360 assembly

Main caps should be numbered with an arrow. Arrow tip goes forward.

farna wrote: You need to check the bearing clearances. Also, are the main caps in the correct positions and turned the right way? I'm assuming they are the caps you took off that block also. They have to go back in the same position they came out of the block, or rather were machined in the block. It's been so long since I rebuilt and engine... rod caps are numbered, I can't recall how main caps are marked... but of course the rear main and thrust bearing cap are obvious.

Caps are the same that came with engine. You are correct. The caps are numbered and have an arrow cast in them for the forward direction.

Sounds like your issue is just mismatched sizes on crank and main bearings. Will likely have to take the crank back and have just a little more taken off, unless the cranks was turned only 0.010 and you have 0.020 bearings.

long story ensues... you can stop reading now...

I had something similar happen, but with rods, and was my stupid mistake. Got the rod caps on backwards when rushed on a rebuild of a 195.6 OHV six. Short block was supposed to have been ready a couple months before I finally picked it up -- machine work done but in pieces. Easier mistake to make than you think! Rods and caps are numbered on the same side, but 196 rods, pistons, and caps have marks that go to the front of the engine. I had intended to drop the motor in that weekend (motor and machine shop were at my dad's place, four hours from where I was stationed in the USAF at the time), and expected a ready to go short block. Boy was I mad!! Told them to load it up and give me a bill for what was done. I'd already made a two other trips up, several weeks apart, to get the motor. They could have called and saved me the trip (though I was visiting family on all occasions as well), but I didn't know it wasn't ready until I got there. After two months of "it will be ready" I'd had enough!

So now I'm assembling the motor and rushed. Put pistons in with marks to front (pistons have an offset dome, so can't be put in backwards and still get the head on), in the correct order. Flip it over, stick rod caps on, in the correct order with marks to front. What I DIDN'T check was the rods themselves, or pay any attention to the stamped numbers on the rods after I flipped the engine. Since the rods are marked to the front, they should have been correct, but the shop had put the rods on the pistons backwards!! I didn't notice, so caps were on backwards. So it's not that tough a mistake to make, if you assume the shop knew what they were doing. Up until that point it was a reputable shop... at least it had been! That's why I went four hours out of my way to have them do it.

Engine was tight, but would turn over by hand. Starter was having a hard time spinning it fast enough to crank for the first time though. My brother checked it too, said it was tight, but not too tight. I had built 2-3 engines before, he about a dozen. Ended up hooking it to my brother's pickup and pulling it about a quarter mile in 2nd gear... thankfully I had an older M35 auto with rear pump. Had a 50' tow strap -- an auto lurches forward when it starts, better to push if possible.

I was so darned mad when as I was assembling that engine it's a wonder I didn't screw it up big time! It ran fine -- I found out about the rod issue ~18 months later when I burned a hole in a piston due to dual carbs -- trash in the rear carb jet caused a lean condition in #6. When pulling the rod cap I noticed he bearings were showing some copper -- after about 19-15K miles?? So I inspected the rod closely and immediately found the issue, and checked all others. The shop where I was stationed didn't want to risk cracking a piston taking it off (196 pistons were hard to find in the mid 90s, expensive customs now!), so they resized the rods to fit as installed.

I had picked up that motor on a Friday, and drove the car the four hours back home on Tuesday. After fuming and rushing all weekend I called the bank Monday and cancelled the check I'd written. Got a letter from the shop a couple weeks later threatening to send the bill to a collection agency. I wrote them a nice letter spelling out the dates they'd told me it would be done, the three trips I'd made since they didn't call, and a car I had to rent for a weekend trip because the motor wasn't broken in enough for a long haul (32 hour round trip two weeks after I built it)., that I figured THEY OWED ME about $200, but it wasn't worth taking them to court over. Never heard from them again!

While you have the crankshaft out, if you have a set of v-blocks and a dial indicator check that the crankshaft is straight.

Buy a pack of Plastigauge, it's cheap and accurate.