Torque to turn rotating assembly. How much?

[squeakfinder]

Anybody know how much torque it should take to turn the crank, pistons and rods on a 440?

What I have:

75 Block, bored .060 over
69 steel crank, stock specs
LY rods
Speed Pro power forged pistons
#TRW-L2355F60
Federal Mogul crank and rod bearings

This is what is inside the engine now. I don't have the timing chain hooked up. I plastigauged the mains and rod bearings and they are within spec. Plenty of assembly lube on the bearings. Plenty of oil on cylinder walls. When I turn the crank with my torque wrench it takes 59 foot pounds. Does this seem about wright?

[Rayzor]

I have nearly the same setup on my 440 that is also 60 over.  Its pretty tight to spin over to. I thought almost to tight and have gone over all my clearences and they are cool. Just wondering, when your block was bored how close were the pistons to bore clearence? My power forged with the moly coating on the sides call for a minimum of .001 That to me seemed way to tight for forged pistons so I speced out for a .003 fit up. Somthing to think on there as .001 seems way to tight. If I get over to the shop I will get a break over torque spec for you and we can compare notes.

[no318]

Sounds way to tight with heads off.  ARe the heads on or off?

[squeakfinder]

The heads are off. And they are at .001 clearance. I checked ring end gap before assembly on every ring and they were within tolerance.

[Rayzor]

It takes 46 ft. pounds to get my motor spinning. Thats with the roller timing chain installed and the heads still off. Did you set your crank thrust yet? I still stand by my thoughts that .001 is to tight for a forged piston. I would have prefered mine be put at .005 to .007 but the .003 I settled on was just a comprimise over the spec on the box they came in.

[Rayzor]

You may wnt to read this link, Cudaken wiped his pistons out at .001.
http://www.dodgecharger.com/forum/index.php/topic,5477.msg67271.html#msg67271 

[Dennis K]

You didn't say if you are using a rope seal or not, but that can add a lot of resistance as well, which is why most people prefer the rubber seals. I like the original style rope seals because I've never seen one leak.

[squeakfinder]

Yep, I set the the thrust before putting the rods in. And it has the rubber rear main seal. I even mic'ed the cylinder's after getting the engine back from the machinist and they were wright on. .001 minimum clearance is what it reads on the box that the pistons came in. So, what is the maximum clearance supposed to be? It doesn't state that on the box! That sure doesn't sound like much room for heat expansion.

I guess I need to find Federal Moguls tech line phone number. My machinist is 30 miles away and probably busy. I hate the thought of tearing the thing apart and taking back.

Thanks for the link to the thread Razor. I'm not sure what cudakens clearance was.
.00015?  Maybe there was an extra zero added. I can't imagine the pistons even fitting into the engine.

Larry

[squeakfinder]

Well, I thought I would try one more thing. By the feel of it, it didn't really seem like the engine was as tight as my torque wrench said it was.

So I barrowed a bar type torque wrench from friend to double check mine. Mine is the type that clicks, so I was only measuring break away torque with the clicker type, but, I didn't think it would be that much different. And it wasn't. But what I found was that my torque wrench was waaaay out of calibration.

My break away torque was 32 to 35 foot pounds, rotating torque is about 30 to 32 foot pounds with the other torque wrench. 

Thanks everyone.

[Rayzor]

Cool, hope it works out! Now watch, just for me opening my trap I will have massive blow by  

[firefighter3931]

The rule of thumb for forged aluminum pistons is .001 clearance for every inch of diameter. INMO, you are way too tight with the current spec. You need to account for thermal expansion. I would be rehoning the bores, if it were mine. 



Ron

[tecmopar]

Ron's rule of thumb is correct, there's not a lot of guys that know it though., Plus, it increases as the CR goes up. Take my 4.6 Ford motor for example, its a 3.55 bore and the clearance stated by Manley is .0035, see the corrolation. In a 4+" bore and a 9 or 10:1 CR you want about .0045-.0050 clearance, at 11-12:1 CR you need about .008. The Forged pistons do expand quite a bit as compared to the Factory cast ones, which don't, that could be run with only .001-.002. I think you may be a bit too tight there and rethink it before causing yourself some big headaches, good luck.

[max]

Ron's rule of thumb is correct, there's not a lot of guys that know it though., Plus, it increases as the CR goes up. Take my 4.6 Ford motor for example, its a 3.55 bore and the clearance stated by Manley is .0035, see the corrolation. In a 4+" bore and a 9 or 10:1 CR you want about .0045-.0050 clearance, at 11-12:1 CR you need about .008. The Forged pistons do expand quite a bit as compared to the Factory cast ones, which don't, that could be run with only .001-.002. I think you may be a bit too tight there and rethink it before causing yourself some big headaches, good luck.

.001 clearance is way to tight on those forged pistons. i'm wanting to say the forged pistons in my 426 are right around .005 clearance.

[squeakfinder]

I talked to my machinist today. He said .0015 is what he finished it at. He said it used to be aluminum pistons got set at .005 clearance but now days .001 to .002 is common.

I called the Federal Mogul tech line and spoke to Paul. He asked if the pistons were coated. I said yes. He said I wouldn't have a problem. "No problems with heat expansion?" I asked. He said no, and that the clearance written on the box was correct.

I don't know. Maybe its the alloys they use now. Maybe the coating on the skirts deflect enough heat off the pistons to make this work.

  Larry.

[firefighter3931]

Larry, inmho....the spec from FM is still too tight. You should be able to turn the engine over with 25ft lbs of torque. 



Ron

[Rayzor]

Now you guys have me freaked out to. My pistons are the coated type and call for .001  Like I said I went .003 as a comprimise. Should I pull it back apart and go for a .0045 clearence or.......

[tecmopar]

No body is trying to freak you out but I have to agree with Ron, unless they have developed some new kind of aluminum in the past 6 months. In all my years of building motors with Forged pistons I'm always looking for 3-4 or 5 thousanths clearance. As I said, I just did a 4.6 Ford and with a 3.55 bore the clearance is .0035, on the install sheet and I also called Manley to double check. Good luck.

[firefighter3931]

No body is trying to freak you out but I have to agree with Ron, unless they have developed some new kind of aluminum in the past 6 months. In all my years of building motors with Forged pistons I'm always looking for 3-4 or 5 thousanths clearance. As I said, I just did a 4.6 Ford and with a 3.55 bore the clearance is .0035, on the install sheet and I also called Manley to double check. Good luck.

Forged aluminum will expand regardless of coatings. Tight pistons create heat, friction and rob power. 


Ron

[Rayzor]

Is it likely or possible that newer forgings are machined for a controlled amount of expansion allowing a tighter fit like the cast type? Also the sizing of the piston was recomended to be done about half way down the skirt on the coating. I wonder how thick the coating is. Hmm 

[tecmopar]

Just in case you didn't see my reply in your other post, as far as I know the coatings are for piston scuff, it will not stop the piston from expanding as it gets hotter and they will grow. If you have ever had a motor with Forged pistons before you should know that they are noisy on start up but quiet down as the motor warms up because the pistons have expanded and file the hole better, good luck.