To stroke or not to stroke my 427

[ERA Tom]

Hello all, I'm getting close to buying pistons and heads for my 427 project and I am considering using a 428 crank to stroke it to 454 cubic inches. Since I need to bore the block and buy new pistons anyway, I figured I might as well stroke it. The thing is, I already have a nice Lemans crank so I am wondering if the performance will be noticably better at 454ci, or should I just go with the shorter stroke Lemans crank. Any opinions? Thanks, Tom.

[cobrashoch]

Just curious why you are hug up on the so called Lemans (stock) cranks? Is your aim to stay with the stock stuff? The 428 crank will indeed give you more net power, but your CAR may not run as well. Too many times guys will confuse power with how a car runs. If you are staying with the stock stuff, my vote is for the 427 crank.
cobrashock

[clayfoushee]

I run a 427SO bored 22 over with a mild cam and 428 crank. It idles well at 800rpm, runs cool, and has had no issues in 5000 miles. Oil pressure is consistently 75lbs, above 2000 rpm and never lower than 35-40lbs. at hot idle. It also has a very flat torque curve and pulls like a tractor from 2Krpm.

[Zoom This]

Just from a power point of view you can expect an increase of about 25 more lbs. of torque with the increase in cubic inches. General rule of thumb is about 1 pound of torque for every inch increase if cubic inches.

[Cracker]

I've had both the 428 crank & currently run a LeMan's crank (3.781 stroke). For me, a short stroke with it's high & fast revving package is what I like - if I want a tractor I jump on the Kubota not in the Cobra. In my cars the tq. is a waste to lump around at 2K all day when my wheels would spin with much less. The horspower found higher in the rev range is what I really enjoy. The crank you have is terrific - don't settle on a 428 unit when you have the best they offered 40 years ago - forged is great and billet is ok (but not forged) and cast is what you use if you have to and you don't have options (or want pieces to an engine that originally cost 1/4 that of a side-oiler). JMO

[ENTDOC]

I will go with Cracker on this one.My SO is stroked with a 428 crank but it came that way,I did not build it.If I were starting from scratch,I would use the 427 crank.It has always made sense to me that Ford used a shorter stroke for a reason,and built the motor around that crank for the high revs it could generate.I think stroking it actually takes away from the reason the 427so was so good in the first place.Remember ,the 428 was designed to produce more low end torque for the big city cruisers of the day and for a lower price. chuck

[Anthony]

Since you already have the LeMans crank, I would just use that. Obviously, if you wanted your engine to be a true 427, then use the stock stroke crank.

If you had to buy a crank, then I would get the stroker crank, either 3.98, or new scat stroker ?4.25". Any time you stroke any engine, with all other things being equal, you will always make more max torque and max Hp. Granted, the output per cubic inch may be a little less, but overall power output will be greater at all rpms, except maybe at the very top extreme. More ci will also tame the cam a little bit.

I can't remember if the LeMans crank was one of those "heavy" forged cranks. Some drag racers would use the cast 390 cranks (same stroke) as they were lighter and would rev faster than some of the forged ones, for better acceleration. So, maybe, a cj crank may be lighter than a LeMAns crank, but again, I'm not sure about that.

Ford built the 427 for NASCAR racing, which had a 7 liter limit displacement. Ford put the bigest pistons in the FE, with the appropriate stroke to get to 427 ci. The bigger bore allowed bigger valves for better breathing and top end HP, what was needed for Nascar. If Ford could have put even biggger pistons in it, they would have, but they were at the limit for the FE block. They changed that when they designed the 429/460 block with larger bore spacing allowing even a bigger piston and shorter stroke to meet the 427 ci displacement limit.

The 428 engine was a cheaper block to cast compared to the 427 block which required special casting processes to get the water jackets right. With the 428 engine, you got the displacement of 7 liters, without the more expensive cost of the 427 block. I also believe the slightly smaller bore of the 428 gave slightly better emissions, as it had better combustion with a smaller diameter bore, and would be perfect for passenger cars.

A billet crank, other than being the most expensive, is generally the lightest, and is available in just about any stroke you want.

[decooney]

Gotta question for those with standard (standard stroke) 427 FE powered Cobras on the street. I see all this talk about higher revving.


How much time do you actually spend above 6,500 rpms with your 427, on a regular basis, on the street?



I sort of went for torque with the 428CJ, and now see that shorter stroke and less torque might be nice too (less tire spin), but still think about preserving my valvetrain too. May do an aluminum 427 standard stroke next time, but don't care to rev 7k either for fear of breaking valvetrain parts or worse.