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Discussion Starter · #1 · (Edited)
i've got some strange markings on one of the lifters in my pontiac 400.
the bottom one in this pic looks different than the other 15.
the wear pattern is longer and there is a slight rifling on it, almost like it's ribbed.
it mic's the same as the rest.

WHAT IS THIS FROM?

p.s.
this is in a mild 400 build.
30 over
rv cam about 218 deg and .458 lift. or so
roughly 10-12k miles

i have some lift noise in the motor when the motor is coming down off the revs and only at about 1000rpm.

IMG_5776.jpg
 

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steelcomp was here
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i've got some strange markings on one of the lifters in my pontiac 400.
the bottom one in this pic looks different than the other 15.
the wear pattern is longer and there is a slight rifling on it, almost like it's ribbed.
it mic's the same as the rest.

WHAT IS THIS FROM?

p.s.
this is in a mild 400 build.
30 over
rv cam about 218 deg and .458 lift. or so
roughly 10-12k miles

i have some lift noise in the motor when the motor is coming down off the revs and only at about 1000rpm.

View attachment 168986
The "ribbing" is just the machining on the lifter. The difference in the contact area (shiney part) is just the difference in the lifter bore diameters. We're talking less than a thousandth of an inch here.
Lifter noises..."tic tic tic" are usually an oil pressure issue.
 

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Discussion Starter · #3 ·
The "ribbing" is just the machining on the lifter. The difference in the contact area (shiney part) is just the difference in the lifter bore diameters. We're talking less than a thousandth of an inch here.
Lifter noises..."tic tic tic" are usually an oil pressure issue.

by lifter bore diameter, do you mean the bore depth?

also how do i diagnose the oil pressure issue?
 

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Or Seth, either one
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I had to blow it up a bit to really see what you're talking about. I haven't seen a million lifters, but I also haven't seen one like that before. Odd that it is not the same as the other 15.

lifters.jpg
 

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Centerless ground..

Looks like the grinder picked up a chip and the operator didn't catch it.... Not a big deal unless it has "highs" associated with the grooves.....OR, it was cut undersize in the "rough" form, and the centerless grinder didn't clean it up.... Those things are mass produced, spit out of machine, (raw) at more than 4 a minute.... ID, OD, grooves, collars etc etc, and cut off to go to the next production step.....After heat treat, the OD is centerless ground to finish size, (+/-.0001-.0002), and the ID is cut to size using diamond impregnated inserts to less than .0001 error... In 5 + years I probably made 10-20,000 lifters..... Roller "tappets" for Harleys, but a lifter is a lifter....

Ray
 

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I had to blow it up a bit to really see what you're talking about. I haven't seen a million lifters, but I also haven't seen one like that before. Odd that it is not the same as the other 15.

View attachment 169008
If you look those same marks exist in the unworn area of the lifter as well. Up towards the top of the lifter. Very faint, but the same marks. Running and "polishing" the lifter just makes them stand out more. Like Moneypits said, its in the machining of the lifter, not the running.



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I hate posting in this section but for another pontiac enthusist I will

my pontiac 400.
i have some lifter noise in the motor when the motor is coming down off the revs and only at about 1000rpm.

View attachment 168986
Is this after a hard run or all the time? Are you running the stock rocker studs that bottom out or adjustable? Did you measure for proper length pushrods during the build? I've seen loose clearances coupled with poor valve train geometry and poor quality lifters create "the clack" after hard runs, then goes away once the oil cools down a bit. Whats the oil psi when they are clacking, if it's low It could be the oil is getting hot and you are possibly getting collapsed lifters. Noisy lifters can be caused by a few events. Some noise might be considered normal.
There is information missing in your post. Mild cam specs. and 4.151" bore are not much to go on.

Few on this board are real familiar with Ponchos so it is always cool to read about something besides Olds, BBC and BBF.

There is a very informed guy on this board with the user name Steve Barcak who eats, sleeps, lives and dreams Pontiac. His resources extend into the largest Pontiac pool known to mankind. :))THumbsUp Perhaps he will see this, or if not, a PM to him could get you on the right Wide Track if your issue cannot become resolved.
 

