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383 performance upgrade questions #815690
09/27/10 12:47 PM
09/27/10 12:47 PM
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greg383 Offline OP
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I have a 68 383 that im trying to get more power out of.Its out and on the floor and now im going through the process of finding the right parts to make power on a semi budget.I am rebuilding the entire engine.I would like to know what pistons and bore would be best.I would like to run the biggest cam that i can without having to do a custom valve train.It already has 906 heads with 2.08 intake valves.Im looking for at least 400 to 450 hp.Anyone have any ideas?

Re: 383 performance upgrade questions [Re: greg383] #815691
09/27/10 12:58 PM
09/27/10 12:58 PM
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Columbia, CT
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moper Offline
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The hardest part about building a 383 is piston choice. Because they are all fairly short in terms of the deck height. For a street engine I'd run KB400s and have them set to be proud of the deck by .010. That should give you close to 10.25:1 assuming the heads are milled a little and the chambers are somewhere around 88cc and the gasket used is the std FelPro blue. Then stick a modern grind cam in it. The problem is, blueprinting a 383 is not a "budget" build. Then again, 400+hp from one is not a budget build either, IMO anyway. In any event, pay attention to actual compression figures vs what you read it "will" have. Because unless you blueprint the parts, you won't have anywhere close.


Well, art is art, isn't it? Still, on the other hand, water is water! And east is east and west is west and if you take cranberries and stew them like applesauce they taste much more like prunes than rhubarb does. Now, uh... Now you tell me what you know.
Re: 383 performance upgrade questions [Re: moper] #815692
09/27/10 01:09 PM
09/27/10 01:09 PM
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Suffolk,VA
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ireland383 Offline
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Yeah, the KB400 is the only real choice for any decent compression. My pistons wound up at .024 below the deck and with an 84cc head, .039 head gasket, I was able to squeeze out 9.25:1. I'm around the 400 hp mark. You'll need to make sure parts all work together. Rear gear, stall (if auto), headers, cam, and carb. Good luck!

Last edited by ireland383; 09/27/10 01:10 PM.
Re: 383 performance upgrade questions [Re: greg383] #815693
09/27/10 01:15 PM
09/27/10 01:15 PM
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Brookeville, Md
Mr.Yuck Offline
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any reason you HAVE to do that motor? I'd check online and here for a done short block, or something done. If you are going thru all the trouble of rebuilding an engine you might as well go find a 440 and rebuild it. It's going to cost the same and you'll get much more out of it.
That said Summit, Jegs and PAW have some pretty good rebuild kits. I'd look online for things like used headers, intake, carb and so on. You can save a bunch buying used.


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Re: 383 performance upgrade questions [Re: Mr.Yuck] #815694
09/27/10 01:35 PM
09/27/10 01:35 PM
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JohnRR Offline
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Quote:

any reason you HAVE to do that motor? I'd check online and here for a done short block, or something done. If you are going thru all the trouble of rebuilding an engine you might as well go find a 440 and rebuild it. It's going to cost the same and you'll get much more out of it.
That said Summit, Jegs and PAW have some pretty good rebuild kits. I'd look online for things like used headers, intake, carb and so on. You can save a bunch buying used.




I knew when I saw your name on the bottom of the list on the thread listing page that you were going to tell the guy to build a 440 ...

Re: 383 performance upgrade questions [Re: moper] #815695
09/27/10 01:43 PM
09/27/10 01:43 PM
Joined: Jan 2003
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JohnRR Offline
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Quote:

The hardest part about building a 383 is piston choice. Because they are all fairly short in terms of the deck height. For a street engine I'd run KB400s and have them set to be proud of the deck by .010. That should give you close to 10.25:1 assuming the heads are milled a little and the chambers are somewhere around 88cc and the gasket used is the std FelPro blue. Then stick a modern grind cam in it. The problem is, blueprinting a 383 is not a "budget" build. Then again, 400+hp from one is not a budget build either, IMO anyway. In any event, pay attention to actual compression figures vs what you read it "will" have. Because unless you blueprint the parts, you won't have anywhere close.




Dave you are on track with the compression of the 383 , I have been doing a little revision on my 383 and realized a goofed on my calculation , missed the sign for the piston above the deck. If you put a flat top at zero deck and cut the heads to 80 cc wit ha .021 shim gasket you get just over 10.0 for compression , the flat top will be better the choice and it's cheaper to cut the head than the block I would think, though the block needs to be squared , you just cut off less .

The bad thing is the only piston choices are KB162 , .024 in the hole and a 5cc canyon for a valve relief , speed pro , .015 in the hole but no valve reliefs , or a Diamond , .019 in the hole and smaller than the KB valve reliefs but they are $$$.

400 to 450 HP is not a budget build on a 383 , if you think it is because you read that mopar muscle mag article that's on the net you need to know the dyno that test was run on was known to be HAPPY ...

Maybe a 440 is a better choice ???

