torque to turn a short block??

[rodman99999]

Has anyone ever done a torque reading on what it takes to turn a 3.8 short block? I just assembled mine/installed cam, and it seems kinda tight. Clearances: mains- .0016(torqued to 90lbs, ARP studs), rods- .0018(torqued to 50lbs(ARP bolts), piston skirt/wall- .0045, rings gapped to .0022(plasma moly), crank endplay- .006. I used the red assembly lube on the bearings and soaked the pistons in 5W-20 oil. I've only been turning it with a 10" adjustable. Gotta get my big 1/2" socket set from where my car's parked(building the engine in my dining room), so I can find out how many ft/lbs it's taking. Should I worry?

 

[SFITurbo]

As I remember, mine didn't require alot of effort once it started turning. Best guess would be 25 ft lbs? Your clearances were the same as mine, I used stock bolts and nuts though.

 

[Quick6'n'-K.C.]

I had a tta motor sent here that was as tight as a drum for a buddies car, it would actually HURT my hands if i tried to turn it by the flywheel and it was not possible to turn by hand on the balancer...
I was reluctant to install it, had hypers, but it lasted 30K and the cam went flat, nothing to do with how tight it was when fresh.

Since YOU know how it was supposed to be built, just seems that it should be put together and broken in.
I would prime the oil pump and install the cam sensor when the motor is on the engine stand,...soooo much easier.

Forged or hypers, stock pistons?

3/8 10 inch is too small
BW

 

[rodman99999]

OOPS- Speed Pro forged slugs(L2481F, STD), bore= 3.801. I was kind of expecting to be able to spin the crank(when that's all that was in there), like on the small block 400(last engine I built). Of course: there's alot more clearance on those.

 

[Ormand]

I was kind of expecting to be able to spin the crank

In spite of the tighter clearances, you should still be able to spin the crank. Without the flywheel, it won't keep spinning, but it should turn freely, and not stop turning as soon as you let it go. If not, maybe the thrust bearing was set wrong, or the crank is not quite straight, or???

 

[KWIKR 1]

OOPS- Speed Pro forged slugs(L2481F, STD), bore= 3.801. I was kind of expecting to be able to spin the crank(when that's all that was in there), like on the small block 400(last engine I built). Of course: there's alot more clearance on those.

with only the crank installed in the block and the right clearances , you should easly be able to spin it with one hand and also move it back and forth on the thrust . sometimes if you use a heavy bearing prelube it tends to make it a little more difficult . I usually use a straight 50wt/GM EOS mix on the bearings for assembly . One time I use a sort of honey oil/Lucas prelube and this did make the crank a lot harder to turn by hand . I'm no expert but I've done 2 Chevy SB and 3 Buicks and this is usually the case for me .

 

[MSDGN]

Crank alone should spin freely...the crank should be checked for freedom of movement periodically as the mains are torqued...with pistons/rings/rods assembled it can be tight...mine turned pretty easy without the heads...put the heads on and it was a little harder to turn...I was using a 1/2 breaker bar...did the crank spin freely after it was installed?

 

[Blown&Injected]

My assembled short block seems like it turns too easy. While it is now all together and bolted to the trans it still seems like it turns easier than other engines I have turned. Although it is all together I will still put a torque wrench on it and keep turning it down until it clicks before turning and then up it until it turns without clicking.

 

[rodman99999]

Like I said- I used the old, trusty(and heavy), red assembly lube. The crank wouldn't spin freely, even when in there by itself. I've got .006 endplay on it. It takes 19-20 lbs/ft to turn over with pistons and cam(put my handy-dandy torque wrench on it today). There certainly are a variety of experiences with the assembly of these engines. If it spun as freely as a SBC(with all the thick lube in it): I'd be a bit worried, given the differences(then again: the thought of a bent crank has crossed my mind). So how many other's out there have had tight short blocks that gave long service? Please- ease my mind!!

