and thus he bangs his head on the wall...

[skywalker]

Okay, so I'm working on assembling my engine..

I check the clearances on the main's with plastigage, all A-OKAY.

I torque the bad boy down and I cease to be able to rotate the crankshaft.

Mind yout his is the first time I've assembled an engine. Anything I'm missing?

 

[pabear89]

Check to make sure that you did not place the caps on backwards.
I place a mark on the side of them to keep from doing that.
sometimes if they get turned around they will pinch the crank.

PB

 

[brianj5600]

Main caps have arrows on them pointing forward. Rod caps are square on one side rouded on the other ,but I dont remember which way they go.

 

[jackmach1]

I think the rear main seal if the rope kind can make the crank not spin freely, but it should spin...

 

[gjz30075]

I think the main caps are not in the correct order. The rear one is obvious so you can screw up four of them. Remove them one at a time to see which one could be the culprit. It's going to have to be swapped with another one. After you get the right order, MARK THEM!

 

[skywalker]

I think the main caps are not in the correct order. The rear one is obvious so you can screw up four of them. Remove them one at a time to see which one could be the culprit. It's going to have to be swapped with another one. After you get the right order, MARK THEM!

Actually, they were marked (come with numbers cast into them.) However the problem turned out to be related to a bearing.

However, I've run into a new issue, albeit extremely similar.

As soon as I torque the bolts on a single rod, the crank again becomes impossible to turn. I've tried starting at a lower torque and then turned...i've got the cylinder walls well lubed. Everything is installed straight as far as I can tell, and I rechecked the rod bearings and they're fine.

Anything I'm over looking?

 

[gsxrken]

You may not have a straight block arcross the main journals, or the crank is off. Is it the same one that came out of the engine? Did you have the block line honed?
Lastly, don't trust the bearings that come in the box. I verify the part numbers are the same and mike each one just to be safe. One .020 mixed into an 010 crank could be what is screwing you.

 

[rbohm]

had the same problem with an old studebaker six. when the #5 rod was tightened down the crank would not turn at all. turns out the rod bearing was the wrong size. we replaced it with one of the right size and the crank turned just fine.

 

[69Rcode_Mach1]

I can't stress this enough. MIC EVERY SINGLE MAIN CAP, ROD CAP, AND BEARING GOING IN THERE!!! DO NOT TRUST THE PLASTIGAGE!!!! That is straight from my machine shop. And I had first hand experience. The first time I dropped in my engine I had oil pressure issues, do you know why. My bearings were the wrong size, so I had almost no oil pressure 5 psi if I was lucky. Could have fried everything I was lucky. I went by the book and used plastigage on everything, the plastigage said my clearances were fine, but they weren't which caused me to have to pull everything back out and do another teardown.

 

[SoCalCruising]

I'm going to guess that you are now experiencing the problem pabear described. Each rod bearing has one side with more radius than does the other side. The large-radius side goes against the crank cheek. If you do this backward on just one rod, the crank will not turn, or will turn only with much resistance.

It's tough to get accurate inside measurements without an inside micrometer or dial bore gauge, but lots of engines have been built using plastigauge so I'm thinking you got a bearing, or two, or three (depending on how many you torqued down) backward.

 

[rbohm]

I can't stress this enough. MIC EVERY SINGLE MAIN CAP, ROD CAP, AND BEARING GOING IN THERE!!! DO NOT TRUST THE PLASTIGAGE!!!! That is straight from my machine shop. And I had first hand experience. The first time I dropped in my engine I had oil pressure issues, do you know why. My bearings were the wrong size, so I had almost no oil pressure 5 psi if I was lucky. Could have fried everything I was lucky. I went by the book and used plastigage on everything, the plastigage said my clearances were fine, but they weren't which caused me to have to pull everything back out and do another teardown.

hmmm, i have never had a problem with plastigage ever. i just make sure i use the right one, there are three different sizes to choose from.

 

[69Rcode_Mach1]

I know there are the three different ones, and I picked the right one. I must have read it wrong in my inexperience. I will not risk it anymore, I will always mic it to be sure. I created too much headache for myself to risk doing it again.

 

[SoCalCruising]

skywalker: what was the problem?

 

[Ronstang]

skywalker: what was the problem?

Exactly what you said here. He IMed me Monday about this issue after posting this and I told him to check to make sure the rods were not backwards with the radiuses facing the wrong direction. He confirmed it yesterday after his test and messaged me to let me know but obviously did not check this post as his problem was already identified. Good call.

 

[SoCalCruising]

Thanks for the update.