MotorHead

Putting in CC 282 soild cam tommorrow and was just reading some info from the CC website and it says to set the lash cold with the "hot" specification and then after you break it in do the whole proceedure over again.

Jeesh it's a pain the **** to do it once, there must be some rule of thumb for setting it cold ?

wallyknoch

Set them cold! I`m sure you have watched fuel drag racing. Well we don`t break in cams {an old wise mans tale} If they are not right the first time we don`t go to the next round. Try this easy proceedure. I presume the engine is in the car and you can bump the engine around with the starter. Pull the coil wire too. Start from the first rocker arm and as the intake closes adjust the exhaust to the correct lash, go to the next and as the exhaust starts to open adjust the intake to the correct lash. It`s "as the intake closes adjust the exhaust, and as the exhaust starts to open adjust the intake". Simple proceedure and no oil splashing all over. As you have lashed one side go to the other side and finish up. :D Have fun :cheers:

427Hotrod

This procedure is dead on...I think I posted it somewhere here today also. If you this stuff a bunch, you quickly learn this method is the simplest and fastest.

On a regular iron core cam, there is likely to be a little movement of things when you initially run it. You will want to set it again after you run it a few miles regardless. I usually get it all broke in, which is necessary on something that is not a steel roller, and then drive it a few miles and maybe let it heat and cool a few times. Then I set them again when cold and forget about 'em for a long time.

With aluminum heads, usually .005-.006 tighter than the hot lash works for a cold setting. Iron heads, maybe .003-.004 tighter. The only way to know for sure on YOUR engine is to set them cold and then run it long enough to really warm up the oil...not just the water and then immediately pull a cover and check at least one intake and exhaust. After you get that measurement, you will know what to set them at when cold from then on.

If you plan on doing any head retorquing, do it before you set valves.

JIM

MotorHead

Thanks guys this is what I was looking for "With aluminum heads, usually .005-.006 tighter than the hot lash works for a cold setting. Iron heads, maybe .003-.004 tighter. "

Jughead

Sheez Jim! I read to set them looser on a new cam. 0.025 exhaust and 0.022 intake. Cam spec 0.20! :confused:

Motorhead: what're the specs on that cam?

MotorHead

I think that is correct Comp Cams says after it warms up the lash will be looser, so it makes sense to start them off a little tighter not looser.

CC 282S - 0.022" lash intake and exhaust 236 duration @ 0.050, .495 lift

LeAnn82Collector

I used this info from the Crane Cams site when I set up a blueprint LT1 cam I got from them:

Compensating for a Cold Engine when Adjusting Valve Lash

When installing a new cam, the engine will be cold but the lash specifications are for a hot engine. What are you to do? There is a correction factor that can be used to get close. We mentioned that the alloy of the engine parts can be affected by thermal expansion in different ways, therefore the amount of correction factor to the lash setting depends on whether the cylinder heads and block is made out of cast iron or aluminum. You can take the “hot� setting given to you in the catalog or cam specification card and alter it by the following amount to get a “cold� lash setting.

With iron block and iron heads, add .002�

With iron block and aluminum heads, subtract .006�

With both aluminum block and heads, subtract .012�.

Remember this correction adjustment is approximate and is only meant to get you close for the initial start up of the engine. After the engine is warmed up to its proper operating temperature range, you must go back and reset all the valves to the proper “hot� valve lash settings.

BTW, just realized I'm logged in as my wife. This is Corvgreg. This is the link:

http://www.cranecams.com/mliftfaq.htm


[Modified by LeAnn82Collector, 6:31 AM 7/21/2003]

WESCH

Hi

This is all right, if you must have it right on .
But than again, what difference does it make .002 up or down.
I tried them all on my 68 big block L71 solid lifter.
With engine running, warm, cold and found the difference so minor that it nearly can't be measured.
I now set them any time I feel like, weather the block is cold or warm, but newer with the engine running naymore. Too messy and too hot.

Just my soughts. At .024 setting or so, what is .002 more o0r less doing ?
Specially with original stamped steel rockers !!

Good luck. Gunther :seeya

wallyknoch

We run them up and down on the lash. Tighter, increases the lift. Our heads and block are aluminum {Donovan 471} and the lash does not change run after run unless we change it. If it does tighten up, we know a valve has a problem and they are titanium and not very cheap. As far as my Chevy engines, I use stock long slot rocker arms as they are the best way to fly as they require very little maintenance in a full fendered Vette with nice paint jobs or any other pieces {Camaros, ect} comparitively equiped. Just use NEW rocker arm nuts. :cheers:


[Modified by wallyknoch, 3:35 PM 7/21/2003]

MotorHead

Can you adjust them with engine running like hydraulic lifters ? Like adjust them untill not ticking and that's it ?

427Hotrod

No, you can't set them like a hydraulic. You must set them with a feeler gauge.

Not sure what Comp said. I can see setting them a little loose initially for a brand new motor start up since things will move around some. Since they don't know how much they are going to move, they are erring on the side of loose rather than tight.

Some valve jobs are done with a 44* angle onthe valve and a 45* on the seat that makes a slight interference. That quickly changes as the valve "fits" itself to the seat during initial run in. As the valve sinks in a little, clearance will tighten up some. But we're not talking huge numbers here.

