Topic: valve spring discussion?

[Don R]

 I'm curious if anyone measures valve spring tension? I have some old tech heads and a head or two with newer APE springs and retainers. I have the feeling our valvetrain is light enough to not require a lot of spring tension even at higher lifts but am thinking some of the old tech springs were serious overkill as far as spring pressure.
 A few years ago, I took an old head apart that had short springs, thick spacers and aluminum retainers. The last one had a retainer that was on the verge of failure, so I tossed all of it out.
  Was there ever an on head spring checker for the sohc engines?

[PeWe]

My shop mechanic shim for 90 lbs if I have got it right. 6.6mm stemmed valves. (The 5mm valves less.)
CycleX has some numbers.
http://www.cyclexchange.net/Tech%20Tips%20Camshafts.htm

[Tracksnblades1]

Think out loud Don…

What are you thinking?
Too much open pressure for the masses in motion..?

[PeWe]

I forgot to mention if seats have been cut several times, maybe ex is sunken for valve to valve clearance. Thicker shims needed.
DP315 cam and 34/28 mm or 33.5/28.5mm valves are rather close.
It must be handy to have tool for measure the spring force.

There are experts on this forum that know all these details and much more.

[bwaller]

 I think this is an important function. Mike recommended 75lbs for my 550 race head. I have access to a spring tester and use on each assembled valve. I sourced different thickness shims plus with oem gives lots of selection. I check tension on every tear down, and replace springs every two seasons.

Shims can be slightly different for each valve depending on who does the seats. This is where experienced machinists help.

[Don R]

Think out loud Don…

What are you thinking?
Too much open pressure for the masses in motion..?

  I regularly check the springs and monitor the lash on my race car and have seen problems with coil harmonics (cavitation?) and stack height too tall, these 750's seem pretty impervious to such issues.
  The 3 ported heads I recently bought have silver retainers (aluminum or Ti?) and RC engineering springs. One of these heads has before and will see some boost in its future. 
  That fuels my desire to learn a little more about the springs we use.

[Tracksnblades1]

Think out loud Don…

What are you thinking?
Too much open pressure for the masses in motion..?

  I regularly check the springs and monitor the lash on my race car and have seen problems with coil harmonics (cavitation?) and stack height too tall, these 750's seem pretty impervious to such issues.
  The 3 ported heads I recently bought have silver retainers (aluminum or Ti?) and RC engineering springs. One of these heads has before and will see some boost in its future. 
  That fuels my desire to learn a little more about the springs we use.

Back in late 70’s I saw some aluminum retainers (anodized)  all in excellent condition on an old 836 with RC cam and 12.5s..
Heard horrors stories of the same with the retainers pulling through…

On a tangent, the kibblewhite 33.5/ 5mm intakes are near 10grams lighter than F2 34s..
A miniature roller tip rocker may solve some of the observed upper 5mm valve guide wear and may relieve some valve stem flex with less than optimal rocker arm geometry..? Variable lash adjustment would be interesting..
.
PeWe has a good post on this 5mm bronze guide wear on his 392 head. I didn’t read whether he thought his rocker arm/ valve stem height geometry was spot on or not. It does read he’s move on to the stiffer 6.6mm stems and cast iron guides.

Makes a guy wonder when he’s sitting on a fresh stage 4 Rieck 5mm head…🤔

[Don R]

 I've set up the pushrod length on a big block chevy with nearly 7/8" of lift, that determines the sweep of the rocker tip over the valve stem.
  I can see where a high or low valve stem can cause our style of rocker to drag on it as it passes through it's arc. We just don't get to adjust much.
  I've been inside a few 750 motors and haven't seen a stock spring that broke, I have floated valves with an F2 cam in an old K head. It tagged one, I assume it was float.

[Don R]

 If you can find it, it's usually been gone over before. I even posted about my stupid BBC spring issue.
http://forums.sohc4.net/index.php/topic,44023.25.html

[Don R]

 It appears off engine spring check tools are what's available. I think I sold my old beam and pointer checker when I bought the LSM gauge type.

[PeWe]

Think out loud Don…

What are you thinking?
Too much open pressure for the masses in motion..?

