[tom s]

Mike,from Mikes first look he thinks the tangs are off?Like I said he is waiting for the crank.Tom

[Will]

The great thing about 301s is that 350 and larger engines bolt right into their place with minimal hassle.

[MarkS57]

Originally Posted by Will

The great thing about 301s is that 350 and larger engines bolt right into their place with minimal hassle.

Absolutely and exactly what I did. Bought a used 75 350, rebuilt the heads and hacked .030" off to bump the compression a bit, added a qjet & manifold. Great car, wished I still had it.

[wbnapier]

I spoke to the machinist today. He's done with the diagnostic.

He is 100% sure the problem is with the #5 bearing. The bearing sits too far rearward, due to the locater tangs. This combined with an aftermarket forged crankshaft with the large fillet radius resulted in catastrophe.

"Too far rearward" as compared with an older Clevite bearing and modern FM bearing. The older Clevite bearing is defined as when they still ground the tear-drop relief in the #4 thrust face. That older series Clevite bearings and FM bearings would be no problem with a new aftermarket forged crankshaft. Of note, Clevite's new 10 under #5 bearing is equally problematic too, not just standard size.

The Clevite sales representative has visited the shop to view the problem and the machinist has emailed them some photos. The representative is scheduled to return to his shop in 1-2 weeks.

The machinist has set up my block, a series of crankshafts, and a series of bearings to run through the issue with them as a proper experiment. He is re-align honing the block later this week, but will pause after that so as to keep the set up pure for the testing.

Of note, he has some stock Pontiac cranks, Scat 400/455 cranks, and an Eagle crank he measured and the after market cranks (including mine) are 0.005-0.006 thousandth longer and therefore my endplay is fine, but rubbing up against the #5 bearing, not the thrust bearing. If I had tested end play with a stock crank, it would have been too tight. I don't know if I am communicating that correctly, but something along those lines.

He has reground my crankshaft 10 under, and there is no issue now, as the fillet radius is reduced from that.

The shrapnel in the oil pan is from the bearing, he doesn't see any issue with my block, but I told him I thought I saw a piece missing in a photo which is another photo illusion.

The collapsed spark plugs remain a mystery. He says there is no sign of mechanical interference and those cylinders show no sign of combustion having every occured. His best guess is a dropped them before install and they bent in. I told him no, that didn't happen, but there is no other explaination.

I'm going to contact Butler to see what relied I can get from their side and make them aware. I'll also start ordering parts.

[johnta1]

Glad your getting it figured out!



Also glad you took it apart instead of just trying to work on the plug situation.

[Scott Stoneburg]

Glad you didnt give up, and are getting it back together.

[tom s]

He has 3 diff brand bearings there waiting for the crank to come back.Will know more than.Was there today.Tom

[hgerhardt]

Why can't a guy just put the bearing shells together in a circle (as-installed) and using a 6-jaw chuck on a lathe just put whatever fillet radius/chamfer you want on the bearings?

[tekuhn]

You drove the car a fair distance before the seize, and surely you would have known if the engine was running on 5 cylinders. I tend to agree the spark plugs are a real mystery, but can't believe you wouldn't have detected that severe of a misfire if the gaps were closed from the first fire-up. Especially with a manual transmission and clutch where everything is transmitted to the driveline.

[wbnapier]

Originally Posted by tekuhn

You drove the car a fair distance before the seize, and surely you would have known if the engine was running on 5 cylinders. I tend to agree the spark plugs are a real mystery, but can't believe you wouldn't have detected that severe of a misfire if the gaps were closed from the first fire-up. Especially with a manual transmission and clutch where everything is transmitted to the driveline.

I did detect the misfire. I thought it was A/F or timing. I didn't think it was a no fire in the plugs. My plan was to cruise for a few minutes then return home and figure out the misfire.

And, I used the temp gun on each exhaust port and all were + or - 10 degrees. So, I assumed all cylinders were firing.

Remember, this is my first rodeo... Not an expert.

[tekuhn]

Originally Posted by wbnapier

Remember, this is my first rodeo... Not an expert.

Ah, OK. I didn't realize it was missing from the beginning. Not being critical at all. Has me rethinking whether I need to pull an engine I've had sitting installed in the chassis and never fired yet. I'm pretty sure I used Clevite 77's. This bearing thing could have been easily missed. I think I do understand what the machinist is saying. When you measured your thrust end-play, the crank was stopping short of reaching the rear-facing thrust face on #4 and instead stopping because the crank journal radius was hitting the rear edge of the #5 bearing shell. That would explain the weird noise that you heard when you pushed in the clutch in the final moments before seizure. The number 5 bearing edge and crank journal radius was under extreme contact from the pressure plate pushing the crank forward until it failed.

