Got the block together, #1&3 pistons in, turn it over to install other pistons and find that the #2 rod is slightly stiff on the crank. I noticed when i assembled the con rods that that bearing was very slightly stiffer than the rest - almost unnoticable so i ignored it - all bearings have been plastigauged and were ok in the direction i measured.

Now, after sitting overnight, it seems to have become stiffer - still easy to move by hand, but it definitely wont fall to one side with its own wieght like the others. They have been assembled using assembly lube. Other rods still feel quite free.

Any thoughts on this?

 

Cheers.

Not to insult your intelligence (it insults mine more actually), but I had the same thing happen when I reversed a rod cap.

Na, checked that. I'm glad i can see the marks through the cylinder, otherwise i'd be wondering...

Years ago, I was rebuilding a Pontiac 400 cu engine for a friend, and had simular problem only it was main bearing related. I did plastigage the mains, but that won't tell you that the bearing half was cut to long. If I left the main cap snugged by turning down with my fingers, crank would turn, torque it to spec, and it would lock-up the crank. Found that one of the bearing halves was a tad-bit longer than it should've been, and would get deformed when the cap was torqued down. Installed a different bearing half, all was good.

 

Ain't saying that is your problem, but it could be. There's something definetly amiss on that rod end. Sucks part is that you have to re-split the block to take a look at things again.

 

Just asking this.. You did remove the plasti-gage strip right. I know someone that did that too, but I won't mention his name.....

There is a spec ofr side to side clearance in the journal of the connecting rod. Dissassemble everything and check all the specs too. It is possible that one crank journal is a different size then the others.

 

 

nipper

Checked all the usual stuff already - journals are within spec as are side clearences and oil clearences. Yep, i took out the plastigauge.

I'm gonna go out and see if i can remove the con rod through the cylinder......hey, its worth a try...

Well, i got the rod off, cleaned it up and looked for any obvious probs, there wern't any. So i lubed it up and put it back on (this is all without splitting the block - not easy, but possible).

 

Same deal. Its only stiff at some points - which may explain why the clearence seemed ok when i plasigauged it. Starting to think that maybe a bearing half is wrong.....

 

Any other suggestions/comments?

Anyone else experienced probs like this?

Did you check side clearance with a feeler gauge. There is a spec for this in the manual. Gte your habnds on a micrometer and a caliper and check the bearing and the journal, and make sure the math adds up.

 

nipper

Yes everything like that already checked. Journals are within spec. As is side clearence.

Bearing feels fine when only lightly torqued, only when tightened completely its stiff.

Looking like a bearing may be wrong as mentioned above.....