Deuce lt1 valve lash
 

hi

finished freshened my LT1 and have it all back together and in car
see different info on the net............. regarding valve lash

what is the correct valve lash for 1970 LT1
looking for initial cold settings
then once hot final valve lash settings

thanks so much
chris

Hot is .024 and .030 int. and exh respectively.

I always go .002 looserr for the initial cold setting.

So, .026 and .032.

However, even if you went .024 and .030, you would not hurt a thing.

I've used this since I found it years ago.

Hope it helps!

Tim

http://www.metroli.org/pdf/WHITE%20P...Adjustment.pdf

Latest Lash settings I have from JohnZ and DUKE WILLIAMS on the LT1 is .016 .023 - which is what I set my original never apart LT1 last october...

There is a technical paper on the NCRS website regarding the correct lash settings. Tim references it above.

Nice. Thanks Napa68 for the post and link. Bookmarked.

Maybe this is why the Crane 110951 Blueprint LT-1 cam has 0.020/0.025 settings?

By the way, for those who might be interested I checked Crane's web site and the Blueprint series of Cams no longer are there. Summit still shows them available.

I have great respect for John Hinckley and appreciate his expirementing with different valve lash settings. However, official GM documents as late as 1988 (the last "Chevrolet Power" manual I have) still state .024 .030. To my knowledge there has been no official document from Chevrolet recommending anything else.

I definitely agree that you MUST make the adjustments on either the LT-1 cam or the 30 30 cam with the lifter on the base circle. However, there is no magic number for valvle lash. I have run many 30 30 cams at .030 and never had an issue with exhaust valve seats or over heated valves. In fact, tightening the valve lash would actually make the exhaust valve sit on the seat (where it cools) a little less, as the effective duration is increased, not decreased.

The article also says that there is little or no difference (I think they use the term "negligible" between the lash hot and cold. I disagree. I actually set mine cold, ran the engine hard and re-checked. Every one was between one and two thousands tighter hot. Metal exands when it gets hot.

This is all academic anyway. The actual lash you set does not have to be that precise on either of those cams. Guys have experimented for years with different valve lash. You can definitely run tighter than .024 .030 and do no harm to your engine.

If you run your LT-1 camshaft at .024 .030, it will run fine. There is no reason you can't run it a bit tighter. James prefers running his at .016 and .023, and has had good results. Theoretically, his engine should have just a bit more lope at idle than my LT-1 set at .024 .030.
Personally, I would be comfortable running mine anywhere between .016 .023 and .024 .030. Just make certain they all match.

FWIW my engine was .024 .026 when I checked checked it initially.

It does have a little more lope, but makes less vacuum. IF I understand correctly the reason for less clearance is to allow the ramps to lower the valves to the seats which is easier on the seats and the cam. .

PLEASE NOTE --- THESE SETTINGS ARE FOR factory stamped steel rocker arms (which have an effective ratio of something like 1.37) not rollers, precise, or 1.6 rockers.