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Re: De-stroked Hemi possibilities? [Re: Hemi_Joel] #2813117
08/25/20 02:32 PM
08/25/20 02:32 PM
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Country State of Mind
Semi-Hemi Offline
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To bad they don't allow aftermarket blocks, Indy has or did have a short deck Hemi block.


Losing Faith in this country one day at a time.
Re: De-stroked Hemi possibilities? [Re: Hemi_Joel] #2813262
08/25/20 07:33 PM
08/25/20 07:33 PM
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Charlotte, NC
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LSP Offline
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Are the rules listed somewhere?

Re: De-stroked Hemi possibilities? [Re: LSP] #2813635
08/26/20 04:07 PM
08/26/20 04:07 PM
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Minnesota
Hemi_Joel Offline OP
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Interesting idea there, dad. I like it!

Lsp, the rules are in a book, nowhere online. Pre-74 iron production block and heads, block decking up to .125, 370 maximum cubes, no EFI, magneto or points ignition only, no welding on blocker heads unless it is for repairs. That's pretty much the rules for the engine.


[img]http://i.imgur.com/boeexFms.jpg[/img]
31 Plymouth Coupe, 392 Hemi, T56 magnum
RS23J71
RS27J77
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Re: De-stroked Hemi possibilities? [Re: Hemi_Joel] #2813666
08/26/20 05:38 PM
08/26/20 05:38 PM
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#230 400 block, add bolt in head bosses for upper head stud retention, aluminum main caps, hat sleeve to 4.185" (best ring packages at that bore), 3.350" 8 CW crank, 1.777" rod journals, GRP 6.400" aluminum rods, Gibtech LW COM balanced vertical gas ported billet pistons, .866" x 2.000" x .180" DLC pins, .6mm, .6mm, 2mm Riken ring set, Jesel cam drive, largest cam barrel that will fit, Jesel lifters, 290/275 @ .050 cam - lift depends on heads, Jesel rocker gear, largest pushrods that will fit, largest box/kickout pan that will fit, std volume oil pump, 2"/2.125"/2.250" headers/merge collector, offset heads down .030".

That's a good start, similar to what set the NHRA PRO STOCK speed record in 1981 at 165 mph, when they were real Hemis and small, but with a few updates that would help hp.

Re: De-stroked Hemi possibilities? [Re: LSP] #2813683
08/26/20 06:18 PM
08/26/20 06:18 PM
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Minnesota
Hemi_Joel Offline OP
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Originally Posted by LSP
#230 400 block, add bolt in head bosses for upper head stud retention, aluminum main caps, hat sleeve to 4.185" (best ring packages at that bore), 3.350" 8 CW crank, 1.777" rod journals, GRP 6.400" aluminum rods, Gibtech LW COM balanced vertical gas ported billet pistons, .866" x 2.000" x .180" DLC pins, .6mm, .6mm, 2mm Riken ring set, Jesel cam drive, largest cam barrel that will fit, Jesel lifters, 290/275 @ .050 cam - lift depends on heads, Jesel rocker gear, largest pushrods that will fit, largest box/kickout pan that will fit, std volume oil pump, 2"/2.125"/2.250" headers/merge collector, offset heads down .030".

That's a good start, similar to what set the NHRA PRO STOCK speed record in 1981 at 165 mph, when they were real Hemis and small, but with a few updates that would help hp.


Awesome detail, thanks I like the idea of the bolt in head stud bosses. I never thought of that. A dry sump is okay if that would help


[img]http://i.imgur.com/boeexFms.jpg[/img]
31 Plymouth Coupe, 392 Hemi, T56 magnum
RS23J71
RS27J77
RP23J71
RO23J71
WM21J8A
Re: De-stroked Hemi possibilities? [Re: Hemi_Joel] #2813834
08/27/20 06:16 AM
08/27/20 06:16 AM
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Originally Posted by Hemi_Joel
Originally Posted by LSP
#230 400 block, add bolt in head bosses for upper head stud retention, aluminum main caps, hat sleeve to 4.185" (best ring packages at that bore), 3.350" 8 CW crank, 1.777" rod journals, GRP 6.400" aluminum rods, Gibtech LW COM balanced vertical gas ported billet pistons, .866" x 2.000" x .180" DLC pins, .6mm, .6mm, 2mm Riken ring set, Jesel cam drive, largest cam barrel that will fit, Jesel lifters, 290/275 @ .050 cam - lift depends on heads, Jesel rocker gear, largest pushrods that will fit, largest box/kickout pan that will fit, std volume oil pump, 2"/2.125"/2.250" headers/merge collector, offset heads down .030".

That's a good start, similar to what set the NHRA PRO STOCK speed record in 1981 at 165 mph, when they were real Hemis and small, but with a few updates that would help hp.


Awesome detail, thanks I like the idea of the bolt in head stud bosses. I never thought of that. A dry sump is okay if that would help


Yes, used on BBC's in Pro Stock back in the day on blocks that didn't have the 4 extra upper head bolt bosses.

