Hi guys,
I could need a little help on this one:

My #5 main bearing clearance is kinda lose. Its ok, around .0025 until I tighten down the oilpump. Then it goes up to .0035 which I think is on the lose side! Ive tried to trick this problem by using a stud for the pump, but that doesnt made any change. Im using ARP bolts for the mains, and Clevite 77 P main bearings. The rest of the mains are fine around .0023"

Do you guys have any tips here, Are there bearings out there that can help me get into the ballpark again or do I have to take the block to the machine shop?

Thanks
A-M

FWIW, .0035 I would consider fine for the rear main if it were a BBC. They are almost always a little bigger than the others. If it were my engine, I would run it. If your nervous about it I have seen builders wet sand the cap a little on a flat surface, like a plate of glass. Wouldn't take much to get down below .003". JMHO. I'm sure some of the guys who do this for a living will chime in.

A-M,

Your #5 clearance is OK. The recommended clearance at this position for the Clevite 'P' series bearing is 0.0011" to 0.0041". You are well within that range.

Ok, thanks alot for your input guys!!!

Maybe its ok then. I have spent descent money on this engine so I wanna play it safe =)

Thanks
A-M

PS. It would be nice to hear what Wolfplace & Carl think about this...

Ok, thanks alot for your input guys!!!

Maybe its ok then. I have spent descent money on this engine so I wanna play it safe =)

Thanks
A-M

PS. It would be nice to hear what Wolfplace & Carl think about this...
=
A little looser than I like for a SB but it will be fine,,, run it.
It sounds like someone line-honed the block without a pump attached which is a big no-no ;)

What I would do if I were setting the clearances up would be to put a .001 half in the rear but you would need to buy a complete set of bearings to do this so in your case unless you are really concerned run it
A little loose is far better than a little tight :D

Let me just add some here.

Just to keep the record straight, most bearing manufacturers "build-in" some slight add'l room at the #5 SB bearing's. Been this way for some time!

Now having said that, I would remind all up here, when you "mix-n'match" fasteners and components (oil pump) you MUST check the clearances between those pieces. Many times you'll find some "interference" between the pump housing and the rear main bolt/stud on the passenger side.

Bolts usually leave some extra room where the stud/nut become somewhat closer, BUT, it has to be checked. Years ago I got in the habit of laying a 1.000" strip of newspaper (approximately .003" thick) between the fastener and the pump body on the final ass'y. Make certain this is not an issue with your's! It can be very hard to notice sometimes!

Thanks, Gary in N.Y.

P.S. When we first started dealing with ARP "back in the beginning" we would constantly call there and recommend they place a single 12-point nut in ALL the main stud kits, at least on the BB's, every one of these would "hit"
(come in contact with) the Melling pumps. It took some time, but they finally came through.

And one other thing:

If you are not using a REAL GENUINE oil pump bolt, it WILL hit the back of the bearing shell; and if you're putting the Plastigage anywhere besides the EXACT center of the journal right where the pump bolt will hit it, it will appear to increase the tolerance.

Oil pump bolts are 1-15/16". People all the time use 2" bolts, which will cause problems. Especially on a 400 with the larger journal.

Well, Im using an ARP stud/nut right now so I dont think this is the problem.

Thanks
A-M