Toooo! tight engine

JOHNNYCOBRA · #1 (**permalink**) 08-19-2003, 04:19 PM

351w w/cleavland heads
Can't understand it! The build up of the engine was to spec.

ENGINE HAS:
CLEAVLAND 2 BBL HEADS W/STAINLESS VALVES
COMPRESSION 10.7: 1
HYPEREUTECTIC PISTONS CLEAVOR STYLE DOME .40 OVER
ROLLER ROCKERS ON 7/16 STUDS
LARGER PUSHRODS 3/8
CLEVITE 77 BEARINGS

THE ENGINE IS VERY VERY TIGHT

I HAVE TO USE A BREAKER BAR TO TURN IT OVER

I'VE DOUBLE CHECKED THE CRANK AND ROD JOURNALS
AND BEARINGS MATCHED (ALL WITHIN TOLERANACE!

CHECKED THE RINGS TO SEE IF THERE WAS A MISMATCH (NOT)

CHECKED THE RING END GAP TO MAKE SURE NO BINDING (NO)

THE CYLINDER BORES ARE GREAT AND THE PISTON BORE TO PISTON CLEARANCE IS GOOD?

WHAT AM I MISSING? WHY IS IT SO TIGHT?

HELP!!!!!!

jdean · #2 (**permalink**) 08-19-2003, 04:24 PM

did it turn easily before assembly with lifters etc.?

jmarsey · #3 (**permalink**) 08-19-2003, 04:31 PM

Did you check the crank for end play? Before and after flywheel was bolted on? Did the short block rotate freely? Was the block line-bored? How did the crank feelbefore rods were attached, spin freely?

John

Mr.Fixit · #4 (**permalink**) 08-19-2003, 04:37 PM

Are the sparkplugs in it?

Did crank rotate nicely before hanging pistons?
Did the crank / pistons rotate OK, before you put the heads on?

ENTDOC · #5 (**permalink**) 08-19-2003, 06:43 PM

My 351c seemed too tight at first also,but it cranked fine and now turns over easier(by hand with a long wrench). chuck

snakebyt · #6 (**permalink**) 08-19-2003, 06:52 PM

What size flywheel and bellhousing? If you have the large size (I think it's 164 teeth on the ring gear) you need to use offset pins to mount the bellhousing...

Tom

dewulfmd · #7 (**permalink**) 08-19-2003, 07:24 PM

Sometimes the rear main seal (rope type) can put a large drag on the crank when the rear main bearing cap is fully torqued.

Try loosening the rear main cap and then rotate the crankshaft.

If this works, make sure the seal & journal have plenty of lubricanting oil on it and re-torque to specs.

Note: most new rebuilds are a little tight at first -> check everything listed above and try to start it.

Mike D.

HighPlainsDrifter · #8 (**permalink**) 08-19-2003, 10:18 PM

Johnnycobra;
I assume the engine is installed in the cobra with a manual tranny. Most likely place to look is the clutch disc. Did you install it correctly?....... the center of it should have the 1/2" center section sticking out towards the tranny, if you put it facing the engine then it will touch the flywheel bolts.
Good Luck,
Perry.

JOHNNYCOBRA · #9 (**permalink**) 08-19-2003, 10:57 PM

Thanks for quick response/
I pulled th engine because of this problem. it's now at the short block level and i've pulled 2 pistons looking for problems. Ring gap etc..

Theres no flywheel attached now. and i've pulled the front timing cover to check for problems or interference., but found none
The pushrods and rockers were removed to relive pressure.

I'll try to release the pressure on the rear main bearing and see what happens.

However when the piston/ring assy is removed from the crank
with the piston in the bore it appears really tight when moved in the bore by hand. rechecked the piston to bore clearance but it is right on at .0020

why would the rings make the fit so tight? I even checked the ring depth in the piston grooves?

Sooo... I guess i'll remove all the pistons and see if the crank rotates freely (should spin like a top with no pistons.

