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Looking at 2 engine mods. Whats your opinion?

RobsRR

RobsRR

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I have a numbers matching 383 71 road Runner. Have had it for 30 years. 10 years ago I rebuilt it. It is not used much still runs good. It is 40 over, block was zero decked, I put on Stealth heads they are supposed to be 80 CC. Compression ratio is 9.38 Static. Cylinder compression is between 150 to 160. Pistons are hypereutectic 5cc valve reliefs. Factory intake and a holly 3310 750cfm dual feed vacuum secondaries. Comp cam is hydraulic .475 lift duration at 50 is 233 and 240. (Nostalia Plus Cam). 1 7/8 headers. 3.55 rear. 10 inch turbo action converter I think it is a 3800 stall. Looking back I think the stall is to big. Street car.

Thinking of trying to get more compression if it would help? I would like a snappier throttle response and more low end and hp. I think the low vacuum 12 is causing poor velocity.

I understand the heads can be milled up to 060 safely. Not sure about piston to valve clearance if milled? Not sure where my compression would end up? I also have a edlebrook rpm sitting on the shelf that will replace the factory intake. Does it make sense to mill the heads will I notice a difference or do I just put on the new intake. The intake will have to be milled to fit regardless.(Block Decked.)

Thanks for any input.
 
It seems like you want a good street car. I believe the stock intake needs to go because of your heads and cam. The carb is ok for lower rpm, but may try a little more cfm. Your 12in vac is good. If your heads are not milled, then dont worry about milling the intake unless the block is milled a lot. Test fit the rpm intake without gaskets and see. Your valley pan may or may not come with paper gaskets, those will take up space too. Imho. Good luck
 
I think you would like a dynamic 9 1/2" converter. Tight for street drinking but would launch better then your turbo action.
I wouldn't mess with shaving heads to gain a little compression. If its low miles yet a higher compression piston would be a better choice then shaving. Porting the heads could be a gain. I would do a different cam. Run more valve lift to utilize your heads better....get a more modern mopar profile such as bullet .904 or hughes all could be a noticable upgrade Imo...imo would be a better fit for your combo. Intake...maybe a rpm.
 
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Before getting into any type of machine or porting work, I would change that restrictive intake manifold. You could gain 20-30 HP just by switching to a good dual plane manifold and proper jetting of your carb.

https://www.edelbrock.com/performer-rpm-big-block-chrysler-b-intake-manifold-7186.html

007186_v1_3.jpg
 
Contact Dwayne Porter,he is here on the board. He can go over your wants and what you have to get to where you want to go. You need to look at the total package and he's the man!:lowdown::lowdown:
 
Ironbuilt said:
Before getting into any type of machine or porting work, I would change that restrictive intake manifold. You could gain 20-30 HP just by switching to a good dual plane manifold and proper jetting of your carb.

https://www.edelbrock.com/performer-rpm-big-block-chrysler-b-intake-manifold-7186.html

View attachment 891008
Click to expand...

^^ this.

I like compression. Throttle response is crisper, more horsepower, better fuel efficiency, better idle with a nasty cam.

What is your compressed head gasket thickness? If it’s like .047 I’d get a gasket that gave you around .032 compressed...that’s the same as milling your heads .015. The stealth’s are quench heads so you could definitely benefit from more compression. I’d like 10.5:1 with that cam. Don’t go less than .030 quench or you’re asking for trouble and pinging.

Another rule of thumb is 30hp per point of compression. Aluminum heads are more compression tolerant from a detonation/pinging standpoint than cast iron as they transfer heat better.

If you decide to mill the heads, as a rule of thumb, .040 off the stealths will gain you a full point of compression. Lots of other variables play into compression (bore size, piston down the bore at tdc, piston top volume, all contribute to total volume at tdc), but the rule of thumb would be a great place to start.
 
IQ52 has built many engines with very low compression that made huge power.
There a few places you can get a much better return on investment for performance!
The stock intake should have BEEN gone.
383 engines do well if built to rev! SPIN up that 383 with the appropriate components in place to go along with the higher RPM power band and you will be amazed at the feeling of a push in the seat that doesn't want to stop.
Talk to Dwayne, toss that factory intake, and ENJOY!
Personally I love a well tuned 6bbl, and there's one available for the 383.
 
