Easy Rhino

Does it matter?

The machine shop says my crank miked out, with prior wear and tear, to need journals grinding down to .010 over for both the mains and rods.

So, does it matter which bearings to order?

I was checking out Clevite, and they list P, H, V, M, Z types.

The engine is a .030 over bore 327 in an original 870 block, with the 4680 crank, and using Scat rods with Forged TRW pop-up pistons with 63cc 461 original heads mildly pocket ported and will run a LT1 solid lifter cam. I'm guessing upper 300's HP range.

It will be mostly a cruiser with occasional blasts but no track time and no hard core beating on it. Although it will be built to take it (I hope), I expect to rarely run it up over 6K rpm.

65tripleblack

Use the P series "high performance" tri metal bearings.

SWCDuke

I suggest you measure the crank yourself. Unless the crankshaft has damage there is likely no need to grind, and if it's a SHP crank grinding will remove the surface Tufftriding treatment, which adds durability.

My 340 HP engine crank measured right in the middle of the OE range at 115K miles, was dead-on straight, and passed a Magnaflux inspection. I just had it polished.

The OE Morraine 400 bearings could have been reused, but since I had to remove them to tank the block and Mag the rods I replacement them with same from GMPD.

The fact that the #7 conn. rod had a crack clear across a bolt seat proves that I didn't drive it like an old lady.

In fact, everything I measured was within OE spec except the cylinder bores, which had 3-5 thou taper, and I blamed that on the crummy OE foam filter, which wasn't good for filtering out anything much smaller than a humming bird.

Duke

Robert61

You want P series is a street engine. H and V are race bearings. I have no,idea what M and Z are. If you have the crank ground I prefer to get the bearings first measure the I.d. Of the bearings installed and have the crank to the proper size for clearance.

Critter1

That's exactly what I was thinking. It's unusual for a crankshaft from a running engine to require grinding. Not saying this is the case but that sounds like typical machine shop shenanigans. I would definitely look into this.

And if they tell you that the block should be line bored, Look elsewhere for a machine shop.

Many machine shops have a lot of expensive equipment that they're trying to pay for.

Westlotorn

I would stay with either Federal-Mogul or Clevite for engine bearings. Both have been providing bearings for over 50 years.
Certainly measure the crank yourself or get the exact numbers.
For an engine that does not exceed 6,500 RPM the stock bearings would work fine. They did from the factory and they still can handle that RPM.
If your crank polishes and leaves your bearings a little loose you can choose to buy 1 under bearings to tighten it up. If you are loose on the rods and mains you will have lower oil pressure at idle. A good safe number for Rod and Mains would be .00175 to .00225 clearance.
The performance engine bearings are stronger but also have more clearance built in at the parting lines to allow for high RPM rod deformation. This is necessary for high RPM clearance because the big end of the connecting rod will egg shape at high rpm and this can cause oil starvation using stock bearings. The Performance bearings will also cause more oil spill at idle and lower the idle oil pressure.

cardo0

I'm gonna just follow this thread as from what I've read bearings are consistently changing even in the product lines within a brand like Clevite 77. Yes Clevite has been reboxing their own products with less/lessor grades of bearings. I'm sure Clevite still makes good bearings but you have verify your getting the good tri-metal bearings and not reboxed bi-metal or even coated single metal bearings.

What I will say is its important is to inspect your bearings with an at least 4X magnifier. And that's something most shops (nearly all shops) won't do for you. Don't be surprised to find tiny ***** of material right on top of the bearing surface. But look for other defects to.

Well as far as grinding cranks to an undersize thats done all the time and the more serious builder will just retreat the crank chemically and or thermally. Hard to know how much of that is needed for a street warrior. I'm sure you can decide what to do when the cost to recondition exceeds the cost of a nice new aftermarket crank. More likely your motor will see no more than a few thousand miles a year and a couple dozen straight line blasts. If something does bust it will either be right away or with the next owner but unlikely in between. Thats my 2 cents.

Robert61

I can say over the years I was in engine rebuilding we ground hundreds of Nitrided cranks. I never saw any ill affects. To me for a street engine it's just not necessary. You're putting a lead bearing on it which is going to wear first? If you do any maintenance at all changing the oil it will last the rest of your time. I couldn't begin to calculate the number but Chevrolet nitrided performance and some truck cranks. All the rest were not nitrided and lasted just as well. I would think the number would be less then 10%. Too us hold be able to look at your crank and see if it needs grinding. If you run your nail across it and feel anything grind it!

Easy Rhino

Thanks for all the inputs. With all the crap parts being sold from overseas and such, you can't just go to the counter man like in the old days and get known good parts.

As far as the crank goes, I suspected that it might need an undersize grind to clean it up. When I tore the old engine apart I was surprised how badly the prior builder had thrown it together. The rods were the worst, where they didn't protect the journals from the rod studs - gouges, with matching tear-outs on the bearings. The mains didn't have rod stud nicks, of course, but had threading on the journals and bearings that you could catch your fingernail on.

