quick question about crankshaft

[superbee1]

I have just started putting my 440 back together. I have installed the crank, cam, timing chain and pistons. How hard should it be to turn the crank with a breaker bar? When i use the breaker bar to roate the crank the presure needed to spin it reamins constant, just not sure how hard it should be.

[firefighter3931]

With the heads off it should rotate with 20-25 ftlbs of torque. 


Ron

[superbee1]

just checked it with the torque wrench and it looks like it takes around 40 ft/lbs to turn. should i be worried since the pistons and rings are new?

[Challenger340]

Rotational Drag on a freshly rebuilt engine is dependant upon many factors, Honing, Brg. Clrc., Lubricants, surfacer areas, Pressures, basically, all oppositional frictions associated with what has been machined.

Ron is correct in a "ballpark" figure of the 20-25 ft/lbs for a new performance style rebuild.

You, as the final assembler of the parts, have a responsibility to ensure all machining that has been performed to specifications, and more importantly, to your satisfaction.

As Stated, many factors can affect Drag.

Some questions;
What type of rings did you install, Cast, Moly, or 1/16: Dbl Moly ?
What Bore finish are they installed upon, 220, 280 or 400 ?
What Bearing Clearances did you find on the Mains ?    Rods ?
What lubricant did you use on the Rings / Cylinders ?
What Lubricant did you use on the Bearings ?

If this is NOT a "new" machined Pkg., did you clean the carbon from the Ring Lands on the Pistons, BEFORE installing the new Rings ?

Bob out.

[superbee1]

Here are the rings i used:

http://store.summitracing.com/partdetail.asp?autofilter=1&part=SLP%2DE%2D424K030&N=700+0&autoview=sku

Clearances are to spec,., ex. .009 for rod clearance.
I used assembly lube on all bearing surfaces and based upon the suggestion from Don  Taylors book dipped each piston in oil before installing.
I did not put assembly lube in the cylinders just coated them with oil.

Sorry to sound so stupid, this is my first rebuild.

[firefighter3931]

Superbee ; what were the piston to wall clearances ? What pistons ? Main clearance ? Rod clearance ? Is the cam installed yet ?

The .009 number you quoted can't be right....it would be good to know the exact clearances. 


Bob, brings up some good points. I tend to set them up a little looser than most to allow for thermal expansion....this is why the 20-25 ftlb number is what i am used to seeing. 



Ron

[john108]

I seem to remember Mally69 discussing an issue with having to touch-up the center main cap/thrust bearing area because of a tight crank.
John

[superbee1]

i am using speed pro 2266 flat tops 30 over. what should my clearance numbers be? The cam is installed along with the timing chain. I removed the main caps and turned it buy hand without them in place and still around the 40-50 ftlb range.

[firefighter3931]

i am using speed pro 2266 flat tops 30 over. what should my clearance numbers be? The cam is installed along with the timing chain. I removed the main caps and turned it buy hand without them in place and still around the 40-50 ftlb range.

The cam will make it more difficult to turn over....increased drag. Did the cam slide in or did you have to push it in ? Can you freely rotate the cam by hand ? New cam bearings ? Sometimes the cam bearings need to be clearanced with a scraper 

The piston to wall clearance with a forged piston is supposed to be .001 for every inch of bore diameter so if your's is .005 that would be fine.

Main and rod bearing clearances should be .002 (min) but i like them at .0025



Ron

[superbee1]

cam turned fine by itself very smooth and free. I've checked piston to wall clearance and that seems to be actually a little more than.005 so that appears fine as well. I am stumped.

[firefighter3931]

cam turned fine by itself very smooth and free. I've checked piston to wall clearance and that seems to be actually a little more than.005 so that appears fine as well. I am stumped.

What was your crank end play ?   


Ron

[superbee1]

can't remember what the end play was. i do remember it was very very very small.

[firefighter3931]

can't remember what the end play was. i do remember it was very very very small.

How small 

It should be in the .008-.017 range 


You never did give the rod & main bearing clearances. What about the rod side clearances ?



Ron

[superbee1]

end play is within that range. as for the rods it seems to change. it will be .009 between rods and less but still clear between rods and bearings then after a rotation the clearances change. the rod ends are bolted to specs. i am starting to think about just tearing it back down.

[firefighter3931]

end play is within that range. as for the rods it seems to change. it will be .009 between rods and less but still clear between rods and bearings then after a rotation the clearances change. the rod ends are bolted to specs. i am starting to think about just tearing it back down.

