tight engine

JOHNNYCOBRA · #1 (**permalink**) 03-30-2007, 08:19 PM

Ive assembled my 351cleavor using all my best effort, however i seem to have an ongoing battle to find the reason for an extrememly tight engine!

I double checked the bearings actually tripple checked for the proper bearing clearance.
I have checked and found that the cam retainer plate bolts could have been causing a drag on the aft side of the cam gear. Fixed but problem persists.
checked the valve settings to see if there is any valve to piston contact! found none.
looked at the cam lobes and dont see any problems!

what am i missing? the engine is so hard to turn over by hand i have to use a small breaker bar to turn it.

Ps: I have not fired the engine yet and wont try till this is resolved.

Any help is appreciated!

blueovalfanatic · #2 (**permalink**) 03-30-2007, 08:33 PM

Are you sure the timing chain gear (cam) is not rubbing against the block itself? We had that happen with a 351W awhile back and took awhile to find the problem.

Good luck,
Greg

JOHNNYCOBRA · #3 (**permalink**) 03-30-2007, 08:41 PM

Il take a look in the morning but when i removed the chain cover and dampener last time i didnt see any evidence of it. in fact it appeared to clear the block by about half an inch. it is by the way a double roller from cloyes.

Jahred · #4 (**permalink**) 03-30-2007, 10:09 PM

I'm curious on a related question. I've been chasing down starter problems but am concerned the problem may be that I over torqued rod bearings......if I am saying that right. I dropped oil pan to inspect rod bearings after repeated oil in crankcase issues and I set torque just slightly higher than what it took to "break them loose" - I thought that made sense, but later ran accross numbers suggested torque spec was 20 to 30 lbs lower. Lets say as much as 60 vs 90.

Can that be "trightening" engine and causing starter engagement issues? If the spark plugs are in, is there a general rule as to how much torque it should take to turn engine over manually (514).

Chasing down starter problems in the am, but was curious to get some input on this bearing matter. I suppose I should just re do it.

Barnsnake · #5 (**permalink**) 03-30-2007, 10:30 PM

Turning a fresh engine with newly honed cylinders, an agressive cam profile, and heavy valve springs will take a fair amount of torque even with the spark plugs out. I wouldn't expect to do it with a ratchet handle.

CHANMADD · #6 (**permalink**) 03-30-2007, 11:29 PM

Have you primed the oiling system yet?

Jac Mac · #7 (**permalink**) 03-31-2007, 03:17 AM

Johny Cobra,
Try this for starters, If you have the pan off check the end float of the crank by prying it forward/ rearward, it should move quite freely and have around 0.005"( magnetic base dial gauge reqd to check ), if you used a rope type rear seal it may be quite tight.

If thats OK check the end float of each pair of rods on each throw. This can be anything from 0.011" up to around 0.020". Each rod should move freely and independantly from the other on each journal. If not you may have a bent rod or even installed one back to front so that the brg shell ( which is offset in the rod ) is riding on the fillet radius of the journal.

Check those above points before looking further, they will cause the most harm if any are present.

Jac Mac

Dwight · #8 (**permalink**) 03-31-2007, 06:20 AM

I'm in the process of build an 354 / 5.0. With the crank, rods, pistons, rings, cam and timing chain installed it took 22 lbs of force to turn two rotations. I read that is should take between 30 - 35 ft lbs of torque to turn the assembly.
If you have the rockers / push rods installed then the pressure of the springs will make a big different. The lifter to lifter bore cleanance should be checked. If the lifter is to tight then hone the bore to the proper cleanance.

Dwight

blykins · #9 (**permalink**) 03-31-2007, 07:25 AM

Did it turn over easily with just the crank in the block?

Rick Parker · #10 (**permalink**) 03-31-2007, 09:29 AM

Jac Mac makes some good points. It is possible that a rod is installed 180 degrees on a piston and it is mating with the crank incorrectly.

dynoroom · #11 (**permalink**) 03-31-2007, 09:59 AM

1st check that you have crank thurst, sounds like you checked everything you should have "in" the motor, so is the flywheel on? Sometimes the bolts are too long and go through the crank and hit the rear main cap, look at that. Do you have rod side clearance? If it a Cleavlor does that mean you have an aluminum block? How did you check your bearing clearance, plasti-gauge, dial bore gauge or?

RICK LAKE · #12 (**permalink**) 04-01-2007, 06:26 AM

JOHNNYCOBRA John over the last couple of years some things have changed. The rod torque installation has gone from a tork wrench to a rod bolt stretch bolt measurement of .004-.006" with ARP bolts. This is done a couple of times. Once on the bench, then in the motor. Unless you are running a real loose motor, it is going to be hard to turn. A tork number would help. You will find it, go back the the beginning of the assembly and redo each step and recheck the rotation for how hard it becomes. Hope you used per assembly lube on all bearings. Rick L. Ps I put a motor together with the rods on the wrong sides because the motor was up side down

It still spun be was real tight.

fsiewert · #13 (**permalink**) 04-10-2007, 11:44 AM

Check to see how tight the cam is in the block...I had a 351M block that had a cam bearing issue and the cam wouldn't turn with new cam bearings x2. We buffed the cam journal on that bearing and the motor ran for 120,000 miles when the pickup was sold.

cobrashoch · #14 (**permalink**) 04-14-2007, 05:37 PM

Rings, Rings, Rings, check em'. Most home builds screw this one up. Many more things to look at than just gap. Molys should have polished walls, Iron rings cross/hatch and so on. I know this is hard, but if take out the slugs and it turns easy you have found the culprit. Some rings are designed to cut into the block too, and boy do they turn hard and break in slow. Just a lead.