.sohc4.net/index.php/topic,100352.msg1675840.html#msg1675840
Static and Dynamic Timing: http://www.hondachopper.com/garage/carb_info/timing/timing1.html
Airbox Gasket Replacement: http://forums.sohc4.net/index.php/topic,114485.msg1290000.html#msg1290000
"Café" : http://forums.sohc4.net/index.php/topic,84697.msg953814.html#msg953814
PD Carb Choke Linkage: http://forums.sohc4.net/index.php/topic,100352.msg1669248.html#msg1669248
                                    http://forums.sohc4.net/index.php/topic,110931.msg1248354.html#msg1248354
                                    http://forums.sohc4.net/index.php/topic,48858.msg515204.html#msg515204
Follow up on your damn posts: http://forums.sohc4.net/index.php/topic,144305.msg1791605.html#msg1791605
Taiwanese Cam Chain Tensioners:  http://forums.sohc4.net/index.php/topic,155043.msg1774841.html#msg1774841
Gumtwo Seat Cover: http://forums.sohc4.net/index.php/topic,164440.msg1897366.html#msg1897366
Primary Drive: http://forums.sohc4.net/index.php/topic,166063.msg1919278.html#msg1919278
Tank Latch: http://forums.sohc4.net/index.php/topic,165975.msg1919495.html#msg1919495
Shorten your forks: http://vintage-and-classic-honda-s.456789.n3.nabble.com/How-to-shorten-forks-td4042465.html DO NOT CUT THE SPRINGS!
Clutch How To: http://vintage-and-classic-honda-s.456789.n3.nabble.com/How-to-change-and-adjust-a-clutch-SOHC-td4040391.html
Late model K7/K8/F2/F3 front sprocket cover removal: http://forums.sohc4.net/index.php/topic,178428.msg2072279.html#msg2072279
630 to 530 conversion: http://forums.sohc4.net/index.php/topic,180710.msg2094423.html#msg2094423

Sent from my Tandy TRS-80!

Offline Davidov

  • Hot Shot
  • ***
  • Posts: 284
  • 1978 CB750 F3
    • My CB750F project log
Re: Cam tower stud replacment
« Reply #19 on: August 03, 2014, 04:08:46 PM »

I'm glad I was able to describe the condition so that others could understand. I had to pull this engine four times in order to track down this leak, and I had not intended to pull the engine at all. After pulling the engine for the fourth time, removing the valve cover, cam and cam towers, while staring at the top of the head contemplating removing the head yet again, I noticed three of the four cam bearing bolt holes would fill up with oil. The fourth would not. So I put on my sleuthing cap and was able to "reverse engineer" the process that created this condition as well as why this location leaks so profusely after being compromised. This will be on my "check" list of every subsequent build. The oil leak created by this condition is an oil leak that could not even exist in an undamaged engine.

As for the cam tower bolt that is even longer than the others, the bolts have obviously been further shuffled with other engine bolts. New game of "Where's this bolt go?"!

The wording was a little misleading, but my picture shows the 3 proper length bolts for the cam bearing caps and the 1 longer bolt that matches the length of the cam tower bolts.

So it looks like I'll be using your solution of using a stud in the punctured hole.
-David

Offline madmtnmotors

  • When did I get to be a
  • Really Old Timer ...
  • *******
  • Posts: 6,106
  • Sunny Central Florida
Re: Cam tower stud replacment
« Reply #20 on: August 03, 2014, 04:16:36 PM »

I'm glad I was able to describe the condition so that others could understand. I had to pull this engine four times in order to track down this leak, and I had not intended to pull the engine at all. After pulling the engine for the fourth time, removing the valve cover, cam and cam towers, while staring at the top of the head contemplating removing the head yet again, I noticed three of the four cam bearing bolt holes would fill up with oil. The fourth would not. So I put on my sleuthing cap and was able to "reverse engineer" the process that created this condition as well as why this location leaks so profusely after being compromised. This will be on my "check" list of every subsequent build. The oil leak created by this condition is an oil leak that could not even exist in an undamaged engine.

As for the cam tower bolt that is even longer than the others, the bolts have obviously been further shuffled with other engine bolts. New game of "Where's this bolt go?"!

The wording was a little misleading, but my picture shows the 3 proper length bolts for the cam bearing caps and the 1 longer bolt that matches the length of the cam tower bolts.

So it looks like I'll be using your solution of using a stud in the punctured hole.

Ahhhh, be sure to check your cam tower bolts and make sure one of them is not shorter than the rest. That's an easy way to pull the threads out at the tower bolts location when the shorter bolt doesn't reach far enough.
TAMTF...


