Im rebuilding a 390 and i got the grank in and it rotated fine i put pistons 1 2 3 and 4 on and it rotated ok it was a little hard to move, then i put piston 5 in and i cant even rotate it by hand now.... is that normal or did i screw somthing up? and what can i use to rotate it now?
It sounds like you may be installing the connecting rods backwards. Look at the rods down where the two rods would be riding together on the crank journal. You will notice that one side of the rod has a slight bevel and the other side is machined flat. The beveled side must go on the outside against the crank, the flat side goes next to the adjacent rod on the journal. The more rods you install the worse the interference. If you find that you do have them backwards, depending upon what type of pistons you are using you may have to pull out the piston pins and turn the pistons around as well.
I agree with Flawebmaster, you might also want to platigauge your clearence between the bearings and the journals just to be on the safe side. Check also the main caps to make sure there're on the right journal and all arrows pointing forward to the front of the motor
oh man.... after i posted this i neglected to check it because i thought it was just because of the piston rings and the friction on them. i put a breaker bar on the crankshaft snouth with the bolt and i can rotate it that way, its stiff but it seems like it should be like that.
With every piston you put in it will get harder to rotate but if you hank on it hard enough, it'll rotate and that is normal. Did you oil the pistons and the chambers before installing?? If not that could be your problem! And also you want to put a generous amount of lube (I like to use STP honey oil) on the bearings before installing?? If you don't have any pre-lube on the bearings disassemble now and or you'll be turning the crank again and buying new bearings.
yeah i did oil and lube everything. the onlyhting im woried about is the way the connecting rods face, like the whole flat side and concanved side.... i didnt check for that, mainly cause i didnt know.
PS... i put a breaker bar on the cranp pully bolt and it rotates its tight cause of it bein a fresh assembly. i made sure the crank rotated freely before i put any pistons in.
You must look at the flat side of each rod at the big end. One side is totally flat, the other side has a slight bevel. This beveled side goes to the outside toward the crank. If you don't understand this go to a machine shop and they will explain. Very important!
i understand it but is there a way to check without having to take the rod caps off? I have the motor all together and i dont really wanna have to take it all apart again.
If your using aftermarket rods you can plainly see the flat side and the champhered side. If your using stock rods there is a square nub on the cap and it is slightly beveled. You'll have to look at them from a side angle. I believe the lower side of the angle goes towards the crank, but get a second opinion in case I'm wrong.
im not gonna lie, im completley lost on what to look for... is there anyway you could find a pic and show me what you mean? this is my first rebuild and i really didnt know about the 2 different sides.
im using stock rods, i just dont know what the nub is your talking about.
it might help... but i dunno what im lookin for. im just gonna take the caps off and look. if i were to run it now without checkin and lets say i had some the wrong way what would happen?
When your looking at the connectiong rod cap right in the center there is a nub about one inch long by a half inch wide. The square side faces to the pairing connecting rod and the tappered side, usually champhered and cresent shaped, faces the crankshaft.
Also, the bearing tangs (fitted slots) should face the outward of the engine.
Have you torqued the heads yet?? If not, look at the pistons and they have either a notch or an arrow pointing forward to the front of the engine.
I don't want to be a wise ass, but why did you do this overhaul when you obviously don't know how to? Buy a book, and save time and money. Check out Amazon.com How to rebuild Ford big blocks.
You can also check your local library. They might have a Ford or Chilton manual. Ours here has both oem and aftermarket manuals. My kids clued me in on that. Honestly if your not sure about things stop now, take it back apart and be sure you've done it right. Anything your not sure of ask about. Is it a hassle? Yes but you'll be glad you've done things right. These guys know so take their advice. JMO and best of luck.
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Related Threads
?
?
?
?
?
Ford Forums
1.4M posts
115.4K members
Since 1999
Ford Forum is a community to discuss all things Ford. Check out our discussions on the Ford Escape, Mustang, Edge, F-150, Raptor, Explorer, Focus, Fusion, Fiesta and more!