Big bore small cu inch?? - 460 Ford Forum
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post #1 of 7 (permalink) Old 06-27-2011, 12:05 PM Thread Starter
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Big bore small cu inch??

I'm totally kicking this around, no firm plans yet, but more wondering than anything else. My buddy has a 429, I believe its .060 over that I'm interested in building. My thought is, a set of out of the box TFS A heads or something similar, that way if I build a bigger cu inch motor later on down the road, my heads can "grow" with me so to speak. I know there is no replacement for displacement, but at this point I can afford to put this deal together and start saving for a bigger cube shortblock in the future.
Please give me any input you might have, the motor will be going in a tube frame altered, backed by a powerglide if you need more info, weight with the bbf figured around 1600lbs.

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post #2 of 7 (permalink) Old 06-27-2011, 12:19 PM
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If I'm not mistaken, that's an awfully small bore for those heads.

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post #3 of 7 (permalink) Old 06-27-2011, 12:31 PM
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Head vs bore size

I think I read on here that with the smaller 2.30" Intake valve on an Ahead you can get away with a .030" overbore. That said you should be good to go with your .060" overbore but you will need a custom piston if you stay with the 3.59" crank. If you go with a 4.3" or 4.5" crank there may be a .060" over shelf piston availible. Once you move up to a 2.35" Intake valve I think you need a minimum 4.50" bore to clear.

Maybe one of the experts will chime in here to either confirm or correct this data.

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post #4 of 7 (permalink) Old 06-27-2011, 12:38 PM
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Cool

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Originally Posted by prosandguy View Post
My buddy has a 429, I believe its .060 over that I'm interested in building. My thought is, a set of out of the box TFS A heads or something similar, that way if I build a bigger cu inch motor later on down the road, my heads can "grow" with me so to speak...the motor will be going in a tube frame altered, backed by a powerglide if you need more info, weight with the bbf figured around 1600lbs.
That 1600-pound altered would go like a bat out of hell if built correctly.

It is suggested that A460 cylinder heads be used on a boresize of 4.44" or larger, but yes they can be fit a 4.42" bore with some simple effort.

The bigger problem I see is the need for a very custom 429 piston in order to give you a reasonable compression ratio (c/r). It would take a 20cc dome just to get you to 12:1 if you have a 3.59" stroke and A460 heads. (Going blown alcohol? Then 429 Flat tops will put c/r at 9.4:1.)

I would suggest you go to a 3.85" stroke 460 crank since it will dramatically increase your piston options, lighten the piston, etc. A 14.5cc Diamond dome-top would get you that 12:1 c/r, which is half the dome volume requirement of the 429 piston...if Diamond can put the pin low enough in the slug. (Going blown alcohol? Then 460 Flat tops will put c/r at 10:1.)

As this is fun build I would suggest a factory 3Y crank and aluminum rods. The 3Y crank should balance as an internal balance set up with the aluminum rods; also it will not be necessary to drill out so much material from the counterweights.

Paul

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Last edited by Paul Kane; 06-27-2011 at 12:43 PM.
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post #5 of 7 (permalink) Old 06-27-2011, 01:30 PM
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I've ran the A460 heads on a 4.375" bore [+.015"] . Bigger the bore the better in this case.

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post #6 of 7 (permalink) Old 06-27-2011, 06:49 PM
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If it's already .060 over take it to .080 since you need custom pistons for the A460 heads anyways. I've ran a 514 and a 557 (.080 over) with A460 heads and it worked great.
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post #7 of 7 (permalink) Old 08-17-2011, 07:39 AM
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That was an interesting build that I did several years ago as a test engine. Mike from Extreme Machine hired me to build that 557 just to demonstrate what their cylinder heads could do on a very straightforward engine build that anyone could duplicate without much trouble.

The engine ran very well but it's somewhat dated. At the time inexpensive steel forgings were not available for the big Ford so I used the Scat cast crank. A steel crank would be easier to balance and more durable.

Also on that build I used an off the shelf JE piston and then modified it to work with the EX head's A 460 style valve relief. Pistons could be ordered with the correct reliefs already in them for no a whole lot more money.

This engine lasted through my dyno testing, some track testing we did in Wes' roadster and about 75 passes in a dragster. It was taken down by the crank breaking in the back rod throw. This ruined the block and some pistons but it didn't do any serious damage to the cylinder heads, valvetrain, cam etc.

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Last edited by DaveMcLain; 08-17-2011 at 07:52 AM.
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