Wilbur



Projects:
"Evolution": http://forums.sohc4.net/index.php?topic=100352.0
"P.O. Debacle": http://forums.sohc4.net/index.php/topic,126692.msg1441661.html#msg1441661
F2/F3 O-rings: http://forums.sohc4.net/index.php?topic=113672.msg1300721#msg1300721
Cam Tower Studs: https://www.mcmaster.com/#93210a017/=t19sgp
Clean up that nasty harness: http://forums.sohc4.net/index.php?topic=137351.msg1549191#msg1549191
http://forums.sohc4.net/index.php/topic,148188.msg1688494.html#msg1688494
http://forums.sohc4.net/index.php/topic,139544.msg1579364.html#msg1579364
                                          
Charging system diagnosis: http://forums.sohc4.net/index.php?topic=1012.msg8345#msg8345
Get the manuals: http://manuals.sohc4.net/cb750k/
The Dragon: http://forums.sohc4.net/index.php?topic=45183.msg1571675#msg1571675
Headlight Switch: http://forums.sohc4.net/index.php?topic=113986.msg1283236#msg1283236
Branden's leak free top end thread: http://forums.sohc4.net/index.php?topic=107040.0
Engine Lifting Made Easy: http://forums.sohc4.net/index.php/topic,58210.msg1684742.html#msg1684742
                                      http://forums.sohc4.net/index.php/topic,100352.msg1675840.html#msg1675840
Static and Dynamic Timing: http://www.hondachopper.com/garage/carb_info/timing/timing1.html
Airbox Gasket Replacement: http://forums.sohc4.net/index.php/topic,114485.msg1290000.html#msg1290000
"Café" : http://forums.sohc4.net/index.php/topic,84697.msg953814.html#msg953814
PD Carb Choke Linkage: http://forums.sohc4.net/index.php/topic,100352.msg1669248.html#msg1669248
                                    http://forums.sohc4.net/index.php/topic,110931.msg1248354.html#msg1248354
                                    http://forums.sohc4.net/index.php/topic,48858.msg515204.html#msg515204
Follow up on your damn posts: http://forums.sohc4.net/index.php/topic,144305.msg1791605.html#msg1791605
Taiwanese Cam Chain Tensioners:  http://forums.sohc4.net/index.php/topic,155043.msg1774841.html#msg1774841
Gumtwo Seat Cover: http://forums.sohc4.net/index.php/topic,164440.msg1897366.html#msg1897366
Primary Drive: http://forums.sohc4.net/index.php/topic,166063.msg1919278.html#msg1919278
Tank Latch: http://forums.sohc4.net/index.php/topic,165975.msg1919495.html#msg1919495
Shorten your forks: http://vintage-and-classic-honda-s.456789.n3.nabble.com/How-to-shorten-forks-td4042465.html DO NOT CUT THE SPRINGS!
Clutch How To: http://vintage-and-classic-honda-s.456789.n3.nabble.com/How-to-change-and-adjust-a-clutch-SOHC-td4040391.html
Late model K7/K8/F2/F3 front sprocket cover removal: http://forums.sohc4.net/index.php/topic,178428.msg2072279.html#msg2072279
630 to 530 conversion: http://forums.sohc4.net/index.php/topic,180710.msg2094423.html#msg2094423

Sent from my Tandy TRS-80!

Offline Davidov

  • Hot Shot
  • ***
  • Posts: 284
  • 1978 CB750 F3
    • My CB750F project log
Re: Cam tower stud replacment
« Reply #21 on: September 15, 2014, 10:59:36 AM »
Follow up:
One hole was completely punched through, and the other was cracked (I could see a sliver of light).
These are the cam bearing caps nearest the cam chain tunnel, on either side.

I used a stud in both locations, with Loctite brand liquid thread sealant.

I was debating whether to use a proper length bolt with sealant, but the sealant could gunk up the oil passage on the tower.
The only downside to studs was going to be less room to install the camshaft. I had no trouble at all installing the camshaft with the new studs.

The true test will be on the road now!
-David

Offline madmtnmotors

  • When did I get to be a
  • Really Old Timer ...
  • *******
  • Posts: 6,106
  • Sunny Central Florida
Re: Cam tower stud replacment
« Reply #22 on: September 15, 2014, 11:50:48 AM »
I was debating whether to use a proper length bolt with sealant, but the sealant could gunk up the oil passage on the tower.

That was my concern as well. Also, how would the next guy know to use sealer there?

The only downside to studs was going to be less room to install the camshaft. I had no trouble at all installing the camshaft with the new studs.

It does make for a tight fit when reinstalling the cam, but it is far from impossible. Worth the effort in my opinion.

The true test will be on the road now!

Good luck. You have certainly prevented two major oil leaks before they could even happen. I've still got the oil stains on the shins of my jeans.
TAMTF...


