Pushrod damage or more...? 289 mild

[DD (CA)]

newbie status here...

Thanks for your responses Gaz and Doc.

Rods: Standard Comp(?). Did not seem bent (table test).
Ends: All at rocker arms side, some at both ends
Lube: Break in JGibbs BR oil. Amount... dunno, when motor was running, it flicked oil at us at idle, think every arm working. But, its something I would have looked at more closely. Pressure 50-60 always.
Spin: We checked spin at rest, but not during running motor. And then after lock down, not sure we monitored.
Lifters: Buttom surface still convex, smooth, no real notice of wear.
Nuts: Were lock nuts, changed to polylocks. Polylocks not backed off.
Head: Slot (no guides needed)

So, mech replaced lifters and rods, sent me on my way. I'm now reading about break-in, when using new lifters and old (<300m) cam. I'm anxious... Mech talked me out of it. So, even though may be "too late," may drain and replace with BR oil, run 2000-2500 at 20mins, and see.

Other tips idea really welcomed, thanks.

DD (CA)

[Gaz64]

Did your mechanic use cam lobe lifter lube on assembly, both times?

Did he run the engine at 2000 rpm for 20 minutes?

How much lifter preload, about 1/2 turn after zero lash?

[DD (CA)]

Hopefully he wasn't only using on me.... I digress...

yes. used at least THIS time, I saw on faces of lifters.

Locked at ~1/2 turn after zero turn of pushrods (not solid lifters, so no lash).

NOT run in at 20min this time.... I drove it. City drive; variable rpm, but mostly around 2000-2500 at 40mph for at least 20 min. Expressway allowed that. I babied it. Still may have done damage; TBD.

Its certainly quieter, but there's a history here, and I sense it may be repeating soon... But, wondering if I should dump oil (retain some for readings), put break in oil back in, run stationary cam break in procedure, then drive. At this point, I think I have to drive, I'll get into full rebuild history later. (NOS service block; gone through, etc, etc)

DD (CA)

[Gaz64]

Well, that sounds like a mistake on his part.

Any new flat tappet cam, needs to start up instantly, and be held above idle speed, about 2000 rpm to run-in the cam lifter surfaces.

Any idling is a no-no.

Sounds like he needs to do some more study on current aftermarket flat tappet cams, and the necessary procedures.

I would reassess the pushrod rotation while the engine is running, as a start.

A sample of oil for analysis is a good idea.

Gary

[Three Peaks]

Sounds like most of the usual culprits were already mentioned above. So, a couple rare issues that may come up and things to check-
What type of rocker arm mounts do you have? Pedestal or stud? If you are running aluminum heads, it is possible that the studs are pulling out of the head slowly. Not a common issue, but I've heard it happens.

Check your rocker tips for wear. I have the Comp Pro magnums on my 393 mainly because I had heard instances like yours of the tips on some of the Mag tips having issues on a couple car forums. No way to tell how accurate these reports are, but your wear pattern on the rod end is suspect at the least.

Overly heavy springs for the purpose could also cause some of the rod problems you are having. Did you check if your springs are suitable for the purpose? Proper seat pressure, no spring bind when loaded, installed properly?

Last thing for now- as mentioned above it sounds vaguely like a cam losing lobes. Take a micrometer and set it up on your head on each valve rocker to read at the rod lobe and run the engine through a rotation. Record this for each lobe (16). Hopefully, you know what the lift is supposed to be so you can check your results against the Cam card. If not, at the least comparing each measurement to the others, a few will pop out as being out of a reasonable amount of variance.

That should keep you busy for a while. Once you've checked out all the ideas above and this one, at the very least you should have an idea where this is headed.

Bob

[Texasdoc]

Originally Posted by Three Peaks

Overly heavy springs for the purpose could also cause some of the rod problems you are having. Did you check if your springs are suitable for the purpose? Proper seat pressure, no spring bind when loaded, installed properly?

This.

Most (a lot anyway) aftermarket heads seems to have springs for rollers, not tappets. Roller springs are generally too heavy for flat tappets. If you have two springs per valve (inner and outer), take the inner spring out for the break in procedure.

Even if you did everything right, you can wipe a cam lobe with ease.

[DD (CA)]

With massaged porting and screw in studs. So, the aftermarket Al head idea doesn't fly...

FWIW, Comp and Crower both pretty firm on "break in procedure" after new lifters / old cam, but I've also been reading some pretty astute counter arguments from HAMB, Z28 and hotrods sites.

Also informed me it was worthless to undergo break in now that I've driven it for a bit....

I'm torn a bit. Babied the thing so far, but if the rocker arms get loose again...

[jhv48]

FWIW, my cam was from Crower. But that was a long time ago.