383 Horsepower/Torque predictions

BGarff

BGarff

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Hi, guys.
I have a 66 383 2bbl motor that i have shaved heads for to get to 10:1 compression, a single plane weiand Team G intake, Holley 4150 650cfm that has been choke honed to 730cfm, a set of 1 5/8" long tube headers, and a hyd flat tappet cam with 0.507 int./0.510 exh. 284 int./296 exh. 2300-6500. Any predictions on what kind of power i will have? It has the gold box for electronic ignition.
Thanks
 
What are your predictions and are you going to dyno it?
 
What head castings and are they ported?
516 castings unported ~340-360
906 castings unported~370-380
 
add a few stickers, that's good for at 5hp per sticker more hp the bigger the sticker is
 
350+/- a few, Ive asked similar questions and was told by many who have more experience than myself, quite a few on this site.. #1 to get to 10:1 on a 383 requires new pistons. Theres no way to get that much compression with just milling the heads in a 383 as the pistons are so far below deck. You might be 9.2:1 even thats pushing it with a .60 cut. #2 That's a big cam for a slightly warmed up 383. Youd need some good porting and a valve job and be sure to have a solid 10.1 for it work properly. #3 your intake is matched up to your RPM range with the cam fine but Im assuming your running a C body of some sort, (4,000 lbs.) and at least 3.91 or better gear or itll be a pig down low and no fun to drive on the street. Which begs the question, do you sink good money to get power out of a 383 or is it more prudent to find a good 440 and spend the same money and get good power to move a big car out nice.
I may be way off here and I am always open to further education.
 
Last edited:
BGarff said:
where does that number come from? if the motor had 280 stock, with a cam, shaved heads, hot 4bbl and intake, and headers, it will make waaay more than a 15hp difference
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I think there are so many variables and unasked/answered questions here that any prediction of HP or torque is impossible.

If that 280 figure is what they advertised back in 1966, you can toss that out the window. Those weren't realistic numbers back then.

More importantly, you haven't said a word about what condition this engine is in. Is this a fresh rebuild or is it the way it was form 1966 with a zillion miles on it?

Choke honed carb? That term is something I'm not familiar with as far as carbs go. That's something you can do to a shotgun. Please elaborate.

I'm not sure what you want your end result to be, but IMHO, if you are looking for performance in a C body, you are headed the wrong direction. Low end torque is the ONLY answer to lugging 4000 or so lbs up from a stoplight. The single plane manifold and big cam aren't the way to go. Then you gotta ask yourself... is a 383 the answer?
 
You will definitely need a converter with that cam and power brakes are not going to play well either. Choke hone is either milled off completely and blended or angle cut and smoothed I'm not sure.
Have fun with it and you might even learn something and that's not a bad thing.
 
Well when I looked up the weight online, i found a couple sites saying it weighs around 3500, and i have a 2500 stall converter, and the machinist doing a valve job and shavung the heads said it will have around 10:1. History on the motor: never rebuilt, 60k miles, pulled heads off and the pistons had virtually no carbon(i cleaned them and the deck anyway and now they look new), sleeves have almost mirrorlike finish,when I pulled the oil pan from the bottom with oil in, the oil had no chunks or metal shavings. And the head gaskets were steel. When I bought the carb the seller said it was professinally choke honed. (i had an old 650 next to it and it is visibly larger. also, he pointed out how the barrels were more cone-shaped from the milling. Also, the car has a 3.55 SureGrip. Hopefully it doesn't sound like as much of a disaster now. This is my first time building an engine and I'm only a teenager. Every dollar going in, is one I've earned. ALL advice is much appreciated.
 
This is my first time building an engine and I'm only a teenager. Every dollar going in, is one I've earned. ALL advice is much appreciated.
Click to expand...
OK, now you made me feel bad. :(
350hp. :thumbsup:
 
also, stock, the heads gave it 9.2:1 so, its gotta be higher, but how much is the question....
 
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