[Sun Tuned]

Right!

Joe be mindful of the timing mark when you set the timing. If it's jumping around a bunch you might need to pull dist and look it over. Mark should be fairly steady.

I believe he did mention a replacement polymer gear.

[grivera]

Joe- I think you mis-spoke re: defective bushing - it is metal as reported by Paul (gtofreek) in your other thread. The distributor gear is polymer and was reportedly in good shape. When Paul shipped the distributor to MSD for warranty repair, they replaced the bushing but kept the gear, so you had to purchase another one. Is this correct?

[TedRamAirII]

I dont know anything about this whole deal, but if the bushing was worn out, s seems as though there is abnormal side pressure on the distributor. Is the gear on the cam a little too big, pushing the dist gear with too much load? What else could wear out a bushing in such short order?

[Tom Vaught]

Different question, how much timing did you have at full advance on the engine on the dyno?

Tom V.

[Scott Roberts]

I would not say the builder Failed to secure the pick up"! I have never had one fall out but it happens. Most dont like to braise or weld a pick up because the heat can distort a pump. I know this because I pulled one down that had that exact issue... the pump took out the engine...
I know you are not very experienced with car from your posts... He did secure the pick above what most do by using lock tite... Melling has had some quality control issues lately...

[Va68goat]

grivera,
You're correct.

Tom Vaught,
I may be wrong but grivera may know more than I do. We've been friends for a while and he has spoken to Paul a few times. I believe Paul said it was 32 total advance? I'm new to cars...excuse my ignorance.

Scott Roberts,
Yeah..I'm sure I mis-spoke again. This is one helluva way to learn about motors but I've learned more in 2 years than I have ever known. All of this is way over my head.

[Shiny]

Originally Posted by TedRamAirII

I dont know anything about this whole deal, but if the bushing was worn out, s seems as though there is abnormal side pressure on the distributor. Is the gear on the cam a little too big, pushing the dist gear with too much load? What else could wear out a bushing in such short order?

I've wondered the same since first reading about the wear. Agree excess side load (a lot) sounds more likely to cause the wear than a bushing defect but is a good mystery to solve.

Did MSD explain why replacing the bushing would reduce the wear?

What could be defective? If the bushing is designed to maintain an oil film then maybe shaft/bushing clearance is a factor but that feels a stretch to explain the wear.

Hard for me to think abrasive debris would grind this bushing up so much compared to other bearings exposed to the same debris.

Are the bushing and shaft materials known? How are they different than Pontiac's materials?

If the torque needed to drive the oil pump was extreme for some reason, maybe the side load would be higher, but you ask a good question about potential for interference.

Could a cam bore be displaced toward the distributor shaft and cause interference?

Cam or distributor (more likely IMO) gear eccentric? Distributor shaft not concentric with housing (runout)?

Distributor gear expand thermally or by absorbing oil?

[Va68goat]

TedRamAirI,
What you wrote is pretty interesting. I have the motor back and we timed it, adjusted the idle and the exact same knocking noise is present. Maybe it wasn't a faulty distributor bushing that failed. Maybe the distributor bushing was the result of the problem. Hey Ted..have you seen the pictures of the witness marks on the oil pump shaft? Before I sent the motor back, we pulled the motor, switched out the oil pump and shaft and started it up. The same noise was present. I'll post the pictures of the the oil pump shaft

Shiny,
I called MSD and spoke to them. I explained everything to them about the bushing but I may have made a mistake when I told them it was recurved and a polymer gear was added. They told me that they would charge me $150 to replace the bushing. Paul and Jeff contacted them and they replaced the bushing for me. I wish I could give an educated guess about what I think the problem is but what you're saying is interesting.

Rocky Rotella,
The distributor came with a different gear. I was told by Paul to go with a polymer gear. I ordered what he requested, he recurved the distributor and added the polymer gear.

[Va68goat]

Before we sent the motor back to Arizona, we pulled the motor again, switched out the oil pump and oil pump shaft and this is what we discovered. I was told that the faulty distributor bushing was the source of the knock. Now that I have the motor back and the exact same knocking noise is present, is it safe to assume that the distributor bushing MAY have been the result of the problem...not the cause?

[Jay S]

It might be the pickup falling off and the distributer bushing going out are related issues. The oil pump is the hardest pull on the distributer gear. It could be some debris from the Loctite or something else was pulled into to oil pump and made the pump pull really hard for a moment and the force took out the bushing on the distributer from the side load on the gear. With no screen on the pump it sucks in what ever it finds.

Most us that have built a lot of engines have had something bad happen like this at one time or another. It is really difficult to make everything right $$ wise between the parts manufacturer, the builder and the customer after it happens because there are so many dimensions to to original issue. We point fingers and just go in circles. Sorry you drew the short straw. Most of us pull that short straw out at some point with something, but your getting a crash course.

99% off the time what Paul did on that pickup should have been fine and better than most that shove it in with nothing.

[MarkS57]

Originally Posted by Va68goat

Before we sent the motor back to Arizona, we pulled the motor again, switched out the oil pump and oil pump shaft and this is what we discovered. I was told that the faulty distributor bushing was the source of the knock. Now that I have the motor back and the exact same knocking noise is present, is it safe to assume that the distributor bushing MAY have been the result of the problem...not the cause?

