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Bore & Stroke?
It will soon be getting down to the wire on the Keith Craft build of my 427 SO. I would like to know which bore & stroke is the best to get and why. At his point I have talked with Keith and some of the specs on the motor are as follows. Stage 1 Edelbrock Heads, Blue Thunder Med Rise Intake, 750 Holley, fairly mild hydralic roller cam and 10 - 1 pistons. Cast Pond block. He has suggested the 482 bore. Thanks.:confused:
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Apparently originality is important to you, else why the Side-oiler (not the best design for the street) in the plastic replica. Soooo, for originality sake, I'd go with the 4.23" bore and the 3.78" stroke. Your only other option, to stay the course originality-wise, is a 4.13" bore with a 3.98" stroke to give you the 428 inch displacement many original cobras actually came with, though if you choose this option, you may have the wrong block? Any more hard questions? |
I have asked Keith for a cast Pond block. He says no problem. Last year I heard some bad rumors about the Genesis blocks.
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Soooo, for originality sake, I'd go with the 4.23" bore and the 3.78" stroke.
Do these dimentions really come out to 427 cubic inches? Bob |
427SnakeSC
Within the confines of an FE all that really matters is total cubic inches. I'd make it at least a 482. If the cost is about the same make it a 526. Either way it should be a fun ride!! Steve |
Genesis
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but those have been resolved now. The person to ask about Genesis blocks would be Barry Rabotnick, he does his FE builds with Genesis blocks including the FE he did for the Engine Masters competition. ....Fred |
Seasoned block!
I went with a vintage/seasoned block, so boring was limited.
Remember this post? I posted my spec's here: http://www.clubcobra.com/forums/showthread.php?t=70167 jdog P.S. There is no other sound like a big bore FE!:) |
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I assume Ford has been fudging math results for decades. All should note that bores and strokes published are ones that are hoped for at the manufacturing level. Actual bores and strokes can vary quite a bit and Ford even made allowances for the manufacturing variances with different size and weight pistons and rods. |
The bore and stroke of the 5 liter is 4X3. It comes out to 302 cubic inches.
The bore and stroke of a Windsor engine is 4X3.5 (which is the same as the 60s FE). It comes out to 352 cubic inches. I presume Ford chose to call it a 351 to avoid confusion with the old 352 FE engine. The bore and stroke of the 427 calculates out to 425 cubic inches. I've always wondered why Ford chose to call it a 427. Bob |
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It is all marketing and they can call virtually anything anything. Chrysler can call the overweight bloated Challenger concept a "Pony Car" even though it is based on a full-sized frame and design. I think there was already a 425 (Oldsmobile?), a 426 (mopar) and Ford just wanted something close to differentiate the engine. Is a Ford 428 or Ford 429 really? |
Here is how to figure Cubic Inches. Have fun!
Cubic Inches = Bore x Bore x Stroke x.7854 x 8 Poolw |
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Your aftermarket block probably comes with a 4.25" bore. All he should have told you was that it's pretty much impossible for him to take a 4.25" bore back down to 4.23". Why all the subterfuge? Honestly, if you're spending the coin on a new block, what's the cost of a set of custom pistons in the grand scheme of things? And you can specify the correct offset instead of taking none or the GM's version (4.25" is a GM size and you'll get "GM" pistons). So it starts: a genuine "sideoiler" block (only it's an aftermarket "Pond" block that's had some design "upgrades") displacing "427" (only it was easy to bore and stroke it up to 60's Cadillac displacement using "GM" parts and new crank from China) in a genuine CSX cobra (with the modern plastic body). I just wish people'd be more upfront and honest about things. Here's an honest truth: there's no replacement for displacement. |
My current Genesis block seems to be just fine - no issues and it made 752HP at 6300 RPM at the Engine Masters deal on 91 octane. Same engine got shipped over to Kaase's for photos and it went 759HP on Jon's dyno...
The aftermarket blocks are all referenced to go to 4.25 bore. The reason is not pistons - - the guys at Diamond will make me any piston I can dream of. We've done some for FEs with blowers, and some for 300 ci inline sixes with turbos... The forgings are FE specific and not converted GM anything. The reason is piston ring availability. Since the original moter was the only one using that 4.233 bore, standard size rings have become virtually non-existant. Chevrolet size based 4.250 rings are inexpensive and plentiful. I cannot imagine a reason not to go "big" - but I suppose we could tweak a 391 truck forged crank offset in the "wrong direction" to put the cubes back at 427 with the slight overbore. Wierd but possible. I'd go big if it was mine. Wait a minute - - I'm doing something a lot like that for next year's Engine Masters Challenge - - taking my 4.350 bore motor and destroking it to meet the 434 cube rules ... I guess the wierd label fits :) |
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Brad |
Okay, okay, you've convinced me! I'm going to go with what Keith recommended, the 482. Thanks guys, for your advice and opinions!:) After all, it isn't a '66 I'm building here!
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Is it better to go with a big bore and short stroke or vice-versa in these cars?:confused:
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It depends on where you want your HP. If you want it beween 2,000 and 4,500 RPM go with stroke. If you want it at higher RPM go with bore.
Personally, I like my HP at the lower end. That's also why I have a dual plane manifold, Bob |
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Usually. Stroker engines don't tend to turn as fast anyway. Drag racing long stroke, road racing big bore.
Bob |
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