I'm installing a LT4 hotcam in my 87 TPI and on adjusting the valve lash I got my Haynes manual out and it said get it to zero lash and then 1 full turn, That's what I did but wanted to know if thats too much should I have only done 1/2 or 3/4 turns with this cam? I can turn the engine over with a s****et and wrench and it seems fine. I just want to make sure I don't have them too tight. Thanks

 

AHAHAHAH!! You misspelled "socket" and the BBS hammered you!!! It's kind of like you can't talk about the place the pilot goes in the plane - the ****pit - or the thing you drain your radiator with - the pet**** - which almost sounds obscene anyway.

But seriously... the thing that you are doing has nothing to do with what cam you are using. You are setting things so that the lifter is forced down somewhat into the range of the travel of its little hydraulic valve. I agree, one full turn is way too much for a performance application, because the lifter has a tendency to "pump up" during the closiong portion of the valve motion at high RPM as the valve train unloads due to the inertia of all the parts, which makes the valves hang open. What I usually do is zero-lash all 16 of them - quickly - then shut the engine off and go back and add somewhere between ¼ and ½ of preload, sepending on how long I want it to be before I have to do it again.

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"So many Mustangs, so little time..."
ICON Motorsports

[This message has been edited by RB83L69 (edited April 01, 2001).]

 

i set mine at zero then add little more than 1/2 ,sorry i know i'm not vader

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ICON Motorsports

1st & 3rd

 

i 1/4 lash. always have, never had a problem.

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85 IROC 350 11:1keith blacks,.555lift erson roller cam,1.5 crane roller rockers,edelbrock intake,holley 4150 750dbl pumper, nitrous oxide,full length heddman headers,true dual exhaust, 11"stall converter, 700R4, 3.73 locker

 

I use 1 full turn. The only time the lifters will "pump up" is if the valves float. And the only reason they will do that is if your valve springs are not adequate for the RPMs you run.

Using less lash is a "crutch" for weak valve springs. The lifters "pump up" but then they bleed back down more quickly since they only have a 1/4 turn of lash to bleed back down to.

However, it's a minor point, since I used to use only 1/8 turn of lash for years with no problems. But since I got my education in "Valve Springs 101" I don't do this any more and i set the rockers for the proper ROCKER ARM GEOMETRY which is almost always about 1 full turn down from zero lash.