 

[MSDGN]

Maybe I used incorrect wording...by spin freely I don't mean turn the crank and it will spin a few times around...on mine with a girdle...after the crank was installed with mains torqued down I could turn it very easily with my hand...not actually spin it...I used the white lithium asembly lube from NAPA...if you had to use a wrench to turn the crank when it was the only piece installed then I think you may have a problem...JMO...I set my mains and rods at .002...

 

[rodman99999]

I just backed the mains off(all but the rear main) to the tune of about .020 each(popped loose). It takes the same 20 lbs.ft to turn it with those three bearings floated. I would think if there were a problem with the crank(like bent): that should have freed it up some(or am I screwed up in my thinking)?

 

[Blown&Injected]

Well, fully assembled (no spark plugs) and bolted to the trans/converter it took about 35 to 40 ft lbs to turn.

It is a 40 over full roller engine.

 

[rodman99999]

Well, fully assembled (no spark plugs) and bolted to the trans/converter it took about 35 to 40 ft lbs to turn.

It is a 40 over full roller engine.

I appreciate that input. It'll give me a reference point when I get the rest of my stuff bolted up. Is that fresh, or with miles on it? Thanx!

 

[gmpower6]

Rod when you put the motor together did you get the 2 dot's on the rod's going the right way? 1,3,5 go one way and 2,4,6 go the other. One side facing the front of the motor and the other side going to the fire wall.

Maybe you got some turned around by mistake?

Sean

 

[DMan]

I just finished breaking in my engine this afternoon. Did a minimal rebuild, new rings, new stock pistons, cylinders honed, crank polished, new bearings all around. All stock internals. This engine has 103,000 total miles on it.

Fully assembled with no plugs this engine also required about 40-45 ft lbs to turn over.

My main clearances were on the order of 1.8 to 2.0 thou (just outside factory specs). All other clearances are in factory spec.

By the way, at the end of my 30 minute-2500 rpm break in this afternoon, engine temp was 200deg F, and oil pressure at idle was 35 psi! (Stock oil pump - not high volume).

Denis

 

[KWIKR 1]

Rod when you put the motor together did you get the 2 dot's on the rod's going the right way? 1,3,5 go one way and 2,4,6 go the other. One side facing the front of the motor and the other side going to the fire wall.

Maybe you got some turned around by mistake?




trying to picture it ,I think that would be almost impossible to do. the rod end would be binding up against the piston (if hung incorrect on piston and piston was installed in proper direction .due to the rod offset). DS boses/2 dots face to back of engine , PS to the front .


IMO If ALL clearances check out to be correct and you know nothings bend . I would not worry about it .

 

[Blown&Injected]

engine has not been started yet
.0023 on the rods and mains

 

[Jerryl]

Has anyone ever done a torque reading on what it takes to turn a 3.8 short block? I just assembled mine/installed cam, and it seems kinda tight. Clearances: mains- .0016(torqued to 90lbs, ARP studs), rods- .0018(torqued to 50lbs(ARP bolts), piston skirt/wall- .0045, rings gapped to .0022(plasma moly), crank endplay- .006. I used the red assembly lube on the bearings and soaked the pistons in 5W-20 oil. I've only been turning it with a 10" adjustable. Gotta get my big 1/2" socket set from where my car's parked(building the engine in my dining room), so I can find out how many ft/lbs it's taking. Should I worry?

Don't think 20 lbft it is that much on a new engine with rings and heavy assy lube.

 

[rodman99999]

Rod when you put the motor together did you get the 2 dot's on the rod's going the right way? 1,3,5 go one way and 2,4,6 go the other. One side facing the front of the motor and the other side going to the fire wall.

Maybe you got some turned around by mistake?

Sean

Well Sean- 1,3,5 are facing back, the rest toward the front. Is that correct? My machinist put the pistons on the rods, and I installed them according to the arrows on the pistons. He does alot of Buick engines, so I trusted his procedure. Hope that wasn't a mistake!

 

[gmpower6]

That's right just checking.

Sean