Johnny

Bob Putnam · #10 (**permalink**) 08-20-2003, 08:51 AM

In my experience, before the cross-hatch on the cylinder walls is "broken" the engine requires roughly 50 lbft to turn. I hope you aren't looking for a problem that isn't there.

auto10x · #11 (**permalink**) 08-20-2003, 11:08 AM

Any time you bore/hone the cylinder walls and install new rings, plus a new rear seal ¨rope¨it WILL be very tight, guaranteed. Sounds like you have a normal rebuild.
auto10x
Bill

JOHNNYCOBRA · #12 (**permalink**) 08-20-2003, 11:31 AM

You might be right about the 50lbs to turn the engine after a new bore on the bloock with new rings.

I don't believe it takes 50 lbs to turn. maybe I'm just nervous about all the cash I sank into it and don't want to trash the engine.

I'll finish checking the rear seal and piston gap on the other pistons then re-assemble everything, since I can't seem to find any problems.

Glad you guys could offer some help. I'll post the results when I fire it up.

Johnny

trularin · #13 (**permalink**) 08-20-2003, 11:38 AM

Okay, how about this.

Dissassemble the engine and place everything out as you get ready to reassemble.

Put one part on and turn the crank.
Put the next part on and turn her again.

Do this until you either assemble the engine, or find a part that appears to violate a size/tightness/clearance issue.

Beats the heck out of blueprinting everything again.

You probably missed a measurement.

Just my $0.02

blykins · #14 (**permalink**) 08-20-2003, 01:32 PM

I really don't think you have anything to worry about. Especially if it's that hard to turn with the heads on it and plugs in it. You're dealing with 10.7:1 compression...it's not gonna freewheel. I had to use a 1/2 drive ratchet or breaker bar to turn mine over...and it wasn't easy. I really don't think you have to worry. BTW, are you using a main girdle?

JOHNNYCOBRA · #15 (**permalink**) 08-20-2003, 01:44 PM

I'm not using a main girdle

My wife says I may need one though!

The heads are off, so compression is'nt causing any drag.

I think I should just do a complete disassembly and add
one piece at a time, then I'd know if its a problem or not.

Besides It's almost dis-assembled now.

I'll work on it this weekend, I need to hide from my wife anyway for awhile.

Johnny

blykins · #16 (**permalink**) 08-20-2003, 02:01 PM

Reason being, I had a problem with my main girdle and the holes not being drilled true. I had to bore them out.

Johnny, I really wouldn't worry about it at all. If all your bearing clearances were fine, let it go.

What did the piston manufacturer recommend as a piston-to-bore clearance? I guess it differs from each piston manufacturer, but I think mine was .004". Like I said before, you're dealing with high compression...it's not gonna turn like it does with just the crank in the block. You're turning a lot of mass...with a lot of compression.

Great Asp · #17 (**permalink**) 08-23-2003, 12:59 PM

JOHNNYCOBRA · #18 (**permalink**) 08-23-2003, 05:53 PM

YOUR RIGHT BUT I DIDNT KNOW IT WAS YOURS

I'LL DELETE IT AND FIND ANOTHER.

JG

gman · #19 (**permalink**) 08-23-2003, 06:12 PM

My engine builder reversed a rod and the chamfer was on the inside of one rod. as soon as I corrected this the engine turned freely. The bearing will be to the outside of the rod instead of the inside and will bind. check all the rods! Gman

JOHNNYCOBRA · #20 (**permalink**) 08-24-2003, 01:29 PM

I WASNT AWARE OF THE CHAMFER!

WHICH SIDE IS THE OUTSIDE? i ASEMBLED THE RODS AS INDICATED IN THE MOTORS MANUAL.

THE ROD NUMBER STAMPED ON THE ROD CAP IS TO THE OUTSIDE OF THE BLOCK FOR EACH ROD.

THE PISTON NOTCH IS POINTING TO THE FRONT OF THE ENGINE !

JG