[Jimbobeast]

Originally Posted by johnta1

!st thing is check that the push rods are not hitting/rubbing anything all through its travel up and down. (pushrod guide should just be wider than pushrod and the closed end of the guide should not hit the push rod at all)

2nd thing is check that the rockers are not hitting /rubbing anything except the push rod cavity for the push rod ball and the end of roller does not touch anything except the valve tip. (roller doesn't run off end of tip of valve, etc)

If it was mine I probably would have bought chromoly push rods that has no balls on it.

It all looks good, John, I can't see any rubbing or witness marks on the pushrods. The rockers also appear to have no interference.
First thing to recheck will be the open pressure, then I'm going to re-adjust (if possible) the pushrod guide plates to get the closed end of the opening as far from the pushrod as possible.
After removing all the pushrods, 3 balls had fallen out and almost all showed visible signs of the balls being crammed down ointo the shafts. This has been the same on all 3 sets of stock pushrods (again, 11/32, 9.2" which came stock on the RAIV). All are breaking at the rocker end. If it was too much spring pressure then at least one of these 48 rods would show damage at the lifter end, right? To my thinking, something is happening between the guide plate and the rocker arm pushrod seat. Could the geometry be off and the rockers torqueing the top of the pushrods against the guides at full lift? Remember, this motor has not seen 2000 RPM and these pushrods are disintegrating after 15 moinutes of break in.
I'm also going to remove the plugs and slowly turn the motor by hand and carefully watch pushrod and rocker travel. I will probably just go back to a stamped steel 1.65 rocker, since the only thing unchanged through three broken pushrod cycles are the rockers.
I've ordered chromoly pushrods but I'm afraid the cam will get wiped if the original pushrod material is not the problem.

[Jimbobeast]

Originally Posted by turbo69bird

Did the machine shop assemble this engine with the inner springs binding? If so I’d pull that whole engine apart and check EVERYTHING. If they couldn’t catch that on assembly they shouldn’t be in the machine shop business .
That being said . Take the good push rods from another cyl and put them together on those two cylinders and crank the engine over and watch the push rods and rockers for it to destroy the push rods something is big time wrong I’d expect you’d be able to see it.

I feel for you my friend sucks when stuff like this creeps up.
But I don’t wanna see you throw a rod because the machine shop didn’t dot its I s and cross its T s. As much as it sucks at this point, id be tearing that thing down completely and starting over, Because I wouldn’t trust their work

I understand and agree. I'm not sure the coils were binding, but the spring pressure was certainly way too much, and I thought that we had found and solved the problem, but obviously that was not it (or not the major part).
As previously stated, that machine shop closed its doors 10+ years ago and the owners/machinists (I knew them personally - good guys) are all deceased. In their defense they machined 5 other engines for me over the years (and assembled the heads) without problems.
And yeah, it sucks. I had planned on selling this car at Mecum Kissimmee in January and I was right on track until this happened. Oh well, we press on.

[Jimbobeast]

Originally Posted by b-man

Rocker arm slots hitting the rocker studs at full lift?

Are you still using the Comp roller tip arms or did you switch to Comp full roller rockers?

These Comp Cam roller tip rockers have a longer slot than the stock stamped steel units but that would make great sense in explaining the pushrod failure. Maybe full rollers are in my near future.

[Jimbobeast]

Originally Posted by chuckies76ta

Sounds like those pushrods must be binding in the heads. Something is binding. Like mentioned put it together spin it over by hand and check valve train. I have a set of 5/16" x .116 one piece Smith brothers pushrods here if interested. They have been used for a season here. Still perfect shape. The length is 9.300" I also have a set of full PRW roller rockers 1.5 Ratio with poly locks you could try. Nothing wrong with them.
Something you could try is to install just the pushrods and rockers on the cylinders that are causing the breakage. Leave all the other pushrods and rockers off. Remove the spark plugs to let the combustion air out of the cylinders while you turn it over. Check them for any visible binding.

Yes, Chuck, that is what I'm going to do next. I would take you up on the offer but this motor takes 1.65 rockers. If I went to 1.5 rockers on a RAIV engine, what would be different, except less lift and HP?

[steve25]

Chuck the RA4 guide plates take bigger 11/32" push Rods so he would have to swap out the guide plates also.

[SD455DJ]

Originally Posted by Jimbobeast

These Comp Cam roller tip rockers have a longer slot than the stock stamped steel units but that would make great sense in explaining the pushrod failure. Maybe full rollers are in my near future.

I agree with B-man. I wonder if the pivot slots weren't machined correctly and are colliding with the rocker stud nearing full lift. I would inspect the suspect rocker arm slots with others that aren't causing the problem. Also check the studs for any witness marks too.

I certainly feel for you man!

Dennis

[chuckies76ta]

The O/P could take one of those 11/32" push rods to a machine shop and have them tested to see how much pressure/force it takes to push the ball into the push-rod. That would defiantly something I would want to know. Now, that you know your open and closed spring pressures, you can kinda work backwards to see what is binding. Hell, he can run the engine with just the outer springs installed to break in the cam. Great time to make sure there is no coil bind on springs. Can you put a feeler gauge in between the springs coils at full lift?

