[grivera]

Originally Posted by Sirrotica

FWIW, thinking about it last night, if the crank counter weight was interfering with the oil pump driveshaft, it would be timed with the timing chain and gears. The shaft would only hit at a specific time causing only a portion of the shaft to be polished, which it is only polished on one spot. It can't hit the counterweight for a full revolution as the counter weight is roughly flat on half 50% of the circle.

Now the driveshaft is turning at half the speed of the crank due to the 2 to 1 ratio of the timing chain, making the spot rubbing maybe 25% of the circumference of the driveshaft.

Going from memory, I seem to recall that could be what I saw when the shaft was photographed. I know it may be a long shot, but the known noise is somewhere in the drive of the distributor and oil pump area, and hitting the counterweight would make a noise that was intermittent each revolution of the crank. It would also explain the driveshaft only being polished in one spot. If the long shot I dreamed up is correct the interference would be very slight. I don't know if that crank residing in the engine presently is an aftermarket crank, (since its a 467 based on a 400 block it almost has to be) but we all know the chi coms have been known to manufacture parts without the utmost in quality control.

This may be something, or it may be nothing, I just want this to be put to bed. The oil pump shaft only being polished in a small area still sticks in my mind, and I think it is interfering with some other internal engine part that isn't stationary.

There you go, a possible cause, I could be totally wrong, but there is a small chance I could be right. If the oil pump shaft was put back together 180 degrees from where it was initially in this last disassembly, it should now have 2 polished spots on it, if it happened to be put back in the original position it would still only have one spot.

It would also explain why when replacing the oil pump and shaft in the first go around, the noise persisted. One other thing is an oil lite bushing is pretty benign due to it softer nature and for only being circulated for a minimal amount of time in the engine it seemed to do quite a bit of damage to wear surfaces, (bearings rings cylinder walls) usually reserved to steel or iron circulating through an engine, not oil lite bearing material.

Anyway something to check out, since the obvious things have mostly been checked out by this time.

I believe Paul used a factory 455 crank

[Sirrotica]

Then is this block not a 400, (I was under the impression it was a small journal block) it's a 455 large journal block? or is it a 400 block with the 455 crank mains cut?

I've never read that portion of it, or missed it, or forgot, one of the above.

[chiphead]

455 block with stock 455 crankshaft. I see it now, that's the counterweight passing under the cam every revolution. What if the counterweight is kissing the pump shaft or the bottom of the dizzy gear? Would that leave any witness marks? Since the driveshaft turns 1/2 as fast as the crank, the shaft should show two marks, maybe one worse than the other.

That is one thing I was worried about on my 434 stroker build. I'll post some pics I took of my build, to show how close those parts are. I took some good pics of the area when I mocked everything up.

[Sirrotica]

Yes it would, and the oil pump shaft has a polished or scratched portion only on one side, from the pictures shown in the past. I've always wondered why there is such an unusual section shiny only on one side of the pump driveshaft. There should also be marks on the counterweight if they were touching. However I've never seen any pictures of the rear of the counterweight, just the weird pattern of scratches on the black finished oil pump driveshaft.

But if it's a factory block with a factory crank, it lessens that my theory is correct. Pontiac was probably much closer in tolerances than aftermarket is. Maybe just a theory that has zero basis, but it sounded good given all the clues uncovered.

As the crank is running twice as fast, there would be 2 points on the oil pump shaft contacting the counterweight. The pattern is very strange I do remember that it started and stopped abruptly on the shaft. It always has stuck in my mind that it was a really strange wear pattern if it was from rubbing on the cast lug inside of the block the pattern should be all the way around the shaft, not starting and stopping.

If the pump shaft was a tiny bit oversized it could also cause it to hit the counterweight and make the noise.

[Sirrotica]

Thinking some more about it, if the short block was built, and the pump and shaft was in the block, rotating the assembly over without the distributor in the block wouldn't show contact with the counterweight either by rotating the assembly, and looking for a spot of binding visually, or going by feel for a point of resistance. Only when the distributor is installed and the oil pump shaft is centered would there be contact with the counterweight.

Depending upon how clean the used crankshaft counterweight was when assembled a witness mark could easily not be seen if there was only light contact.

The metal produced from contact would also explain why cylinder walls and main and rod journals might be damaged from a extremely low hour run time, requiring rings and bearings on the second build...….

[mgarblik]

Originally Posted by Sirrotica

Thinking some more about it, if the short block was built, and the pump and shaft was in the block, rotating the assembly over without the distributor in the block wouldn't show contact with the counterweight either by rotating the assembly, and looking for a spot of binding visually, or going by feel for a point of resistance. Only when the distributor is installed and the oil pump shaft is centered would there be contact with the counterweight.

Depending upon how clean the used crankshaft counterweight was when assembled a witness mark could easily not be seen if there was only light contact.

The metal produced from contact would also explain why cylinder walls and main and rod journals might be damaged from a extremely low hour run time, requiring rings and bearings on the second build...….

This entire area of the engine assembly needs a very close look , (If and When) the engine comes apart again. The noise has been confirmed in that area of the engine. A quickly worn distributor bushing kind of indicates some sort of side load on the distributor shaft. Seems like you may be drilling down to the problem area. Whole thing is really bizarre, but the parts have minimal clearance back there. I had a billet crankshaft counterweight kissing the pump shaft on our very first IA I engine block. The little cast retention loop had to be modified a little to allow a better line up and the counterweight chamfered a little more.

[Va68goat]

TedRamAirII,
From what the tech said, he noticed slight "uneven wear" on the new distributor gear. The new distributor bushing and gear have less than 2 hours of idle time. When Paul recently discovered the bad distributor bushing, he said he tore the engine apart. I'm imagine that he checked the cam gear.

