[CraigG.]

Hey Everybody,
Is it cost effective to turn a 3.25 crank down to 3?
Thanks Again, Craig

[CraigG.]

It is an Eagle Forged crank.

[hurryinhoosier62]

It’s possible but it would probably be easier and more cost effective to sell the 3.25 main crank and buy a 3.00 main crank. Do you have a COMPETENT crank grinder you really trust? The thrust would have to be welded and re-cut along with making sure to provide a generous radius to strengthen the journals.

[mgarblik]

Originally Posted by CraigG.

It is an Eagle Forged crank.

What's the stroke? I might be interested in it.

[65nss4spdGTO]

I’ve had this done before by Shaftech, when I’m turning the rod journals down at the same time. Don’t forget the thrust size is different, I have them weld it up and machine the thrust to size. If you do it this way, you don’t have to worry about bearing spacers and can insure the correct thrust clearance.

It typically costs around $350, but I usually add a few extras too, secret squirrel stuff.

Calvin Hill
Hill Performance
708-250-7420

[hurryinhoosier62]

Calvin, it the way Smokey did it back in the early 60s when he warned PMD engineers that the 3.25 mains would not survive at Daytona.

[Dragncar]

Originally Posted by hurryinhoosier62

Calvin, it the way Smokey did it back in the early 60s when he warned PMD engineers that the 3.25 mains would not survive at Daytona.

I thought he ran bored over 389 SD blocks and crank ?

[Steve Barcak]

This company is very good with repairing and welding cranks, etc. You may want to get a quote from them. They are worked on a few of my forgings. Gladly, none of my billets have needed serious repair ( yet ).

http://www.marinecrankshaftinc.com/

[Steve Barcak]

Originally Posted by Dragncar

I thought he ran bored over 389 SD blocks and crank ?

am sure he tried everything as would be expected.

[grnmnstr]

Originally Posted by CraigG.

Hey Everybody,
Is it cost effective to turn a 3.25 crank down to 3?
Thanks Again, Craig

Why do you want to? What is the reason? What size block do you intend on using?

I have a motor going together that will utilize the 3.25 journal. Forged, cryo'd. Will probably only see 7000. 10.0 car. Maybe 700-750 HP. IA2 block.

If you do not intend on spinning it over 7000, I think the 3.25 crank is fine.

[rohrt]

Is there a special process to do the welding on the thrust surface? I assume I couldn't just lay a bead down myself with my mig welder.

[GoatZillaRacing]

I'd sell it to someone who can use it the way it is and buy a 3.00 main crank.

[hurryinhoosier62]

Originally Posted by Dragncar

I thought he ran bored over 389 SD blocks and crank ?

After the 421s failed in ‘61, Smokey cut down the forged 990 cranks to 3.00 mains and ran them in +.030 over 389 blocks. Every part was genuine PMD as required by NASCAR. You are aware that a +.030 389 had the same bore size as a standard bore 421?

[tom s]

Back then there was really not much of a rule book!Smokey pretty much skirted most of them.Tom

[hurryinhoosier62]

Originally Posted by Dragncar

I thought he ran bored over 389 SD blocks and crank ?

Originally Posted by rohrt

Is there a special process to do the welding on the thrust surface? I assume I couldn't just lay a bead down myself with my mig welder.

Hell NO! Crank welding is done with a dedicated crank welder that uses an arc immersed in a granular media. Back in the old days, they used an arc welder and a high nickel rod. I seriously doubt any home grade MIG could generated enough penetration into forged steel to weld a thrust flange. Then, you would have to be concerned about warpage AND annealing of the base steel.

[hurryinhoosier62]

Originally Posted by tom s

Back then there was really not much of a rule book!Smokey pretty much skirted most of them.Tom

Precisely, Tom. NASCAR didn’t have the mandatory engine tear downs like they do today. As long as the internal parts had the correct PMD part numbers on them for the particular application it was all “legal”. I sometimes wonder WHY the PMD engineers didn’t want to listen to Smokey.. I met him once: cranky old fella!

[Mark G]

Why over 1000hp on nitrous built in 2012 still like new .. don't fall for all the hype 3.25 can get it done ..I ran a stock block 3.25 crank 600hp n/a for 10yrs ..

[Dragncar]

Originally Posted by hurryinhoosier62

After the 421s failed in ‘61, Smokey cut down the forged 990 cranks to 3.00 mains and ran them in +.030 over 389 blocks. Every part was genuine PMD as required by NASCAR. You are aware that a +.030 389 had the same bore size as a standard bore 421?

I am aware of all of it. I knew about this from Dan Whittmore who knew Smokey. Smokey gave him all the details on a lot of stuff.

[Dragncar]

Originally Posted by hurryinhoosier62

Hell NO! Crank welding is done with a dedicated crank welder that uses an arc immersed in a granular media. Back in the old days, they used an arc welder and a high nickel rod. I seriously doubt any home grade MIG could generated enough penetration into forged steel to weld a thrust flange. Then, you would have to be concerned about warpage AND annealing of the base steel.

Penetration is over rated. You just need enough to get the job done for something like this. Cast cranks get spray welded to build up the thrust. Not even really welding from what I have seen.
The more penetration the more a weld will pull and warp.
The most common stick rod in use today, 7018 is a shallow penetrating rod.
I use a lot of 6010 under it when I am after penetration on dirty/rusty steel. 6010 goes deep.

[hurryinhoosier62]

Originally Posted by Dragncar

Penetration is over rated. You just need enough to get the job done for something like this. Cast cranks get spray welded to build up the thrust. Not even really welding from what I have seen.
The more penetration the more a weld will pull and warp.
The most common stick rod in use today, 7018 is a shallow penetrating rod.
I use a lot of 6010 under it when I am after penetration on dirty/rusty steel. 6010 goes deep.

Name ONE company that is successfully spray welding cast cranks....We welded cast cranks EVERY DAY and never used plasma welding. In our experience it was NOT durable enough for a rotating part. To build up flaws and pits in castings, yes.