Lash adjustment

[heshtesh]

Getting ready to set lash on my first solid roller the mfg. recommends .021 int. side .023 exh. side hot. Should i allow a couple thou extra clearance due to the fact my initial set-up is cold. I figure later i can do the math and calculate the expansion of the alum heads so i can do them cold.

[curtisreed]

You will pick up about .005-.006 after the motor heats up. If you need .021 hot set them at .015-.016 and .017-.018 cold.

That is with iron block and aluminum heads.

Curtis

[heshtesh]

Curtis: Thanks for the info, i'm surpised they expand that much but i will use your info for my starting point. Again Thank You.

[russ67chevelle]

my big chevy stuff requires .004 to .005 less clearance cold.most were fine with .004 tighter,but about 2 per side needed to be slightly tighter when checked hot

[chevyart]

i have sbc iron block and iron heads. i set my valve cold just the opposite. i set them looser and when they heat up they tighten (example) i set them cold around 26 to get about 22 when hot. is this correct chevy art

[Tod74]

You will pick up about .005-.006 after the motor heats up. If you need .021 hot set them at .015-.016 and .017-.018 cold.

That is with iron block and aluminum heads.

Curtis

X2

I have a Big Chevy with iron block/aluminum heads and mine opens up about .006 when it heats up. What I do is set them about .006 tight to get the thing started, then get it up to operating temp and check them and see how much they opened up.That way you know how much and then you can do the math and just set them cold every time. JUST MY OPINION

[curtisreed]

heshtesh, one other thing I would mention is the way I set the lash. If you are shooting for .020 setting, (arbitrary number), I use a .019 and .021 feeler guauge as a go and no-go. .019 goes easy and .021 will not go, gets you right on .020. I guess I have been a machinist to long to just set it with the size gauge I am shooting for.

Curtis

[TS1955]

There was some discussion on this subject a little while ago. So the last time I adjust the valves on my motor, ( small blocl chevy, cast block & aluminum heads) I set them .006 tight cold. Warmed the engine up to 200 degrees, pulled the rocker covers and the lash was right on the money.

TS1955

[CamBirdRacing]

heshtesh, one other thing I would mention is the way I set the lash. If you are shooting for .020 setting, (arbitrary number), I use a .019 and .021 feeler guauge as a go and no-go. .019 goes easy and .021 will not go, gets you right on .020. I guess I have been a machinist to long to just set it with the size gauge I am shooting for.

Curtis


KD tools make s go-nogo feeler gauge. I have one. Pretty cool to get your lash adjusted "just right".

[TheRabbit]

Their will always be a debate over setting lash over hot vs cold. Hot is better, but the average racer doesn't do it fast enough to keep the temp steady. I've been through this so many times with my engine builder and this is his take on it. The lash is set and adjusted correctly during breakin once the motor is hot. Once I get it I check and see what feeler guage will fit. I don't care what size it is. Just get my feel for it. Noone can tell you .016 - .018 cold or .022 or .024 is perfect. Everybody has a different feel for .022. Some tight, some loose, some snug. .002 isn't going to make a difference, but they all need to be the same!! If you error do it on the tight side! What I'm trying to say is set them the same everytime YOURSELF. Smaller or lazy cams likes more lash, but even that isn't always 100% true. A good valve train SHOULD NOT MOVE. IF IT DOES SOMETHING IS WRONG!!! Take notes which ones you have to adjust and which way. If you have to keep getting tighter you probably have a seat problem. Bottom line is if you have to adjust the same ones next time look at everything really close!!

[cepx111]

A good valve train SHOULD NOT MOVE. IF IT DOES SOMETHING IS WRONG!!! Take notes which ones you have to adjust and which way. If you have to keep getting tighter you probably have a seat problem. Bottom line is if you have to adjust the same ones next time look at everything really close!!


Good point Rabbit, I like the idea of taking notes too - good info.

Cp

[heshtesh]

Fellow Motorheads thank you very much for the provided info,based on the fact you all recommend between .oo4-.006 i'm going to split the difference and go with .005. The keeping of records makes perfect sense,as i work in the metal fab industy i make go/no go gauges on a regular basis and will make a set specific to the task at hand. As for valve train stability i'll be using a Jesel shaft rocker system for the first time that some of you previously indicated would be well up to the task of maintaining the desired stability. As this engine is in a daily driver with full exhaust and no stereo i should have little trouble identifying any changes in valve train noise if any thing starts going south. Again Thank You for all the input.

[TheRabbit]

Not to ramble on, but I use to be obsessed with valve lash. I'd adjust after every race. I'd always find one or two that just seem exactly right. I use to take the tempeture of the rockers before I adjusted 'em. If it wasn't 180* I'd crank it up and get the temp up. Took me all day to set the lash :oops:. I worried about it to the point of talking to 4 of 5 different engine builders about hot vs cold, .022 tight fit, snug fit, loose fit and so on.
I'm finally at peace with my lash now that I do it Cold and Snug!! LOL.
THANKS TO STEVE VANCE FOR HELPING ME THROUGH THAT! :) !
Also remember a small cam or lazy cam likes more lash. Bigger cams, more aggressive cams like tighter lash :wink:

[heshtesh]

The Rabbit: I'm running a 262/267 @50 618/625 with a 106 split, doe's the snugger setting at recommended lash setting equate to longer cam life?

[TheRabbit]

I don't think so. The tighter lash does make the cam seem a little bigger, but don't go overboard with that either. Of course the more you drive it the more you will need to check it. Just don't do like I did and overthink it or do it to much. Jesel are good rockers and you shouldn't have any problems or very much movement. My suggestion would be to get them all the same as the spec sheet says HOT (may take a few times to get all of 'em right) then find whatever feeler guage fits that setting when it's cold and use that from then on. Just remember if you error, error on the tight side and I mean from snug to firm, not snug to tight and you'll be ok.

[heshtesh]

Thanks Rabbit i know the feel i'm looking for with the feeler gauges,soft drag.

[HigginsRacing]

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.