Topic: 1972 CB750K2 (start from scratch) project. Cases back together

[Davez134]

Well, weather report says it's gonna be almost 70 degrees here in Vegas tomorrow. Scrambled and got all my stuff cleaned, masked and ready to go for paint!




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[Davez134]

Paint today. Perfect temp outside. VHT cast aluminum on head. VHT wrinkle plus on everything else...









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[Davez134]

Kibblewhite HD studs installed. Case threads were clean and in great shape, so no loctite used, just small amount of anti-sieze. Motion pro stud installer made it very easy, torqued down per instructions.




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[edwardmorris]

Cool tip! Didn't know of the stud nut thingy. One question though, why the anti-sieze? IIRC these need to stay in place with locktite...I'll see if I can dig up an installation vid where someone actually used red loctite on HD studs 

[Davez134]

Instructions said only use loctite if threads feel "loose." Don't know how to quantify that, but they did not. Instructions stated to use either lube or antisieze. Didn't use lube cause I didn't want false readings/hydrolock. The threads that go into case on the studs are an interference thread and grab awesome. I just barely touched the threads with antisieze, just enough to provide ease of installing. Hope I did it right.

Also, saw this...reply number 5
http://forums.sohc4.net/index.php?topic=112239.msg1260853#msg1260853

[edwardmorris]

Thanks! Saved to notes.

[Davez134]

Thanks! Saved to notes.

No problem. Good think there is no limit on search feature, I would have wore it out already

[edwardmorris]

I wish the google custom search comes back here. Lately, I've been using their advanced search to only search these forums, and now they're throwing that nasty little captcha test each time (type the letters in the pic to proceed crap). I guess somehow I managed to get close to that limit  . I backed off before they start to block me out completely 

Edit: From my notes from a while back,

http://forums.sohc4.net/index.php?topic=101358.msg1132684#msg1132684

it seems like some prefer loctite, others don't, I'll have to dig into it soon.

[Davez134]

Well, if mine come loose and top end falls off, I'll post pics

[Davez134]

None of my friends have any tools to loan for degreeing my cam. Made some today, see if I can get repeatable numbers. If not I guess I'll have to buy some.

Piston stop from old spark plug and brass m6 bolt. Welded a m6 nut inside for adjustment.



High res degree wheel image backed by thin clipboard type material. Hole drilled dead center, 12mm bit to match alternator side bolt shaft



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[timbo750]

I am very curious,  what is the purpose of the spark plug and brass bolt??

[Bootsey]

Looking great, that tank & sidecover colour is awesome!

[Davez134]

I am very curious,  what is the purpose of the spark plug and brass bolt??

I haven't degreed in a cam yet but have been reading enough to where I'm pretty sure I understand. The purpose of the bolt in the spark plug is to find true TDC.  You get a piston (im using #1) near TDC, thread the "piston stop tool" into spark plug hole and turn the motor forward until the piston comes to a stop touching that brass bolt, record that number on the degree wheel. Then turn motor backwards, when it stops against the bolt record that number. The difference in the two numbers is True TDC. (I think ) Once you have found that, you remove and move on from there. I have a Webcam and adjustable sprocket.

[timbo750]

It makes sense to me Dave. I have not hot that far yet on my build snd on the car engines I have worked on I have always relied on the manufactures markings.

[edwardmorris]

IINM, the stock cams can be done using the factory markings, but I'll be running a megacycle on my K3, so this is good learning.

[Davez134]

IINM, the stock cams can be done using the factory markings, but I'll be running a megacycle on my K3, so this is good learning.

Yeah, I used stock cam on my last motor, used factory markings. Easy. I'm doing a webcam 41 on this one. I'll post up more for ya if I come across any more good info. Plan on getting it done this weekend.

[Davez134]

Dave. - the method you're using will work well. If, you get to it prior to assembly, mark the timing plate with true TDC by using a dial caliper on top of the piston while head is off. Then, install degree wheel and adjust cam after installation of the head.

But you're doing a great job post-assembly

Sweet, I'm going to do that! Seems much easier. don't have head on yet. I just got done setting ring gaps and installing pistons. I will find tdc with your method tomorrow when I start up again. Thanks!

