Westlotorn with a well reasoned analysis.

 

Mark, I have saved and printed your post above. Hopefully I will never need it but it's an excellent analysis in case I do. Thank you!

 

Mark/Westlotorn, huge thanks for the time you invested in your reply! I have gone through it twice and will go through it again another couple of times before heading to the shop with notes/cheatsheet in hand! A heartfelt thanks!

 

My late to the game two cents. I thought spun rod bearing on your first post. Mark wrote an excellent analysis, so I will only add that this reeks of improper rod bearing crush caused by improper rod bearing torque, an out of round rod journal, or improper rod bearing clearance. All of these would be the fault of the shop that rebuilt the engine. I will double or is that triple down on there is no way they can call the crank bent. Out of round rod journals are fairly common on high mileage engines that have seen “spirited” use and must be measured and trued carefully. Kind of a lost art in our throw away society and probably something this shop didn’t spend enough time inspecting.

I hope you didn’t tell the original shop that you potentially over-revved the engine. Never offer potential root causes, particularly when you have a failure so early in the engine life. If you did, it is now very easy for them to shift the blame to you by saying you bent the crank due to an over-rev which is an easy get out of jail free card for this shop. All the best in getting this resolved.

 

Hi everyone, went to the shop and covered what I think were the most important points within the limited time that I had, a couple of videos below. Any thoughts or observations welcome!

1. Official diagnostic was spun rod bearing. No broken rod, thankfully (I seem to have misunderstood) and no bent crankshaft (don’t know what happened there, because the phrase “bent metal” was definitely used over the phone). Oil filter was clean, oil was plentiful.

2. What to do now? The engine stamp numbers match the vin - I leave to your expertise to determine if it’s original or a restamp (picture below). Assuming it’s the original engine to the car and given no major damage, I am leaning towards rebuilding it:
a) replace crank with a new one (shop said that beyond the damage, this one had already been machined down to the limit)
b) the shop recommended changing 2 connecting rods that did not look good, but not all 8. They would get American made bearings for all 8 rods.
c) flat pistons or stock domed? (And corresponding lifters and cam)
d) aluminum heads or stock?



Engine stamp

 

From what little I know from your posts, I’d upgrade the rods at least to the later 327 rods, have them resized if used and reuse the pistons, cam, lifters, timing chain, sprockets. You can find a crank. I have one here, but shipping across the states isn’t worth the freight. Have ALL the plugs removed and clean the engine, especially the galleries. New bearings, gaskets, rings and you’re back in business.

This based on your low mileage since rebuild. Examination may add or change this plan.

 

For the expense of resizing all your rods I would look at spending $400 and getting a nice set of the modern Scat or Eagle rods. Some are as cheap as $250 a set but the nicer sets cost more.

A set of the 66 and newer 327 small journal rods would be fine and are stronger than the early rods but might cost as much as a brand new set.

I did not find any explanation as to why rod bearings spun on a brand new engine? Something was wrong.

Was the oil pump pick up tube installed properly, how was your running hot oil pressure in this engine?

Looking at your video and freeze framing it looks like the bearings in the engine are at .040 already.

Federal Mogul used to make 327 bearings up to .050 but you would have to check for availability. King Bearing usually had these odd oversizes available also.

I would not hesitate to use a crank ground .040 under. Racers ground the 400 crankshaft .100 under and more for years to take the 400 crankshafts and use them in a 383 engine. Those engines made serious power and did not break cranks due to the undersize.

I am not there and can't look at your parts but there is lots to learn from looking at them hard. The photos showing the Connecting Rods in your block show the bearings were moving in almost every rod shown? That is a fit issue .

 

Thanks Westlotorn. I appreciate your insights! I did not get a clear explanation for the spun bearing, unfortunately. The one assurance I was given was that they would not send it out to another shop this time but that their master builder/owner would build it. I now have to ponder what to do…

I will ask about your other points tomorrow as a follow up, since the car is still in the shop.

Regarding the crankshaft, so even if I got a new one, we should consider grinding it to get some weight off? I will mention this.

