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1971 383 upgrades

383-2bbl has little compression and torque. Torque is how you move weight.

Find a 440, put on closed chamber heads and steel shim head gaskets.
Add 430 gears, bigger cam, aluminum intake, 750 or 850 CFM carb, and Torque converter.
Lighten up the car, are you sure it’s only 3900 lbs? Sounds more like wishful thinking for a c-body @3900.
Go buy a dart to go fast cheaply.
 
Need more detail....is it a bolt on go fast parts deal, a freshening up with stock pistons, or a clean slate w new parts?
 
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383-2bbl has little compression and torque. Torque is how you move weight.

Find a 440, put on closed chamber heads and steel shim head gaskets.
Add 430 gears, bigger cam, aluminum intake, 750 or 850 CFM carb, and Torque converter.
Lighten up the car, are you sure it’s only 3900 lbs? Sounds more like wishful thinking for a c-body @3900.
Go buy a dart to go fast cheaply.
And stop at every dam gas pump you come across. That is not my cup of tea.
 
And stop at every dam gas pump you come across. That is not my cup of tea.
He was wanting to get a C-body in the 12’s or 13’s. No way to get good MPG while doing that trick.

he deleted his original post
 
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He was wanting to get a C-body in the 12’s or 13’s. No way to get good MPG while doing that trick.
Must be one of those mind reading moments. Nothing about a C body till you mentioned it in post #3. I do think some people just like to dream.
 
We had a 71 383...shaved the heads. 070. It wasn't to bad of a performer. Add a cam and springs, edelbrock rpm intake,pocket port the heads w headers.
Buy a 9 1/2" 4200 stall w at least 3.55s. You won't be far off from your goals. Then nitrous. :bananaweed: Pump gas is cheap and those have a big tank....
...our most economical build was a 510 stroker. Mpg in the low 20s and ran 108mph at 3900bs w 3.23s. It was nothing fancy..iron heads and intake.
 
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Ok let me update this. Never mind getting into the 12s or 13s...... This is a stock 71 motor. I need heads. The heads need valve guides.
I’m going to upgrade the cam and do a 4 barrel swap. What heads should I get to put on this? 915s? Aluminum? Looking to raise the compression some. Once again the bottom end will be totally stock. Or just run 906 heads??? Thanks
 
Just wanting to make more power and trying to figure out what heads to go with.
 
Just wanting to make more power and trying to figure out what heads to go with.



Heads will need a Camshaft to utilize the extra Flow potential the Heads may provide.

So wise choice to do Heads AND Cam with the 4 BBL swap.
Closed Chamber Heads are a must.... any closed chamber will do, even the 516 castings will work fine in this application as long as 1.74 exhaust valves are installed, try for a steel shim Head gasket of the Block Decks are adequate(copper coat).... CompCams XE268H works well.
It's NOT going to be a killer off the line.... but once the rpm's come up it will please.
 
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As well as converting to a 4 barrel set up. So yes cam will be upgraded. Don’t know what cam yet but it’s getting swapped
 
Bolt ons to the existing engine 'as is' will yield very limited returns.... if any at all = waste of $

Heads will need a Camshaft to utilize the extra Flow potential the Heads may provide.... think of the "camshaft' as the 'program' of how long and how much the Valves in the Heads open to provide the A/F ?
The same 383 2 BBL Cam =same 383 2 BBL Lift and open = diddly power no matter the Heads.
Really have to disagree here. May not make the 800 hp some think they need but should be able to get into a respectable hp range for a 71 383 with 2 barrel pistons with the right heads and cam. But everyone seems to think we need gas hog 440's.
 
Closed chamber are a must.... 516's are fine as long as 1.74" exhaust is utilized
Try for a steel shim Head Gasket if the Block Decks are adequate ? and use copper coat on the shim head gaskets to aid sealing.
The CompCams XE268H works well.... as does the CROWER HDP271....
it won't be killer off the line unless a small higher stall T/Convertor is also installed, Gearing would help as well ?
but no matter...
once it gets going 'as is' it will please
 
Really have to disagree here. May not make the 800 hp some think they need but should be able to get into a respectable hp range for a 71 383 with 2 barrel pistons with the right heads and cam. But everyone seems to think we need gas hog 440's.

My '69 R/T gets 15 mpg highway with it's stock UN-rebuilt Original 440 Magnum at 145,000 miles ? and I guarantee it'll still blow the doors off anything he does to that 383 ?

I dunno about a 440 being that much of a "gas hog" ?
It doesn't matter what "SIZE" the engine/compressor is...
simply because,
BTU's of heat energy is BTU's of heat energy ?
"power" is directly proportional to the BTU's of heat energy burned ? which the 440 can burn more BTU's per revolution than the 383 ?

And even just cruising when you are "filling" the extra 60 cubic inches of the 440 with fuel versus the 383 ? there can be something to be said when hills/inclines etc having to stick your foot further down in the 383 to add more fuel and maintain speed vrs the 440 ?

Bottom line, IMO, is I just don't see the fuel efficiency factor as HUGE between the 383 vrs 440 if torque production is a critical criterion to fun factor ?
 
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My '69 R/T gets 15 mpg highway with it's stock UN-rebuilt Original 440 Magnum at 145,000 miles ? and I guarantee it'll still blow the doors off anything he does to that 383 ?

I dunno about a 440 being that much of a "gas hog" ?
It doesn't matter what "SIZE" the engine/compressor is...
simply because,
BTU's of heat energy is BTU's of heat energy ?
"power" is directly proportional to the BTU's of heat energy burned ? which the 440 can burn more BTU's per revolution than the 383 ?

And even just cruising when you are "filling" the extra 60 cubic inches of the 440 with fuel versus the 383 ? there can be something to be said when hills/inclines etc having to stick your foot further down in the 383 to add more fuel and maintain speed vrs the 440 ?

Bottom line, IMO, is I just don't see the fuel efficiency factor as HUGE between the 383 vrs 440 if torque production is a critical criterion to fun factor ?
I don't think blowing the door off a 440 was even a consideration even though I have seen it done. There is more to building engines than cubic inches.
 
I don't think blowing the door off a 440 was even a consideration even though I have seen it done. There is more to building engines than cubic inches.


Either you want power, or not. A 500 hp 383 will eat as much gas as a 500 hp 440. But a 500 hp 400 will be easier to build, and will drive better.
 
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Either you want power, or not. A 500 hp 383 will eat as much gas as a 500 hp 440. But a 500 hp 400 will be easier to build, and will drive better.
Care to explain that one. Why will the 400 drive better? I drive cars not engines.
 
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