checking torque on assy engine

**mcshooter** · 12-17-2011, 02:31 PM

i never heard of this before.. a friend of mine called about a show this morning on engine assy. they put together a v8 engine and then checked the torque to turn the crank.. at first it took 43 lbs to turn the crank. then he loosened the rod caps and jammed a feeler gage,as tight as he could between the adjacent rods and retighten the rod caps. the torque then was 11 lbs to turn the crank. even tho i know there is a little clearance on the rod bolts to the cap i never thougth about the cap being slightly off center. i have 4 extra rods on bench so when i checked them i could feel 2 of the 4 were off probably a couple thousants. you could feel the offset on bolt sides of the cap and the other 2 were right in line with the rod. i dont know how much clearance our engines have . on the show they said as long as they do not touch there is no problem but as i have said i had never thougth about the caps being slightly off due to the tight fit when putting the caps on.. but its easy to understand with there being clearance on the cap holes.. a friend of mine had a hard to turn crank on a v8 caddy he put together and when we loosened and retighten the rods the crank turn loosened up ...so i think this would be a good tip when doing a engine assy..of course you folks probably knew this ..

**green-lantern** · 12-17-2011, 10:44 PM

Originally Posted by mcshooter

i never heard of this before.. a friend of mine called about a show this morning on engine assy. they put together a v8 engine and then checked the torque to turn the crank.. at first it took 43 lbs to turn the crank. then he loosened the rod caps and jammed a feeler gage,as tight as he could between the adjacent rods and retighten the rod caps. the torque then was 11 lbs to turn the crank. even tho i know there is a little clearance on the rod bolts to the cap i never thougth about the cap being slightly off center. i have 4 extra rods on bench so when i checked them i could feel 2 of the 4 were off probably a couple thousants. you could feel the offset on bolt sides of the cap and the other 2 were right in line with the rod. i dont know how much clearance our engines have . on the show they said as long as they do not touch there is no problem but as i have said i had never thougth about the caps being slightly off due to the tight fit when putting the caps on.. but its easy to understand with there being clearance on the cap holes.. a friend of mine had a hard to turn crank on a v8 caddy he put together and when we loosened and retighten the rods the crank turn loosened up ...so i think this would be a good tip when doing a engine assy..of course you folks probably knew this ..

I saw the show also. I don't think this would pertain to our engines but I'm not sure. The Buick engine they were building was so old it used a rope type rear seal.

**RealMcCoy** · 12-17-2011, 11:23 PM

Most engines have very tight clearances at the rod bolts, with the bolts actually centering the rod caps, there really isn't much chance of them being off center in the first place... Many modern engines use fractured rod technology that makes it impossible to get them off. (Unless you're a moron and install them backwards.... And yes, I've seen it done.)

**mcshooter** · 12-17-2011, 11:59 PM

i just measured the offset on one of my extra rods and it is .002 ...i no longer have any small hole gages but if someone has some they could measure the holes in the rod cap and mike the rod bolt to see how much clearance they have. maybe someone like ray p. would know the clearance between the rod bolt and cap hole. also i would like to know how much clearance we have between rods.. my friends caddy v8 must of been close as i believe his rods must of been touching ...

**Chris@Rvengeperformance** · 12-18-2011, 06:23 PM

V8s also have 2 rods on some journals, we do not.

**mcshooter** · 12-18-2011, 08:01 PM

fg is correct,forgot about that, but just saw the tv show. it was a buick 350 v8 and the rods were .024 apart so they were not touching, it is the cap is slightly off center that caused the torque to be higher to turn the crank. it does not mean much but it looks like the rod bearing is not even on the journal. when squared up the bearing is even thus less torque to turn the crank. probably as soon as engine is run a little it is evened out.. just that i never saw this before. the shop that did the rebuild of the buick v8 looks like they did a good job and knew what they were doing, not like the shops around here that have destroryed a few guys engines by putting the thrust bearings in backwards..