Heads are on, valve train adjustment question...

[Mikelly]

OK< so yesterday Doug comes up and we decide to mount the Dart aluminum heads, push rods and roller rockers back onto my 383 stroker... So we get the head bolts cleaned up. I re-used the ARP bolts I had instead of spending the $100 for studs... Couldn't see the need in replacing basically new head bolts... Anyway, we got the heads set, installed the pushrods, and then installed the rockers. These are Harland Sharp rollers, and we installed them with only a half turn pre-load on them... What have you guys with large roller rockers (Of the type I described) done for setup on these? We looked in a manual for factory rockers and they wanted a full turn on the adjuster... I just didn't think it was the same for these aluminums... and Doug agreed... What say you guys???

 

Also, big disappointment... My Cutler aluminum intake WILL NOT bolt up to my heads... The two center bolt holes on the intake rail are angled wrong... This intake came off a marine application, so I'm assuming there is a difference in the marine heads???

 

Mike

[Mike C]

It sounds like you have an 87 and newer intake manifold. Or 87 and up heads, but most likely the intake. What year was the boat? My 94 Malibu has the angle bolt GM cast iron high rise intake. They changed the bolt angle on the SBC engines, except for the L98s with aluminium heads which kept the old pattern through end of production, this includes the L98 headed crate motors as well. It is possible to slot the center bolts then make some tapered washers to evenly clamp down on the intake. Some aftermarket intakes ship with fasteners for this purpose, you might can order from Edelbrock or Holley.

 

You are putting together a hydraulic tappet valvetrain? Have you read David Vizards method of lashing the valve train to eliminate lifter pump up? Other than that, the method you described is how I do mine, but I only use 1/4 turn initially. Then relash to zero clatter plus 1/4 turn with the engine hot and running.

[pparaska]

Mikelly,

I agree with no more than 1/4 turn, especially - while prelubing the engine.

 

Grumpyvette has often posted how to prelube, break-in, etc. My experience is that you should leave the lash at 1/4 turn or less (when the cam is on the base circle) while turning the engine every once and a while when running the prelube/drill motor. That way all the lifters can get oiled through the lifter bore oil passages. If you turn them down to 1 turn below zero lash, the lifter may pump up after startup.

 

When I've run hydraulic cams on the SBC, I used to run 1/8 or 1/4 turn after "clicking" while idling. This allows for more top end, since the lifter can't pump up as much as if you turn the adjusting nut 1/2 or 1 turn after the valvetrain "clicks" while idling.

[waynekarnes]

as far as the intake is concerned. i was toying with the idea of using TPI on my 73 350. i was told that on the older heads, just elongate the center hole in the manifold and then the newer manifold would fit the older heads.

 

this may be all you need do to fit your existing manifold.

 

wayne

[Mike C]

The 85-86 305 and 350 tpi units are the old style bolt pattern. All of the Corvetter TPI's were the old style pattern. Only the 87-92 cast iron head TPI manifolds have the new style pattern. But you are correct, they can be elongated. But it helps to have the bolt head apply pressure evenly to the manifold, that is the purpose of the angled washers.