Sirrotica,
As grivera says..It's a 455 block with a factory 455 crank.

Here are the pictures of the oil pump shaft again along with the videos of Paul explaining the damaged distributor bushing.

https://www.youtube.com/watch?v=dmwzlUPfaw4
https://www.youtube.com/watch?v=zRO0vuHfuYg

[torqhead]

Wonder if you could do this same test again that you showed in this video, but take a long screwdriver or something that allows you to push the oil pump driveshaft towards the front of the motor and see if it rubs on the counterweight as the motor is being turned over.

https://www.youtube.com/watch?v=dDZKHIOGWcE

If this turns out to be the problem it may be the 2nd time this may have been seen as mgarblik noted he had something similar occur!

[Va68goat]

torqhead,
That's pretty interesting. I don't know what Paul has the tech doing next. There have been so many hours diagnosing everything but the inside of the engine and I don't know how close we are to actually finding the source of the knock. I was really hoping to get some drive time this season but I'm starting to think the chances of that are slim!

[torqhead]

Originally Posted by Va68goat

torqhead,
That's pretty interesting. I don't know what Paul has the tech doing next. There have been so many hours diagnosing everything but the inside of the engine and I don't know how close we are to actually finding the source of the knock. I was really hoping to get some drive time this season but I'm starting to think the chances of that are slim!

I think you mentioned you guys did do the test pulling the plug wires one at a time to see if the noise changed and it did not. If that was done it's not a rod or piston issue and frankly there's not much else that could make a "tapping" noise on the bottom end as the baffle has also been checked for clearance.

Of all the Pontiac motors I've built over the years I've never seen anything like this and frankly it wouldn't be something that would be on a list, "crankshaft counterweight to oil pump driveshaft clearance", to check from what I've ever heard or seen. Maybe this is done by some folks, just never heard or seen it.

From everything you and the guys are saying that the sound is coming from that region, it's possible and the test is pretty simple to perform. You'd know immediately if it's touching and when the distributor is in it could be positioning the driveshaft a few thousandths forward and causing the "kissing" contact.

[Formulas]

Think about it, those marks are on the top side of the tabs where are the tabs after assy? Just below the oil pump drive shaft boss, those marks were made when the lower distributor bushing was wonky allowing the shaft to contact the boss

If a counterweight was contacting the shaft it would be lower than the tabs, where is those marks ?

.

[torqhead]

Originally Posted by Formulas

Think about it, those marks are on the top side of the tabs where are the tabs after assy? Just below the oil pump drive shaft boss, those marks were made when the lower distributor bushing was wonky allowing the shaft to contact the boss

If a counterweight was contacting the shaft it would be lower than the tabs, where is those marks ?

.

^^^ Good point! Looking at the pics again there are no marks on the bottom side beneath the tabs...

[chiphead]

Is the mark inside the red circle cause for concern?

[400 Lemans]

Hard to tell but in the second pic by his middle finger is that a nicked place lower on the shaft?

[STEELCITYFIREBIRD]

Has it been run with the valve covers off? Or a cover with an opening to hear if it is prevalent to one side?
Is the noise louder at low rpm or just drowned out by other noise? I’d look to eliminate any noise you can....exhaust especially! It may be louder (or not) at increased RPM....and therefore more discernible.

I really think if parts were interfering they would ‘self clearance’ by now, or be producing a lot of shrapnel.
🤔

[dataway]

I wonder if there has ever been a case where the mounting pad for the distributor was off a couple of degrees and pointed the distributor at the wrong angle just a tad. Would probably cause drive gear wear, bushing wear, and probably create a rhythmic noise as the correctly located oil pump drive shaft tried to work with the improperly located distributor drive gear.

Probably not the problem here ... just surprised an error in machining like that has never shown up that I know of, just one degree off would probably do it.

[Va68goat]

torqhead,
The tech that Paul has looking at the motor pulled the plugs wires one by one and the knocking noise remained the same. Here are some pictures of the bottom of the motor when we had to add spacing to the windage tray (First time we pulled the motor).

I also added a picture of the oil pan. I took this picture right when we packed the motor up and it was sent to Arizona a few months ago.

[krisr]

Originally Posted by Va68goat

torqhead,
That's pretty interesting. I don't know what Paul has the tech doing next. There have been so many hours diagnosing everything but the inside of the engine and I don't know how close we are to actually finding the source of the knock. I was really hoping to get some drive time this season but I'm starting to think the chances of that are slim!

Why not try the suggested test yourself with a buddy to bump the key? It's not a hard thing to do and you'll have an answer in like 2 minutes.

[Holeshot71]

There's something I just thought of. When I was mocking up the 455 that I built last year I found the crimped ears on the new Melling oil pump shaft were really close/touching the hole where the shaft goes through the hole. I compared the new shaft to the original and the crimps were crimped slightly off from the original. About a 1/16" if I remember correctly, which made them closer to the block. I ended up chamfering the hole in the block for some clearance. I'm not saying this is the problem here, just something I encountered.

[Va68goat]

STEELCITYFIREBIRD,
We have run the motor with the passenger side valve cover off. Here is the video. https://www.youtube.com/watch?v=KAwSYevxsb4

The knocking is more noticeable at lower RPM and is drowned out with more RPM. The knocking noise is predominately on the passenger side. It's definitely not an exhaust leak. Thats been checked about a dozen times.

dataway,
We ran another distributor and plug wires and the knocking noise was still present. The tech also added a gasket to my original distributor and the sound did not change at all.