[straycat]

Friend installed new cam and lifters in motor he's building. 421 with SD980 heads. Installed a new RA4 cam w/Rhoads lifters. He used break in lube and oil. After start up he noticed 4 push rods on cylinders 1-3-5-7 not turning. Upon looking at the base of those 4 lifters the wear pattern showed they are not turning/spinning. The lifters move freely in their bores, then swapped non turning lifter with one turning and same result. Tried different cam and lifters and same result. The push rods turn freely plenty of clearance with guide plates. He doesn't want to run the motor this way with the fear of ruining the cam. Any suggestions why these 4 don't turn.

[tom s]

They should spin or failure will follow.Tom

[Sirrotica]

Here is a link to why you can wipe cam lobes because of incorrect initial machining of the lifter bores, or worn bores in the block.

There are also some situations where a roller lifter formerly run in a block will cause a problem switching back to a flat tappet lifter.

https://www.motortrend.com/how-to/ch...-lifter-bores/

I actually have never run into the problem you're describing, but there are some subjects where others have run into it. Recently I read that just by blueprinting a SBC lifter bores and sleeving them into the correct position with boring and sleeving them could account for a 20 HP power increase. So yes, they can be incorrect from day one when the block was originally machined, and they do wear out.

Hopefully there is something in the link I posted, that will help your friend out with the problem he's encountering.

[25stevem]

I bet those 4 lifters are rocking in there bore.

[jhein]

My bet's on lifter bores too.

[dataway]

Good article, just the method I used to check the cam and lifters.

In my opinion the vast majority of current slew of HFT failures are due to improper lobe/lifter contact caused by poor component machining, or thousand and thousands of people putting new components in 50 year old blocks with worn lifter bores. Not the oil, not bad materials.

[242177P]

Originally Posted by straycat

After start up he noticed 4 push rods on cylinders 1-3-5-7 not turning.

Think of an individual cam lobe as kind of like a roadway. With roads, there's usually a gentle crown down the center, keeps water from pooling. But with a cam lobe, this crown is offset to one side. And it is paired with a small convex face on the lifters (two new ones face to face will rock slightly if you want to feel it). This is what provides the spin. A new cam could conceivably spin a perfectly flat faced lifter, but it would never work the other way around. Break-in has failed.

All the bad lobes were only on one bank. Weird.

[Cliff R]

What method of testing is being used to determine if they are turning or not?

Are you running the engine at idle speed and have the visible part of the pushrods below the rockers painted with a white or yellow line so you can see them spinning?........

[mgarblik]

Using a dial bore gauge to measure lifter bores is expensive, (if you buy the gauge) and difficult to use sometimes. I purchased a couple precision plug gauges from McMaster Carr to make a set of GO-NOGO gauges. When a lifter bore will let a .845 gauge fall right through, you need a bushing or a new block. .003 clearance or more, your in trouble.

[straycat]

To answer Cliff the motor was run at or above idle speed, I will have to ask. Old valve covers had sides opened up to look in. I believe the lifter bores measured .002 clearance. Yes its a 65 or 66 block.

[tom s]

the last 2 HFT cams I used.the lifters would spin without even firing them up.Intake and valley cover off and just tuning the engine over I could see all lifters turning in the bores.One 4 cyc engine with a reground factory cam and factory springs and a 421 with a 068 and factory springs.The fact with very low spring rates allowed them to start.Both engines had NOS GM lifters.FWIW,Tom

[Singleton]

The fact that you tried a different cam and lifters with the same results clearly points to a problem with those four lifter bores

[25stevem]

I agree full with the above just like I posted earlier.
You need to measure the lifter bores at the top and bottom at two different points on there circumference.

Then you might find that the .002” turns to over .003” in one area.

It might also be that those lifters where not faced right from the get go and now, unfortunately yes those 4 lobes are shot.

[Sirrotica]

Just a WAG, that because the problem is with one bank, and every lifter on that bank is affected, the axis was incorrect when it was originally machined. If that is the case then that entire bank would need to be rebored on the correct axis and sleeved. The other option would be to go to oversized lifters when the bores were redone.

