66 Sat
Well-Known Member
Yeah but the car is powered by the engine is it not?
I think he means the characteristics of a 500 hp 383 will be hard work on the street. It's not all about peak horsepower.
1971 383 upgrades
- Thread starter CoronetMan79
- Start date
I think he means the characteristics of a 500 hp 383 will be hard work on the street. It's not all about peak horsepower.
BSB67
Well-Known Member
Hard to tell if your just messing with us. Hard to imagine a guy with 10,000 posts doesn't understand such basics. But here goes.
It will not drive as well as the 440 because the 383 makes less torque overall, and considerably less torque at lower rpm. Then to make the same power as the 440, it will require a larger cam, making the low torque condition even worse compared to the 440. The 383 will idle worse, it will have poor throttle response at low speed and cruise speed, will likely need a looser converter, and a lower gear ratio to make the power usable.
This is why folks looking for more power with the best street driving manners and characteristics will build 500 inch motors.
mopar 3 B
Well-Known Member
Just like anything else you need to look at the whole package to make things work and not just whats under the hood.
Many forget 1820 times are meaningless for street driven and highway cruisers. I didn't drive 1/4 mile at a time. Why would I want to build a car for that reason only. I do believe this is what the post was originally about. Just a decent road car. Then we do off on a redicules tangent spending big dollars and for what. He doesn't want a race car.
BSB67
Well-Known Member
What is 1820?
The 500 hp was used as an example, but the basic relationship between the 440 and 383 remain the same irrrespective of the hp. Although becomes less important as the performance/hp goal gets low.
The tangent started when you first stated that gas milage was a criteria in this discussion. Can you show me where the OP's states this?
The 500 hp was used as an example, but the basic relationship between the 440 and 383 remain the same irrrespective of the hp. Although becomes less important as the performance/hp goal gets low.
The tangent started when you first stated that gas milage was a criteria in this discussion. Can you show me where the OP's states this?
Challenger340
Well-Known Member
Original title of the thread was 1971 383 upgrades ?
Which I don't think anyways, was canvassing for appearance ideas like Chrome V/Covers or fancy Plug Wires ?
So... IMO
* Heads: Closed Chamber cast iron with as much CR as possible, because in this case even 9:1 will be difficult to attain with the 1971 383 pistons
* Cam: "small" so as not to over cam, unless things like Gearing and T/Convertor are also budgeted ? Examples Crower HDP271 or Comp XE268H were given as probably largest should be considered, plenty of others can be found as well.
* 4 BBL: Dual Plane and Vacuum secondary carburetor probably best
* Ignition Curve: Tuned/Adjusted for whatever Gearing and T/Convertor is utilized for the power curve
The above will pretty much sum up the basics in any "upgrading"..... unless I'm missing something and assuming 'power' was the original intent ? given, costs seem to always be a factor.
I don't think it's off topic after the above, and to further 'useful' discussion to assist the OP.... to then point out some of the pertinent 'characteristics' specific to the 383 Engines for consideration ?
That being.... and common to both the 383 and 400 is the relatively short stroke(3.38"), which tends to make them significantly weaker in lower rpm Torque capability than any of their 3.75" Stroke cousins like the 413/426/440 Engines.... offered merely to highlight the do not over cam portion in the given advice.
Compression ratio present.... as it relates to Camshaft selection to maintain lower rpm characteristic.
Which I don't think anyways, was canvassing for appearance ideas like Chrome V/Covers or fancy Plug Wires ?
So... IMO
* Heads: Closed Chamber cast iron with as much CR as possible, because in this case even 9:1 will be difficult to attain with the 1971 383 pistons
* Cam: "small" so as not to over cam, unless things like Gearing and T/Convertor are also budgeted ? Examples Crower HDP271 or Comp XE268H were given as probably largest should be considered, plenty of others can be found as well.
* 4 BBL: Dual Plane and Vacuum secondary carburetor probably best
* Ignition Curve: Tuned/Adjusted for whatever Gearing and T/Convertor is utilized for the power curve
The above will pretty much sum up the basics in any "upgrading"..... unless I'm missing something and assuming 'power' was the original intent ? given, costs seem to always be a factor.
I don't think it's off topic after the above, and to further 'useful' discussion to assist the OP.... to then point out some of the pertinent 'characteristics' specific to the 383 Engines for consideration ?
That being.... and common to both the 383 and 400 is the relatively short stroke(3.38"), which tends to make them significantly weaker in lower rpm Torque capability than any of their 3.75" Stroke cousins like the 413/426/440 Engines.... offered merely to highlight the do not over cam portion in the given advice.
Compression ratio present.... as it relates to Camshaft selection to maintain lower rpm characteristic.