Last edited by JohnRR; 09/27/10 01:44 PM.
Re: 383 performance upgrade questions [Re: JohnRR] #815696
09/27/10 01:48 PM
09/27/10 01:48 PM
Joined: Jan 2004
Posts: 27,347
Today? Who Knows?
1_WILD_RT Offline
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Quote:

Quote:

The hardest part about building a 383 is piston choice. Because they are all fairly short in terms of the deck height. For a street engine I'd run KB400s and have them set to be proud of the deck by .010. That should give you close to 10.25:1 assuming the heads are milled a little and the chambers are somewhere around 88cc and the gasket used is the std FelPro blue. Then stick a modern grind cam in it. The problem is, blueprinting a 383 is not a "budget" build. Then again, 400+hp from one is not a budget build either, IMO anyway. In any event, pay attention to actual compression figures vs what you read it "will" have. Because unless you blueprint the parts, you won't have anywhere close.




Dave you are on track with the compression of the 383 , I have been doing a little revision on my 383 and realized a goofed on my calculation , missed the sign for the piston above the deck. If you put a flat top at zero deck and cut the heads to 80 cc wit ha .021 shim gasket you get just over 10.0 for compression , the flat top will be better the choice and it's cheaper to cut the head than the block I would think, though the block needs to be squared , you just cut off less .

The bad thing is the only piston choices are KB162 , .024 in the hole and a 5cc canyon for a valve relief , speed pro , .015 in the hole but no valve reliefs , or a Diamond , .019 in the hole and smaller than the KB valve reliefs but they are $$$.

400 to 450 HP is not a budget build on a 383 , if you think it is because you read that mopar muscle mag article that's on the net you need to know the dyno that test was run on was known to be HAPPY ...

Maybe a 440 is a better choice ???




The dyno operator heard 383 & thought he was working on a Chevy stroker so he plugged in the Chevy Big HP code... How do you suppose every SBC to go on dyno for the magazines makes 700+ hp....

Re: 383 performance upgrade questions [Re: JohnRR] #815697
09/27/10 01:48 PM
09/27/10 01:48 PM
Joined: Jan 2003
Posts: 24,562
Brookeville, Md
Mr.Yuck Offline
Not enough dumb comments...yet
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Posts: 24,562
Brookeville, Md
Quote:

Quote:

any reason you HAVE to do that motor? I'd check online and here for a done short block, or something done. If you are going thru all the trouble of rebuilding an engine you might as well go find a 440 and rebuild it. It's going to cost the same and you'll get much more out of it.
That said Summit, Jegs and PAW have some pretty good rebuild kits. I'd look online for things like used headers, intake, carb and so on. You can save a bunch buying used.




I knew when I saw your name on the bottom of the list on the thread listing page that you were going to tell the guy to build a 440 ...




he doesn't have to, but it makes more since from a power perspective. He could do a 400 or a stroker too.... Depends on what the engine needs and what he wants it to do. If it needs the crank turned, bore, decked and bla bla bla, it cost the same to do it to a 440. If all he needs is a hone, set of pistons and rings than do the 383, but if it needs a ton of work, do it to a biiger engine.

Re: 383 performance upgrade questions [Re: Mr.Yuck] #815698
09/27/10 01:59 PM
09/27/10 01:59 PM
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Cincinnati, Ohio
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superbeedave Offline
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I had my 383 rebuilt last year and I thought I did my research. I also, have the KB400's that are .020 down in the hole with the .039 fel pro head gasket. I am running the compcams Xtreme energy 268 cam with the 906 heads and matched valve springs. If I could do it over I would have .020 milled off the heads and used a .02 shim
that would have gotten me just at or over 10.1
I really was shooting for 9.70. It would have worked had It been at 0 deck. Good luck! Remember to do your homework cause after it is together you will start questioning yourself on what you should have done or didn't do.

Re: 383 performance upgrade questions [Re: greg383] #815699
09/27/10 08:31 PM
09/27/10 08:31 PM
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Temecula, Ca.
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zzyzxpat Offline
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Look at 440 Source or one of the other stroker kits. For the buck, it's not bad.


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Re: 383 performance upgrade questions [Re: superbeedave] #815700
09/28/10 09:39 AM
09/28/10 09:39 AM
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greg383 Offline OP
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Im really looking for the best combination to make the most amount of power,Im building this one for a friend of mine and he really insists on this engine size. I tried to tell him that bigger is better but he wants this one.I would like to know what cam,intake,carb and pistons would make the most power with the 906 heads and what machine work to do to the block and heads that will be ok with out trouble and still be drivable.This is the first mopar ive done so im ignorant in this field.I am getting very interested in it though.

Re: 383 performance upgrade questions [Re: greg383] #815701
09/28/10 10:10 AM
09/28/10 10:10 AM
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Columbia, CT
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moper Offline
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What is the budget figure you're working within?