If that is found to be the problem, there is no cheap or easy fix, gonna be fairly expensive to repair something like this. It's not going to be an operation that any machine shop would perform, it would be somewhat specialized. Being it is a weak point in Pontiac casting to begin with, taking more material out of the lifter area might not be the best choice, looking for another block may be the most cost effective repair.

[turbo69bird]

Yeah so if new cam and lifters were tried w same result, and a turning lifter from the other side doesn’t turn. Then it’s got to be the block.
Did the new cam and lifters work on the other side? So it was the exact same result? If so then yeah gotta be the lifter bores. I’ve never had this happen and I’ve used a block w some previously pretty rusty lifter bores w /o sleeving the bores because I needed to get to a certain race and there wasn’t time , so this surprises me. Sucks to have to take it apart to sleeve the bores but what are you gonna do.

Keep us updated on the fox please when it works out because this is good info, if it’s definitive.

[Formulas]

i personally do not like the current method of shake and bake block cleaning

steel medium vibrating on all surfaces, some surfaces get re'machined some dont like cam bores main saddles and lifter bores

you can argue that that style cleaning done properly induces very little wear but it does no good to critical machined surfaces and not everything gets done properly

[1968GTO421]

While all the posts about "soft" cams and "soft" lifters are definitely things to pay attention to, I suspect that this problem (worn out lifter bores) is certainly an area of the build for us to pay aattention to.

("Soft" referring not only to materials but sorry machine work in the manufacturing of these parts.)

[Schurkey]

Originally Posted by tom s

the last 2 HFT cams I used.the lifters would spin without even firing them up.Intake and valley cover off and just tuning the engine over I could see all lifters turning in the bores.

I don't build a lot of engines, and it's been years since I've used a flat-tappet cam.

When I did, though, the FIRST thing that went in the block aside from cam bearings...was the cam. And then I'd "trial-fit" the lifters. Wipe the lifter bores and lifters with ATF, set 'em in place. Mark the top edge of the lifter, and the lifter bore with a Sharpie.

Then roll the cam over by hand--turning the cam gear with a finger or two, while watching the Sharpie mark on the lifter as it spins away from, and then back around to, the Sharpie mark on the lifter bore.

Some lifters turn faster than others, but they should all turn. For me, they always have spun. Then the lifters come back out, in order, while the rest of the short-block is put together.

Not that it matters on a Pontiac forum, but the Buick Nailhead V8 from '51(?) to '65, is not designed to spin the lifters. There's no taper on the cam lobes, there's no crown on the lifter body, and there's no offset of the lifter bores from the cam lobe. Some Nailheads will spin a lifter, but that's more "accident" than intentional.

Originally Posted by Formulas

i personally do not like the current method of shake and bake block cleaning

steel medium vibrating on all surfaces, some surfaces get re'machined some dont like cam bores main saddles and lifter bores

you can argue that that style cleaning done properly induces very little wear but it does no good to critical machined surfaces and not everything gets done properly

I ask that the shot-blasting be done with the old bearings still in place. The shot can beat-up the old cam bearings, the old main bearings, (if the block isn't going to be align-honed) and the old rod bearings (if the rods aren't going to be resized.) The bearings are disposable by that time, they might as well protect the saddles they ride on.

Some guys pound a cork or rubber stopper into each lifter bore. As long as the cork doesn't get dislodged in the process, seems like a good idea to me.

[mgarblik]

This may sound like a radical and expensive way to fix your engine........but a hydraulic or solid roller cam would solve this problem. Less expensive than a complete tear down and lifter bushings or a new block. Probably about $1200.00-1500.00. Cam, lifters, valve springs, distributor gear. All could be done in the car. Probably make a little more power too.

[tom s]

Just a left fiend question.Is the block a 421 SD block?Remember those blocks and heads were designed for solid lifter cams and lifters that had a pin hole oil hole to restrict the oil to the top of the engine?Paper work for the factory was to keep a high idles,over 1000.Could the lifter bores been allowed to wear more than normal?980s were never designed for hyd lifters.Tom