[Davez134]

So I got pistons/cylinders installed, mls gasket. Found TDC using dial gauge before installing head, as suggested. Man that was way easier than what I had originally planned!


TDC is exactly in line with timing mark



Going to stop here today.


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[Davez134]

So I'm trying to install my cam today, trying to grasp this degreeing thing. Cam is a Webcam 41. Has marks on it just like stocker...

Installed it with those marks as a reference, set #1 at tdc, valve lash to zero, dial indicator zeroed.


Now I turn crank until valve lift is .050" as specified by timing card, degree wheel shows about 30 degrees before tdc, timing card stated intake should open 11 degrees before tdc.


So, do I need to move slotted sprocket to get to that 11 degree mark at .050"? Or am I doing something wrong?



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[iron_worker]

Does your timing card state the cam lobe center-lines? I believe you generally use the center-lines as your reference point when cam timing.

 To find the cam lobe center line:

-Find true #1 TDC (use piston stop method or an indicator through the spark plug hole)
-Adjust degree wheel for to show 0 degrees at the true #1 TDC
-Rotate the crank and record the crankshaft degrees when the valve opens up .050"
-Continue to rotate the crank until the valve begins to close again and closes to the same .050" point
-Record the crankshaft degrees

Cam lobe center-line = (Measurement #1 + Measurement #2) / 2

Check this value against your cam card to determine if you need to advance or retard your cam. You can make this check based on either the exhaust side or the intake but if you adjust one you will adjust both since we only have one cam for both duties.

IW

[Davez134]

Yeah, it states 107.5. I will do that when I get back home, going to the gym, need a mental break. Thanks!

[Davez134]

Does your timing card state the cam lobe center-lines? I believe you generally use the center-lines as your reference point when cam timing.

 To find the cam lobe center line:

-Find true #1 TDC (use piston stop method or an indicator through the spark plug hole)
-Adjust degree wheel for to show 0 degrees at the true #1 TDC
-Rotate the crank and record the crankshaft degrees when the valve opens up .050"
-Continue to rotate the crank until the valve begins to close again and closes to the same .050" point
-Record the crankshaft degrees

Cam lobe center-line = (Measurement #1 + Measurement #2) / 2

Check this value against your cam card to determine if you need to advance or retard your cam. You can make this check based on either the exhaust side or the intake but if you adjust one you will adjust both since we only have one cam for both duties.

IW

So I did all that, and lobe center shows 111 degrees. Timing card states lobe center as 107.5.

[edwardmorris]

Dave, check this out if you haven't already, might help. I've read it a few times and things are still going over my head (I guess you have to actually do this to make sense of it).

http://forums.sohc4.net/index.php?topic=103818.msg1404323#msg1404323

[Davez134]

Here is my cam card:

Last numbers I just got were (.050" lift)
Intake open: 32 btdc
Intake close: 18 abdc
32+18+180 / 2 = 140
-32 = 108 degree lobe center.

Repeated this 3 times, same numbers. Lobe center is almost spot on for intake, but open/closing numbers are way off.

And exhaust is away off too, without me moving anything, gave me like 124degree lobe center. I must be doing this wrong. For a cam that was advertised as "drop in" things are not adding up. My brain hurts.
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[timbo750]

I am no expert on cam timing but I do understand the maths behind it.

No matter where your cam sprocket is adjusted you will always get the same lobe centre measurement, this is because as you make the adjustment you are increasing one measurement and decreasing the other by the same amount so the formula will always have the same result because it is actually measuring something physical on the cam.

I think what you need to do is look at the centre point between intake opening and intake closing. it is a little confusing though as the true way to look at it is that the figure for opening BTDC is actually a negative number then if change this then the formula should be-
-32 + 18 / 2 = -7

This means that the centre of the cam lobe is 7 degrees BTDC with the current setting.

The Cam card reads that you should have the centre set at 17.5 ATDC using the formula I mentioned.

If I have got this terribly wrong someone please let me know but I am almost certain this is correct.