PDA

View Full Version : Valve lash question? SBC

MonteMadneSS84
10-30-2005, 03:31 PM
I got a solid flat tappet cam in my car....it was in there when i bought it...i have no idea what cam it is or anything about it. Just wondering what to set the valve lash at....i set it to .024" but it just sounds way to noisy. My roller cam in my other car was supposed to be set at .025" so thats where i got that # from. Id appreciate any info.....
Hawkeye
10-30-2005, 04:46 PM
All pushrod engines using mechanical (solid) lifters, or mechanical roller lifters, must have an adjustable valve train so that precise adjustment for “Valve Lash” can be made to match the camshaft’s requirements. Valve lash is the running clearance that exists between the tip of the valve stem and the valves mating surface of the rocker arm. (It is expressed in the Crane Catalog as “Valve Lash” and on the camshaft specification card as “Valve Setting”. Both terms mean the same thing.) The amount of valve lash can vary between camshaft profile designs, being as small as .010” on some and as great as .035” on others.

It is important to use the recommended valve lash when you first test the performance of the engine. You must also be concerned with thermal expansion of the engine components. (This is especially true if using aluminum alloy cylinder heads, or block.) For this reason, Crane requires that the valve lash be set with the engine “Hot” on all pushrod engines using mechanical lifters. This will insure that the minimum required clearance (valve lash) is maintained throughout the engine’s operating temperature range.
cobrakillerta
10-30-2005, 05:10 PM
For this reason, Crane requires that the valve lash be set with the engine “Hot” on all pushrod engines using mechanical lifters.

Now how the hell do you do that exactly?
How long would it take for one of our motors to fully cool down and the effects of thermal expansion to diminish...in other words, could you actually get it "hot"... then take off our coils, covers and all that jazz in enough time to spare to do that correctly on an LS1...also incorporating the time it would take to set each individually and finally getting to the last one :confused2:
Hawkeye
10-30-2005, 05:16 PM
LS1's are Hyd/Roller...No lash adjustment required...

On SBC's there is a formula to set them cold...Besides...It takes less than 4 minutes to take the Valve covers off on an LS1
JetStreamLS3
10-30-2005, 05:22 PM
Now how the hell do you do that exactly?
How long would it take for one of our motors to fully cool down and the effects of thermal expansion to diminish...in other words, could you actually get it "hot"... then take off our coils, covers and all that jazz in enough time to spare to do that correctly on an LS1...also incorporating the time it would take to set each individually and finally getting to the last one :confused2:


the beauty of a hydraulic roller.....;)
Action Ed
10-30-2005, 05:33 PM
I got a solid flat tappet cam in my car....it was in there when i bought it...i have no idea what cam it is or anything about it. Just wondering what to set the valve lash at....i set it to .024" but it just sounds way to noisy. My roller cam in my other car was supposed to be set at .025" so thats where i got that # from. Id appreciate any info.....
25 should put you in the ballpark Ive had about 30 different solid lifter cams in my time and most of them were between 20 and 30 thousanths,its gonna seem louder than the roller set at 25 because of the difference in ramp design.
johnebgoode
10-30-2005, 06:22 PM
In addition to what Hawkeye said , once you've adjusted the lash when hot, go back the following morning and check them again cold. Make a note as to where the adjustment is so if ya decide to adjust valves again it doesn't need to be hot,you have your #'s when engine is cold. This also tells you how much expansion you are experiencing when it heats up. Record all info. What I did with my race car was write it on intake so I wouldn't forget. For instance :
I= .013
E=.018 both when cold.
Click here for Cranes valve lash procedure (http://www.cranecams.com/?show=techarticle&id=2&PHPSESSID=d3885b817f18f91b72fa87dd4488fb5c)
cobrakillerta
10-30-2005, 06:31 PM
LS1's are Hyd/Roller...No lash adjustment required...

On SBC's there is a formula to set them cold...Besides...It takes less than 4 minutes to take the Valve covers off on an LS1


Yeah it takes 4 minutes to remove the covers...but there's other shit to remove as well

I guess i meant anything really with aluminum heads
How long do the effects of thermal expansion subside really :confused2: