HELP! New rebuild, engine will not turn.

88 SBF 302. The crank is turned 20/10. New bearings, I honed the cylinders since they didn't look too bad and I put new rings on it. I didn't use plastigage to check clearances. All the caps and mains have been torqued to specs. I've just got the engine on a stand, heads are bolted on, but no timing chain yet and I cannot turn the crank. So no compression or valve train adding to the drag yet. I thought about bolting up a bell housing and starter and see if it would turn but I'm afraid it would break something (bell, starter, flywheel)

This is only the second engine I have built and the last one still runs great after 60k plus miles so I weren't skeered when I started building this one.

I don't know how tight is too tight when you try to turn one. Here is what has never been explained to me. Say that I do have to go back and plastigage everything and I find that things are too tight, then what do you do? None of the books I have seen ever explain the next step, they just go on with the rest of the build steps. Do you have to tear it all apart and take the crank back to the supplier and get them to check it again?

 

always check your clearances with plastiguage . Never assume That the bearings are correct . Also if the pushrods and rockers are installed and you dont have a timing chain on it yet you may be coming up against a valve. But definetly go back and check you clearances .Good luck

 

sure the crank wasnt 10/10? or are the rod caps on right direction?

 

Check everything. If everything looks good, take it apart and see if you can see anything on a bearing that may make it bind up. I work at a machine shop, and every so offen we put it together and it locks up. Usually needs a little massage work on one bearing or so. Also make sure all your rod/main caps are in the right spot, and on the right way. That'll do it too.
DO NOT FORCE IT TO TURN. With plugs out and oil in the cylinders, it should turn over pretty easy.

If everything looks as good as you think it is, then yes, take the crank back to the supplier and have them check it. You may take the short block down there and see if they can solve it. No offence, but if you do not know a lot on assembling engines, it may be a good idea to have a shop at least look at it for you. We have people do that with us all the time. Sometimes it's the customers screw up, and somethimes it may be the clearance on the crank is too tight, or a defective bearing or whatever. Also like mentioned above, with no chain on it, it may be binding with the valve train. Have you tried to spin it boh directions, or just clockwise???
Good luck.

 

crank came from a high volume rebuilder along with the bearings as a whole kit, but its got me thinking. Mains have arrows and numbers so no mixing them up, but I was really careful keeping them in order so I wouldn't mix them up.

So if they clearances are too tight, are we talking I've got to take the crank back to the rebuilder?

 

YEP .. ROD CAPS on incorrectly is a good bet..MOST COMMON mistake and the crank WILL NOT TURN if ya get ONE on wrong !!! check them FIRST .... and if not continue on down the line........

....... jersy Skip

 

Oh yeah, if you think it is in the bottom end, loosen each main cap, one at a time to see if that frees it up. If you loosen one and it still does not turn, torque it back down and go to the next one. You can determin if it is a main problem ,and wich one it is givving you greif.

 

Sometimes the crank will get knicked by a rod bolt when installing. I would pull the rod caps and check the brgs for scratches and see that the brg tangs are all to the outside, toward the pan rail.

 

Check for crank endplay also, could be binding up on the thrust flange.

 

Did you gap the rings? It had to turn over while you were putting pistons in.

 

does a sbf 302 have offset pins in pistons

 

Engine class 101!!! Ok class open the Hillsboro Racing Engine manual to page 1. When putting a engine together spin the crankshaft a complete turn upon placing each part onto the engine,such as each main cap,and each piston and rod. This will eliminate back tracking and trying to find a problem. Follow instruction,drink a six pack,call me in the morning>>>>.

 

Did the crank turn over before you installed piston and rods?? How much thrust clearance #3 main?? How about side clearance on rods?? Also if you checked side clearance on rods you would notice a rod cap on backwards.....Main brg, rod brg and setting thrust are very important.

Have enough bearing clearance so you dont burn it up.

Also make sure you use a good tq wrench because those rod bolts only tq 24ftp so dont stretch one.

Eric

 

It's really hard to diagnose over long distances so I won't/can't tell you what is wrong this time, but will tell you how to avoid this in the furture.
When assembling a motor, rebuilt or not, the first rule is to measure all the clearances before you assemble the motor...............if you don't have access to a good set of micrometers then have a machine shop do this for you, and if you can't do that then at least go down and get some plastigauge and use this on every bearing. It is a pain because you need to put the plastigauge on without any oil and torque the bearing down.....then unassemble it and read it..............not an exact science.
The first thing you put in the motor is the cam..............oil it up and make sure you can spin it with your fingers.
The next thing is to put the crank in (without timing gear/chain) and after torquing the bearings down you should be able to spin it with one hand (make sure the bearings are lubed)....................if you can't something is wrong with the crank............
Next is to put the timing chain/gear on and still be able to spin the crank by hand.
Then.................start putting the pistons in one at a time and make sure each time you spin the motor..............it will get a little harder and you probably won't be able to do it by hand...................but the motor should spin easily.

Now, when you put new rings in the pistons..........did you use an old ring to clean the ring lands.......................did you buy std rings and not oversize...............did you oil the piston/rings really good before you put them in......................most rod caps are marked from the factory with numbers.................do all the numbers correspond to the correct cylinder and are all the numbers on the same side..............

If you can't spin the motor with a 1/2 breaker bar............I would start the disassembly process starting with the rods..............one thing...................you mentioned you hadn't hooked up the timing chain/gear.................I am assuming you don't have the push rods hooked up because without the timing gear being attached could cause all types of issues with the valves hitting the pistons...................

