What to expect from 1970 383 HP

[340runner]

Well, despite all better judgements in me for building a small block stroker or a 440 I snapped on a complete aside from carb 1970 383 magnum out of a 1970 roadrunner. Hey, it was 300$ and it was a impulse buy what can I say. Thing still has oil in it and "ran when pulled". Haven't even put a breaker bar to it yet, hell its still in my jeep because I haven't got anything yet to take it out. It got put in with a forklift.

What can I expect out of this thing performance wise with only top end upgrades? I know that the eddy top end kit is 420hp and about the same torque, but also I see these 2 articles that are throwing down anywhere from 41xhp to 45xhp out of a STOCK HEADED 383. I dont know what's realistic out of the 906 heads or motor or honestly anything with it. Im contemplating sending it out for machine work, but only really to deck the thing to NHRA blueprint spec and if it needs it a quick overbore. If I dont have to, I dont want to. I dont want to spend big money on this thing.

Is it possible out of the stock bottom end and pistons to push a what will probably be after the swap a 3950-4000lb car to the 12s on stock bottom end?

 

[YY1]

My 1970 Super Bee with a fresh "HP" 383 build and 3 angle 906 heads with the MP 284/484 cam (degreed per the MP book/video), stock rebuild 727 (with green waffle clutches) and 3.55 sure grip, running a "franken carb" Holley 600 with 750 metering blocks and power valves and Hooker Super Comp headers and H pipe...

...hung with and frequently won on the street versus two of my friends cars that both ran mid 13 second quarter miles.

Both were Challengers, one with a mild 440 and 3.23 gears, the other a 340 with 280/480 cam, 3500 converter and 3.91 gears.

 

[furious70]

The old resto to rad magazine articles did push good power from the 335hp 383 with all the usual bolt ons

 

[340runner]

My 1970 Super Bee with a fresh "HP" 383 build and 3 angle 906 heads with the MP 284/484 cam (degreed per the MP book/video), stock rebuild 727 (with green waffle clutches) and 3.55 sure grip, running a "franken carb" Holley 600 with 750 metering blocks and power valves and Hooker Super Comp headers and H pipe...

...hung with and frequently won on the street versus two of my friends cars that both ran mid 13 second quarter miles.

Both were Challengers, one with a mild 440 and 3.23 gears, the other a 340 with 280/480 cam, 3500 converter and 3.91 gears.

Well in that case a hp 383 with a 484 cam, headers and 440source heads and a performer rpm in front of a 4 speed with 4.56s and slicks should do well huh?

I also have a nitrous plate kit sitting in the corner of my garage with a full bottle, set up for a 100 shot....

 

[YY1]

You would think so.



...except maybe on the highway.

 

[340runner]

You would think so.



...except maybe on the highway.

Hell i dont play with the highway, its sucks sitting at around 3.5k at 60mph. I already have in the 4.56s with my 340

 

[pnora]

You should verify that it is in fact a 1970 383. Just because it came out of a 1970 does not mean its an original to the car. Lots of things happen in 55 years. You need to make sure its a forged crank motor because you will have to verify the crank pilot, you will need a bellhousing, flywheel, clutch, shields, bell crank.

 

[340runner]

You should verify that it is in fact a 1970 383. Just because it came out of a 1970 does not mean its an original to the car. Lots of things happen in 55 years. You need to make sure its a forged crank motor because you will have to verify the crank pilot, you will need a bellhousing, flywheel, clutch, shields, bell crank.

Well, I will do that, I just got it last night, again haven't even taken it out of my Jeep, but it so far checks out. Has the 383 hp intake and 906 heads. Also, wouldn't my existing flywheel and clutch work? They're both internal balance motors, and i already have upgraded flywheel and clutch so im hoping I can use it. I know ill need to change bellhousing though.
Only thing is that its a auto 383 crank, so it might not be drilled. A angle grinder may meet my input shaft in the future, or a drill to the crank via machine shop

 

[1 Wild R/T]

Should have stuck with the small block..

