[Jimbobeast]

Geometry is the name of the game. I suspect the valves may be longer than stock. Heads come off tomorrow and then we start from scratch.
I never liked Geometry in school.

[Skip Fix]

That sounds like a good plan. That way you know what you have. Get a cheap Spring Height gauge from Summit also so you know where that is. And measure spring pressure on ANY spring as they often are not what they are spec'd at.

[chuckies76ta]

A video for you. https://www.youtube.com/watch?v=MqIAdbKJTlA

Info on P/Y. https://forums.maxperformanceinc.com...d.php?t=877674

[Jimbobeast]

So the heads have been disassembled. The inner Comp Cam spring did not fit over the boss in the head where the valve comes through and was sitting roughly 1/4" above the outer spring, thus dramatically increasing the seat pressure to 180 range (not the 110-115 recommended) and wiping the cam and messing up my pushrods. The boss will be milled and the new springs installed to 1.8" as Butler recommends. The geometry will be rechecked but it looks ok with the roller tip on the center of the valve stem throughout the lift range of movement. The pushrod length will be checked and hopefully I can use the stock units. Or not.

The boss is the area just below the valve seal (also to be replaced with Viton units) and measures 0.785". The inner diameter of the inner valve springs is only
0.750.

[PAUL K]

Well there you have it.... Thanks for the update


I'd guess the inner springs were "coil binding" and that caused the pushrods to fail.

[steve25]

Well like Paul said there ya have it, your root cause.

Actually I am surprised you even got to drive / run the motor for 2 miles before the failure!

Look at the bright side.

Had this happen at high rpm a lifter would have got kicked out and you would have lost oil pressure and then had even bigger problems.

[chuckies76ta]

The boss will be milled and the new springs installed to 1.8" as Butler recommends.

Unbelievable that someone doing your heads messed that up. I don't know enough about springs, but wondering why they would have used a double spring with damper. What new springs are you going with?

[67Fbird]

even though you are all stock configuration it would be wise to take A valve keeper and set of locks to the shop with your heads to verify your keepers do not bottom out on your NEW viton seals after machining.
BALL HIEGTH measurement of the lifters refers to the dimensioin from the LIFTER FACE ---- a BALL placed on the lifter plunger. This is to help you determine how tall or short the dim is for pushrod length comparison. As you can see the RAIV lifter has a decreased BALL height compared to NON RAIV lifters AND a shorter plunger travel (to prevent lifter pump-up) which ALSO tells us the lash setting would be more touchy. .050 vs .0125 as the rocker studs are 20 tpi so you only get a TOTAL of 3/4 turn on the rocker nut befor you BOTTOM out the lifter plunger. Hence ZERO + 1/2 turn is cutting it close.

[67Fbird]

a little bit different than teh 1991 version Crane sold.

[steve25]

In a friendly way I would like to ask you to use the right terminology.

There’s no such thing as a lash setting with a hydro cam unless you intentionally put some in , which by the way can only safely be done if the lifter is of the type with a C clip to hold the plunger in place.

With 1.8” installed height that the OP has and his cams .520” lift there is really no likelihood that the retainer will hit the top of the valve seal, in fact in his photo you can see that such was not taking place.

[Skip Fix]

There’s no such thing as a lash setting with a hydro cam unless you intentionally put some in , which by the way can only safely be done if the lifter is of the type with a C clip to hold the plunger in place.

But Comp did in fact market a 0 lash HFT lifter! Thye had a bulkier 1 way "clip" kind of like my old SpeedPro H lifters did 951R ?

[steve25]

Don’t you think that comp cams and yourself are splitting hairs here?
Lash is clearance, period.

Look up the definition.

A zero setting is not lash, at least not to me.

[PAUL K]

Originally Posted by Skip Fix

There’s no such thing as a lash setting with a hydro cam unless you intentionally put some in , which by the way can only safely be done if the lifter is of the type with a C clip to hold the plunger in place.