  I regularly check the springs and monitor the lash on my race car and have seen problems with coil harmonics (cavitation?) and stack height too tall, these 750's seem pretty impervious to such issues.
  The 3 ported heads I recently bought have silver retainers (aluminum or Ti?) and RC engineering springs. One of these heads has before and will see some boost in its future. 
  That fuels my desire to learn a little more about the springs we use.

Back in late 70’s I saw some aluminum retainers (anodized)  all in excellent condition on an old 836 with RC cam and 12.5s..
Heard horrors stories of the same with the retainers pulling through…

On a tangent, the kibblewhite 33.5/ 5mm intakes are near 10grams lighter than F2 34s..
A miniature roller tip rocker may solve some of the observed upper 5mm valve guide wear and may relieve some valve stem flex with less than optimal rocker arm geometry..? Variable lash adjustment would be interesting..
.
PeWe has a good post on this 5mm bronze guide wear on his 392 head. I didn’t read whether he thought his rocker arm/ valve stem height geometry was spot on or not. It does read he’s move on to the stiffer 6.6mm stems and cast iron guides.

Makes a guy wonder when he’s sitting on a fresh stage 4 Rieck 5mm head…

My 5mm valve stem build was an old ported K6 head that earlier had F2 in valves and stock ex valves most of the time. No guide wear then during 50.000 km. Mild AF SS-1 cam.
Only soft mushrooming F2 valve stems solved by new valves and lash caps I got from Mike. Those valves moved to another ported K2 head.

The lash caps of the 5mm stem setup have marks centered which seems to be an OK geometry. But the design with the rocker arm is  bending.

I noticed that the 5mm stem valve setup was very soft sideways. Easy to flex sideways by pressing thumb.

This together with bronze guides. They survived 25.000km street use.
The guide wear was huge in the upper part of the guide.
Used cams DP315 with relatively low lift and 0.3mm lash, replaced by RC295.  About 50/50 use.

The 392 head replaced that head. It got stock guides and Kibblewhite 33.5/28.5mm valves. 104whp with that head on 970cc + 125-75 late October. (Better compression)

The K2 head made 101whp the year earlier on the 1005cc billet block. Probably more with thinner base gasket for higher compression as the last setup.

The old 5mm valve head is restored with CycleX iron guides and their shiny ss valves. I felt lucky to find 34mm inlet valves made for the head, no need to find matching blanks.
This head to be used on an 890cc build. Case will be bored to welcome the 77mm "sleeved" billet block just for sure.

CycleX guides and their shiny ss valves they got from a race shop sale is a possible low cost rebuild for 5mm heads. I have extra 34mm ss valves for the K2 head using F2 valves.
The 5mm valves are really light. No scale needed to notice the difference.

It must be a formula about the spring pressure depending on cam and rpm.
Really quick closing short duration +high lift+ high rpm must need harder spring setup, right?
My 104whp dyno had a max rev at ca 9500rpm. Max hp around 9000.
100whp 1000rpm earlier. So not much extra to shift later.

[Old Scrambler]

I am not an expert............just experienced

If you are measuring seated-valve spring pressure, what is the S-P at full lift? Should you change springs or use shims if you change cams?

I have had good luck with Bee-hive springs & Ti retainers in my race-motor. After watching the video showing Chevy valves bounce at less than 7,000 rpms, I investigated alternatives and found bee-hives to require slightly lower seat-pressures and more uniform pressure through-out spring compression with 410-lift. To me this means LESS wear and tear on the cam-lobes, rockers, and cam-bearings

Standard double-springs and stock retainers have worked very well in these motors with modest tweaks for high performance apps.  I would strongly consider bee-hives for any maximum performance build.

[Tracksnblades1]

I am not an expert............just experienced

If you are measuring seated-valve spring pressure, what is the S-P at full lift? Should you change springs or use shims if you change cams?

I have had good luck with Bee-hive springs & Ti retainers in my race-motor. After watching the video showing Chevy valves bounce at less than 7,000 rpms, I investigated alternatives and found bee-hives to require slightly lower seat-pressures and more uniform pressure through-out spring compression with 410-lift. To me this means LESS wear and tear on the cam-lobes, rockers, and cam-bearings

Standard double-springs and stock retainers have worked very well in these motors with modest tweaks for high performance apps.  I would strongly consider bee-hives for any maximum performance build.