Babyblue66
Well-Known Member
Probably barely 8 to 1 compression. I worked on a 71 383 hp recently. Stock bore, stock pistons, cc'd out to 8.2 to 1. Put in an Elgin cam, 218 218 @50 450 lift on a 112. Ran good but was soft on the bottom. It did pick up nicely around 3 grand and was pretty strong. I was actually impressed at the rpms that cam pulled. Needed a higher than stock stall to really feel quick. Nery nice street cam though, and a pleasure to drive. More compression would've made a big difference.
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CoronetMan79
Member
Ok change of plans here. I’m just gonna leave the 383 in the car and drive as is for now. It’s a 71 Polara.
I did pick up a 76 400 motor on Sunday. Almost have it completely taken apart. Motor will need bored over I believe. This build will take time cause of $ but need to figure out how I want to do.
I’m open to building a stroker with a 440 Source kit. I would probably use there heads also.
Another option I’m thinking about is just building the 400 without stroking it. Can I get a decent set of pistons and run the stealth heads and make any kind of compression?? I would also be upgrading the cam and intake and torque converter also........ The car will see some strip use but mostly street use. And a occasional road trip. I can also swap gears rather easily because of the 8.75 rear. Just looking for some options on how to build this 400 for my goals...... Thanks
I did pick up a 76 400 motor on Sunday. Almost have it completely taken apart. Motor will need bored over I believe. This build will take time cause of $ but need to figure out how I want to do.
I’m open to building a stroker with a 440 Source kit. I would probably use there heads also.
Another option I’m thinking about is just building the 400 without stroking it. Can I get a decent set of pistons and run the stealth heads and make any kind of compression?? I would also be upgrading the cam and intake and torque converter also........ The car will see some strip use but mostly street use. And a occasional road trip. I can also swap gears rather easily because of the 8.75 rear. Just looking for some options on how to build this 400 for my goals...... Thanks
CoronetMan79
Member
And can I make some power with the 400 without stroking it? Say new pistons aluminum heads cam etc.....
You can make power with a 400 but your really just a crankshaft away from having something your more happy width, either way your boring it and buying pistons. KB has cheaper pistons for a 452( 3.75" 440 crank stroker) or I'd suggest a 4.25 stroke with a good set of rods...you won't regret it. Big heavy car will really like the torque a higher displacement engine will have and it will be more friendly to drive.
mopar 3 B
Well-Known Member
Was just going to suggest a gear change.
71 Polara almost if not a 4000 lb boat. Got to have extremely high gears. Finding some 3:23 or lower would be a vast improvement.
That Polara is a highway cruiser.
71 Polara almost if not a 4000 lb boat. Got to have extremely high gears. Finding some 3:23 or lower would be a vast improvement.
That Polara is a highway cruiser.
JG71B
Well-Known Member
By the time you get done doing a set of stock closed chamber heads you're better off just buying a set of Edelbrock heads and have them gone through. I have a 78 400 4bbl motor I just picked up with 50k miles on it. I plan on doing this and a cam/convert swap over next winter as I'll just cruise it this summer
mopar 3 B
Well-Known Member
Nope just not going to do it. Not when the closed chambers have been setting on the shelf for 47 years just begging to be bolted back on something. Just imagine what $1400 worth of machine work and valves would cost today.
I do understand your reasoning though. Why spend that kind of money today when there is something better out there.
JG71B
Well-Known Member
And those heads sitting on the shelf are 60yo designs. For 1400ish you can get the Eddy heads complete and are also much lighter and will also flow more than any stock head. If using the 383, a cam and Eddy heads are easiest way to go. Or, just get a Voo Doo cam or one with fast/early closing intake to build cylinder pressure with some steeper gears. The 400 stroker plan, that's for a new thread
Challenger340
Well-Known Member
A 400 for all intent and purposes of what you are asking, in regards making power 'as is'.... is very simply a .090" over bored 383 engine... That's IT... That's ALL
wherein,
read all the earlier posts./suggestions to compression and Camshafts still apply 'same-same" as the 383 with NO changes...... as the 400's are also inherently weak in off-idle Torque/easy to over Cam with any changes targeting increasing Compression very helpful.
Challenger340
Well-Known Member
Why not just get a 440 as a starting point ?
Because ANYTHING you do to a 383/400 to increase power using either 383/400 "as is" without a Stroker Kit ?
is going to cost you...
EXACTLY the same Money to do to the 440 but with ONE Big Difference..... the 440 will make waaay more Torque/Power !
Because ANYTHING you do to a 383/400 to increase power using either 383/400 "as is" without a Stroker Kit ?
is going to cost you...
EXACTLY the same Money to do to the 440 but with ONE Big Difference..... the 440 will make waaay more Torque/Power !
JG71B
Well-Known Member
He already has the 400. I agree though
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