I will definitely look at Scat and Eagle rods, thank you.

On your last point about bearings moving on all the rods, I think it’s a trick of the light on the oil: I ran my finger over them and they were super smooth & shiny, except for 2 of them, 1 being super rough.

 

Not sure what you are thinking of with get some weight off the crankshaft. Hope I did not lead you down that path.
Any 327 crankshaft with the small journal mains and rods could drop right in and replace your damaged crank. The stock cranks are available for little money, maybe $100 to 150 for a nice one. The early cranks were all forged so very high quality factory stock. The early cranks did not have the threaded snout but that can be added on any early crank to match the L79 type with the harmonic balancer bolt hole threaded.

If your engine was custom balanced your existing crank may have had weight removed or added but if it was balanced the engine build would state that.
If the shop mentioned grinding a crank it is just making sure the new crank has perfect size and finish. Since bearings are available in several sizes as mentioned already it is nice to find a standard or 10/10 crank because it gives you the ability to grind it again and again if future rebuilds are ever necessary. Strength wise a Std, 10 or even 40 crank is just fine, I would not hesitate to run any of them really hard with no worry.

When you hear 10/10 or 10/20 it refers to the crank size on Rod Bearings and Main Bearings and cranks get cleaned till they have a perfect surface. Sometimes a crank ends up with a mix, maybe Mains ground 10 but rods ground 20. You just need to know what you have when you order bearings.

Your observations on the connecting rods. You are not looking for smooth surface on those rods to indicate they are good. You are looking to see the Cross Hatch pattern that is honed into the rods when they are manufactured. The only thing that removes that cross hatch is bearing movement. The bearings are not supposed to move once torqued into the rod. On teardown the cross hatch is normally seen clearly on both the bearing back and on the connecting rod surfaces where the bearings are installed. What I noticed looking at the pictures were shinny spots without cross hatch which has me thinking the bearings were moving inside your rods. That should not be happening. But again, pictures are not always perfect. I do think when we see 6 rods that look like they have had a bearing movement indicating the crush was not adequate and 1 that has a spun bearing, lack or crush or lack of oil supply are the two common causes of a spun bearing.

One thing not mentioned when discussing the cost of new connecting rods. If you rebuild your old rods or buy a rebuilt set of old rods it is recommended that you install new Rod Bolts. This is prudent and ARP bolts are a good choice but are not cheap so you need to factor in the cost of new bolts along with reconditioned rods. New Rods come with new bolts and several are available with ARP bolts so it makes the purchase of the new rods more attractive. If I had a good set of the 66 and newer GM 327 rods I would not hesitate to use them if they were reconditioned and had new rod bolts.

At this point your engine has metal in the oil system since it had a rod bearing failure. A full tear down and cleaning of all the oil passages is necessary to get all the damage particles out of the oil galleries.

I know we have beat on several things and possible causes. One more possible cause of rod bearing failure is detonation. If a cylinder is firing at the wrong time pressure in the cylinder can jump from a normal max pressure of 600 PSI wide open throttle to well over 3,600 PSI when detonation starts.
In detonation the connecting rod bearings can pound out and fail resulting in a spun bearing. Detonation is a cylinder lighting off before the piston is at top dead center. So a piston is headed up and something lights off the fuel charge well before it should. Now you have 7 pistons pushing forward and one piston trying to blow back down because of early detonation, the 7 pistons pushing will win and the 1 piston gets pushed up into the explosion of the early combustion creating huge pressure in that one cylinder. 3600 PSI can damage rod bearings, blow head gaskets and break pistons and piston rings. The weakest link fails first.

There are many causes for detonation but the result can be damage like yours.
Common detonation causes:
- over advanced timing
- lean burn in a cylinder, usually a vacuum leak
- mis wired spark plug wire
- low octane fuel with high compression

So, how was the new engine running prior to failure? Did it pull hard when you accelerated or did it seem to be struggling to accelerate? Any pinging at all? Do you know the timing settings?

