What was the original bore and stroke of the 427 in the Cobra?

[rsimoes]

What was the original bore and stroke of the 427 in the Cobra?

[Perf. Eng. Eric]

I think it was around 4.133. Some of the builders would go .017 overbore and run a 4.250 bore, as best I can remember. Hope this helps

[PatBuckley]

3.78 stroke w/ a 4.23 bore.....was stock.

[Excaliber]

The original Ford book I have lists it as 4.233, my block is .017 over bore, a typical size. 4.250 results. .017 is SO standard you can buy "standard oversize" pistons in a 4.250 size.

But those "stock" oversize pistons may not work just because the "bore" is correct. The "compression height" (piston pin location) also has to be compatible with the engine block deck height. And LOTS of blocks HAVE been decked over the years!

Mine was, so I was forced to order custom pistons for my "stock" .017 over bore to get the right piston height at TDC.

Stroke was the same for 390, 391 Truck, 406 and 427 at 3.78"

410 and 428 went to 3.98"

[SCOBRAC]

Blocks varied. They were color coded accordingly for easy identification. The most typical side oilers selected for racing aside from being square and dimensionally correct were 4.2325". Many "standard" blocks were 4.233-4.235"

[Excaliber]

Interesting point Michael. The piston to bore clearance spec was .007, which is a lot, generally speaking. My new custom pistons are spec'd at .0035, for instance.

I'm betting that back in the day they still used the same "basic size" piston for the same "basic bore", thus piston clearance could have varied per motor by several thousandths? It's possible!

Perhaps THAT is why some motors just naturally seem to run stronger than others, even true today. Some spec race divisions demand "exact" factory specs for the motors. I've heard rumors that some teams "with connections" go through a ton of new "parts" searching for the "perfect" valve, or piston or head or whatever. No machineing allowed, so you go through the "bin" and find those perfect parts to "blue print" your motor.

Reminds of a Darryl Waltrip comment years ago. He (or his team members) would hang out by the Goodyear truck that brought the tires in. There they would carefully go through them and pick out those "perfect" tires. This gave them a measurable advantage on the track and other teams knew those boys "were up to something", but cound not figure out WHAT! When it was discovered, NASCAR stopped that and tire distribution was closely watched!

[rsimoes]

Where would one find an original 427 block?

I noticed that the Genesis 427 crate motor is actually a 468.

The orginal 427 was 425-426, right?

[PatBuckley]

Turk is selling one - check with Gessford Machine.

( I apologize if this "answer" is too "succinct" and I didn't start telling you about "my" block and pistons.... )

Pat

[SFfiredog]

It is a "de-bored" block with the reduced bore size of 4.050"
This was done to fit into certain "class" racing 6.5 litre engine sizes.
It is the extremely rare lightened "race block" that eliminated the heavy cross bolt mains, extra overly heavy side oiler oil passages, and the very heavy screw in freeze plugs.
This block took 15 lbs. off the front end making handling much better.
Also, to throw off the competition, nowhere on this block does it say, "427"
Many racers just assume it is a standard 390 block,
little do they know...
I also have the matching rare, lightweight cast iron crankshaft.
The cast iron "racing" crank is 17 lbs lighter than the heavy forged steel standard 427 crank.
I can make a package deal, but it won't be cheap

Gee, this sounds like every e-bay ad I read

[PatBuckley]

Funny Mike...how much do you want for it?

Dip**** - how come you have to tell everyone about your stuff all the time? Who cares about you? BTW - I got $5 that says your attempt at an engine build doesn't make it a hundred miles - that is assuming your trans works....

[Excaliber]

Phuck you Pat, plain, simple and to the point.

If you got a personal problem (obviously more than one you short $hit) take it off line. Or will this be yet ANOTHER thread Ron will have to close because of an a$$hole gashole?

[computerworks]

Right...take it off line and settle this, will ya?