Engine rebuild woes
 

My rebuild is not going as planned. Everything going smooth until the last rod cap. As soon as its torqued on the engine takes a great deal of force to turn. Loosening the studs allows the crank to turn freely. Loosened 1 2 and 3 rod caps and torqued 4 down and its at the same nearly impossible to turn crank. Caps installed correctly, standard size bearings, piston installed the correct way. Only thing we did to the crank was take some emery cloth and went around it a few times. Even swapped bearings with #1 and still same result. Also put in old bearings for shits and giggles, no beans. I think its something stupid that might be going on. Any ideas would be much appreciated. Getting plasti gauge tomorrow.

So you are saying even with the old bearings it doesn't spin? Or just with the new ones? Could be new ones are mislabeled oversize bearings. I guess you don't have an inside mic you can use to measure with do you? Also, are you 110% sure you haven't mixed up the rod caps at all?

This happened to mine once, turned out I threw one old bearing in with the new. All the old ones looked ok, all 32 new and old bearings were "STD" size. One out of 8 with the rods is apparently enough to lock it up pretty good.

Are they the used factory rods? or new aftermarket ones?

I have come across 1 or 2 aftermarket rods that were a tad small on the big end bore.

You didn't take any measurements or use any plastigauge at all during the build?

Sav.... Not all guys are number junkies like us. :giggle:

I would bet you have stacks of notebooks filled with specs from different builds from over the years.

Plastigage.

(Or however it's spelled.)

3 things to check:
- Rod is not pushed to one side of the piston (too far forward or back along the length of the piston pin) so that it no longer lines up square to the Crank rod journal.
- piston is not turned in the bore (causing the rod to not be square to the crank)
- Piston is stuck in the bore (damaged piston ring, not enough end gap on one or more rings, piston has a nick during installation, ...)

Disconnect the rod at the crank and see if you can push the piston up the bore... All 4 pistons should have about the same resistance.

1 and 2 are not reasonable causes of any problem, because they do not happen. Tightening the big end of the rod will ALWAYS line the piston up in the bore and line the rod up on the crank.

Plastigauge results as follows.
Cyl 4 .0015
Cyl 3 .002
Cyl 2 .002
Cyl 1 taper .003-.0015

I replaced the 4th Cyl bearings with used bearings to see if it would turn after it was torqued and it wouldn't (however I couldn't verify this was Cyl 4 bearings). I micd the new and old bearings. Same width. Rod caps 115% mated with correct pistons.

Cyl 1 and 4 have issues, Have you figured out just why your spec on 1 is so screwy?
What is making #4 tighter than the rest?

My guess is that Cyl 1 is screwy because I cracked the ringlands on the piston possibly causing uneven wear. I did drive it 1500 miles after the incident.

I would take the crankshaft to a machine shop to get checked.

I don't really have an option. Going to have to get the crank turned and buy new bearings. Thats what i get =). Would a .0015 clearance be the cause of the inability of the crank to turn?

What's the taper with the old bearings? Any difference?

I couldn't verify which bearings belong to #1.

Did you check rod end play with a feeler gauge, see if something is binding up? What did you change in the rebuild, are these aftermarket rods (eagle). What is the crankshaft thrust(endplay)? You should be writing down your measurments, Plasticgauge sucks balls.

Are they the stock main studs, or something like ARP?

All stock including hardware. I do not have a thrust dial indicator. The only thing that was changed in this build was #1 piston and rod (since the piston on #1 was cracked @ the ringlands), main and rod bearings, and piston rings. I really need to invest in some higher quality measuring equipment. Ill have to check rod end play.