Too Tight Rebuild

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coyoteduster

coyoteduster

Moldy Oldy
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Ok here's my situation, I am rebuilding a 1970 318, bored 30 over, standard crank, all new parts, rings, crank bearings and rod bearings, that's as far as I have gotten because once I torque down, the crank is almost impossible to turn unless I use a wrench on the crank. not possible to turn by hand at all.. USING ARP crank bolts, stock rod bolts..
using all recommended torque settings, For the ARP bolts, and stock torque for stock bolts.. this motor had a blown head gasket and had set for a time resulting in rust in several cylinders, Honed them almost to a shine.. but some residue is still barely visible..

anyone have any ideas before I tear this down once again?
:banghead:
 
Need to narrow the problem down is it crank only? Bearings right? I had a motor line bored that some how the machine shop screwed up the thrust bearing cap. When I torqued that one cap down the crank would stop turning.
 
did you check your clearance. plastigage is cheap insurance. might also point at who's to blame for the bind.
 
How much torque are we talking about to turn the crank?
And how far assembled?
A completely assembled engine (without spark plugs)can require a fair bit of torque to turn over.
If it's just a rotating assembly you should be able to pinpoint your tight spot or spots easily enough.
 
Try with only #'s 1 and 5 bearings installed, then #'s 1,3,5, the #'s 2, 4 etc. If the block is misaligned, or the crank is bent you'll figure it out pretty quick this way. I also always use plastigage when assembling an engine to verify clearances.
 
Did you mix up the main bearing caps?

They should have numbers cast in them from 1 - 4 and then the rear. Make sure that they are in the proper order and position (not backwards).

Install them backwards?

You need to put the sides with the anchor slots together.

When they are all together correctly the numbers are sequential from front to rear on the same side of the engine.


Then check your bearing clearances with plasticguage.
 
Snake said:
What about the end gap of your rings.
Click to expand...


Good point Snake.

Let's start with the crank, once that is verified, go to the pistons, rings & rods.

After the crank is in and turns freely, then check your ring gap for the rings and then install the rings on the pistons and start putting in the pistons and check bearing clearances with plasticgauge. See how many you can get in before it gets tight. It should get a little tighter with each one, if it gets real tight, look closely at that piston/rod/ring that made it get tight.

If you find one main bearing or rod bearing clamping makes it get tighter, also check behind the bearing shell and make sure that no dirt got behind the bearing shell. That could take up your clearance and make it tight.
 
Your post is totally confusing. First you say it is almost impossible to turn when the crank is torqued, then you talk about honing cylinders. One gives the impression just the crank is installed, the other gives the impression the short block is together. We cannot help you unless you help us.

1) when the crank itself is installed and torqued you should be able to turn the crank easily by placing your pinky on a counterweight and pushing. If you cannot, loosen main caps one at a time until you find the offender.

That's all I have until you come back with more info on where exactly you are with this assembly.
 
Yeah on last 2 posts. Does the crank, with nothing attached, spin with you fingers? If no, stop. If yes, then install 1 piston at a time, and turn it over. It will take a wrench, and take more effort for each one. By the time it is buttoned up, you will want a 4 foot breaker bar to turn it.
 
Maybe someone else can answer this cause I'm not sure but the problem may be the ARP main bolts. I know when you install ARP studs you have to have the block align honed because their diameter is larger and moves the main caps around a little. Not sure if ARP bolts cause the same issue but the guys are right that you need to narrow it down by starting with just the crank installed. If you can't spin it easily with your pinky finger there's a problem. If the crank spins free the next step is to check the ring end gaps and if ok install a piston and check the rod bearing clearance.

And why are you using ARP bolts yet torqueing them to stock bolt specifications? They always come with a spec sheet telling you what to torque them to and that's exactly what you need to do. They are a better bolt that'll give the main caps more clamping force when torqued properly. When not properly torqued they aren't much better, if any, than stock bolts.
 
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