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383 pistons in 426 wedge #302465
04/28/09 09:38 PM 04/28/09 09:38 PM
Joined: Dec 2005
Posts: 261
Eastern ohio
Alexdodge Offline OP
enthusiast
Alexdodge  Offline OP
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Eastern ohio
One of my other engines is a 426 marine block. When I put this motor together I used 383pistons and 440 connecting rods in it being it is the same bore . So now I'm told that the pistons set low in the cylinders and I probably only have about an 8 to 1 compression. I don't remember how low they sit low compared to the originial 426 pistons. Is it possible to use a very thin set of head gaskets to make up for some of the difference in the piston height to get the compression higher? I don't want to get into shaving the heads. Just an idea.
Thanks, Alex
Re: 383 pistons in 426 wedge [Re: Alexdodge] #302466
04/28/09 09:48 PM 04/28/09 09:48 PM
Joined: Jan 2003
Posts: 30,983
Oregon
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AndyF Offline
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Oregon
Yeah those pistons are probably 0.200 down in the hole if not more. Unless it is a tow truck motor you might want to pull it down and buy some pistons that are designed to work in that combination.
Re: 383 pistons in 426 wedge [Re: Alexdodge] #302467
04/28/09 09:51 PM 04/28/09 09:51 PM
Joined: Jan 2003
Posts: 74,937
U.S.S.A.
JohnRR Offline
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the tallest 383 piston has a CH of 1.932 , a sixpak piston has a CH of 2.061 and that puts it .020 in the hole. It's going to cost you almost as much to deck the head on to surfaces as it will to get a correct CH piston .
Re: 383 pistons in 426 wedge [Re: AndyF] #302468
04/28/09 09:51 PM 04/28/09 09:51 PM
Joined: Dec 2005
Posts: 261
Eastern ohio
Alexdodge Offline OP
enthusiast
Alexdodge  Offline OP
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Eastern ohio
With these pistons the car is a real dog. Don't know where to go from here. Its only a touring and cruiser but I still would like it to run better than this. Any one have any ideas?
Alex
Re: 383 pistons in 426 wedge [Re: Alexdodge] #302469
04/28/09 09:53 PM 04/28/09 09:53 PM
Joined: Jan 2003
Posts: 74,937
U.S.S.A.
JohnRR Offline
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Quote:

Thats where the problem comes in, just can't find anyone that sales them anymore. Alex



call Bob Mazzolini or you can have Diamond make you a set .
Re: 383 pistons in 426 wedge [Re: JohnRR] #302470
04/28/09 09:57 PM 04/28/09 09:57 PM
Joined: Dec 2005
Posts: 261
Eastern ohio
Alexdodge Offline OP
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Alexdodge  Offline OP
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Would anyone have a address for these people?
Thanks, Alex
Re: 383 pistons in 426 wedge [Re: Alexdodge] #302471
04/28/09 10:02 PM 04/28/09 10:02 PM
Joined: Jan 2003
Posts: 104,346
Garden Grove, CA
OzHemi Offline
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http://www.bobmazzoliniracing.com/

I went and got a Hemi block from him a few years ago, great to deal with

Re: 383 pistons in 426 wedge [Re: OzHemi] #302472
04/28/09 10:06 PM 04/28/09 10:06 PM
Joined: Dec 2005
Posts: 261
Eastern ohio
Alexdodge Offline OP
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Alexdodge  Offline OP
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I'll check them out, thanks, Alex

Re: 383 pistons in 426 wedge [Re: Alexdodge] #302473
04/28/09 10:30 PM 04/28/09 10:30 PM
Joined: Aug 2005
Posts: 1,074
Wichita Kansas
CH3NO2 Offline
super stock
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Wichita Kansas
show us your 383 pistons, you can always put in a longer rod. Steve

Engine by DeTar http://www.kansasbadman.com
Re: 383 pistons in 426 wedge [Re: CH3NO2] #302474
04/28/09 11:15 PM 04/28/09 11:15 PM
Joined: Dec 2005
Posts: 261
Eastern ohio
Alexdodge Offline OP
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Alexdodge  Offline OP
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A longer rod? I already have 440 rods in there now.

Alex
Re: 383 pistons in 426 wedge [Re: Alexdodge] #302475
04/29/09 01:18 AM 04/29/09 01:18 AM
Joined: Jan 2003
Posts: 30,983
Oregon
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AndyF Offline
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Oregon
A Hemi rod is longer than a 440 rod but might not be set up for the same pin. Only good solution is to get the right pistons so you can get the compression back up to 9.5 or 10:1 or whatever it is that you want to run.
Re: 383 pistons in 426 wedge [Re: AndyF] #302476
04/29/09 03:24 AM 04/29/09 03:24 AM
Joined: Aug 2003
Posts: 12,291
Kent, Wa
340SHORTY Offline
Truck Nut
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Kent, Wa
put a blower on it or turbo it. that compression is perfict for either...