[AG]

Ditch the ball tipped PRs and get one piece.

[Jimbobeast]

Originally Posted by AG

Ditch the ball tipped PRs and get one piece.

Should be here tomorrow

[Jimbobeast]

Originally Posted by chuckies76ta

The O/P could take one of those 11/32" push rods to a machine shop and have them tested to see how much pressure/force it takes to push the ball into the push-rod. That would defiantly something I would want to know. Now, that you know your open and closed spring pressures, you can kinda work backwards to see what is binding. Hell, he can run the engine with just the outer springs installed to break in the cam. Great time to make sure there is no coil bind on springs. Can you put a feeler gauge in between the springs coils at full lift?

Yes, they are not even close to touching

[Jimbobeast]

Originally Posted by SD455DJ

I agree with B-man. I wonder if the pivot slots weren't machined correctly and are colliding with the rocker stud nearing full lift. I would inspect the suspect rocker arm slots with others that aren't causing the problem. Also check the studs for any witness marks too.

I certainly feel for you man!

Dennis

Oriignal stamped steel rockers ordered from Butler this morning along with new grooved balls. The pockets in the Comp Cam roller tip rockers that hold the pushrod tip are much deeper than the stamped steel units and maybe that is causing some binding or pressure but from the way all the pushrods are starting to flare out it seems that a longitudinal force is at play. Rockers binding makes the most sense.
In any case, I did not order these Comp Cam rockers. Maybe they are not correct for a pontiac? I am just eliminating all variables.

[steve25]

So what are you saying here?

You today ordered from Butler Pontiac style stock steel 1.65 rockers?

[Jimbobeast]

Originally Posted by steve25

So what are you saying here?

You today ordered from Butler Pontiac style stock steel 1.65 rockers?

Yup.

[Jimbobeast]

OK, I'm cautiously optimistic that I may have found the source of the problem. As stated above, the only constant feature through 3 sets of pushrods was the rocker arms. They are indeed Comp Cam roller tip 1.65 ratio, but they were supplied by the already suspect defunct machine shop. In comparing the Comp cam units to stock stamped steel OEM rockers, the pushrod makes contact with the body of the rocker at minimal movement (see photos). The cup for the pushrod ball is also way deeper and would hold the pushrod tighter causing the rocker end of the pushrod to break. Maybe these are not even Pontiac rockers? There are definite witness marks on every one of the rocker bodies where the pushrod would make contact through the valvetrain rotation. I just was not looking in that spot before. Whaddya think?

In photo 1 the OEM unit is on the left, showing the range of motion (rocking) before the pushrod contacts the body of the rocker.
Photos 2 and 3 further demonstrate my point, #2 is the OEM unit. See how far it can rock before contact occurs?
Photo 4 shows the witness marks from the pushrods.
Photo 5 shows the depth of the pushrod "cup" but more importantly shows how close the rocker body comes to the pushrod cup (left) compared to the OEM stamped steel unit.

[steve25]

You found your problem!

I am surprised you did not have many more push rods break!

Here’s the difference in the factory rockers between 1.5 and 1.65.

Also they might be 1.6 small block Ford rockers, and not Pontiac.

If they are not Ford rockers then they are made for 5/16” push rods and as you found out they can not be used with a true RA4 valvetrain and it’s 11/32” push rods.

[Jimbobeast]

So the difference in 1.5 and 1.65 rockers was to move the pushrod contact point closer to the pivot (center)?
These comp cam units are stamped 1.65

[steve25]

Yes, the higher the ratio the closer the push rod socket will be to the ball.

So they say 1.65 they are Pontiac then and simply .will not accept 11/32” push rods.

[johnta1]

So the difference in 1.5 and 1.65 rockers was to move the pushrod contact point closer to the pivot (center)?

Yes.

[Kenth]

Clearly NOT Pontiac 1.65 roller tip rockers.

[Jimbobeast]

I threw away the roller tip rockers and balls, got some simple Pontiac stamped steel 1.65 rockers and balls, another (the 4th) set of 11/32 pushrods and carefully assembled everything. No clearance issues. She started up and I ran her at 2000 RPM for 20 min (with fresh oil and ZDDP additive). Hmmm, running smoothly, no leaks, no smoke, no bad noises. I removed the valve covers and checked everything visually - "Look, Ma, no broken pushrods!" (see photo 1 and 2). The valvetrain looks happy all coated with glistening honey-colored oil. All is right in the world again. I consider this a great victory. The rest of the 1970 bits and bobs were added back on (hopefully for the last time). I have to admit I'm quite pleased with myself. It has been too long of a journey. Anyway, I'm putting the wrenches aside for a week and heading to my little cabin in the NW Georgia smokey mountains. Golf, fishing and relaxing. That's my story and I'm sticking to it.