IMHO

 

I have to agree with E.C.. The engine was turning over when you assembled it wasn't it? There's a good chance that you have valve interference.

 

Yep. I second that.

 

Lots of great advice. Thanks guys! I'll tear into it and see if I missed anything or what the deal is.

 

when stripping the engine down for the rebuild did you bother to mark the caps so that they could be put back in the same position on reassembly?not gapping rings not checking clearances are pretty pisspoor engine building techniques

 

I'd like to know if your valve train is installed. You seem to keep skiping over that question.

Also i Know with the rockers and Push rods out of my 360 FE it was very hard to turn over with the plugs in due to compression. Are your plugs installed with no valve train?

Can you rotate it backwards at all or is it completely froze up?

I'd bet on valve interference myself. Like others have said, It had to rotate while you installed the pistons, right?

Mike

 

Did you clean out the ring grooves?

 

DOH! I typed up this LONG explanation of what I've done and the post didn't save.

no pushrods or rockers or plugs so no valve interference or compression to contend with.

I was very careful upon disassembly keeping everything separated and making sure the numbers were correct before I took anything apart.

I just checked this not 30 minutes ago to satisfy any possibilities...

The mains have the number and direction arrow cast in them. They were correct when they were removed and correct now.

Same for the rod caps. They have a number stamped. Numbers match the rods and on the same side. Pistons have a notch to point them the right way. All of these are correct and nothing mixed up.

I cleaned the ring landings with an old ring and looked to all be clean before I started putting on the rings. Pistons and rings were coated liberally along with the cylinders with 30w.

All caps and mains with moly assembly lube liberally applied as I went. I was very careful inspecting every part before it went in. Good thing too because one of the main bearings had a blemish I had to go and exchange.

So I backed down the torque starting with the rear main and was able to turn it some, but still very stiff. Trust bearing does not appear to be binding, but I still need to get out the guage and check.

Here is where I think I went wrong. I used a 3 stone hone and drill to clean up the bores. I did not get the 45 deg crosshatch I expected. This would help explain the slight grinding sensation I am getting when I had all the mains loosened and tried to turn it. I plan to take it all apart, get a bottle brush hone and clean them up. I'll clean up the lube and try to plastigauge everything this time.

 

So, did you mic the cylinders to see how much wear from top to bottom. I am assuming the new rings you purchased were for a standard bore and not oversize. What type of rings did you purchase, cast, moly, chrome?????????
It would be normal when turning a new ringed motor over by hand to "get the grinding feeling" if they were cast rings because they are actually honing the cylinders............
When you said the crank was turned 20/10 I assume you mean the mains were turned .020 under (for a .020 over bearing) and the rods were turned .010 under (for .010 oversize bearings)............did you verify this? Usually rods wear more than mains.............just a thought.
Let us know.

 

See post #12. Now drink 2 six-packs,call me in the morning>>>>.

 

Look at your rod bearings. They are offset in the rod big end. The end that is not right up to the edge of the rod goes toward the chamfer on the rod jurnol. The two edges that the bearing is flush with go togeather. You need to have room for the radius at the end of the rod jurnol. If you don't have rockers and pushrods in yet you don't have valve to piston interfearance. If you do and no timing chain you may have a valve wide open when the piston comes up and runs into it. You should never turn over an engine in which the crank and cam are not in time. I just read your last post. Disregard that which needs disregarding. It's not the crosshatch.

 

PS I don't know how close things get in a 302 Ford, but in a 270-302 Gmc if you try to turn the crank without turning the cam the rod big ends will hit the cam lobes and lock it up. My brother spun his Pinto with out timing the cam. * bent valves. Those starters can do a lot of damage.

 

I'd ditch the plasti-gage, just get mics or a good set of calipers and or a bore gauge

Insert bearings, tighten down the caps, then mic the crank then mic the inside of the bearings. I do that before I put anything together, gives me a peice of mind befor starting.

Generally, you won't have to fit the rings, over the past several years, I've never had to file one...ofcouse I'm not building 800HP blower motors, but if you ordered the right stuff for the rebuild, usually waht you end up doing is making sure they sent you the right stuff...sorta "at home QC"

Good luck.

 

I think you found your problem. Like RichFox says, definitely check the edge radius of the bearings and rods, but if you loosen a main cap and it spins, my guess is there's a bearing size mismatch, the crank is bent, or the block needs line bored. If you pry gently on the counterweights against the main cap or block, you should be able to quickly verify if the thrust bearing is binding. You should be able to feel the crank move slightly even a few thousandths. Personally, I'd at least plastigauge it but I'd trust a nice micrometer and a dial-bore gauge even more. Whenever I'm assembling an engine, I turn the crank over after each piston/rod assy is installed to verify that everything's going smoothly. Good luck!

 

I was thinking about this a bit more...do small Fords need a "thump" on the crank to set up the thrust bearing...ala like a BBC?

 

No I didn't mic the bores. Cast rings, standard bore. I removed a cap and main and checked again, Mains .020, rods .010. BUT...now its got me thinking. What if they sold me 20 mains and 10 rods when it should have been 10 mains and 20 rods? That's going to suck. Hopefully I won't get any hassle trying to exchange them since the bearings had already been installed. After all, it wouldn't be my screwup.

The bearings and the rods have notches in them that fit together so they can only go on one way.

 

At this point in the game I would call in help!! Forget the 6-packs you need a engine builder to help you out>>>>.