[wbnapier]

Originally Posted by tekuhn

Ah, OK. I didn't realize it was missing from the beginning. Not being critical at all. Has me rethinking whether I need to pull an engine I've had sitting installed in the chassis and never fired yet. I'm pretty sure I used Clevite 77's. This bearing thing could have been easily missed. I think I do understand what the machinist is saying. When you measured your thrust end-play, the crank was stopping short of reaching the rear-facing thrust face on #4 and instead stopping because the crank journal radius was hitting the rear edge of the #5 bearing shell. That would explain the weird noise that you heard when you pushed in the clutch in the final moments before seizure. The number 5 bearing edge and crank journal radius was under extreme contact from the pressure plate pushing the crank forward until it failed.

Exactly. He said that with aftermarket crankshafts, specifically my Scat and an Eagle he measured, they are longer compared to the stock Pontiacs he measured. Either overall or in a specific area, I don't know.

So, when one measures end play, you get a good mesurement. This is a false measurement though. Had I used a stock crank, I would have had too little endplay with these bearings and known there was a problem.

I don't know what to suggest to you. Of course, based on my experience, I would tear it down. Remember, my machinist bought a 10 under set of Clevites, and same problem as mine. So, this wasn't a one off error.

I emailed Butler tonight. I want them to test the Clevites vs. FM.

[tom s]

I have had engine builders do exactly that on bearings WHEN they know there is a issue!Most ASSUME if bearing clearance is proper they dont HAVE to do something to brand new bearings!It seems like something has changed on Clevite 3 1/4 main bearings compared to other brands.The set Mike has in his shop also dont have the little half moon cut outs on the #4 bearing?The rep looked at them and was at a loss as the box said maid in the USA.Inquiring minds need to know!Tom

[Ben M.]

Originally Posted by tom s

The rep looked at them and was at a loss as the box said maid in the USA.

We can at least rest easy knowing that our quality USA box makers are still employed and doing good work. I don't trust anything out of the box these days.

[chiphead]

This sparked a memory of something.

Last year when I was building my 434, I test fit a set of Clevite mains. As I recall, the rear main bearing (3" main block) was messed up. The oil groove in the upper didn't match the groove in the lower half. It would have been hard to spot if I wasn't really paying attention. I took them out of the block and lined the bearings up, the oil groove was WAY off. I sent them back to summit and went 4040M1.

Avoid clevite bearings.

[mgarblik]

It is a shame to hear that Clevite MAY be having some quality issues. Clevite has been a good name brand for my entire engine building life. I personally have not been using Clevite bearings for Pontiac builds in the last 15 years or so. Only because they really didn't offer a race bearing and those were the type engines I was building. From a dimensional, fit and finish, and overall quality standpoint, I have been impressed with King Bearings for our 3" main blocks. Ever since Federal Mogul moved all the performance bearing manufacturing to Mexico, the quality has become a little looser and many of the new bearings come in dirty. Easily corrected, but not an indication of quality. King bearings are made in Israel and come in immaculate and very carefully packed.

[OG68]

Originally Posted by mgarblik

It is a shame to hear that Clevite MAY be having some quality issues. Clevite has been a good name brand for my entire engine building life. I personally have not been using Clevite bearings for Pontiac builds in the last 15 years or so. Only because they really didn't offer a race bearing and those were the type engines I was building. From a dimensional, fit and finish, and overall quality standpoint, I have been impressed with King Bearings for our 3" main blocks. Ever since Federal Mogul moved all the performance bearing manufacturing to Mexico, the quality has become a little looser and many of the new bearings come in dirty. Easily corrected, but not an indication of quality. King bearings are made in Israel and come in immaculate and very carefully packed.

My engine builder recommended King over Clevite, due to what he perceived was a lack of quality.

[1968GTO421]

Originally Posted by mgarblik

It is a shame to hear that Clevite MAY be having some quality issues. Clevite has been a good name brand for my entire engine building life. I personally have not been using Clevite bearings for Pontiac builds in the last 15 years or so. Only because they really didn't offer a race bearing and those were the type engines I was building. From a dimensional, fit and finish, and overall quality standpoint, I have been impressed with King Bearings for our 3" main blocks. Ever since Federal Mogul moved all the performance bearing manufacturing to Mexico, the quality has become a little looser and many of the new bearings come in dirty. Easily corrected, but not an indication of quality. King bearings are made in Israel and come in immaculate and very carefully packed.

Thank you for this info. I was told about 10-12 years ago by a machinist King bearings were made in China so I've avoided them. Thanks for seting the record straight.

[wbnapier]

Does anyone know why Clevite no longer grinds the teardrop-shaped relief in the thrust bearing? Does FM or King do this?

[johnta1]

Probably saving money?
(extra maching step)