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To Worry, or not to worry?

ok.
so not to worry?
Well, in my opinion, things like this depend on how much money a person is willing to spend to prevent "possible" failure. I have been a Pontiac 400 owner for about 14 years now, and have torn my motor down four times, and at least half a dozen others. But, this definitely does not mean that I am a Pontiac expert by any means though, so this is my "What I would do" response. I have been a master mechanic for almost ten years though, so I do have more than enough professional back ground to not lead you in a direction that will end in disaster. If anyone wants to post to agree or make suggestions to my response, feel free - no good mechanic wants to go uncorrected!

So, first I would decide what kind of operation I would be doing with the motor, how long I wanted to keep the car, and how much money I wanted to invest. To me, this looks like a very minor factory defect. I would agree with Moneypit and Seelcomp - its probably machining. From your picture, these lifters look like they are (just a guess by side appearance) speed-pro hi rev lifters. I have had nothing but great experience with these lifters. They are not the best out there, but they are the best for your money in my opinion, and they don't float at almost 6K RPM! The other thing I am noticing in the picture is that the lifters have a lot of dings in them. It might just be dirt, but if it is not smooth I would replace them.

Pontiac blocks are also prone to kicking off a chunk of the lifter bore during lifter failure and dropping it in the rotating assembly "downstairs." This would be bad news - not only would you have to replace or repair the block, but there is little chance any of the parts will end up salvageable for anything more than scrap metal. That being said, my 400 had around 160,000 miles on it at purchase/rebuild. The lifters had cupped into the cam lobes, and I had to heat the block to get the lifters out of their bores because of the lip that had been worn in both the top and bottom stroke of the lifters.

Under correct operating conditions, lifter bores and lifter sides should not see any more force under high engine load than under normal engine load. The biggest thing to worry about is high RPM, valvetrain geometry, cam lift, spring tension and lubrication. The symptom you mentioned about ticking after coming down from high RPMs sounds like a lube issue to me. I have seen this type of thing on other modified motors (non-Pontiac), and it is often related to the oil capacity of the engine. When you bring an engine up in speed, it pumps more oil, and it takes this oil time to fall back to the pan, when the engine is still turning, it slows this process even more, causing potential drops in oil pressure. Believe it or not, this symptom can increase when running a high volume or high pressure oil pump because more oil flow equates to lower oil levels in the pan. Some easy things that combat this are a deeper oil pan, slightly overfilling the crankcase, boring the lube return channels, orificing the oil pressure channels, knife edging the crank, installing a windage tray, installing a crank scraper, using a dry sump lube system, and polishing the interior engine surfaces. Low oil pressure is usually first "heard" in the lifters long before damage occurs anywhere in the engine. I would start by clearancing the cam bearings, since this is about the only place that pressure can be lost without causing additional noises. Its also not uncommon to find over-clearanced cam bearings in all types of older OHV GM V-8s. One easy, but not always accurate tell tale is the distributor gear. Pull the distributor and look for gooving or "apple coring" on the gear face. This is almost always related to cam bearings if the distributor bushings are tight.

To make a long story short, it looks like the problem is with the lifter itself, and under normal conditions, it should not be a problem. But, to err on the side of caution is important with Pontiac lifters. If only one is like that, then it is undoubtedly deficient from the others. I would replace the lifter, and make note of which bore it came out of, checking that one again next time I had it open. That is what I would do now, but if I had a money tree in my back yard, I would install a lifter bore support bracket, bronze lifter bore sleeves, and a brand new set of High performance roller lifters :'D

Good Luck!
 

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Marks are from being made on a screw machine ( retreat marks) .the lifter was cut under size. Did not clean up during centerless grinding... Poor Quality Control.....I think it would cut the lifter bore like a fine file...
 

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Marks are from being made on a screw machine ( retreat marks) .the lifter was cut under size. Did not clean up during centerless grinding... Poor Quality Control.....I think it would cut the lifter bore like a fine file...
fine file that wouldn't be equal to ultra fine emery paper 1000 grit no problem at all. remember the motor has oil in it.
 

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fine file that wouldn't be equal to ultra fine emery paper 1000 grit no problem at all. remember the motor has oil in it.
EXACTLY. Either the thing was cut slightly deeper on the screw machine, or ground sligthly less in the centerless grinder, either way, its been ground flat on the "threads". I doubt you could feel that with your finger nail. You couldn't file the edge of a credit card with that thing, let alone an oiled lifter bore.



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