Wilbur



Projects:
"Evolution": http://forums.sohc4.net/index.php?topic=100352.0
"P.O. Debacle": http://forums.sohc4.net/index.php/topic,126692.msg1441661.html#msg1441661
F2/F3 O-rings: http://forums.sohc4.net/index.php?topic=113672.msg1300721#msg1300721
Cam Tower Studs: https://www.mcmaster.com/#93210a017/=t19sgp
Clean up that nasty harness: http://forums.sohc4.net/index.php?topic=137351.msg1549191#msg1549191
http://forums.sohc4.net/index.php/topic,148188.msg1688494.html#msg1688494
http://forums.sohc4.net/index.php/topic,139544.msg1579364.html#msg1579364
                                          
Charging system diagnosis: http://forums.sohc4.net/index.php?topic=1012.msg8345#msg8345
Get the manuals: http://manuals.sohc4.net/cb750k/
The Dragon: http://forums.sohc4.net/index.php?topic=45183.msg1571675#msg1571675
Headlight Switch: http://forums.sohc4.net/index.php?topic=113986.msg1283236#msg1283236
Branden's leak free top end thread: http://forums.sohc4.net/index.php?topic=107040.0
Engine Lifting Made Easy: http://forums.sohc4.net/index.php/topic,58210.msg1684742.html#msg1684742
                                      http://forums.sohc4.net/index.php/topic,100352.msg1675840.html#msg1675840
Static and Dynamic Timing: http://www.hondachopper.com/garage/carb_info/timing/timing1.html
Airbox Gasket Replacement: http://forums.sohc4.net/index.php/topic,114485.msg1290000.html#msg1290000
"Café" : http://forums.sohc4.net/index.php/topic,84697.msg953814.html#msg953814
PD Carb Choke Linkage: http://forums.sohc4.net/index.php/topic,100352.msg1669248.html#msg1669248
                                    http://forums.sohc4.net/index.php/topic,110931.msg1248354.html#msg1248354
                                    http://forums.sohc4.net/index.php/topic,48858.msg515204.html#msg515204
Follow up on your damn posts: http://forums.sohc4.net/index.php/topic,144305.msg1791605.html#msg1791605
Taiwanese Cam Chain Tensioners:  http://forums.sohc4.net/index.php/topic,155043.msg1774841.html#msg1774841
Gumtwo Seat Cover: http://forums.sohc4.net/index.php/topic,164440.msg1897366.html#msg1897366
Primary Drive: http://forums.sohc4.net/index.php/topic,166063.msg1919278.html#msg1919278
Tank Latch: http://forums.sohc4.net/index.php/topic,165975.msg1919495.html#msg1919495
Shorten your forks: http://vintage-and-classic-honda-s.456789.n3.nabble.com/How-to-shorten-forks-td4042465.html DO NOT CUT THE SPRINGS!
Clutch How To: http://vintage-and-classic-honda-s.456789.n3.nabble.com/How-to-change-and-adjust-a-clutch-SOHC-td4040391.html
Late model K7/K8/F2/F3 front sprocket cover removal: http://forums.sohc4.net/index.php/topic,178428.msg2072279.html#msg2072279
630 to 530 conversion: http://forums.sohc4.net/index.php/topic,180710.msg2094423.html#msg2094423

Sent from my Tandy TRS-80!

Offline InAquaVeritas

  • Enthusiast
  • **
  • Posts: 133
Re: Cam tower stud replacment
« Reply #23 on: November 21, 2014, 09:58:09 AM »
Holy cheese, your story made me double check the threads on my cyl head, and guess what......TWO of the bolt locations on the camshaft bearing caps (cylinders 2 and 3) were punched through.   :o Cyl 2 was clearly open to atmosphere, and cyl 3 threaded hole was just barely punched through, OI!

So how does some twit end up with 1 extra longer bolt for the cam towers?

This will be on my "check" list of every subsequent build. The oil leak created by this condition is an oil leak that could not even exist in an undamaged engine.

As for the cam tower bolt that is even longer than the others, the bolts have obviously been further shuffled with other engine bolts. New game of "Where's this bolt go?"!

Thanks for the heads up! I will definitely be checking these before I rebuild mine as well.

To cheat my way through the game of "where's this bolt go" I got into a habit of taking bolts out an laying them out in the pattern they came out in with the heads pointing out. Take a photo of this, take a photo of where it came out of and if it's a cover, put all the bolts in their respective holes in the cover and it it away. Where the bolts can't go back into their holes I tape them together.

Way before camera phones could display anything but an 8-bit portrait I almost destroyed the clutch side of my first moped: early '80's Honda MT 50cc. Different size bolts, 16 years old and not thinking more than 5 seconds ahead and the attention span of a 2 year old. Stopped when the case was deforming around the hole...just in time....got hit and totalled it about a month later
Surf bum trying his hand at wrenching!

Past "bikes" ;)
1981 Honda MT 50cc - Torn apart, put back together and got run down on..
1994 Derby Senda R 50cc - Fell apart
2001 Derby Senda R 50cc - 13/45 changed to 15/70, hit 90 kph in under 150 meters! Undriveable fun!
1987 Suzuki GN250 - Sold
Current bikes
1977 Honda CB750 F1 - F2 engine, '05 ZX6R front end and wheels, '04 ZX6R shortened swing arm converted to twin shock. http://forums.sohc4.net/index.php?topic=133411.0
1987 Honda XR600 Supermoto conversion. CR250 forks and triple. SM wheels, discs front and back. Rebuilt engine. Loudest exhaust in the world: Leovinci X3