Fordged 318-3 truck crank or Poly crank, need help ID

-
D

Dragonbat13

Well-Known Member
Joined
Jan 18, 2012
Messages
379
Reaction score
18
Location
lake charles Louisiana
Scored this,

[ame="http://s218.photobucket.com/user/dragonbat13/media/EbayCrank318-3_zps01784246.png.html"]EbayCrank318-3_zps01784246.png Photo by dragonbat13 | Photobucket@@AMEPARAM@@http://i218.photobucket.com/albums/cc265/dragonbat13/EbayCrank318-3_zps01784246.p@@AMEPARAM@@218.photobucket.com/albums/cc265/dragonbat13/EbayCrank318-3_zps01784246.p[/ame]

Had done a little research and saw some places said the Poly 318 crank would swap into an LA and that it had an 8 bolt flange,

Other places said that an 8 bolt was on the 318-3 truck crank, then others said there was never an 8 bolt smallblock crank.

I got 145 into it, did I get something usefull or a turd?

Its been so long since I looked at a smallblock crank that I really couldnt tell, but it looks correct to me. For 100 and 45 shipping I though it was an OK deal if its what its supposed to be.

Thanks for looking.
 
The Poly crank and the 318-3 crank will interchange without issue in the block. Your only possible problem area is the pilot hole size & depth. The 8 bolt flange is odd to get but not hard to get a flywheel for. Just look in the "Racing" sections when looking for parts. Your more likely to find it there first than in the stock/OE sections.

You got a good deal.
 
Never say never.i have a 3 engine with an 8 bolt flange.not common but factory
 
rumblefish360 said:
The Poly crank and the 318-3 crank will interchange without issue in the block. Your only possible problem area is the pilot hole size & depth. The 8 bolt flange is odd to get but not hard to get a flywheel for. Just look in the "Racing" sections when looking for parts. Your more likely to find it there first than in the stock/OE sections.

You got a good deal.
Click to expand...


I found some factory looking eight bolt flexplates at Jegs. Those should work shouldnt they? Also, the pilot could be modified for the pilot snout of a standard torque converter, correct?

I plan on using a 2300-2800 convertor on this crank. I would think the crank could be made to fit the normal six bolt stuff and just use the eight bolt flywheel or flexplates?

Complete plans with this crank is to first run a 904 in the car, then later down the road convert it to a five speed with a keisler/tremec transmission setup.
 
ANY factory MoPar steel crank is da shizzle. You dun good.
 
I remember well the 8 hole flanges for the old style poly/hemi cranks..

I also just checked a stage 3 - 318 truck crank from a late 60's- 5 ton ,, it has 6 hole flange.. I gotta get some more oil on it...

and solid throws,, this cranks gotta be heavier than stock for sure,, my 340 crank has hollow thows, I THINK// gotta go look..
 
The poly cranks are forged. Look for casting lines. If you don't see any, it's probably a poly unit. Poly cranks are interchangeable with LA cranks.
 
I had a poly crank and it was 6 bolt, forged, but had some xtra pieces on the throws were there was no regular counter weight. was from a 66 Fury. Tossed it as a bearing was spun.
 
Yep, I know a forged crank when I see it,, and both my forged 340 cranks have hollow or mostly drilled through throws,, and the stage 3 had solid throws,, which would greatly increase rotating weight..

Hey DragonBat,, are the throws solid on that crank??
 
4spdcuda66 said:
The poly cranks are forged. Look for casting lines. If you don't see any, it's probably a poly unit. Poly cranks are interchangeable with LA cranks.
Click to expand...

Not all of them. There were two generations of poly engines. The 318 poly is the only one that interchanges. It's the second generation poly.
 
The other thing that might be an issue is the thickness of the 8 bolt flange. The picture looks quite thick.
Years ago a buddy was looking for a 426 hemi crank (which is stock with an 8 bolt) and found a 413 forged truck crank with the 8 bolt flange. But the flange was much thicker on the 413 and would have been an alignment issue with the flywheel. Not sure if it applies to smallblocks, but just throwing ideas out.
 
