[The Swede]

PLEASE HELP ME GETTING THE NUMBERS RIGHT !

It's a SB Chevy (355cu/in)-forged pistons-alu rods-aluheads.

Feel free to correct any missplaced zeros !

Main bearings = 0.0020-0.0025 inch.

Rod bearings = 0.0020-0.0025 inch.

Rod side clear = 0.009-0.0018 inch.

Piston to Head = In some forums they say 0.40 to 0.80 inch but I guess they mean 0.040-0.080 inch.

Piston to valve = In=0.080-0.100...Exh=0.100-0.145 inch.

Crank end = 0.003-0.009 inch.

 

[BillK]

Swede,
Those all look correct to me. As you said, the piston to head should be .040 to .080 ... shoot for the low nd of this if you can, if not dont worry too much about it.

 

[The Swede]

BILLK.....should it be 0.40 or 0.040 inch ?

 

[Wolfplace]

BILLK.....should it be 0.40 or 0.040 inch ?

=
It should be .040" as Bill posted but I would recommend no closer than .050" EDIT( make this .060",, see next two posts) minimum with alum rods.

Also, the side clearance will probably be more like .020 & this is not a problem, it is correct.

 

[ToyzRMe]

Swede, If you're using ALUMINUM rods, you're going to need at least .060" of piston-to-deck clearance to allow for rod stretch. .065 should be safe under 8500 rpms.

I run .058 in my 355" aluminum rod motor with .0065 piston to wall clearance. The head occasionally leaves VERY slight witness marks in the carbon on the piston flat area. This is shifting at 7600 rpms and going thru the traps at 7400.

The rest of the clearances you posted seem close. I would shoot for around .003 or so on the rod bearings with aluminum rods.

Randy

 

[Wolfplace]

Swede, If you're using ALUMINUM rods, you're going to need at least .060" of piston-to-deck clearance to allow for rod stretch. .065 should be safe under 8500 rpms.

I run .058 in my 355" aluminum rod motor with .0065 piston to wall clearance. The head occasionally leaves VERY slight witness marks in the carbon on the piston flat area. This is shifting at 7600 rpms and going thru the traps at 7400.

The rest of the clearances you posted seem close. I would shoot for around .003 or so on the rod bearings with aluminum rods.

Randy

=
Randy is correct for a higher RPM engine .060 is a much safer number than .050. for quench.

I have run .050" to 8500 in a 3.76" stroke BB & the pistons were showing signs of contacting the heads but with no damage,,
This is probably closer than you want but I figured it kept the rods from stretching too much

 

[The Swede]

THANK'S GUYS....Beginning the assebly tomorrow.....

 

[BillK]

Swede,
Sorry, in my haste I missed the aluminum rod part