 

[TorRed]

Well, my 70 Roadrunner outran every other car I ended up racing including a 429 Mach 1, built 351C Mach 1, 454 Chevelle, 455GS Buick, etc. I rebuilt the motor with a strong "3/4 Race" Crane Cam, TRW Pop-up Pistons, Hooker Headers, Cheetah valve body in the 727 Auto and 3.91 rear gear. That's why I'm strongly considering keeping the stock 906 heads with a little work, and the stock stroke. Otherwise I'm probably going to build a 432 stroker and put my Stealth heads on. Good luck!

 

[rickseeman]

If it really ran recently I would try to get it running kinda as is. I wouldn't start tearing it down, that can get expensive and time consuming. If it needs work it will tell you.

 

[340runner]

If it really ran recently I would try to get it running kinda as is. I wouldn't start tearing it down, that can get expensive and time consuming. If it needs work it will tell you.

Oh it hasn't ran recently, it just ran before it was pulled >10 years so it probably needs rebuild

I also dont have a run stand and I dont wanna swap in a stock 383 in place of my 340

 

[rickseeman]

In hillbillyland they just put the center sump of the oil pan in a tire laying on the ground.....

 

[Some Car Guy]

Don’t run a 484 cam. You’ll need the bottom end power it will take away. A stock 383 hp will run well. Confirm on the pad below distributor if it is an hp. The stock cam was pretty good. I ran a 70 383 hp for year and it was a factory build. No time slips, but it impressed all who rode in it.

Dwayne porter had one running some impressive times with stock heads.

 

[R413]

It's 55 years old, what's inside? Get a head off and see what pistons it has. Flat top, dish, valve reliefs. Measure how far down they are. Go from there. Sell that 70 383 to a restorer.

383 will run good. Whatever you do to a 383 it costs the same to do to a 440. Be on the hunt for a 440 or buy 400 and put in a 440 crank or a stroker kit. Much more piston choices for a 400 block.

 

[340runner]

Don’t run a 484 cam. You’ll need the bottom end power it will take away. A stock 383 hp will run well. Confirm on the pad below distributor if it is an hp. The stock cam was pretty good. I ran a 70 383 hp for year and it was a factory build. No time slips, but it impressed all who rode in it.

Dwayne porter had one running some impressive times with stock heads.

Im gonna need the bottom end with 4.56s? I already have a massively overcammed 71 340 that someone shoved 8.5 to 1 comp pistons, I think the 383 should have more low end at any rate

I will say the 340 takes off when you get past 3k, aluminum heads, headers and intake with a 750dp let's it keep pulling past 6500 when I shift

 

[340runner]

It's 55 years old, what's inside? Get a head off and see what pistons it has. Flat top, dish, valve reliefs. Measure how far down they are. Go from there. Sell that 70 383 to a restorer.

383 will run good. Whatever you do to a 383 it costs the same to do to a 440. Be on the hunt for a 440 or buy 400 and put in a 440 crank or a stroker kit. Much more piston choices for a 400 block.

You think a cheapo rebuild and nice paint will take this 300$ 383 into profit for me? Hell 300$ in parts and if it runs, do you think I can get 1000$ out of it at least?

 

[340runner]

It's 55 years old, what's inside? Get a head off and see what pistons it has. Flat top, dish, valve reliefs. Measure how far down they are. Go from there. Sell that 70 383 to a restorer.

383 will run good. Whatever you do to a 383 it costs the same to do to a 440. Be on the hunt for a 440 or buy 400 and put in a 440 crank or a stroker kit. Much more piston choices for a 400 block.

Yeah, I also like the 383 though since if bottom ends correct, itll have better than 7.5 to 1 comp unlike a smogger 440. It already has a forged crank, unlike most smogger 440s. My point is im not looking for 500 all motor hp, if I can get honest 420 im happy with myself. I think that's good enough with a 383 bottom end, and its a better start if the ends only 420 imho.

I also like a motor that'll pull above 6k, gotta make those 4.56s useful

 

[furious70]

I doubt a rattle can rebuild nets you a profit.

I wouldn't spend money on a 432. It either works for you with cam, intake, headers, carb or keto the 340

 

[340runner]

I doubt a rattle can rebuild nets you a profit.

I wouldn't spend money on a 432. It either works for you with cam, intake, headers, carb or keto the 340

Carb or Keto the 340?

Also, what's a 432? I think the 383 with a 440 crank is 426 at std bore and 438 at 30 over, unless I'm misunderstanding

Sorry for not understanding, never heard about it