Technical Hemi Novice

Hello!
Well, last year my father passed, and I decided to hold onto his roadster. It has a 331 Hemi (from the 50s, I think). I am clueless on these engines. I grew up on SBCs.
Right now, the intake is a dual quad set-up. I want to change it to one carb. I have been trying to search for an intake but, I just don't know what I'm looking at.
I am asking for help from the H.A.M.B.

Can you find and send me a link to buy an aluminum intake for a single 4 carb? Looking for polished if possible. Also, Is a 450CFM carb enough for a street driven 331hemi? Thank you. .............Joe

 

https://hothemiheads.com/

 

My condolences on losing your father. Sounds like he was one of us.

Judging by the water crossover between the heads, that's definitely a '55+ Chrysler Hemi, but even better, it seems there is a thumb-sized gap between that crossover and the valve cover which indicates a 392. ID your engine on your own, it's fun and you'll start to know the differences.

https://www.jalopyjournal.com/forum/threads/hemi-tech-identification.121000

As linked above, Hot Heads will have an intake for it. But I think I see you already have their intake base that accepts interchangeable carb mounts. If so, order just the upper plate for a single four barrel and that's all you'd need to change. Yes the engine will run with 450cfm and probably get decent mileage too. But it may be a little small for mid and high end power.

 

That was my first thought. But my blind searches came up empty. Thank you.

 

Sorry for the loss of your dad.

Very cool car, if you decide to sell the dual quad intake I may be interested.

 

I believe this is what you need, from Hot Heads Research and Racing, Inc.
https://hothemiheads.com/intake_manifolds/1x4_TRC_adapter_plate.html

 

I'm not sure. I'm not near the car now. I will try to get better pictures. But, the intake, if I recall correctly, has the words California Custom Speed Equipment cast into the intake. The shape of the top plate has a slight curve in the front whereas, the plate in the link looks like all edges are straight. I'm just now learning about this engine. I could be way off base.

 

What's wrong with the 2 4s?

 

I'm no Hemi expert, but I got this Hot Heads manifold from them 15-20 years ago. It's a much better manifold than just changing a top plate. I had it polished after I'd removed some cast-in bosses (for nitrous, I guess) that were right above the ports.

 

Here's a hemi ID chart.

My Hot Heads single 4 bbl intake is the same as @Stan Back 's but not polished.
It's basically a hemi equivalent of Edelbrock's airgap performer rpm.

A 450 cfm carb will work ok on a street car but would fall down at high rpms. A 500 would be better.

Hope this helps.

 

Just like to keep it simpler. And I'm not a carb guru/tuner. Right now, it has two 450cfm carbs.

 

One carb will be fine. Most driving is at part throttle where the total airflow isn't relative. Tis way better to be under carbed than over.

 

If what you have is working why change it....Looks to me like it has progressive linkage so it is running off of a single carb most of the time...

 

It's not working. The carbs operate together. I can't figure out the electric choke on the front carb only. Which to me isn't right if the back carb is just opening with no choke. It has a hard time starting. Sometimes it floods. And when I do get it to start, I have to keep the rpms up til it gets warm so it will idle on it's own. I really think the set up now needs the linkage to be progressive and the choke needs to be dialed in. Then, maybe I would be fine with the current set up.

 

Unless I see your picture wrong, the choke is on the rear carburetor.

 

That is not a Hot Heads intake, but an older PAW tunnel ram. The tops do not interchange. PAW made a bunch of different top plates for that intake including a single 4bbl, but there hard to find now since PAW went out of business. The Hot Heads dual plane would be the better way to go.
Changing to a single 4bbl will also require reworking your throttle and transmission kick down linkage(assuming you have a torqueflite)
As for carburetor size, a 600 cm would work well and be the cheapest.

 

Take a look at the front carburetor.

The front passenger side hold-down bolt has the carburetor part numbers in front of it.

Like this:


I do not recall Edelbrock making a 450, but I could be wrong.

 

Also, the block identification and serial number is on the lip on the top of the block, ahead of the valley pan.

Please clean that off and post what is there.


It is the stamped alphanumeric code, shown as "serial#" in the above photo.

 

The trans is Chevy th350 joined by adapter plate. I am heavily leaning towards the manifold you mentioned however, if I could fix what I have, that would be ideal.

 

Yes, correct! I just noticed that. Good catch. I really haven't looked hard at this engine save twenty minutes.
Should the choke be on the front carb? And also, Should the front carburetor be working first before the progressive linkage starts to open the rear?

 

Progressive linkage doesn’t really work too well with dual quads.

 

Choke on the rear carburetor would be correct.

 

That looks to be a possible A.I.U. Orange, CA intake.

 

I would stick with the 2x4 setup myself .
Sounds like the carbs need to be gone through anyway ,,since it had been sitting for some time.
That should fix any problems you might be having .
If it was running good before,,,,it should run well again .

Tommy

 

Correct, the A.I.U intake and the PAW intake are one in the same.

 

Below is a better pic of the intake. The carbs #1403 so now I know they are 500cfm.

So, I changed the spark plugs. To me, the gap was tiny on the old plugs. Measured .05. So, I gapped the new plugs at .76. The engine wouldn't fire at all. Flooded to hell. I re-gapped the plugs at .05 and it fired right up. Didn't think plug gaps were that crucial. But, still wouldn't stay running until warm. I think carb rebuild is needed. I know today's gas ruins these carbs when sitting. Just going to keep at it until it is fixed.

 

Another thing to consider is,,,how old is the gas in the tank ?
That can make a big difference,,,just like the plug gaps .

Tommy

 

Hey, CJ;
A friend has a 392 hemi, w/a HotHeads dual-quad manifold. Ran the duals for awhile, preferred a little better fuel economy, & used the rear carb. Works just fine, no issues. He drives the Tbucket all over, from IL to Tenn & Missouri, etc. Essentially, he just disconnected the linkage on thefront edelbrock, although I think he may have put a plate under it to seal the throttle plates. Try it on your manifold, may work ok. Worst case, you get to run both carbs. Or, iffen you're ndy, you (or someone else) could make a single carb adapter-plate that bolts on, in place of the duals. Those carbs aren't too bad to rebuild.
Marcus...

 

I can't tell what kind of ignition you have, but .076 is a bit much. The stock gap is .035, but .045 will work depending how good your ignition system is.
Dad and I have a 392 with the same intake your running with two 600 cfm holleys and it runs good. We run a MSD ready to run distributor with the plugs gapped at .040.

 

Id fix the carbs and what ever it takes to keep the 2x4 .

Id love to find one of those manifolds . The carbs likely just need to be cleaned and some good gas in the tank . Be sure you have no vacuum leaks or simple issues

If you insist on a single 4 barrel Id get a top plate made for the manifold, you have .

Sorry about your father . He had a cool ride any pics of the whole thing ?