Hello:

I'm a newbie in the process of assemblying my 350 with the following parts:
-KB Silvolite 120 pistons .020 over
-Total Seal TSS rings
-Scat 4340 I rods
-Stock crank .010 under both main and rod bearings
-Pro topline 170cc 72cc cyl heads
-Crane 216/228 compucam

The block is from my 1979 Blazer. The engine is going into my 1986 camaro with it's TPI converted to speed density. I'll be mostly using it as a daily driver with the ocasional race at the strip once in a while just for fun.

1) I've found different numbers all over the Internet, so maybe someone here can tell me what should the ideal main and rod clearances be for my application? I know there's a range. Where within that range should I be?

2) What should the diameter be between bearing caps without the bearings?

3) I have two friends currently in the same step of assemblying their pontiac 400 engines. They found somewhere that they should be closer to the "tight" side of the range, so they grounded off about 0.001 of their main caps so they were right on. They are pushing me to do the same if my clearances ar too loose. Is this appropriate? Or are they looking for trouble? They say they don't need to align bore because it's "only" 0.001.

4) Also, can someone advice on which oil grade to start the engine for the first time? I've been told to start it and take it to 2000rpm for 20 minutes, and then change that oil. Which grade should I put then?

Any help appreciated.

 

1) http://www.chevytech.net/1c6o1.html
2) You should be checkign the clearance with the bearing installed.
3)Your friends are idiots. If a standard bearing is too sloppy. and your SURE your crank and mains are NOT outta round or tapered, you need to have the crank ground to .010 under and use a .010 oversized bearing.
4) Use plain jane 10w-30 and break it in per your cam card instructions, than change oil.

 

Holy cow Ive never heard of anything like that evr.Grinding on the mains ahhh.There is plus& minus size bearings to take up or open up space .Bearing shells are designed to be squeezed a certain amount together to obtain roundness change that quench and yer askin for an outa round bearings and a misaligned crank..Gettin the mains trued wont chance your bearing clearences changing to the proper size bearings will.

 

Thanks for your replies.

1) This is what confuses me. According to that link, clearances should be:
No. 1 0.0008 - 0.0080
No. 2-4 0.0018 - 0.0020
No. 5 0.0010 - 0.0036

According to CHEVY PERFORMANCE SMALL BLOCK by John Baechtel, clearances for "high perf. stret" should be:
0.0025-0.0037

According to John Lingenfelter on Modifying Small-Block Chevrolet, clearances for a "daily driven small block"
Mains 1-4: 0.0020-0.0025
No. 5 0.0025-0.0030

I just finished measuring, and I have:
No.1 0.0025
No.2 0.0030
No.3 0.0025
No.4 0.0030
No.5 0.0020

What would you do in my case? Whom should I listen to? Books don't mention a solution for reducing the clearance in 0.0005 or so. My friends had similar clearances, so they took layed some sandpaper on a very flat workbench and sanded about .001 off each cap, right on the surface that contacts the block. They ended up with clearances of about 0.0010 on every journal. Sounds very logic, but wanted to ask first if I should do the same.

2) I am checking the clearance with the bearing installed. I just wanted to find out the diameter without the bearing so I can have another point of reference. These friends found what this clearance should be and discovered their's was larger by about 0.0010, which encouraged them to do the sanding.

3) I'll use 10w-30. Thanks.

I'm currently working on this engine. I'll go measure rod clearances now. I'll let you know.

Any more advice is welcome.

Thanks