valve lash roller cam

[andy16]

asuming all other variables are optimal what is the best lash setting to prolong lifter rocker and valvejob life. i understand cams come w reccomended lash but that setting is for peak hp. leaving hp out of the equation what is optimal lash for a roller cam . leaving the cams factory reccomendations out of it basing info on extending life only. thanks

[usafracer]

Well all things even then a 0 lash would be easiest on valve train.

[andy16]

thanks lol. i agree a tighter lash is better but how tight is too tight dont want the valve hanging open either. .005-.010 i have ran .018 hot lash plenty of times before w no problems but just wondering how to make it last long as posible i fugured somebody on here has had acess to a spintron or data and has tested it sometime or another.

[tutt71]

There are a lot of variables here, but to simplify this question I will assume this is some standard lobes here. A lobe has an area called a "lash ramp" which transitions the base circle area to the actual lobe or "lift ramp" area. The initial transition to the "lash ramp" is the hardest on parts due to the fact that is where the tappet begins to first move. The "lash ramp" usually has a specific lifter rise rate or acceleration through .030 or so of an inch before it transtions to the actual lobe. Therefore any lash between .001 and .030 has the same amount of destructive force on the components involved. Once you go more than .030 then the lifter is starting up the actual lobe and has a much greater speed of movement which would cause more destructive force. "Tight lash" lobes have a shorter lash ramp before the actual lobe and usually require lash to not be more than .020. Lash is usually changed from the cam makers "recommended" numbers to provide the most power. So, having said all of that, i recommend using the lash amount that your engine builder determined made the most power with your particular combination.

[andy16]

that is the information i was looking for i appreciate the response and i learned something thanks. ill keep it where it was unless i ever dyno it preciate it

[dynoman14]

Andy,
You might also want to check with the cam grinder as most cams will have a recommended lash per lobe design. Some lobes are tight lash-.008"-.012", some are medium-.012"-.020" and some are old school.020"+.

If I ever have no info on a solid tappet roller, my rule of thumb is tighter lash with higher lift, and I usually start at .014"Intake and .018" exhaust. If the cam is over .700 lift I drop each setting .002", if the cam is over .800"lift I drop another .002".

For a solid flat tappet I start out at .018" Intake and .022" Exhaust and adjust down same as the roller.

It is not a perfect method but it has worked for me for 35+ years. What you will find is most racers don't know how to adjust their valves properly and if you know how to adjust your valves properly you will pick up major power and add significant life to your valvetrain.

[DaveBauerSS6]

Andy,
You might also want to check with the cam grinder as most cams will have a recommended lash per lobe design. Some lobes are tight lash-.008"-.012", some are medium-.012"-.020" and some are old school.020"+.

If I ever have no info on a solid tappet roller, my rule of thumb is tighter lash with higher lift, and I usually start at .014"Intake and .018" exhaust. If the cam is over .700 lift I drop each setting .002", if the cam is over .800"lift I drop another .002".

For a solid flat tappet I start out at .018" Intake and .022" Exhaust and adjust down same as the roller.

It is not a perfect method but it has worked for me for 35+ years. What you will find is most racers don't know how to adjust their valves properly and if you know how to adjust your valves properly you will pick up major power and add significant life to your valvetrain.

Be careful with that advice. I would throw a 800 lift cam in the trash if I didn't know absolutely what it was. In fact any roller/ solid cam, if you cant ID it.

[andy16]

i dont know what cam it is i never had this engine apart myself but builder told me .018 on both and i never moved it and i never had any trouble and wouldn move it without some solid info but it seems to be too risky to mess w so ill leave it alone.