But Comp did in fact market a 0 lash HFT lifter! Thye had a bulkier 1 way "clip" kind of like my old SpeedPro H lifters did 951R ?

I think it was actually .000 to .002 I remember those lifters. They worked well and would RPM like a solid. I believe they came with washers to use under the rocker stud and self locking adjustment nuts.

[Kenth]

Originally Posted by Jimbobeast

So the heads have been disassembled. The inner Comp Cam spring did not fit over the boss in the head where the valve comes through and was sitting roughly 1/4" above the outer spring, thus dramatically increasing the seat pressure to 180 range (not the 110-115 recommended) and wiping the cam and messing up my pushrods. The boss will be milled and the new springs installed to 1.8" as Butler recommends. The geometry will be rechecked but it looks ok with the roller tip on the center of the valve stem throughout the lift range of movement. The pushrod length will be checked and hopefully I can use the stock units. Or not.

The boss is the area just below the valve seal (also to be replaced with Viton units) and measures 0.785". The inner diameter of the inner valve springs is only
0.750.

There is a set of OEM replacement RAIV valve springs on ebay.
You don't need to modify your original heads with these TRW VS952 springs.
They will fit as intended unlike the CompCrap springs.

HTH

[steve25]

All I mean to say is that with a hydro cam I think the term zero preload makes more sense then zero lash.

[67Fbird]

when you PRELOAD the lifter to accomplish a ZERO LASH setting.

Fixed it!

[PAUL K]

Originally Posted by 67Fbird

when you PRELOAD the lifter to accomplish a ZERO LASH setting.

Fixed it!

Lol...... I prefer the 1/4 turn , 1/8 turn, 3/4 turn terminology


It gets real complicated when you have the HR cam with SR lifters using an aluminum block and heads. You want about .004 clearance hot and everything expands about .010.

[Skip Fix]

Originally Posted by PAUL K

I think it was actually .000 to .002 I remember those lifters. They worked well and would RPM like a solid. I believe they came with washers to use under the rocker stud and self locking adjustment nuts.

Yes they said zero to 0.003. I ran 0 when I tried them. I forgot which cam in the RAIV 400 I ran them on I think the UD 304/312 after I got tired of the noise of the Rhoads! Also the Rhoads bled down(as they are supposed to) so the rocker would be loose when I was checking all the cylinders . So I was never positive I had really set that cylinder and have to do it again!
So I agree Steve if running 0, 0 preload is as good a description.

[Jimbobeast]

Originally Posted by Kenth

There is a set of OEM replacement RAIV valve springs on ebay.
You don't need to modify your original heads with these TRW VS952 springs.
They will fit as intended unlike the CompCrap springs.

HTH

Already mostly done. My neighbor has a racing transmission business and is himself a drag racer (and winner) for over 30 years. Taking 0.035 off the boss is easy (or so he says). He has a cutter made for just that purpose. Following that we will shim the springs to get 1.80" installed height, check the seat pressure and the pressure at full lift, then assess the valvetrain for geometrical symmetry and figure out the proper pushrod length. If all this does not work I'll put a small block chevy in. Just kidding.

[Jimbobeast]

I knew Dave and Johnny Yow well when they owned/operated Yow's Auto Machine Shop here in Bradenton, Florida. Great guys. They were true blue (no pun intended) Pontiac racers since the 60's and had done the machine work and head assembly on 5 previous motors of mine, including another RAIV, all without incident, over a span of 25 years. Sadly, they and the business have long ago passed. I can only think that they told some shop worker to put the springs on this motor and he did not have the experience/knowledge to appreciate the problem. For that matter, even Butler Performance never said anything about machining the heads to make the springs fit. I will be speaking with their tech guys in the next few days and we will see what they say.
I'm going to Mecum in Kissimmee on Thursday. I was hoping to have this car at the auction but I guess I was meant to drive and show it for another year first. Things always work out.