I am truckless..
Re: 383 pistons in 426 wedge [Re: 340SHORTY] #302477
04/29/09 08:13 AM 04/29/09 08:13 AM
Joined: Jun 2008
Posts: 3,914
usa
L
lewtot184 Offline
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usa
hughe's has oem 426 street wedge pistons.
Re: 383 pistons in 426 wedge [Re: lewtot184] #302478
04/29/09 09:44 AM 04/29/09 09:44 AM
Joined: Dec 2005
Posts: 261
Eastern ohio
Alexdodge Offline OP
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Alexdodge  Offline OP
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Yes!!! Hughs Engines has an assortment of 426 wedge pistons in stock. Thanks, Alex
Re: 383 pistons in 426 wedge [Re: Alexdodge] #302479
04/29/09 10:41 AM 04/29/09 10:41 AM
Joined: Jan 2003
Posts: 10,686
North Dakota
6PakBee Offline
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North Dakota
Quote:

One of my other engines is a 426 marine block. When I put this motor together I used 383pistons and 440 connecting rods in it being it is the same bore . So now I'm told that the pistons set low in the cylinders and I probably only have about an 8 to 1 compression. I don't remember how low they sit low compared to the originial 426 pistons. Is it possible to use a very thin set of head gaskets to make up for some of the difference in the piston height to get the compression higher? I don't want to get into shaving the heads. Just an idea.
Thanks, Alex



8:1 with what heads? If you are running the stock 516's I doubt it would be that low. With 906's I'm guessing it would be close. I would think a set of 915's would be a good option. Again not running the numbers, just guessing.

"We live in a time when intelligent people are being silenced so that stupid people won't be offended".
Re: 383 pistons in 426 wedge [Re: 6PakBee] #302480
04/29/09 11:27 AM 04/29/09 11:27 AM
Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
patrick Offline
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a cheaper alternative might be to get a 4.15" cast stroker crank.

kb-silvolte.com shows the #1271 piston (for a 383) as a 1.848" comp height.

1.848+6.76+(4.15/2)= 10.683", or .042" in the hole based on the blueprint height of 10.725" for an RB block.

based on my calculations assuming a .040" head gasket and 88cc heads, you're looking at about 9.96:1 compression

use a largish cam or a wide LSA to make the intake closing point late to bleed cyl pressure, and it should run on pump premium.

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Re: 383 pistons in 426 wedge [Re: Alexdodge] #302481
04/29/09 11:36 AM 04/29/09 11:36 AM
Joined: Dec 2006
Posts: 3,533
Indiana
F
Fury Fan Offline
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Quote:

With these pistons the car is a real dog. Don't know where to go from here. Its only a touring and cruiser but I still would like it to run better than this. Any one have any ideas?
Alex



If you want some easier-than-pistons ideas, I'd recommend:
1. Install -516 heads for the closed chambers and smaller valves/ports (higher velocity).
2. Advance the cam a few degrees. If you have a 'big' cam, consider a swap to an RV or stock cam.
3. Put a fast advance curve in the distributor. Due to your total lack of quench, you still might have detonation issues even though your compression is low, you'll just have to see.
4. Make sure you have a dual-plane intake and a smaller-size carb (or maybe a smallblock Thermoquad?). If not, try to find a 413 or 1966 440 intake, they have smaller flatter runners and might give more velocity than a performance intake. They are easily identified because they kinda look like they've been stepped on.

Parts I seek: driver doorpanel, 65 Sport Fury, prefer black, needs to be 7-8 on 10 scale, might buy set 16" x 6" Dodge truck wheel(s), from early 70s?, takes 9" dogdish - need for a research job so cheaper is better. 69-73 C-body caliper brackets and/or splashields Send a PM.
Re: 383 pistons in 426 wedge [Re: patrick] #302482
04/29/09 12:54 PM 04/29/09 12:54 PM
Joined: Mar 2008
Posts: 5,746
Ontario, Canada
Dodgem Offline
master
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Quote:

a cheaper alternative might be to get a 4.15" cast stroker crank.

kb-silvolte.com shows the #1271 piston (for a 383) as a 1.848" comp height.

1.848+6.76+(4.15/2)= 10.683", or .042" in the hole based on the blueprint height of 10.725" for an RB block.

based on my calculations assuming a .040" head gasket and 88cc heads, you're looking at about 9.96:1 compression

use a largish cam or a wide LSA to make the intake closing point late to bleed cyl pressure, and it should run on pump premium.



better check your math
1.848 + 6.76 + (3.75/2= 1.875) = 10.483 - 10.725 = -.243
About 7 to 1 compression give or take
Re: 383 pistons in 426 wedge [Re: Fury Fan] #302483
04/29/09 12:56 PM 04/29/09 12:56 PM
Joined: Jul 2008
Posts: 403
NE Ohio
7
71 FJ6 Charger Offline
mopar
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NE Ohio
Dont mean to hi-jack the post,but can you use 426 wedge pistons in a 383 with stock heads,crank and rods?

'71 383HP FJ6 Charger SE
Re: 383 pistons in 426 wedge [Re: 71 FJ6 Charger] #302484
04/29/09 01:20 PM 04/29/09 01:20 PM
Joined: Mar 2008
Posts: 5,746
Ontario, Canada
Dodgem Offline
master
Dodgem  Offline
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Quote:

Dont mean to hi-jack the post,but can you use 426 wedge pistons in a 383 with stock heads,crank and rods?



Piston part number please??
I think you will find a 426 W piston will stick out of a 383 a couple hundered thou.
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