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390 cast iron crank durability

September 12 2003 at 10:23 PM

  (Login FairlaneGT390)
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My Ford Performance book says the FE cast crank is good for 6000-7000 rpm and up to 600 horsepower (unblown). So can I assume that to build a 390 with 400-450 horsepower at 6000-6500 rpm would be ok? (with 10.0-10.5 comp, heavy duty connecting rods and forged pistons, for street/strip pushed hard often)

I will definitely have oil mods done to the block and high volume oil pump with 7qt oil pan. I'm looking at the Crane 300/310 solid cam.

:)Brian G.
'66 Fairlane GT 390 4spd


    
This message has been edited by FairlaneGT390 on Sep 13, 2003 5:43 AM
This message has been edited by FairlaneGT390 on Sep 13, 2003 5:43 AM
This message has been edited by FairlaneGT390 on Sep 12, 2003 10:41 PM


 
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(Login hakcenter)
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Cast Steel ?

September 12 2003, 10:50 PM 

Cast Steel ? Ya that crank is in most regards about the same exact strength of a SCAT crank.

Its never horse power that breaks things anyhow.

I can tell ya many stories but... I'll tell my favorite crank story.

My father owned a 390 flatbed. And we overloaded that thing every day... finally after 1 job... the crank broke, and all hellish nooises you can imagine were happening.

But the strangest thing is, we drove it home!

When we pulled the block apart.. the crank broke into 3 pieces, and each break was the perfect wedge, to continue to make the crank spin.

Parts break from abuse

 
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(Login FairlaneGT390)
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Thank you for helping me to be more specific

September 13 2003, 5:50 AM 

about which type of metal crank I'm referring to. I changed the title of my question.

:)Brian G.
'66 Fairlane GT 390 4spd


    
This message has been edited by FairlaneGT390 on Sep 13, 2003 6:19 AM


 
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(Login hakcenter)
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Re: 390 cast iron crank durability

September 13 2003, 8:26 AM 

Oiling was really never a problem... I find it strange that your crank is a cast iron... I pulled my block last night, and remembered it to be cast steel...

1966 428 Cast Steel crank.. odd.

In any case, you aren't really ever going to break the crank without some serious serious torque running through the block, or a heavy load. I would have the crank rebalanced and your good as gold.

EDIT: After a small amount of research, yap its nodular iron. Sorry


    
This message has been edited by hakcenter on Sep 13, 2003 1:57 PM


 
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Dave Shoe
(Login dshoe)

They worked great in NASCAR 427s back in 1963.

September 13 2003, 10:23 AM 

Ford invented the nodular iron crankshaft back in 1951, and the FE was designed specifically for a nodular iron crank. Crankshaft grade nodular has some properties which are superior to forged steel, such as unsurpassed lubricity, reduced weight, and low cost. FE cast iron cranks are regularly hammered mercilessly on the strip and track, and have a great reputation for reliability. The reduced mass can be a performance advantage. Be sure to magnaflux any crank, and be sure the journal fillets are properly sized, as fillet form is the weak point in most any crank.

All cast iron cranks are basically made of the same grade of pearlitic nodular iron, though there are some minor variations in alloys, each of which have their own benefits. There is no such thing as a gray cast iron crankshaft - it's just not a suitable crankshaft material.

Also, if you see advertising claiming an FE crank is made of "cast steel", don't believe it. It's false advertising of a nodular crank, intended to get you to buy their product and ignore the honestly described competition. I'm unaware of the existence of any cast steel FE cranks. "Cast steel" may sound better than "cast iron", but it's just not as desirable a material for cranks.

Even General Motors' "Armasteel" cranks and rods are actually made of cast iron with an arrested malleabilization heat treatment process. When the Ford patents expired, GM started converting to nodular iron cranks. Some cast steel cranks have been made over the decades, but they generally don't compare favorably with nodular iron, forged steel, billet steel, or austempered nodular.

Shoe.


 
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(Login hakcenter)
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SCAT

September 13 2003, 1:35 PM 

Over the phone, SCAT claimed to make their FE forged steel

 
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(Login qikbbstang)
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Pull the pin on this Hand Grenade

September 13 2003, 5:59 PM 

Dug through my old Super Fords and found the article on a Kuntz and Craft built 427SO that displaced 402CuIn and pulled 8000RPM and 770 HP. the Crank a much worked 390 Cast Crank. Its all in the assmbly.

 
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(Login JohnsonsRacing)
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Yep!!! I read that also

September 13 2003, 9:32 PM 

I went back and read that article also.. Paul had the crank turned down to a chevy rod journal and lightened ... We used to run a 390 crank in our motors..but went to the 427 steel shaft..Actually our backup motor has a 390crank in it...We just tear it down more often than the steel shaft motor... I belive it will last but not as long as a steel shaft..


Stephen Johnson #2162
Horace Johnson #2167
SS/D 427 Ford Fairlane NHRA-IHRA
Ex-Van Cleve

 
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