[dynoman14]

Andy,
If you want to know what the cam is I'll run it on the Cam Doctor for $20. That will tell you what you need to know.
BTW, I will gladly take anybody's roller cams they are getting ready to throw in the trash and pay shipping also. I can re-grind, and re-nitride just about anything so; just saying...
Later,
Mark

[DaveBauerSS6]

Andy,
If you want to know what the cam is I'll run it on the Cam Doctor for $20. That will tell you what you need to know.
BTW, I will gladly take anybody's roller cams they are getting ready to throw in the trash and pay shipping also. I can re-grind, and re-nitride just about anything so; just saying...
Later,
Mark

Help me out here,,, the cam doctor reads the profile of the cam lobes and center line. And it tells you what the lash is. How dose it work??

I had a bad experience with a major cam manufacturer on a regrind. Never again.

[perfconn]

Cam doctor will tell you everything about a cam except the valve lash.It tells you all that with a degree wheel and a 1 inch dial indicator.

[DaveBauerSS6]

Cam doctor will tell you everything about a cam except the valve lash.It tells you all that with a degree wheel and a 1 inch dial indicator.

That was fast,, so we've made the full circle.
You are still left making guesses from what .012 to .028 lash settings, and don't forget you have to do two lobes. Vegas odds makers would love this one.

I'm sure anyone that has the money to put together a motor that would support a .800 lift cam would not play these odds. Hopefully someone building a .500 lift motor on a budget doesn't do this and waste his time. When I show up to the track, I don't want to fart around with a motor that has the lash wrong.

Just for the record, I will pull a cam out and buy another one before I would change the degreeing to advance or retard it. I used to drag race and did the redegreeing and it did make small changes in the ET. But I never felt it was worth the effort. Just a bracket racer.

[sj valley dave]

If you had a cam doctor lobe profile that shows how aggressive the acceleration ramp is, etc, you could give the info to a cam guy like Mike Jones @ Jones Cam and he would be able to tell you what amount of lash you would need...

[dynoman14]

Man, both them Daves are about the sharpest spoons in the drawer.

Once I have the cam profile off the Cam doctor I guess I could look at the profile myself and determine the lash spec, I didn't spend 3 years at Reed Cams as National Sales & Tech. Manager just for fun...as I recall I did a number of classes for race engine builders on cam design and lobe selection. Anyway, no biggie just another job on the list of many, I remember the friends and good times more than anything else, and let me tell you there were some good times at trade shows with the Reed bunch back in the day.

Last time I checked Cam Doctor was accurate to .0001" and .001*, your degree wheel and dial indicator must be way better than mine. For cam lobe acceleration info I think you need a little more than a degree wheel, just my humble opinion.

If need be I can have it adcoled in a day, and those measurements are out to .00001" / * but that takes a little longer as I have to ship it off. I get like 100 free a year and have never used more than about 50.

As a bracket racer or whatever you guys race, I doubt either of you have had to work much with engines that run at sustained RPM limits of 9000 average 3-4 hours or, endurance efforts that average 7000-8000 for 12-24 hours. Rather than being any good I guess I must have just been lucky to have been in the right place and time to get the work I have gotten because I prolly don't know as much as either of you.

Maybe next time I go to work on one of my Serdi Machines in an F-1 or MotoGP engine shop I'll drop your names in conversation and see if they have heard of either of you.

BTW, Andy16 is one of the guys I took with me to PRI when we took Matt Bienemanns first show booth there and set it up for him. Matt paid cash / traded me a GNX for his first Serdi 100 and Andy was one of my best students in how to work on and operate a S-100. Prolly got 50+ machines in the Charlotte Area alone and Andy helped me sell a couple of them. Hell, probably 20 machines came off the S-100 I put in Jerry Hemmingsons' Race Engine Shop ( mostly Pro-Stock Drag Stuff ).

Andy lives right there by Mike Jones, so I guess he can just run by there with the cam and see...

[stockcar5]

I didn't spend 3 years at Reed Cams as National Sales & Tech. Manager just for fun...as I recall I did a number of classes for race engine builders on cam design and lobe selection. Anyway, no biggie just another job on the list of many

interesting that mark claims now to have worked for a cam company whos founder/owner has died and is now out of business. guess nobody can disprove his story....interesting...LOL!