My quick engine rebuild just keeps getting better and better. There was 1,000th of an inch of wear in the crank, and the crank was not out-of-round, nor tapered...this means it does not need to be ground. So far so good. I looked at the bearings and they read .009; thus, I ordered the standard .010 oversized bearings. I had thought everything was perfect.

However, after reading the 1974 Overhaul manual and 75 suppliment (no changes btw), the .009 bearings do not necessarily mean that 1,000th of wear should mean installing .010 bearings. Apparently, if the bearings could not be precision matched then about .009 was ground off and either .009 or .010 bearings (due to the cap and block boaring having a possible error of .001") were installed in order to meet the tolerance requirement for a gap of .0013 upto .0025 for mains #1, #2, #3, #4, or a gap of .0023 upto .0033 for main #5.

Well, after measuring my caps and journals and inspecting the block I see the crankshaft has 009 stamped on one of the counter weights in big numbers, and also the block to pan mating surface has a 9 stamped on it. Thus, I have one of those special blocks. I installed the .010 bearings and could not turn the crankshaft without like pounding on it with a hammer. It was stupid, but no damage done. After doing some calculations I have determined that I only had .0003" of gap between the bearing and the journal...waaayyyy too small of a gap. I was actually lucky to get it to turn at all! Oddly enough the bearings are still in good shape even after spinning the crank about one cycle so I might just save them for the 100,000 mile rebuild.

Anyway, I call Kragen who got me the first .010 bearings from Sealed Power (Federal-Mogul). They say the .009's don't exist! Huh? They look it up in their computer and sure enough they don't list a .009 bearing. They do have a .001 undersized so I ordered that, and will pick it up tomorrow to see if that is what I need. If not Kragen found a set of .009 for $95! Holy Cow! Bearing sets are only like $35, and the hi pro are just $10 more usually! Autozone straight up says I'm crazy and they don't exist, so I hung up on them. Well, I call a machine shop thinking OK I'll have the crank ground then. The guy says it would be $95, but it would need to be ground to .020 over cause he can't just take off .001" unless I wanted it to be like oval shaped. He then recommended that I just use a .009 bearing which he stocked there for just $61. LOL It's not the $35 that I expected, but at least I don't have to give up access to my crankshaft to some shop that has probably hired a teenager to come in for a couple of hours on Saturdays to load and unload crankshafts onto their lathe...OK, so I'm being pessimistic, but after getting the numbers milled off my block what do you expect?

Will it never end?

 

Dude,

You are gonna owe me a beer.

Here is what is going on. This is not something that many people will know about so listen up. You have a factory reground crank in that engine. For reasons known only to GM, if they had a bad crank for some reason, they would re-work it buy regrinding it down .009" and use special bearing shells that were designed for that size crank. These bearings are not available to the general public so they will be very difficult to obtain. I am assuming they did this for quality control purposes or for warranty reasons but either way, it was done by the "General".

The solution is to grind it .020"/.020" and run the matching bearings. You realy should not try to grind off .001" according to my crankshaft guy. He knows more about it than I do and I trust his judgement in this area.

Now, where's that cold brew?

-Mark.

 

Uh...in the mail?

I was actually checking back in to update this thread. You are dead on man. I looked at the bearings that Kragen had and they were not correct. I used my vernial caliper to check the thickness of the bearings that Kragen gave me, the bearings were stamped .001 under, but were actually .005 under. I returned them.

So, I called a shop to have my crank ground...I suggested polishing to just take .001 off and he said he would if what I really wanted was tapered and oval journals. He told me he would grind it to .020 though; but, then said he wanted to save me some trouble and money and said he had some bearings that would work! The .009 bearings are being produced by Federal-Mogul and being sold under the trade name Sealed Power. Kragen does handle them, but they want like $95 for the bearings, while machine shops usually sell them for like $61. So, my bearing delima has been solved. Thankfully, the rod bearings fit like a glove.

 

I saw your post and laughed a bit. I thoght I was the only one who ever saw a .009" factory regrind.

My crank guy cut mine .020"/.020" and resized a pair of rods for me as I had one journal wiped out when I did the tear-down. I had another issue that required surgery to the engine a few years ago and I was told back in '95 that I had a bottom end issue to deal with. It took a long while for me to get time to fix all of it but now it is done. My engine was finaly completely reassembled yesterday and I got the hood back on so it has been a big milestone for me.

Good luck with the overhaul.

-Mark.

 

This good to know info and thanks for posting R&R. Yea, I read Chevy would recylce motors with a rebuild if found defective before sale - or without rebuild if removed from a rejected car. This really screwed up the machine marks experts as the block numbers where machined off and restamped for new/different application. Did you record the block numbers before deck maching? It would be interesting if the stamped number refects a different vehicle/combination than yours.
Its a bit of a surprize that the mach shop can't just polish off 0.001" and still keep it round? Since your crank now has 0.001" wear, I'm thinking with a good brg cleaning and crank polishing the 0.010" under brgs could work. But I would not test thier advice and use something out of round. And BTW you still need a couple thou" clearance to turn the crank and have oil flow. The old Pontiac hi po motors (Ram Air) came stock with like 0.008" clearance or more. So what i'm say'n is loose is cool. An old trick to loosen up brgs is to scrub'm good with scotch brite (greenie pads) to smooth the surface before install. Good luck. cardo0

 

Good to hear a success story stingr69, I hope you see you the road soon. Thanks for the posts man.

cardo0 - I know I wrote the block numbers down somewhere...I'm even sure I posted the numbers on the forum when I joined back in 2001, but a search of the archives didn't come with anything. I can see some of the numbers, and the last three of my VIN are barely readable. But, I did determine that it is indeed stamped with my VIN and the correct codes for my car as well as the date the engine was made puts the engine around a month before my car rolled off the line. I'm very sure the numbers are correct. Also, the casting numbers are all correct.

I'm debating re-stamping them myself in another spot on the block. Since I am the rebuilder, then I believe I have a duty to keep the engine properly marked, and if a sub-contractor has marred the markings; then, it would be my duty to remark them to make sure everything is correct. Another example of this duty is when the dash cap is removed and replaced. If the VIN number tag is damaged then I would have to fabricate a new one, or order a new one, and install it on the new dash cap. The important part is that the VIN visible through the windshield matches the VIN on the owner's certificate so that it is indeed the same exact car. Thus, I think it would be important for my records and if I ever sell the vehicle that the block carry the same numbers since the numbers were removed, but the block is indeed the same block and then should have the same numbers so that the block numbers match the numbers on the rest of the car including the VIN. However, since some of the numbers are still visible on the deck, then I'm going to stamp the new numbers like one line down from the old numbers.