In my Un-educated opinion I think
More compression would help. And the recommendation of the rpm performer from @Ironbuilt is a good one too... that stall does seem a little too high. You could try eddy street 5090 heads at 75 cc chamber
 
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Sounds like you’re getting the HotRod bug.... Its a highly contagious condition. I know it happened to me. So while the RPM intake would be my choice Of the options you mentioned and it certainly will get you a little bit, it won’t change the car much. My advice is to stop and really decide what you ultimately want. Are you going to be happy with just a little more power, or do you want serious power? My Satellite is a 383 car, and I played with the original 383 for a while. But eventually realized what I wanted to do was drag race, So I started a Street/strip 451 build. 10 years later, I can offer that I’ve never missed the 383 days!

whatever you do, have fun!
 
LemonWedge said:
Sounds like you’re getting the HotRod bug.... Its a highly contagious condition. I know it happened to me. So while the RPM intake would be my choice Of the options you mentioned and it certainly will get you a little bit, it won’t change the car much. My advice is to stop and really decide what you ultimately want. Are you going to be happy with just a little more power, or do you want serious power? My Satellite is a 383 car, and I played with the original 383 for a while. But eventually realized what I wanted to do was drag race, So I started a Street/strip 451 build. 10 years later, I can offer that I’ve never missed the 383 days!

whatever you do, have fun!
Click to expand...
Yup, no replacement for displacement....
 
Another engine build by committee. Sometimes silence is golden.
 
No, no. no. The threads are about the free flow of ideas. It's just that some of them are like throwing a hand full of sand at a bottle cap. Some grains hit the mark and others miss wildly.
 
Let's see if I'm off base. OP said he wanted snappier low end. Stock intake should be fine. 'Twere it me, I would try a smaller cam before I changed anything. 3800 stall speed sounds very inefficient for a cruiser.
 
As just suggested your problem is the cam.For the street something that pulls hard from 800 - 4800
or 1200 - 5200....but you didn't want to hear that. A big cam and 275R6015 tires can make most engines very lazy at lo speeds.
2400- 2600 stall and lots of lo end torque for the street.
 
The OP might want clarify his goals a bit. Is the engine coming out of the car? ARE looking 2 bolt on 2 parts and looking for the most gain, and what kind of gain?
 
The old say'in "speed costs, how much you got?" IMO the 383 is a fine street performer. The combo you have seems like a good start. Updating the intake will get you something, a little larger cam some more with those heads. A little pocket porting on the heads & basic port match will give more than an increase in CR. IMO the CR you use is strictly dependent on what gas you plan to run. 9+ to 10.5 should work OK on pump premium. The 10" Turbo Action should be fine (if not broken, & I broke several when drag racing), my latest Turbo Action 10" "tight" worked great on the street & track behind 500" motor. A 9 1/2" Dynamic would also be a good choice. BTW some effort at tuning the 3310 gives great results & they're very forgiving on engine size & combination.
 
Wow, Thanks for all the input!!
Goals: just looking for a little more. Low end more important than top end. It is definitely a street car and will always be as long as I have it. I just got the more power bug after buying a 2016 challenger 5.7. Anyway, I have the intake already. It has been sitting on the shelf in the garage staring at me for the last 3 or 4 years. Since it will need to be milled to fit what I have now, I was thinking about doing the heads at the same time. I was wondering if bringing up a point would make a difference? It sounds like it will. I may go with a smaller converter down the line. I know my cam is not the most aggressive performance grind but it is in it sounds good so it will stay. I will contact the local machine shop too, they have always given me good advise. I am always open to any other suggestions. Thanks in advance.
 
GrabberOrange69 said:
^^ this.

I like compression. Throttle response is crisper, more horsepower, better fuel efficiency, better idle with a nasty cam.

What is your compressed head gasket thickness? If it’s like .047 I’d get a gasket that gave you around .032 compressed...that’s the same as milling your heads .015. The stealth’s are quench heads so you could definitely benefit from more compression. I’d like 10.5:1 with that cam. Don’t go less than .030 quench or you’re asking for trouble and pinging.

Another rule of thumb is 30hp per point of compression. Aluminum heads are more compression tolerant from a detonation/pinging standpoint than cast iron as they transfer heat better.

If you decide to mill the heads, as a rule of thumb, .040 off the stealths will gain you a full point of compression. Lots of other variables play into compression (bore size, piston down the bore at tdc, piston top volume, all contribute to total volume at tdc), but the rule of thumb would be a great place to start.
Click to expand...
I believe I used the felpro gasket .039 compressed thickness for quench. I like what you said about compression. Have you milled a set of Stealths before? No one I spoke to could tell me how much I needed to take off. I have heard 25 to 60 thousands. My block is zero decked.
 
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