Rotation resistance??
 

Does anyone check torque needed to turn a rotating assembly after being assembled? Just bottom end no cam and chain. What did you get?

We do all the time. Usually just the assembled rotating assembly. Type of cam bearings and core diameter will affect the amount of friction along with the cam drive set up. Not long ago we had two identical short blocks that came together at the same time. One had a trick ring pack and the other used a basic performance ring set up. Going from memory the trick set up required 22 lbs/ft to rotate the engine and the other was 34.

Home builds can use a Go// No-go method. Many / every time i check short block TQ resistance, there is a purpose to see about a few tings;

During MainCap install, and particularly the Thrust Cap. So that means #4 Cap install plud another Cap, to get the feel of what causes a rotation bind. Once resolved, then all .caps go on and rotational TQ is dead smooth. Rear Seal is minor if 1-piece. Rope adds a bit but smooth rotational TQ.
No seal, and the crank ought rotate with 1-finger tugging a counterweight.

Each Slug add TQ due to CYl walls, but you ought check Rodplay (and rock) on Crank before install to avoid surprises. Yea i've seen 35'Lb to low 20s due to stock stack vs Chevy stack. So you will kinda know the rotational TQ depending on the Ring stack and CYL hone money you decided on.

Finally, that's about it.

With just the crank it had 2-3ftlbs of resistance with rods and pistons it 25-30 with classic race rings in it so I’m happy with that.

Yes your fine with that especially if your using 5/64” rings.

Your numbers look fine to me as well. Using assembly lube vs just engine oil can add 5-10 ft. lbs rotating torque as well. I am talking about thicker liquid like Lucas , Torco, or Sealed power assembly lube. The viscosity is very high.

Would rear main seal choice would have likley impact?i believe yes in my experience

Absolutely. A fresh rope seal adds allot of drag until it breaks in. I generally assemble, crank, pistons and rods, cam and timing chain. Then check rotational torque. If I am happy with it, I then remove the rear cap and pack the bottom half of the rope seal and install. But to be honest, I haven't used a rope seal in a Pontiac in 10 years or more. Too many good modern options to mess with that ancient technology nowdays. The viton seals, lubricated add little drag.

You are using lip seal On factory and or Eagle serrated cranks w good success ?
Has anyone ever done a dyno test to isolate your the seal drag? Lot of work but I wonder what it would
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I don't think there would be much difference. I remember packing the original GM seals and they almost locked up the motor once you torqued the cap. And I remember after those seals broke in the engine turned as if there was little drag.

H-O used to claim a 5 HP difference but I'm guessing that was a calculated number. Hard to find a Dyno back then that would read that accurate in a back to back test.

I know I read somewhere but can't remember the source that a rope seal, once broken in has less drag than a rubber/viton seal. But that's certainly not the case when the rope is new. I have removed the pistons and rods from old Pontiac engines with rope seals and the crank can be turned easily with 2 fingers. Not scientific, but almost no drag you can feel. As far as the viton seals on serrated crankshafts. I personally don't like Eagle crankshafts so I have never used one in a Pontiac build. There have been many comments on the forum and other sites that some Eagle cranks have very aggressive serrations that could tear the viton seal or leak through the serrations. If you can easily catch a fingernail on the serrations, polishing this area with 280/320/400 cloth would be a minimal treatment IMO. Factory crankshafts I just polish in the normal way with a 400 grit, worn polishing belt and they seem to work just fine with the viton seals.

The newer graphite rope seals have very low drag, but of course, a certain amount is relevant to the installation.


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