Aluminum heads on a "stock" B/RB engine

[Bad B-rad]

You've given so little info. Please tell us a little more about this "basically stock" engine. After 50 years, there are very few stock engines. Usually someone has been in them before and made some changes. If you are not the original owner, or have not owned the car/motor for 35 years, be skeptical that the motor is stock.

What is the engine size?
What is the measured compression ratio?
What is the cranking cylinder pressure?

Generally speaking, factory heads with unknown detailed history are likely weak performance wise, and any new aftermarket aluminum head will give a noticeable boost in power.

 

[Bad B-rad]

MY 383 is stone stock( when I got it) 7400 miles, I pulled the 906 heads and installed a set of reman 346 heads with Mopar steel shim head gasket and the Mopar Performance copy of the cast iron 4bbl intake that came stock.

The theoretical engine I am asking questions about would be any stock B/RB MAGNUM/Road runner engine.

When I say stock, I mean factory compression, and cam. I am trying to get rid of all the variables , so the numbers gained would be from heads only.

EDIT: the intake manifold is Mopar Performance PN4529117, claims it flows more air then stock, I always thought it was just an aluminum copy of the original one.

 

[Bad B-rad]

Thanks for all the great info!!!!
Learned quite a bit!!!

 

[Bad B-rad]

With my current set up, I would only be interested in the 440 source heads, do to the price, and with paint it will look stock.

I do realize the other aftermarket head offer greater gains, but if I stay with this #'s matching 383, I want to keep the stock look.

 

[33 IMP]

In that case, if your car runs good with the heads you have now and they dont need a rebuild, and....
You want to keep a stock look, intake, carb and exhaust.....
Imho, the amount of gain you get from JUST the head swap would not be worth the effort or expense. I'm not even sure you would notice.
I am planning to do basically what you are talking about, pure head for head swap, hopefully in the near future (depending on if my local 1/8 mile strip ever opens up again.) But... i am going from mildly ported 906s to rpm's, with a 850 d.p. aftermarket intake, .557 purple shaft, headers, 4500 stall and 3.91 gears. I expect more change from my swap than i think you would get.

 

[PRHeads]

On essentially any 383/400/426/440 that’s in good mechanical and operating condition....... remove old stock heads...... install stealth heads...... you will see an increase in output.
The smaller and milder the combo, the less gain you’ll see.

None of the aftermarket aluminum heads I’ve seen for a BB Mopar have a heat crossover passage for the choke/cold weather operation, so the factory choke mechanism won’t function correctly.
Most people don’t care, but on some combos it could be a deal breaker.

On a near dead stock 383, running thru exhaust manifolds, some mild porting on the 346’s would likely get you 90% of the max gain offered by the stealth heads, and might retain slightly improved throttle response by virtue of the similar flow achieved with about a 20+ cc smaller runner volume, and the higher discharge coefficient you get with the equivalent flow while retaining the smaller valves.

 

[JackR]

I was wondering about the 440 source aluminum heads. I’ve used other aluminum heads on other engines with good results. I have the 440 source heads on my yet to be fired 440. Still need to paint them though. Ran out of time (and too hot now in AZ to Garage paint) as needed to get k frame into car for final body/gap check.

bodywork.

 

[Bad B-rad]

I do have headers on the car, and the 346 heads, with the Mopar duel plane p4529117 intake manifold, I used the fel pro valley tin with head cross over blocked.
I also have a 1965 Hemi aluminum water pump housing, I have not yet installed.
I am still running the stock Holley Carb (1969 "H" code 330HP 383 with a/c) at the moment, and a new set of stock points.
It runs great, but I will be swapping to electronic ignition(hidden in car)
I kinda want to keep it all MOPAR Performance, or Direct Connect vintage parts.
I am definitely going to put some miles on the car before I do anything more to the engine.

I been thinking the 440 source heads and maybe FItech efi.

Sounds like the heads will help quite a bit, plus the weight reduction of all the aluminum vs cast iron parts, and make it a touch more efficient.

 

[Kern Dog]

 

[origcharger]

So then the added flow of the heads made a large change?
Did you keep the same cam?

Sorry, no before and after comparison.
Cast crank/low comp 440 was pulled from a 76 Chrysler and sat in my garage for 15 years. In the spirit of make do with what you have, in 2018 I checked the bearings, slid in a Comp cams XE262H, 440 source heads, Edelbrock Performer intake, hi po exhaust manifolds and put it in my red 66 Charger that hadn't moved under its own power for 20 years. It now also has Holley Sniper EFI, TTI 2 1/2" exhaust, is still pulling hard and a joy to drive