Your rod side clearance is too tight. What crank & rods are you using ?


Ron

[superbee1]

i am using the factory rods and crank. what should the clearances be between each rod and between rod and crank?

[superbee1]

ok here is the latest. i went ahead and pulled the pistons. the crank and cam turn just as easy and smooth without the pistons. when i was taking the pistons out i noticed that some of the rod bearings were scored pretty badly (thank goodness the crank is undamaged). what could cause this scoring by just hand cranking? they were lubed with assembly grease and everything.

What the heck do i do now?

[firefighter3931]

ok here is the latest. i went ahead and pulled the pistons. the crank and cam turn just as easy and smooth without the pistons. when i was taking the pistons out i noticed that some of the rod bearings were scored pretty badly (thank goodness the crank is undamaged). what could cause this scoring by just hand cranking? they were lubed with assembly grease and everything.

What the heck do i do now?

Ok you need do describe in detail exactly what was done to the crank and rods during the rebuild :

crank turned...if so how much ?

Rods resized ? reconditioned ?

You still haven't stated what the main and rod bearing clearances were and how they were checked ?

There is something definately wrong if the bearings are scored from just hand rotation. It's a good thing you pulled it down !


Ron

[superbee1]

the crank was turned 10 under. the rods were just cleaned up and checked for truness they were not resized. since the pistons are out i guess the rod to main clearance is a moot point now. after looking at the rank it looks like there are some raised nicks on the crank that weren't noticed beforehand. the spoots on the crank line up exatly where the score lines are on the rod bearing.

[firefighter3931]

the rods were just cleaned up and checked for truness they were not resized.

Did you install new rod bolts ? It's allways a good idea to upgrade the rod hardware, recondition and resize.

since the pistons are out i guess the rod to main clearance is a moot point now.

It may be a moot point but the assembled clearances might give you some insight into the problem at hand. If they were too tight this was a problem.

Obviously the crank wasn't prepped properly as evidenced by the scoring on the bearings. 




Ron

[superbee1]

Ron,
could you tell me what the clearances should be

[firefighter3931]

Ron,
could you tell me what the clearances should be

Well, the factory specs call for ;

Mains .0005-.0015
Rods .0007-.0020

I like them at .0025 on the mains and rods for a hot street/performance build   



Ron

[superbee1]

just dropped off the crank at the shop they are going to polish out the burrs. hard to believe thigs that small can cut bearings like that. just to make sure i understand right, there should be .0025between rods and mains and .0025 between rods?

[firefighter3931]

just dropped off the crank at the shop they are going to polish out the burrs. hard to believe thigs that small can cut bearings like that. just to make sure i understand right, there should be .0025between rods and mains and .0025 between rods?

Nope, rod bearing and main bearing clearances should be .025....that is the clearance between the bearing and the rod & main journals.

The rod side clearance should be at least .017....if you can't stick a .017 feeler guage between the rods when installed in the engine....it's too tight.



Ron

[superbee1]

thnaks for all your help with this ron. i should get the crank back any day. i will let you know hoa it goes.

[firefighter3931]

Keep us up to speed on your progress. 



Ron

[six-tee-nine]

Hey Ron,

I appreciate your dedicated help to all of us and willing to learn as always i've read this topic with great interest.....Thanks

As you stated, side clearences are easy to measure with a feeler gauge
But I have a question about the rod and main bearing clearance, how do you measure them?

[Steve P.]

It is pretty easy to nick the journals when putting in the piston/rods. They make a set of vinyl sleeves to put over your rod bolts when installing. I just cut a set out of clear vinyl tubing I picked up at the local Ace Hardware. It works just as well and besides protection of the crank and rod bolts you can make them longer than what they sell and they will help guide the rod home. They have both thin and thick wall tubing. You will need the thin wall.

[firefighter3931]

But I have a question about the rod and main bearing clearance, how do you measure them?

There are a couple of ways to measure :

(1) mic out the crank then mic the rods (dial bore guage) and compare the readings making sure the clearances are sufficient. This is the best and most accurate method and requires the proper measuring tools and knowledge. 

(2) Plastiguage is often used and is reasonably accurate. The plastic strips are placed on the main and rod journals of the crank then with the bearings and caps installed they are torqued down to spec. The plastic is then compressed and removed to compare to a scale which measures the clearance.



Ron