Bearing Clearance on a 10.30 motor?

[Chris McDade]

Building a new motor for the GN right now. What bearing clearances do you recommend? It will half track/Street car. It will be a mid to low 10 car.

109
.030 Weico pistons
RJC girdle
214/214 flat Tappet
Iron Heads and intake fully ported.
66 S trim turbo
9" art Carr 3200 Stall.

Thanks in advance

 

[turbodave231]

There are lots of differing opinions on bearing clearances.

I have had very good success with .0017-.0021 on the rods and .0020-.0025 on the mains.

As long as you have very round, close toleranced main and rod journals you can get away with tighter clearances. Poor tolerances (out of round and/or tapered) journals will have problems with tighter bearing clearances.

Obviously, tighter bearing clearances will provide better oil pressure.

Dave

 

[bison]

.018-.020 mains and .020-.22 rods. You will overpower your converter before you can maximize the use of the other parts in your combo.

 

[Chris McDade]

Thanks for the info on the bearings clearances.

Should I go with a PTC converter?

Thanks

 

[Chris McDade]

Don't you usually run tighter rod bearings than mains?

 

[TurboSpeed]

yeah to force more oil to the cam= higher oil pressure

 

[TURBO 6]

Should I go with a PTC converter?

Thanks

A PTC 9.5" N/L would be the way to go for the best performance.