I trust this shop, as he has been there forever and has a big following, I have many friends have used him, his prices are good and he is timely, and I have not had any examples of any attempts to upcharge me. I recommend him to others as well. My last time down there it cost me $300 to have my 327 block all the plugs and cam bearings knocked out, hot tank cleaned, mag-checked, cylinders bored .030 over, dimensionally checked, and new cam bearings and new brass plugs reinstalled, and all the head bolt/stud threads chased. I tried to find any dirt in the oil galleries when I got it home, but it was spotless.

When I took the crank in, without being asked he checked his 2-3" caliper on his standards block, then miked the journals and inspected them with me watching, which I didn't even ask for him to do in front of me. He was hoping to see if there was anyway to just polish it and use it, but it was too far scratched. I think I can trust him. He gets too much repeat business, and is too-well known in local circles to mess up his customer base.

Anyway, when I get the bearings in hand I'm delivering the rest of the rotating assembly to him to get it balanced.

Easy Rhino

I've heard the same thing about the nitriding.

Funny thing you mentioned the fingernail - my gouges were waaay bigger than a fingernail - no way was I going to put fresh bearings up against that. It was more a matter of whether or not .010" would clean it up or if it needed to go .020".

Robert61

I'm serious about getting your bearings first measuring then grinding. That's the only way you will get the clearances you want. Just grinding it .010, will it work yes but you'll have to live with what you get. If you don't have the tools to measure this precisely get him to do it. Pay little extra but be happy knowing it's right. Myself, I like .002-.0025 on rods and mains.

Easy Rhino

Since you brought it up, I seem to recall a thumbrule - something like .001" clearance per inch of journal diameter. So, for a small journal, rod clearance should be .002 and the mains should be .0023?

Robert61

That is the rule of Thumb! I don't know who he is but that's the rule. Some will say tighter but that's not for me.

65 396

Kevin,
Have you decided on a cam yet? Will you do anything to the heads to gain performance?

Critter1

Sounds like you found a good engine builder and machinist. Kind of rare these days.

Easy Rhino

Hey there, Lee.

First, I'm pocket porting the heads and having a 3-angle valve job done. Oh, and I'm also port matching the heads to the intake and exhaust manifolds. I know there is more power in a new set of aluminum heads, but I'm going to use date-correct 461 heads.

When I get the rotating assembly back balanced from the shop, I'll assemble the short block and measure the piston top deck clearance, as I'm shooting for a quench in the .035 range. With 62-63cc heads and dome pistons I'm shooting for a true 10.5:1 SCR, or thereabouts, with the right head gasket thickness. Then I can pick the cam to get the DCR and the flow desired. Right now I'm leaning towards an LT1 cam profile with solid lifters. What I'm shooting for is a totally correct-looking L76 with that high-winding top end and that lumpy, clattering solid lifter sound, with a little more juice, but with no external clues. I'll be using a correct Holley 2818-1 on a winters 461 intake, and the correct 2 1/2 inch ram's horns exhausts.

I think so. Really glad, too. You read so many cases of guys with no decent shops close by (this guy is no more than five miles from the house), or shops screwing up their engines, or building crappy engines.

Westlotorn

Share your machinist name and keep him busy so he stays around a while.
Good shops need the good press to overcome the attitudes created by the bad shops.

MarkC

Kevin, do you have a projection on when you will have your car back on the road? Also, take a look at the .018 stainless head gasket. That’s what I used to help get compression up.

Easy Rhino

Good point. I don't think a machine shop is the same as a vendor? If so, I apologize to the mods in advance.

It is Magnum Machine: http://www.magnummachineincorporated.com/the-shop/

He is at 921 Business Park Drive, Chesapeake, VA. It is not a glamor shop, but more like the old time machine shops that I knew 50 years ago. It's just north of the Greenbrier area. Kurt is the owner, and I have recommended him frequently, including recently to a friend who is just starting a rebuild of his newly acquired '53 Chevy pickup. There is actually a shop closer to my house, but the machinist/owner can be difficult to work with.

LOL, Mark. You mean in relation to a calendar?? Not so much. I fit it in when I can, and earlier this year got an unexpected promotion (read: more assigned employees) so time has been at a premium.

As far as head gaskets go, I'll determine the needed gasket thickness when I measure my assembled short block deck clearance, so that I can set the quench and SCR in the desired ranges. The good news is that you can still find several available gasket thicknesses.

Westlotorn

The biggest change in engine bearing has come in the last 15 years.
The EPA has mandated eliminating or reducing toxic metals from production.
Copper, Lead and tin are all on the endangered list.
Because of this mandate Federal Mogul developed their A series engine bearings.
These are Aluminum with high silicon and are actually amazing technology.
Talk to any machinist and ask what the cranks look like after 200,000 miles on these bearings. As long as they have decent oil the cranks come out with zero wear and a better finish than they had new.
In the late 90's these were first installed in new cars and trucks.. Initially they had a limit on max horsepower, I think it was around 400.
The newer versions of the A series bearings are stronger and I think the horsepower rating is above 500.
Read up on these before choosing your bearings.
The A series,are bored to size so size variation is mostly eliminated.
Before getting too excited while I know they are available for the 350 I'd have to look and see if the 327 small journal is covered.
Copper lead tin bearings are still the norm in Diesel engines where 16:1 compression running 40 pounds of boost is common.