Does it make a diference? Depends on the cam. The old 30/30 Duntov was specifically designed with LONG clearance ramps to allow lots of valve clearance to be taken up gradually when folks let the adjustment get way out of whack. But newer more aggressive cams can be fairly sensitive to .002 or so changes. Not huge, but I've seen 10 hp swings with small adjustments on a dyno. It can effct several degrees duration on some cams.

The engine is also much smoother and drives much better when they are all set the same regardless if it is .002 looser or tighter. Consistency is important.

I usually stay to the tight side of the specs.


JIM

wallyknoch

Why set them with the engine running? You don`t need to. Use the proceedure I described in an earlier post whether hydraulic or solid. :thumbs:

MotorHead

I find it real easy to set hydraulic lifters with the motor running takes me 10 minutes using an old valve cover with a slot cut in it so it is not messy.

Takes me an hour or so the other way, taking out all the spark plugs and watching the lifter movement while turning the motor by hand is a real pain in the ****.

Thanks for all the help :D

Chuck Harmon

Very interesting topic. To add a bit of fuel to the fire, is there any problem caused by valve lash that is too tight, as long as the valve fully closes? I realize this will significantly increase the cam's duration and therefore the characteristics; but, if given a choice I would much prefer too tight than too loose. I see loose settings causing the lifter to slam into the side of the new aggressive cam lobes without the benefit of the ramp and causing catastrophic cam failure. Burned valves would result with NEGATIVE lash, but I don't see any mechanical problems with MINIMAL lash.

Comments?

Chuck

p.s. I intended to set my new solid roller cam cold about .006" tighter than specs and leaving things at that. I believe that especially with a carbureted engine, individual cylinder temperatures will vary at different engine loads. I suspect a/f mixtures, therefore temperatures, will be quite different cylinder to cylinder at idle than at partial or full throttle. A cold setting on a still engine should be more accurate.


[Modified by Chuck Harmon, 7:43 PM 7/21/2003]

bence13_33

Chuck:
There is nothing wrong with going +.006" (looser) or -.006" (tighter) and anything in between. As you know a tighter lash makes the cam seem bigger and increases the effective valve lift thus giving you more top end (vice versa) the looser valve lash makes the cam seem a little smaller and decreases effective lift and gives more bottom end. I'm sure you know this already Chuck so I don't mean to insult your intelligence I'm just posting this for anyone who may not know.

I do agree with you though. I think a looser valve lash can cause unneeded stress on the cam lobe. I believe though that the opposite is also true. Too tight of a valve lash and you will also run into problems...possibly bent pushrods.

EDIT
I just realized that I usually set my valve lash to .018" cold. The cam calls for .022" hot. I wonder if I would notice any difference lashing them to .018" hot...or possibly .016" hot? I may try that the next time I head to the track.


[Modified by bence13_33, 10:11 PM 7/21/2003]

Chuck Harmon

Bence,

Absolutely no insult taken. But I don't see how more stress would be added to push rods with tighter lash. Valve spring binding might be a problem if you were already on the edge, but how would more stress be made simply by starting the "lift" process a few degrees earlier? I would think that if anything, the stress and the shock would be less with tighter lash.

Chuck

427Hotrod

I'm with you Chuck...as I said... I prefer to stay on the tighter side of specs.

With very mild cams and long clearance ramps you can get by with sloppy stuff and not hurt things. But aggressive cams have a pretty narrow window they need to stay within so that the cam picks up the lifter at a point that won't cause problems.

I don't really consider setting valves a pain. I *like* playing with the engine and it gives me a chance to make sure everything is healthy once in a while. And they sure run nice right after you set 'em!

If you really don't like setting them once in a while, you need to stay with a hydraulic cam.......and try to catch up to the guy with the solid!!! :D


JIM

wallyknoch

If you really don't like setting them once in a while, you need to stay with a hydraulic cam.......and try to catch up to the guy with the solid!!! :D


JIM[/QUOTE] :iagree: :D :thumbs:

norvalwilhelm

. I think a looser valve lash can cause unneeded stress on the cam lobe. I believe though that the opposite is also true. Too tight of a valve lash and you will also run into problems...possibly bent pushrods.

Chuck I was reading what Shane said above and I agree that too loose a lash could cause shocking to the valve train, the clearance is suddenly taken up. Also if the lash is too tight a vavle might be left hanging open and possibly burn.

I set my valve's once a year.
I bring the motor to TDC and set 4,8 exhuast 2,7 intake
rotate the motor to BDC set 3,6 exhaust 1,8 intake
rotate the motor to TDC set 5,7 exhasut 3,4 intake
rotate the motor to BDC set 1,2 exhuast 5,6 intake.

Job done. Make a chart , put it on the wall and do all valves in 3 1/2 turns of the motor.
I called Comp cams about their specs and they said it was only a ball bark and I could increase of decrease by up to .010.

MotorHead

Here is the way I set them, can you see anything wrong with this method :

1...8....4.....3
6...5....7.....2

I take number 1 close to TDC on compression stroke and look at number 6 rockers or if you have the intake off I look at the lifters. When #6 exhaust is closing and just when the intake begins to move or you can see the lifters are equal that means #6 is in overlap and now both #1 valves can be adjusted as they are both on the base of the cam. For #8 you look at # 5 and so on.

BTW I would tell anyone that was running a solid cam and complaining about setting the lash to go back to hydraulic land too :lol:

My initial complaint wasn't about setting the valves every 6 months or whatever as required under normal operating conditons that does not bother me, rather it was about trying to find a shortcut around having to do it twice for a new cam :D