Scram,
 Did the video show the beehives correcting the sbc valve bounce? Or was it just an informational one.?
Some old sbc cam grinds were known valve train killers…some good info came from these killers though…Even Killers can be ran with valve springs that don’t contribute to the Problem. As Don was pointing out on his bbc..

[Tracksnblades1]

I'm curious if anyone measures valve spring tension? I have some old tech heads and a head or two with newer APE springs and retainers. I have the feeling our valvetrain is light enough to not require a lot of spring tension even at higher lifts but am thinking some of the old tech springs were serious overkill as far as spring pressure.
 A few years ago, I took an old head apart that had short springs, thick spacers and aluminum retainers. The last one had a retainer that was on the verge of failure, so I tossed all of it out.
  Was there ever an on head spring checker for the sohc engines?

A long time ago, Crane Cams,  I believe used to write shorter valve springs that were shimmed to coil bind clearance at the installed camshaft’s actual max lift would result in very stable non resonating springs. Instead of a spring that could handle .650 lift installed in a .450 application that would never see anywhere close to coil bind clearance. At 10,000 rpms the retainer end of the spring is moving full travel @ 83.33 time a second while the other end sits on the shim. They used to compare the spring to a cylinder of water and a slinky at the frequency. Only place shorter may be better 😜

[Don R]

 This was killing my racecar springs. It took a cam change to set it all in motion, the engine had 400 runs on the previous springs then 30 and 32 before breaking them. We got around 300 runs out of the next set before the defect in the heads finally killed one. (Head) Now it's fresh again with about 40 runs on it.
   Edit, When that cam ate a lifter and my builder said comp couldn't/wouldn't weld it I was happy to get rid of it and lose its claimed extra 30HP.

[Tracksnblades1]

Don,

Video worth a thousand

The Slinky CraneCams was talking about

Look how much clearance between coils at lift..

[PeWe]

It would be fine with a list of spring setups for various cams and max rpm.
Then run with lowest pressure possible but still on the safe side.
KH cams more rounded profiles must be more valve train friendly.

[Old Scrambler]

Most NASCAR videos are considered reliable..........especially concerning valves and head-flow.

Some friends of mine (Mueller Bros.) decided to go racing at the Daytona 500 from the late '60s into the '80s. I occasionally watched and maybe handled a wrench when they would be working in their shop in Random Lake, WI. They always ran GM junk with a Pontiac grill The home-built motors were never at top HP, but they usually finished the races. Depending on which cam was installed, the valve-springs were always individually checked for open and closed compressed pressure. In their later years of competition they sourced new springs and numerous other components from well-known teams. Those parts often had no manufacturer ID on the boxes.  I learned that the spring-material was very important to maintain performance to get to the finish line.

Today I observe that numerous beehive springs come in various colors and shapes. I suspect that not all are equal.   

[PeWe]

Yes, not highest hp but reliable build feels like a good idea. But where is the limit?
- Revs only?
- Compression with ignition OK as long as no pinging?
- Beehive springs act as progressive springs?

I had to search and found info
https://www.enginelabs.com/engine-tech/engine/beehive-springs-sound-great-but-will-they-work-for-you/

CycleX has for 5mm valves only.


It would be fine to know the lowest possible spring/seat pressure.
I have a feeling that my heads have a little bit too hard setting to ensure no float but add more wear.

Springs that can make valves to survive a missed gear shift.

Need a video of an open CB750 setup with high speed camera that can show when valves goes wild.
Or which spring pressure needed for 0.400/0.375 lift, heavy valves and max 9500rpm.

[Tracksnblades1]

Yes, not highest hp but reliable build feels like a good idea. But where is the limit?
- Revs only?
- Compression with ignition OK as long as no pinging?
- Beehive springs act as progressive springs?

I had to search and found info
https://www.enginelabs.com/engine-tech/engine/beehive-springs-sound-great-but-will-they-work-for-you/

CycleX has for 5mm valves only.


It would be fine to know the lowest possible spring pressure.
I have a feeling that my heads have a little bit too hard setting to ensure no float but add more wear.

Springs that can make valves to survive a missed gear shift.

