426 heads on a 383...

[ChargerSG]

I have to ask all the enginemechanics here, i read an old CC topic about some dude that put 426 heads(and intake) on a stock 383 and said it looked like a Hemi and did run good after tuning things in, is this possilble at all to put stock 426 cylinderheads on a stock 383?? I have never herd this before...

[69fuchs]

pro stock racers did it a long time ago, but the intake has to be made custom, and some surgery is required on the block to mount the heads (head bolt relocation, oiling problems,pushrod location).  The stock intake is to wide for a 383.

Also, the piston design is different.

[ChargerSG]

Ok, is it the same with those Stage V?

[Chryco Psycho]

it is the same with the Stage V heads , to a point , the heads are physically easier to bolt on but the block still has to be modified for pushrod clearance & oil drain back issues & you still have a problem with getting a hemi intake for a low deck engine

[ChargerSG]

Thanks for clearense in this, i can understand that old pro stock racers did those kind of stunts, but someone is allways playing in their garage I cant understand really understand why they chose a 383, it must be easyier to do it on a 440...

[Ghoste]

Only guessing here, but maybe it was to take advantage of the shorter stroke and get ther rpm into a range where the Hemi style heads could breathe better?  Maybe it was for the lighter weight over the front end?  If they went to the trouble to put them on, they likely stroked the crank and had displacement back where they wanted it.  What were the Pro Stock rules of the time?  Was there a cubic inch limitation on Hemi heads?

[bull]

Sounds like a big hassle. By the time you do all that and spend gobs of money you could have built a kickazz 440 and gone just as fast or faster for less.

[Ghoste]

It is.  It's kind of one of those developments (the Stage V Engineering head) that came about in the early 90's before Mopar introduced the Crate Hemi and original Hemi's were disappearing and folks wanted a Hemi.  This was what came out of it.
I can't explain the reason for Pro Stock racers doing it prior to that.

[ChargerSG]

Hemi is a magical word and people do funny things to get one, in one way or another, myself i go for a 5.7 Hemi  I think thou its funny to read about all those ideas and projekts, cause someone is soon or later is gonna come up with some Hemiheads to 383 or 440 that bolt right on(without costing 5k or more), but i can not understand things like coverting a 318 to a Hemi for $8500.

[69fuchs]

It is.  It's kind of one of those developments (the Stage V Engineering head) that came about in the early 90's before Mopar introduced the Crate Hemi and original Hemi's were disappearing and folks wanted a Hemi.  This was what came out of it.
I can't explain the reason for Pro Stock racers doing it prior to that.

The short deck height made the low deck block stronger. (In theory) the short cylinder walls make them stiffer and stronger.  I have seen several pro stock blocks that have the outsides milled flat....no webbing left.  It seems they would do anything to get rid of weight back then!

[Ghoste]

That would make sense.  I suppose when NHRA forced the Hemi head cars to add weight they didn't specify where it had to be.  If you have to add it, you may as well add all you can to the back.

[Mike DC]

(WARNING: Potentially stupid question ahead . . . )

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Why not just stick the Hemi heads on a wedge-head block and forget about the Hemi's 5th head bolt?  The 383/440's four bolt setup doesn't exactly seem weak; not on a naturally-aspirated street motor.  What's the harm?  Are the other four head bolts relocated on the Hemis or something?

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[Ghoste]

I think (I'm not certain) that all of the Hemi head bolts that are on the inside edge of the head are in a different location.  That would leave you with head bolts only along the one side.  Not good.
There is also the issue of pushrod clearance for the exhaust side and oiling the head.
I'm not sure if the coolant holes line up perfectly or not but it would also be a consideration.

[Mike DC]

I think it was just the one head bolt different on top.  I'd have to get a 426 Hemi head gasket or something and compare it with one of my wedge motors to know for sure. 

But that one top head bolt is definitely in a different place on the two motors.  There's no way to reconcile it with any amount of machining work on the block.  (Not unless maybe you welded a big blob of new steel on the whole area and started over machining the hole.  And for the price of THAT much machine-shop work you would start to wonder about just buying a hemi block in the first place . . . )

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I've also read in several places that there's differences between the Hemi & the 440 blocks in the lifter bores or something.  There's some kind of valid reason that the "Stage V" Hemi conversions needed to use different rocker-arms from the stock Hemis in several spots.  But I don't understand exactly what the difference is.

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