Engine Build troubles

[zachm611]

Hey everyone, i seem to be having some trouble during my build. after plastigauging the bearings i realized i needed oversized bearings so i changed them out today and now the engine is extremely hard to turn over. it used to be fairly smooth. now it doesnt budge at all. piston number 1 was pretty stiff in there. any ideas on what it could be? i was so close to being done with my build and then this happened oh well i guess its better to happen now then when its actually in the car. thanks,

Zach

 

[NewWestSupras]

If the bearings you bought are all the same "oversize", thats most likely the problem. When these motors were originally built, they used inhouse bearings made to suit after measurements. They could be different by small increments, hence the tightening of certain cylinders. I'd recheck all the clearances, and you might have to do some more machining to get them all perfect. I'd ask Ian (IJ) his take on this, as he's been through this quite a bit.

 

[89turborunner]

Did you have your crank inspected? or did you do it yourself? (I do not mean plastigauging, I mean runout on the crank bearing surfaces)

Make sure the bearing surfaces are CLEAN and that they are lubed with engine assembly lubricant.

Plastigage the crank with the oversize bearings if you haven't already.

Typically your crank will not wear into the exact size it should be or oversize bearings... at least not evenly.

Are you talking about the rod bearings, the mains, or all of them? (being oversize I mean).

Having the rod bearing surfaces machined costs crazy money from what I have heard.

Let us know. sorry to hear about your trouble.

 

[Rennat]

Did you do the PROPER torque sequence? this happened to a buddy of mine while building an engine, didnt do the proper sequence, had the crank inspected, it was good, re-torqued it down the PROPER way and everything was fine. haha.

 

[cuel]

Bearings are to tight. Engine should turn smoothly after each rod is torqued. Install one rod, spin crank one revolution. Then you'll know as soon as you have one that doesn't fit right, for whatever reason.

Did you have all the rods checked to make sure they aren't out of round?

 

[Motofool]

from what you stated it seems as though you used plastigage on your stock sized bearings and they were too loose of tolerance so you grabbed over sized bearings without any machine work? in my experience i have never been able to just jump bearing sizes without having something machined IE the main caps decked and rebored, or if its rod bearings having the rod caps decked and rebored, or having the crank ground and polished.

my advice if your unsure is take the block down and have a machinist evaluate the tolerances it shouldn't cost anything at most shops and if it does it should be a flat rate.

if you want to continue diagnosing the problem yourself a few questions i have for you

1) what kind of assembly lube are you usging and how much

2) what did you have machined? go into detail

3) are you installing new hardware arps or are you reusing all old bolts and everything

4) could you turn the crank by hand without the pistons in

5) elaborate on the piston #1 problem

6) have you removed the crank and rods after having this issue and what do the bearings look like? are they shiny or is any coating rubbed off in ANY place on the mating surface to the crank?

this information would let us help you alot more