Need a video of an open CB750 setup with high speed camera that can show when valves goes wild.
Or which spring pressure needed for 0.400/0.375 lift, heavy valves and max 9500rpm.

The comp cams article has a familiar read to a CraneCams publication 40+ years ago. No slinky comparison though.🤔

[PeWe]

Tracksnblades1,
Good info about springs close to bind for stability.
I see now that you mentioned that earlier as found in the article.

The old RC springs were harder than todays springs from APE and Kibblewhite?
Or was it only the oldest version in need of valve cover bolt mod to keep the cam holder in place ?

I have one head with probably Action Fours springs I got in a build 1983 and used many street years, +parked for 20 years. Reinstalled with measured pressure a year ago.

[Tracksnblades1]

Tracksnblades1,
Good info about springs close to bind for stability.
I see now that you mentioned that earlier as found in the article.

The old RC springs were harder than todays springs from APE and Kibblewhite?
Or was it only the oldest version in need of valve cover bolt mod to keep the cam holder in place ?

I have one head with probably Action Fours springs I got in a build 1983 and used many street years, +parked for 20 years. Reinstalled with measured pressure a year ago.

You may be right. Back then some had the belief if a little was good a lot must be better. Think carbs..
RC was kinda the cutting edge back then in the square camshaft profile days and was limited to the springs material available. No cordial spring wire excepting aircraft perhaps... I’ve read somewhere also about the .050-.200 lift profile to predict how radical the profile for manufacturers to determine spring pressures required to keep the lifter/valve from ski ramping off the nose.

Don’s Spring Video sums up what CraneCams reference to a slinky motion.  A gram of intake valve weight savings used to be claimed to add 25 rpms to the max. Your 33.5/5mm intake will weigh 9-10grams lighter than your 34mm ss intake. Should allow for some of your missed shift concerns. I’m not sure whether that weight savings directly translate s to less/softer spring rates without cam profile considerations. Indeed an application video as you stated would be worth a 1000 also. May indicate what is causing the upper guide to funnel.

[johno]

The springs have been the Achilles heel of cb 750 engines and builders in the 70,s & 80,s as we had to use what we could get and we didn't have a big selection to choose from as you suggested. Also as you suggested everyone played safe and run high pressure wether need or not. I also believe people felt safer running high pressures as our bikes had problems jumping out of gear and dropping valves was common. Very expensive exercise dropping a valve.  As we get older we realise the best person to discuss the spring pressures with is the cam grinder. All pro teams car or bikes have very good relationships with their cam grinders, its the best way to stay on top of the opposition. Like lots of other components these days the choice of materials is amazing ie spring wire material. The cam grinders can get very close to what is required after a chat. They talk in terms of rate of change in lift per degree of rotation to determine the pressure required to follow the profile. They not only understand the physics  but have computers that can run profile tests & simulations etc   The cam grinders have been invaluable to me in my days, find them , talk to them, trust them and after all that shop the market to get what you need.

[PeWe]

About the cam profiles.
Each cam designed for a specific application.

The less agressive seems to have another power curve, wake up at higher rpms.
- Ex might be the most important? It open very quick and need to stay away from the piston when closing.

High lift, short duration harder life for the valve train. More power earlier but no need to rev after 9000rpm.

I have had thoughts about the steep closing on some cams. And possible need of springs that force valve to close that quick.
Even stock cam has rather steep close.

-The beehive springs more for the high rpm cams?

Some cam inspiration where some lobes look as rather soft for the valve train as the Action Fours SS-1 and the KHD



#
125-20 cam card IN lift 0.388", measured 0.380" when timed. (Cam data on internet IN 0.338")


#
Probably KH F

#
Super F has a very clear message in the instruction, absolutely not for street
(Had no better photo.)


#
RC295 look a little bit more rounded than the 125-75.


#
DP315 actual lift rather low with recommended lash of 0.3mm. Running IN lift lower than the modest SS-1.

Less lash increase overlap rather much with power loss.

DP315 vs higher lifting RC295


OK, which seat pressure for each cam with rpm ranges and different type/size of valves?

It would be nice if time card could have those data

Edit:
Visited the garage and saw my 34mm valves on the shelf. The shiny CycleX 34mm ss valve is lighter than stock F2 34 mm.
The latter has got a backcut too, still heavier;D
It differ around 1.5-2 grams.

