crank resistance

[Stu J]

During building the rv8 up from scratch today I put in the main bearings, then the crank and then started the con rods with new rings on the pistons too.

After putting in all the pistons and tightening all caps to spec torque I couldn't help but think the crank was a little hard to turn. The front pulley was put on temp just to help but it showed some tight resistance with that... is this normal?
I removed all the pistons just to see if there was any dirt etc but all seemed normal, the crank and big ends are all standard size and oiled accordingly.

I am aware resistance should be there, but this much? without heads on too.

[petecob]

Originally Posted by Stu J

During building the rv8 up from scratch today I put in the main bearings, then the crank and then started the con rods with new rings on the pistons too.

After putting in all the pistons and tightening all caps to spec torque I couldn't help but think the crank was a little hard to turn. The front pulley was put on temp just to help but it showed some tight resistance with that... is this normal?
I removed all the pistons just to see if there was any dirt etc but all seemed normal, the crank and big ends are all standard size and oiled accordingly.

I am aware resistance should be there, but this much? without heads on too.

What you must remember is all parts with bushes have a working clearance when put together correctly
otherwise it would fail because they would be no clearance for the oil to lubricate it.
Pete.

[Sidecarbod]

Are you using ARP studs?

If so they have a much greater clamping force for the same torque setting as the standard bolts. I believe that if you go for 75 ftlbs that you can get away without inline boring the mains using studs but you'd better wait for more replies on that one!

Someone like Russell RAM can give you a lot more help.

You could try just fitting one main bearing cap at a time with the engine inverted so the crank won't fall out, that way you could see if its just one bearing or all of them. You could try some plasti gauge so that you can check for the right clearance.

I recon that without the pistons and rods fitted the crank should be pretty free to spin, especially if you've oiled up the journals. Its not worth risking going any futher until you are sure that its right othewise at best it will play on your mind and at worsed you will chew up the crank!

You have fitted the right caps on to the right bearings?

Cheers,

Pete

[Clarkson]

Have you got the rods round the right way, you must have side clearance.

[Purple AK]

Without the heads on it should all turn fairly freely! So if it's going tight something isn't right. Go back and check what is causing it to go tight

[Stu J]

The con rods are all the correct way round as are the caps too, the end float has been adjusted accordingly and all bearings have been seated correctly.

The piston rings have been measured in the correct fashion, each individually.

Nothing is simple with engines...

[dingocooke]

bear in mind your moving 8 pistons up and down in new bores, if you can turn it with reaonable force its ok; its not going to turn really easily. Relax and get the rest of it together!

[TINKA]

As someone else has already said, you need to fit one thing at a time and then turn the crank to see if it is getting tight, if it stiffens up a lot when fitting one main bearing or big end then you will know where the problem is. I seam to remember that in the book I used to rebuild my 351W they gave a torque setting which if it went above then something was wrong. HTH

[grahamf]

From experience, with the engine inverted put the crank in on the oiled journals. It should spin freely. Now place one cap at a time and finger tighten the fasteners. There should be no difference in the force needed to spin the crank. Next, torque each cap up, checking the crank spins freely inbetween each one. You should find the crank spins quite freely with all main bearing caps torqued up.
When you come to put the rods and pistons in, please remember you have compressed the rings to get them into the bores, Therefore the crank will no longer turn freely. The more pistons you put in, the greater the resistance you will feel when you try to spin it over.
You could try turning the pulley wheel over with a torque wrench and measuring the torque needed. If you post it on here I'm sure someone will be along with a comparison reading of theirs. FWIW, mine, a Ford 400 with cam chain, no hydraulic followers in (yet), neoprene seals, can be turned over with about 50ft lbs of torque.
Hope that's of help to you
Graham

[Sidecarbod]

Originally Posted by dingocooke

bear in mind your moving 8 pistons up and down in new bores, if you can turn it with reaonable force its ok; its not going to turn really easily. Relax and get the rest of it together!

I thought that Stu has removed the rods and pistons now? The crank is in the block on its own.

I agree that with the pistons fitted there is quite a lot of torque required to shift them, especially with new bores, pistons and rings.

Pete