Torque Questions SBC - The 1947 - Present Chevrolet & GMC Truck Message Board Network

kcfirstbuild · 10-16-2010, 01:58 PM

I want to make sure i have the correct Torque Specs.

For my Main Caps and my Connecting rod caps

Main caps all - 70 Ft lbs and use engine oil on the threads '

Connecting rod caps all - 65 ft lbs and use engine oil on threads

I had the crank polished and the guy measured it and said standard size bearings, but i still want to plast a gauge it to make sure.

To my understanding the main bearings should have an oil clearance of
.oo2 - .o03

And the rod bearings an oil clearance of .oo2- .o25

Please correct me if im wrong.

This is my first engine rebuild ever.

Lee H · 10-16-2010, 02:38 PM

Which engine do you have? Yes oil or some other lube on threads. Assuming it's a 327 or 350 my shop manual says 70 on the mains and rod caps at 45. Your not trying to do this without a shop manual are you?

kcfirstbuild · 10-16-2010, 03:22 PM

I have a 307 that is original to the truck.

I have a Chilton ? That i have been going by so far.

Kerry P · 10-16-2010, 03:53 PM

In addition to Chilton there are a ton of good references on building a SBC. A book store like Borders will usually have a number of them that you can review before purchasing. The good ones will include tips that are not always in a spec manual.

Cleanliness is an area where it's easy to miss an internal corner or passage. The smallest details can ruin an otherwise good re-build.

If you are not having the block bored but are re-using original pistons try to measure the cylinder wall tapper before going too far into the effort. I've had low performance SBC do OK with up to .007" taper but I think I was lucky on those.

You've dropped a zero on your rod clearance question. .002 to .0025 is a common spec but in the real word I've worked with .003". But I added a high volume oil pump for when starting with clearances on the high side.

Kerry P

kcfirstbuild · 10-16-2010, 04:52 PM

I have had the block bored and cleaned and over sized piston head put on the connecting rods along with over sized rings.

Ok so I want them in the range of .002 -.0025

Kerry P · 10-16-2010, 05:00 PM

That's the standard range. Sounds like it's being done right.

Kerry P

kcfirstbuild · 10-17-2010, 05:33 PM

So i just got done putting in the new standard bearing s laying some plasta gauge down and torqued them to 70. Took the caps off and measured the Green plasta gauge can came up with .002.

Have not done the connecting rod bearings just yet. Had to stop and roll the truck down to the barn for the winter, but i still have room to work on the motor till I finish it up.

10-16-2010, 01:58 PM	#1
kcfirstbuild Registered User Join Date: Aug 2009 Location: Red Wing Mn Posts: 526	Torque Questions SBC I want to make sure i have the correct Torque Specs. For my Main Caps and my Connecting rod caps Main caps all - 70 Ft lbs and use engine oil on the threads ' Connecting rod caps all - 65 ft lbs and use engine oil on threads I had the crank polished and the guy measured it and said standard size bearings, but i still want to plast a gauge it to make sure. To my understanding the main bearings should have an oil clearance of .oo2 - .o03 And the rod bearings an oil clearance of .oo2- .o25 Please correct me if im wrong. This is my first engine rebuild ever.

10-16-2010, 02:38 PM	#2
Lee H Registered User Join Date: Jun 2010 Location: Upland Ca Posts: 4,147	Re: Torque Questions SBC Which engine do you have? Yes oil or some other lube on threads. Assuming it's a 327 or 350 my shop manual says 70 on the mains and rod caps at 45. Your not trying to do this without a shop manual are you? __________________ 1972 C10 SWB, Air, PS, PB, 350/350THM. Second owner. 1965 Corvette roadster, 44K miles, 327/365 SHP, 4 speed, side exhaust, knockoffs, teak, second owner (bought in 1970), Have ALL numbers matching components. My frame off restoration thread: http://67-72chevytrucks.com/vboard/s...d.php?t=556703

10-16-2010, 03:22 PM	#3
kcfirstbuild Registered User Join Date: Aug 2009 Location: Red Wing Mn Posts: 526	Re: Torque Questions SBC I have a 307 that is original to the truck. I have a Chilton ? That i have been going by so far.

10-16-2010, 03:53 PM	#4
Kerry P Registered User Join Date: Aug 2010 Location: Harrison Arkansas Posts: 164	Re: Torque Questions SBC In addition to Chilton there are a ton of good references on building a SBC. A book store like Borders will usually have a number of them that you can review before purchasing. The good ones will include tips that are not always in a spec manual. Cleanliness is an area where it's easy to miss an internal corner or passage. The smallest details can ruin an otherwise good re-build. If you are not having the block bored but are re-using original pistons try to measure the cylinder wall tapper before going too far into the effort. I've had low performance SBC do OK with up to .007" taper but I think I was lucky on those. You've dropped a zero on your rod clearance question. .002 to .0025 is a common spec but in the real word I've worked with .003". But I added a high volume oil pump for when starting with clearances on the high side. Kerry P

10-16-2010, 04:52 PM	#5
kcfirstbuild Registered User Join Date: Aug 2009 Location: Red Wing Mn Posts: 526	Re: Torque Questions SBC I have had the block bored and cleaned and over sized piston head put on the connecting rods along with over sized rings. Ok so I want them in the range of .002 -.0025

10-16-2010, 05:00 PM	#6
Kerry P Registered User Join Date: Aug 2010 Location: Harrison Arkansas Posts: 164	Re: Torque Questions SBC That's the standard range. Sounds like it's being done right. Kerry P

10-17-2010, 05:33 PM	#7
kcfirstbuild Registered User Join Date: Aug 2009 Location: Red Wing Mn Posts: 526	Re: Torque Questions SBC So i just got done putting in the new standard bearing s laying some plasta gauge down and torqued them to 70. Took the caps off and measured the Green plasta gauge can came up with .002. Have not done the connecting rod bearings just yet. Had to stop and roll the truck down to the barn for the winter, but i still have room to work on the motor till I finish it up.



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