[Don R]

  Thanks, the lobe profile pictures are interesting, I'll try to add mine to the mix.

 My KH "f" cam is clearly welded you can see the different metal from the side view. It works well on the street in an 836. (I also liked the Honda F2 Super sport cam though) I have a pair of RC315's now. Not a lot of guys around here did a cam swap for whatever reason. The stroker motor has an Engle cam in it, fairly aggressive from what I was told.
 The turbo motor had a stock cam as far as I can tell, I'm leaning towards the F2 Honda cam when it goes back together. The PO remembers putting stainless steel valves in one of the heads so I'll check that out too.

[NitroHunter]

Yes Don I was told by Eraldo Ferracci to use the F-2 cam with my turbo due to the 108 lobe centers.

[johno]

There a good bunch of cams there, all to suit there own needs. All good for our 50 year old bikes and a retailer like cycle x that stock a spring selection to cover those needs . Not many people take the 750's to the edge these days but if you decided to do it and have some cash the cam technology has changed a lot these days with polydyne profiles for example ( I know, I know,  they have been around for 20 years but there hasn't been a market or need to produce modern cams for the ol 750's). These profiles have positive and negative ramps on them where they accelerate the valve opening so fast the spring can't control the valve so after the valve opening the cam is ground to quickly slow down rate of opening to let the cam follower stay on the cam and stop the valve from floating off into the sunset. so theoretically the cam profile is like a couple of big waves up the flanks. BUT as we all know the problem for power gains comparable to modern bikes is not the cams or springs , its the cam / valve angles and geometry that's the problem and no matter what we do were reinventing the wheel unless someone courageous like "big bore MR" has a big ticker and deep pockets to get a new head cnc'd up so we can get some serious valve timing and lift into our babies.  hehehe go Mike. yeh baby lol
cheers Johno

[gschuld]

Yes, not highest hp but reliable build feels like a good idea. But where is the limit?
- Revs only?
- Compression with ignition OK as long as no pinging?
- Beehive springs act as progressive springs?

I had to search and found info
https://www.enginelabs.com/engine-tech/engine/beehive-springs-sound-great-but-will-they-work-for-you/

CycleX has for 5mm valves only.


It would be fine to know the lowest possible spring/seat pressure.
I have a feeling that my heads have a little bit too hard setting to ensure no float but add more wear.

Springs that can make valves to survive a missed gear shift.

Need a video of an open CB750 setup with high speed camera that can show when valves goes wild.
Or which spring pressure needed for 0.400/0.375 lift, heavy valves and max 9500rpm.

To make sure there is no confusion.  CycleX does carry a beehive spring kit for OEM stem diameter valves. 

George

[Don R]

Yes Don I was told by Eraldo Ferracci to use the F-2 cam with my turbo due to the 108 lobe centers.

That's good to hear, Thank You.

  I understood the advantages to the beehive springs are the retainer is smaller and lighter, as is the moving end of the spring itself and each wind of the coil has a different harmonic rate/rpm so it sort of cancels out the slinky tendency. 

[PeWe]

.....
To make sure there is no confusion.  CycleX does carry a beehive spring kit for OEM stem diameter valves. 

George

Good news George!
I did not find it on their website.
Edit: Revisited and found
http://www.cyclexchange.net/F2%20Springs%20and%20Other%20Hardware.htm

ENV-010K for "K" models     $239.00

ENV-010F for 77-78 "F" models     $239.00

ENV-010-5MM for Kibblewhite 5mm kits     $239.00

One more thing to consider for next order.
- Any info about which type of cams/rpm area that will get best result with these springs?

I left some CB parts at my nearby tuning shop where I tried to pump him on seat pressures.

One absolute answer is difficult.
Much depending on cam  profile,  avoid airborn rocker/bounce after the lobe tip. 
Too hard springs take hp, too soft causing rocker arm airborn which take hp too
Plus eventual damage $$$

 I checked a few of my cams when back. One had less marks just after the IN tips.

The shape of Beehive springs  will make coil less prone to bind. Compress spring, the smaller wounds goes more to the inside of the wider.