A strong crank, but I'd look into the flange thickness as stated before. Another thing, whatever piston/rod combo you're going to use; I'd have the rotating assembly balanced.
Good luck
 
I just bought this because its forged and its supposed to be the 340 stroke and supposed to fit an LA. And I suppose that whatever is up with the rear flange I can make it work as long as the crank will bolt into a block. Thats alot of supposes, but who can argue with the price. Course I havent actually gotten it to my door either.

The way I want to use this crank is in a siamese 340 block. Some super lightweight pistons in a natural aspirated engine with some decent rods. Try to get the bobweight down as much as possible. With the balance Ill hope to find a machine shop that can turn the outmost parts of the counterweights down to get most of the balance in check then finish it with drilling. Or possibly even some heavy metals to allow the counterweights to be cut down even more. In other words, try to make a superlight rotating assembly with as much weight as close to the centerline of the crank as possible. At least thats the plan. May be a few years before that happens though, but by that time these cranks will really be hard to find for a good price. So I went ahead and got it.
 
It'll WORK. PERIOD. IF the crank flange is really thick, it will not have a flywheel register. This is a simple fix for the machine shop to cut a flywheel register on the flange. There is enough meat to do it. I've done if before myself. Also, don't worry about "the crank throws are solid it'll be heavy blah blah bullshit bullshit." First off, I can clearly see the throws are not solid. Even if they were, just balance her up and let her rip. The extra strength you would gain would far surpass any negative issues regarding weight. Besides, it's fairly close in to the crank centerline and therefore not as critical as say a heavy *** mafungo piston swinging in the stratosphere at 7500 RPM. Run it. It's billy badass.
 
First up, Rusty Rat Rod has got the right idea and is dead balls accurate.

Dragonbat13 said:
I found some factory looking eight bolt flexplates at Jegs. Those should work shouldnt they? Also, the pilot could be modified for the pilot snout of a standard torque converter, correct?

I plan on using a 2300-2800 convertor on this crank. I would think the crank could be made to fit the normal six bolt stuff and just use the eight bolt flywheel or flexplates?

Complete plans with this crank is to first run a 904 in the car, then later down the road convert it to a five speed with a keisler/tremec transmission setup.
Click to expand...

Ask Summit which one you'll need.
The cranks can be machined for a modern trans easy. Do not modify the crank to "make it work" , just use the correct flexplate. Use the 8 bolt stuff. Do not make the 6 bolt stuff work. The only part that gets attention is the pilot bushing for the manual trans. That may require machine work.
 
rumblefish360 said:
First up, Rusty Rat Rod has got the right idea and is dead balls accurate.



Ask Summit which one you'll need.
The cranks can be machined for a modern trans easy. Do not modify the crank to "make it work" , just use the correct flexplate. Use the 8 bolt stuff. Do not make the 6 bolt stuff work. The only part that gets attention is the pilot bushing for the manual trans. That may require machine work.
Click to expand...


So I should just be able to get a correct flexplate for the 904 and everything will work out? The flexplate will not need the register, just a flywheel for a manual?
 
No the flexplate needs a register too. I'm just guessin on the register, since you didn't include a pic of the back of the flange. Does it have a register? If so, just treat it like any other crank. Get a flex plate and go.
 
RustyRatRod said:
Also, don't worry about "the crank throws are solid it'll be heavy blah blah bullshit bullshit." First off, I can clearly see the throws are not solid. Even if they were, just balance her up and let her rip. The extra strength you would gain would far surpass any negative issues regarding weight. Besides, it's fairly close in to the crank centerline and therefore not as critical as say a heavy *** mafungo piston swinging in the stratosphere at 7500 RPM. Run it. It's billy badass.
Click to expand...

LOL .. so very true,, thnx much,, I didn't see that tag wire thru the throw..

I agree, the solid crank will be heavier, but cheap trade-off for strength.

I'll use this crank in my next nitrous build,, thnx again..
 
The seller got with me today, and everything is going to work out on the deal. Gonna get the flexplate that came with the crank.

He told me it came out of a 1969 318. This sound legit?
 
'69-318's were a forged crank. Flex plate included? BONUS!
 
Entirely possible. I would snag it I believe.
 
You must log in or register to reply here.
-

Back
Top