Yes 4 compartment dry sump by all means with 20ish inches of vacuum.

Re: De-stroked Hemi possibilities? [Re: LSP] #2813862
08/27/20 08:26 AM
08/27/20 08:26 AM
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Minnesota
Hemi_Joel Offline OP
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So the only reason that I can see to use the low deck block and give up the strength of the Hemi block is to improve the rod stroke/ ratio. Is it worth it?

Mechanical stack injection would probably be the hot ticket for induction.

How much horsepower will this thing make?


[img]http://i.imgur.com/boeexFms.jpg[/img]
31 Plymouth Coupe, 392 Hemi, T56 magnum
RS23J71
RS27J77
RP23J71
RO23J71
WM21J8A
Re: De-stroked Hemi possibilities? [Re: Hemi_Joel] #2813874
08/27/20 08:50 AM
08/27/20 08:50 AM
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The low deck block is stronger than a RB/HEMI block. Thicker main webs, Shorter/stiffer cylinder wall, shorter pushrods. Shorter piston. It all just adds up to a better package.


69 GTX 68 Road Runner
Re: De-stroked Hemi possibilities? [Re: JERICOGTX] #2813892
08/27/20 10:07 AM
08/27/20 10:07 AM
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Minnesota
Hemi_Joel Offline OP
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Originally Posted by JERICOGTX
The low deck block is stronger than a RB/HEMI block. Thicker main webs, Shorter/stiffer cylinder wall...

What makes you think that? It's only two bolt main. The Hemi has better iron in it and I thought that the main webs were improved on the Hemi block.


[img]http://i.imgur.com/boeexFms.jpg[/img]
31 Plymouth Coupe, 392 Hemi, T56 magnum
RS23J71
RS27J77
RP23J71
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Re: De-stroked Hemi possibilities? [Re: JERICOGTX] #2813896
08/27/20 10:15 AM
08/27/20 10:15 AM
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Stuttgart, Arkansas
rickseeman Offline
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Originally Posted by JERICOGTX
The low deck block is stronger than a RB/HEMI block. Thicker main webs, Shorter/stiffer cylinder wall, shorter pushrods. Shorter piston. It all just adds up to a better package.


I probably wouldn't phrase it exactly like that. Yes, most people feel the low deck block builds a better wedge for the reasons you stated. But that doesn't mean it make a better Hemi. The pushrod angle gets even worse if you make a Hemi out of a low deck. Thicker main webs don't make up for the cross bolted mains on the Hemi block. If he wants a Hemi, there are still some of the old Chrysler 366 cu in Hemi cranks out there. And new light weight rods and pistons are easily available.


2011 Drag Pak Challenger
Re: De-stroked Hemi possibilities? [Re: rickseeman] #2813901
08/27/20 10:25 AM
08/27/20 10:25 AM
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So if you decked a hemi block to 10.6 and went with the 3.35 crank and 6.4 rods, would a 2.52 compression distance be a problem?

Maybe wouldn't be too heavy if a strutted piston?

Re: De-stroked Hemi possibilities? [Re: INTMD8] #2813923
08/27/20 11:53 AM
08/27/20 11:53 AM
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Hemi_Joel Offline OP
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Originally Posted by INTMD8
So if you decked a hemi block to 10.6 and went with the 3.35 crank and 6.4 rods, would a 2.52 compression distance be a problem?

Maybe wouldn't be too heavy if a strutted piston?


Id have to check with the piston guys.


[img]http://i.imgur.com/boeexFms.jpg[/img]
31 Plymouth Coupe, 392 Hemi, T56 magnum
RS23J71
RS27J77
RP23J71
RO23J71
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Re: De-stroked Hemi possibilities? [Re: Hemi_Joel] #2813925
08/27/20 12:06 PM
08/27/20 12:06 PM
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Charlotte, NC
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No to a Hemi block, waaaaay too tall, one of the reasons my combo specs the bore,stroke,and rod that it does. Uses a 1.785" compression height piston. 2.520" piston if anyone would even make it would be a heavy brick, bad idea.

Re: De-stroked Hemi possibilities? [Re: rickseeman] #2813939
08/27/20 12:54 PM
08/27/20 12:54 PM
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fredericksburg,va
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Transman said the shorter rod lost power. Maybe the shorter deck with a shorter piston, gonna need a lot of meat up in the head

Re: De-stroked Hemi possibilities? [Re: LSP] #2814224
08/28/20 08:10 AM
08/28/20 08:10 AM
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Charlotte, NC
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I'd fab up a main girdle out of aluminum to help tie the bottom end together, like the Milodon 426 Hemi block was.
That along with the aluminum rods and main caps will be plenty of structural integrity for a 370 ci motor.
Should be capable of 900 hp possibly, at least 9500, maybe 10,000 rpm

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