383 questions
Thread Starter
Racer
Joined: Dec 2004
Posts: 336
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From: crystal lake Il.
383 questions
I`m getting ready to put a 383 in my 75 with a th400 trans & 3.70 rear. Will my performer intake & eb 600 cfm carb be ok? I was told I need a different flex plate, does anyone know which one, perhaps a part # from summit. The motor should be close to 400hp 450 tq. Thanks for any help.
Race Director
Joined: Dec 1999
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From: Forked River NJ
The Performaer intake and 600 carb are to small. You need a different flexpalte if the rotating assembly is externally balanced. Mine is internally balanced so I can use an internal balance flywheel. On my 383 I am using a Victor Jr intake and an 825 Mighty Demon carb. What type of cylinder heads and what cam are you going to use?
Melting Slicks
Joined: Jan 2005
Posts: 3,028
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From: Madison Ms
Well, I wouldn't say they are to small........They will work fine. But, as the others said, to maximize performance, consinder switching the intake and carb. EDL air gap and 750 cfm carb should do it!!
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Joined: Sep 2005
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From: South of giving a damn
St. Jude Donor '11, '17
It's easier to rejet a carb than to get one to flow at the maximum rating. If your funds (or the wife's patience) are getting thin then stick with what you have, it will work. You may even be satisfied with the results. The best way to tell is to drive it for a while & then see if someone has a 750 you can borrow for testing. Hard to test the intake, but I would recommend an Air Gap for either carb.
Race Director
Joined: Dec 1999
Posts: 19,610
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From: Forked River NJ
No there is nothing wrong with an exteranally balanced engine. You just have to have the right flywheel and balancer for whichever one you have. Ask if it is internal or external.
If you are interested I do have a Holley 750 DP carb for sale. I ran this on my old combo for about 5K miles. It is in perfect working order. I am going to fire up my new engine with it then switch to the 825 Demon.
If you are interested I do have a Holley 750 DP carb for sale. I ran this on my old combo for about 5K miles. It is in perfect working order. I am going to fire up my new engine with it then switch to the 825 Demon.
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NCM Grand Opening Veteran
Joined: Sep 2005
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From: South of giving a damn
St. Jude Donor '11, '17
Originally Posted by Gordonm
No there is nothing wrong with an exteranally balanced engine. You just have to have the right flywheel and balancer for whichever one you have. Ask if it is internal or external.
If you are interested I do have a Holley 750 DP carb for sale. I ran this on my old combo for about 5K miles. It is in perfect working order. I am going to fire up my new engine with it then switch to the 825 Demon.
If you are interested I do have a Holley 750 DP carb for sale. I ran this on my old combo for about 5K miles. It is in perfect working order. I am going to fire up my new engine with it then switch to the 825 Demon.
Both items will be listed for a 400ci SBC (which was externally balanced). Some people prefer the internal balancing so that their 350 flexplates & harmonics work, but in reality it doesn't matter, as long as you remember which you have.
Melting Slicks
Joined: Sep 2004
Posts: 2,412
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Originally Posted by Gordonm
The Performaer intake and 600 carb are to small. You need a different flexpalte if the rotating assembly is externally balanced. Mine is internally balanced so I can use an internal balance flywheel. On my 383 I am using a Victor Jr intake and an 825 Mighty Demon carb. What type of cylinder heads and what cam are you going to use?
and me too. 
Except I have a Mighty Demon 750. The Performer RPM also works nice on a 383, in fact I have one for sale. 
I just took it off of my 383, has 1K miles on it. http://forums.corvetteforum.com/show...post1554695133
Also I would stick with an internally balanced engine if you can afford it. What kind of heads and cam are on this engine...?
Last edited by enkeivette; Apr 1, 2006 at 03:25 PM.
Melting Slicks
Joined: Dec 2000
Posts: 2,635
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From: Union Ontario
Internally balacing a 383 kit is not expensive. The manufacturer did mine and I didn't see an upcharge although my builder might have eaten the cost since he had to spend time finding me a flywheel if it was externally balanced.
Racer
Joined: May 2005
Posts: 470
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From: Amelia Ohio
It sounds like the engine is already assembled. If it is externally balanced 383 then there should be a balanced plate that goes on under the flywheel and it does not matter what type flywheel or flexplate is used.
Chris
Chris
Thread Starter
Racer
Joined: Dec 2004
Posts: 336
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From: crystal lake Il.
Evalu8r- The engine is assembled, and what you are saying internal or external, once put together it has to be balanced. I guess I have some questions when their shop opens on monday.
Race Director
Joined: Dec 1999
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From: Forked River NJ
If the engine is external balanced you need a balancer and flywheel that are externally balanced. Internally balanced you can use pretty much any flyweehl and balancer from anything but a 400 motor. Not really a big deal just ask them if it is internal or external.
Race Director
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From: Who says "Nothing is impossible" ? I've been doing nothing for years.
OK hold on, don't want to get screwed here do you ? WHen my 406 was balanced ( externally balanced ) I had to bring everything in including pistons, bearings, rings, rods, crank, flywheel and harmonic balancer.
He took some serious weight out of the flywheel ( he drilled holes around the cirumference ) to get the whole assembly balanced properly. When I got it dynoed on a an engine dyno the operator said the motor ran very very smooth.
So I would be thinking twice about about buying an externally balanced motor without the harmonic balancer and flywheel/flexplate it was balanced with
He took some serious weight out of the flywheel ( he drilled holes around the cirumference ) to get the whole assembly balanced properly. When I got it dynoed on a an engine dyno the operator said the motor ran very very smooth.
So I would be thinking twice about about buying an externally balanced motor without the harmonic balancer and flywheel/flexplate it was balanced with
Racer
Joined: May 2005
Posts: 470
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From: Amelia Ohio
I'm no pro on this subject but the way it was explained to me by speedway motors on the externally balancing is the crank, pistons, rods and harmonic balancer is balanced as a whole. There is an additional balancing plate that is used on the flywheel end. This is what I have. All of the flywheels and flexplates are already balanced so with my setup it does not matter. However i believe you can provide your flywheel/flexplate to be balanced with the rest of the assemble if one is available eliminating the need for the extra plate like I have. So in a nut shell painterman52 you need to talk to the person or company that did the balancing and assembly to determine what you need to make the driveline connection. If I'm wrong please let me know.
Chris
Chris
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From: Who says "Nothing is impossible" ? I've been doing nothing for years.
NO you just get the same harmonic balancer and/or you get the new flywheel balanced the same as the old one.
Some shops balance the rotating assembly to a stock GM flywheel so you can just buy another GM flywheel but this could run into money if you have to add weight to the crank as in heavy mallory metal.
I am not an expert on the balancing as obviously I don't have the equopment to do it but you do have to be carefull in this area, nothing worse than an out of balance motor
Some shops balance the rotating assembly to a stock GM flywheel so you can just buy another GM flywheel but this could run into money if you have to add weight to the crank as in heavy mallory metal.
I am not an expert on the balancing as obviously I don't have the equopment to do it but you do have to be carefull in this area, nothing worse than an out of balance motor