Nice to have if possible...
Color the cam lobes and inspect afterwards?
Special surface coloring needed
Adjustabe retainers would be fine, turn them as a nut to tighten or loosen. No need to remove head for spring adjustment

[gschuld]

Mike would be the one to answer the spring pressures questions.

My interest in the beehives is for big bore road racing applications. 

Matt, FWIW, is running those springs on his 34/28 valve K race head on his Sportsman bike with a CX7 cam.

The CyckeX beehive springs will handle high lift.  CX10 cam is the plan going fwd on the next engine.

.430” lift on both ends.  The head needs to be set up to run extra high lift(valve to valve clearance and high lift iron guides(available at CycleX)

IMHO, quality double springs are long proven to get the job done.  That said, beehive springs are said to help reduce harmonics, reduce overall valve/spring/retainer weight, and offer better valve control at the higher end of the rpm range, especially in the over 10,000rpm neighborhood.  The high performance OEM world is all about beehive springs for a reason.

There have been some limited reports of double springs losing a noticeable (and surprising) amount of spring pressure after just one racing season.  Perhaps it’s a localized batch issue of a particular spring set, but beehive springs seem to be doing quite well in the longevity department in race engines.

The more modest the cam, and severity in intended use, the less justification for the more expensive beehive springs I’d guess.

Under say .400” lift, street engine use, it could certainly be argued that beehives are not worth the extra cost.

George

[PeWe]

Thank you very much for the details.
I saw this thread and got ideas about correct seat pressure (as low as possible), valve in control with minimum wear.
For modified street bike, longetivity.

I should have known this last summer when I ordered a complete spring set with tensioners from CycleX.

Use beehive with the 125-75 cam that is very "civilized".

It seems that seat pressure is relatively low compared to the old double springs when reading CycleX spring description.

I understand why this kind of spring is popular in high power engines and rev torturing applications if this can keep everything in control with lower seat pressure than with older type of springs.

[Don R]

 The information I get is horsepower loss/spring pressure is minimal, the spring pushes back on the ramp as much as it takes to open. My worry is wear and breakage. My racecar has 300 psi off the seat. I don't even think about the open pressure.

[Tracksnblades1]

PeWe,

Could you have a conversion kit ready in a few months..?

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwiIyKXR-Zj1AhWqlIkEHT88Dp0QtwJ6BAgFEAI&url=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DjgOg55g-Hs8&usg=AOvVaw1oGAv7GRevVRiPySHBt00y

Even though I think Ducati has moved on…

[PeWe]

Yes, too complicated with the extra rocker arm. All should have it otherwise. That is valve control!
I remember that Ducati 500 Desmo was one of the bikes I looked at before I decided to buy my blue CB750 K6.

I did a quick search now to see if Ducati still use it. Found interesting history.
https://www.cnet.com/google-amp/news/desmo-valves-race-car-ducati-mercedes-motorcycle/

Finding and adjusting the best spring to fit your application is what we have.
Hopefully no longer need of bolts thru valve cover keeping the cam holders in place
 
Standard designs often begin as high tech for race.

Same with cars where granny's car can have a DOHC engine with turbo,  intercooler and electronic injection, a very old one!

[Tracksnblades1]

PeWe, What about this type ?
With a mini plc board to control regulator pressure based off of an input from an electronic or Hondaman ignition .
Plc could use the input to flag a counter to monitor rpm for a pid or preset air pressure/rpm curve. This would accomplish your goals with one rocker and just the right amount of spring pressure for the given rpm and cam profile..?
You’d be reinventing the wheel. I think GP and F1 have it already.

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwjIvMbKjZ71AhWnjIkEHbilA0cQwqsBegQIBBAB&url=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DHxEiESBLF9s&usg=AOvVaw3CiXvHQFaX8hVSquaNToHW

[Don R]

 Warren Johnson asked NHRA for permission to use pneumatic springs in his pro stock engines. They said it would give him an unfair advantage, he said he would buy them for everyone in the class with his savings on springs. Still got a no.

[PeWe]

Good ideas!
Like the Swedish car manufacturer Koenigsegg, seldom seen in the mirrors except for a ms or 2!!  "What was that? Wind or an jet fighter??"

It would be fine on my bike!
I'll order the 125-75 program at the same time!
Possible to change "cam" program while riding!!