Well, art is art, isn't it? Still, on the other hand, water is water! And east is east and west is west and if you take cranberries and stew them like applesauce they taste much more like prunes than rhubarb does. Now, uh... Now you tell me what you know.
Re: 383 performance upgrade questions [Re: moper] #815702
09/28/10 10:34 AM
09/28/10 10:34 AM
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greg383 Offline OP
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Unfortunatly it is not and unlimited budget but I can spend some money if need be.

Re: 383 performance upgrade questions [Re: moper] #815703
09/28/10 10:38 AM
09/28/10 10:38 AM
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greg383 Offline OP
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I was hoping to put the biggest cam I could that will work good with the 906 heads.The car is an automatic so im stuck with a low stall stock converter as well.At this point it looks like a set of KB400 pistons are the best bet for pistons,but what machine work to the block and heads? and what head gaskets and cam lift?

Re: 383 performance upgrade questions [Re: greg383] #815704
09/28/10 10:59 AM
09/28/10 10:59 AM
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Junky Offline
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Quote:

I was hoping to put the biggest cam I could that will work good with the 906 heads.The car is an automatic so im stuck with a low stall stock converter as well.At this point it looks like a set of KB400 pistons are the best bet for pistons,but what machine work to the block and heads? and what head gaskets and cam lift?



Why are you stuck with a low stall stock converter? Mancini Racing has some affordable converters.


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Re: 383 performance upgrade questions [Re: Junky] #815705
09/28/10 11:02 AM
09/28/10 11:02 AM
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greg383 Offline OP
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They really like to drive the car alot,so I have to keep things with in some reason.I mainly didnt want to put a huge stall converter in it just for driveability

Re: 383 performance upgrade questions [Re: greg383] #815706
09/28/10 11:15 AM
09/28/10 11:15 AM
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oklahoma
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forphorty Offline
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Running a stock converter with a 383 means running a very mild cam .

Re: 383 performance upgrade questions [Re: greg383] #815707
09/28/10 11:56 AM
09/28/10 11:56 AM
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Atco NJ
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Quote:

They really like to drive the car alot,so I have to keep things with in some reason.I mainly didnt want to put a huge stall converter in it just for driveability




thats false - I run a 3800 stall dynamic with 3.23's and it drives like a stock converter = till you nail it!

Re: 383 performance upgrade questions [Re: forphorty] #815708
09/28/10 12:13 PM
09/28/10 12:13 PM
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Puyallup, WA
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StealthWedge67 Offline
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Dont be afraid to go as far as a 3500 converter for the street. I run a 10" converter rated at 3500, and its just fine on the street, although if gas mileage is of concern, you may not want this much converter (??). Point is, if you want to get 400 HP out of a 383 (and that's not going to be easy with stock heads), and are running a 727, youre gonna need at least 3k worth of converter to go with the cam that will get you there.

I did a lot of research on 383 builds, then decided to go to a 451. MAN, am I glad I did that! I built a 500 horse 451 for around 5-grand, just for comparisons sake. But here's where I'd go with the 383:

KB400's are the right choice with the 906's. Have the 906's milled down to get yourself about an 84cc chamber. with an .060 gasket, that should get you to right around 9.5:1. ( an .040 gasket will get you near 10:1, but thats pushing it with pump gas and open chambered iron heads). To make power from a 383, it has to be spun like a small-block, so good machine work and balancing are paramount. I'd go with main studs (have the mainline honed with this upgrade!)

Cam needs to be in the 240+ duration neighborhood. I like the looks of the Comp XE284H, and the XE285. at less than .510 lift, The 284 could be run with stock rockers. If you're willing to invest in some decent rocker gear the 285 will make more power, but I wouldn't try it's .545 lift with the stock gear. Get the lifters and springs to match whatever cam you decide on, but don't go below 240*.

Carb should be a holley based 750. A simple 3310 350 vacuum secondary will work just fine, but going to a higher end carb will make things easier to tune, and run a little better. Either way, a 750 is perfect for a mild street 383. I'd put it on an Eddy Perf. RPM manifold, personally, but there are some single planes that are worth looking at as well. for street use, I don't think you can beat the RPM, though.

This recipe should get you to right around 400 horse, if tuned well. Hook it up to a 3500 converter, and a set of 3.73's or 3.91's, and it should be a low 13 second performer. 450 out of a street 383 is going to be tough to achieve without spending big cash. There will be much more to iron out, but thats my 2-cents.


LemonWedge - Street heavy / Strip ready - 11.07 @ 120
Re: 383 performance upgrade questions [Re: greg383] #815709
09/28/10 12:15 PM
09/28/10 12:15 PM
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Junky Offline
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Quote:

They really like to drive the car alot,so I have to keep things with in some reason.I mainly didnt want to put a huge stall converter in it just for driveability



I run a converter that stalls at about 2200 RPM's, and acts like a stock one around town and on the highway. Ran a Hughes Performance 2500 Street Master that acted like a stock one around town and on the highway. It stalled about 2500 RPM's.


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