Those are telling pictures. By chance, was the concentricity of the cam gear that drives the distributor and oil pump checked? I would believe if the distributor bushing was so worn that eventually the entire circumference of that shaft would show wear. This seems to show the shaft rubbing against the block hole in a consistent pattern.

[Va68goat]

Jay S,
Yeah..I got the short straw. I'm disappointed but not enough to be discouraged about staying focused on getting to the bottom of this. On the other thread, people are still convinced that it's ignition, timing, spark knock..whatever. I don't want to focus on that because I too feel these pictures are telling. The car is timed correctly, the idle is adjusted properly, the firing order is correct, the plugs were inspected. Again, I'm clueless about these old cars but if I have the exact same noise as before after the distributor bushing was identified as the source of the knock. It only makes sense that the distributor bushing is the result of the problem, not the source.

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

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

MarkS57,
I have no idea what concentricity of the cam gear means but I know Paul said after he located the bad bushing, he said he completely broke the motor down and discovered the piston rings needed to be replaced, bearings needed to be replaced, the crank needed to be polished and a light honing of the block was needed. I don't know if he checked the cam gear.

[wbnapier]

VA68Goat,

What MarkS57 said about the cam gear concentricity, is in layman's terms, maybe it is out of round / egged / too big in one spot. Therefore, putting excessive / uneven side load on the dizzy and destroying the bushing.

That would fit your theory that the distributor bushing wasn't the root cause, but a victim of another problem.

So, you properly checked the timing this morning and no improvement?

[Va68goat]

wbnapier,

The timing was done a few days ago and reconfirmed yesterday. I have video of both days. The first time it was timed a few days ago, I think the idle was too high to get a fair assessment of the knocking noise. The idle was brought down to 850 and 900 rpm and the noise was absolutely the same as before. I think we are onto something here!

I want to hold off on posting any videos because I want to make sure everything has been looked at. On one of the video's, I started recording before the motor was running. As the key was turned and the motor was starting...you immediately heard the knocking noise prior to the motor actually running!

[mgarblik]

If finding the cause of the noise and correcting it is still the goal after nearly 700 posts on the other thread, and 35 on this thread, I have a suggestion. You are in VA, and certainly there must be some good shops in VA with engine dyno's. My engine dyno is in a concrete block wall cell and we have 2 large industrial mufflers in the cell on the wall and two additional mufflers near the outside wall near the electric extraction fan. We can rig an engine up in the cell to make little exhaust noise enabling the operator and technicians to hear any weird noise from the engine. I still feel strongly the noise you are hearing is being transferred from something in/on the chassis of the car that is not present when the engine is out. I am also confident your engine would not have been shipped all the way to AZ, be taken apart again, repaired, cleaned and inspected, dyno'd again at great expense and time only to be returned with the same problem. Anything is possible, but I find that scenario highly unlikely. So for peace of mind, I would find a shop with a quiet dyno where they can hear engine mechanical noise and have it tested. The shop I dyno at only charges $300.00 for a session. You are so deep in this deal, that may be an option.
Concerning side load on the distributor shaft: I don't think there could be enough side load applied to wear out a lower distributor bushing if it were not defective in a few hundred miles. The drive gear would be stripped off if plastic or heavily worn if metal as well. It would also be difficult to install because it has to fit the gear teeth as well as the shaft for the oil pump below. If you think the distributor is still the culprit, install a stock GM distibutor and see if the noise goes away. That would take 1/2 hour and you would know something. This deal just can't be rocket science.

[Va68goat]

If you look at the pictures of the oil pump shaft, what would cause the oil pump shaft to have witness marks on only part of the shaft. It's definitely not completely around the entire shaft.

Also, before I sent the motor back to Arizona, we pulled the motor and we switched out the oil pump and the oil pump shaft. The knocking noise was still exactly the same. I don't know if that means anything to someone with experience but I think that may be telling as well.

[Va68goat]

mgarblik,
I know this thread and the other one has gone one way too long but at the end of the day, the motor is still knocking. I want this thread to end just like everyone else! There is a place where I can run it on a dyno and I have already contacted them. They're at $600. Don't know if I agree with the noise coming from the chassis considering the witness mark on the oil pump shaft. We are going to try another distributor. That's next on the list.

[n20ta2]

If you disconnect the coil and turn it over can you recreate the knock?

[wbnapier]

On the other thread, there was a lot of talk about the timing being off due to sea-level change and issues during transport. I didn't think 2500 feet would cause such a bad idle / tick. Maybe I'm wrong, but at least you ruled that out.

Good luck.

[Va68goat]

Here are the two videos from yesterday. I didn't want to initially post this because we still have more to do. I don't think anyone can do an honest assessment without knowing where we're at. So here are the videos. We are going to try another distributor. Maybe this will make sense to some of you guys!

https://www.youtube.com/watch?v=ghoG-DsNJOg

https://www.youtube.com/watch?v=RUnO9Fwj0qQ