Sorry to add more to think about but the very worse thing that could happen would be to install another new engine and have the same failure. It is best to find the cause along with fixing your problem in this engine.
A ton of the information discussed in this post is common knowledge and known well by many of our members but someone looking at their first engine failure I hope it helps and please guys correct me if I have mistakes or errors, I will go back and edit.

Mark

 

That engine stamp pad looks good from here, to me anyways. That and no apparent damage to the block screams 'keep it, fix it, reinstall it.' Strongly consider having a different shop rebuild it. Yes go with Scat rods or equivalent - cheap insurance. Have another shop mike the crankshaft, and recheck the block for cracks since it possibly overheated and seized. It appears that you may have dodged a bullet on this one. Good luck. Once you get it home you can consider all the options going forward.

 

If you decide to rebuild what you have , a new builder can give you more confidence in the finished engine. Your new knowledge and experience comes at a cost,
But most of us have had some part of this experience also.

 

The pad stamps are definitely original. This engine should be saved and rebuilt correctly.

 

If Pboyd endorses your pad, you can take it to the bank. And, now would be a great time to clean that stamp pad of all paint using lacquer thinner or acetone on a rag...nothing abrasive that would harm the broach marks. There should be no reason whatsoever to deck the block but be SURE to tell the rebuilder to avoid the stamp pad at all cost.

 

And have the rebuilder respond in WRITING that they will not remove the stamp pad numbers. IN WRITING is your only protection if things go south.

 

Plus, hang a tag, wired on so the machinists in back know what the office knows .

 

I know you have a lot going on with this engine.
I dont want to make things worse. Have you thought about costs of a rebuild compared to
a built long block dressed remanufactured. You can get a 383 with a warranty for 6 to 6500
bucks. Who ever you use for a rebuild ask, whats the final bill and then you can compare.
Like I said before, you can always hold on to your damaged engine and build later. You dont have a totally
stock vette now with your present engine.
Good luck

 

I have been heads down in work today, so just catching up now with the threads. Big thanks, especially to Westlothorn/Mark for all the insight. Any way I can buy a few of you some first-class tickets and we make this a weekend project!?

on your question about detonation, Mark, the engine had been pulling just fine and I didn’t hear any pings at any point.

finally, thank you for your assessments of the stamp pad - most definitely something that will be top priority!

 

I want to place a strong vote for all-new rods. The evidence suggests that the original rods were not properly re-conditioned. Don't even THINK about replacing just the rod that spun a bearing.

The two main "budget" aftermarket rods are the Scat Pro-Stock and the Eagle SIR for under $400 a set. Both are far stronger than the stock rods and right out of the box they are properly sized with ARP rod bolts. I prefer the Scat Pro-Stock rods but the Eagle SIR are okay too.

 

I heard a "Whirring" sound on my '62. Then there was a loud SNAP and POP just before IT seized SOLID! Would not turn over at all.
Towed it back to the shop and could not find anything wrong but it woyld not move!
One of the guys got into the car and said "let me try" and before we could stop him he hit the starter, the engine move a TAD then there was a noticeable "KLINK" of metal on metal. "W the F!"

He hit the key again and the engine truned over easily---all rockes, rods etc seemed to work perfectly! The engine did not fire up because we had the coil wire disconnected--just in case!
Before starting we put it on the lift, pulled the oil pan and found NOTHING! But as I went to reset the pan mylight set off a flash of metal----

Sitting proudly upright and cocky on top of the frame was a 3/8 1/4 in drive socket---mangled beyond belief!
That socket had--at some time in the past--a day, week or YEAR even---slid down the engine, along the bell housing and through the opening for the clutch lever to the throwo out bearing---NO, there was no boot---it must have paid there at the bottom of the pan for who know how long until that one day it rolled into just the right position for the flywheel teeth to scrape on it (whirring) grab it (snap)and sent it up to the top of the bell housing to jam solid and stop the engine cold(BANG).
The funny thing is that when it finally disengaged, it was thrown out exactly the same way it went in and ended up standing stright up and proud for asll to see.
Yes, there is now a proper boot on that opening.

Ya never know!
Eddie