Factory Cast Iron 350 Intake Manifold ?

[54blackhornet]

I am in the process of dropping in a HEi into my 71 350. Running the stock QJet with divorce choke, engine has always run crappy in cold weather and I was told it was the carbon buildup in passage inside the intake. Question can you hot tank the manifold to remove the carbon or find a different intake ? I have an aluminum Edelbrock Performer intake and a Carter AFB from a parts truck, but I would rather keep the Quadajet because of its better fuel economy. Thanks for any suggestions guys.

[enaberif]

Originally Posted by 54blackhornet

I am in the process of dropping in a HEi into my 71 350. Running the stock QJet with divorce choke, engine has always run crappy in cold weather and I was told it was the carbon buildup in passage inside the intake. Question can you hot tank the manifold to remove the carbon or find a different intake ? I have an aluminum Edelbrock Performer intake and a Carter AFB from a parts truck, but I would rather keep the Quadajet because of its better fuel economy. Thanks for any suggestions guys.

Edelbrock performer should be a spreadbore same as the quadrajet and both should bolt up together.

[burnin oil]

Yes you can hot tank the cast iron manifold. The Edelbrock intake should have both carb patterns unless it is a RPM model so you could use it also. The factory setup worked pretty good for running cold and warming up quickly. You may want to check that the thermac controller on the air cleaner is working correctly along with the flapper valve in the exhaust manifold. This is assuming that it is still factory. Aftermarket or bypassed parts will leave you with no options other than verifying the timing and richening the idle screws a little during the colder months.

**edit** I am not sure that the thermac or exhaust flapper cam on the pre 73 trucks. I know they did on the square bodies. You may be able to incorporate them if you like.

[GRX]

Agree. You can have the factory intake cleaned. If you do, be sure to remove the sheet metal heat shield underneath. Held on by 4 pins.

A lot of burned oil and carbon deposits end up there. Besides grit and chunks, you do not want water & soap from the cleaning process soaking in, then making it's way back to your oiling system.

[54blackhornet]

Thanks guys, no flapper in my passenger side exhaust manifold ? I was under the impression that a edelbrock performer was for a edelbrock carb or AFB ?

[enaberif]

Originally Posted by 54blackhornet

Thanks guys, no flapper in my passenger side exhaust manifold ? I was under the impression that a edelbrock performer was for a edelbrock carb or AFB ?

LOL! Nope. Its just a brand. Any carb can fit with or without adapters.

If its a spreadbore slap it on and give'er.

[54blackhornet]

Why do you need an adapter to install a Edelbrock on a stock manifold then ?

[hugger6933]

Because the Edelbrock performer intake is a dual pattern intake. That means it will accept either a speadbore [like a quadajet] or a squarebore[like most commonly known Holleys or Edelbrocks/Carters]. Now being that it has both patterns with the kick out at the back to accept the behemoth type secondaries the square carbs sometimes don't seal on that area depending on the gasket. So that is where the adapter comes in. It is really more of a wider thicker gasket than anything else. I have never had a vacuum leak with the gasket I chosen I guess I'm fortunate or just very very lucky. Most likely the later than the former. Jim

[54blackhornet]

Thanks for the info, I ran the Edelbrock on the stock manifold but thought you needed a adapter ? Stupid me !

[Coley]

Originally Posted by 54blackhornet

I am in the process of dropping in a HEi into my 71 350. Running the stock QJet with divorce choke, engine has always run crappy in cold weather and I was told it was the carbon buildup in passage inside the intake. Question can you hot tank the manifold to remove the carbon or find a different intake ? I have an aluminum Edelbrock Performer intake and a Carter AFB from a parts truck, but I would rather keep the Quadajet because of its better fuel economy. Thanks for any suggestions guys.

Are you sure....that you have the cold start circuit of your existing quadrajet and choke set up correctly?
This is often the cause of poor (cold) running and start conditions.
If that is the case, then swapping manifolds is not going to cure your cold run conditions...just give better warm/hot run performance.
My two bits.
Coley

[snipescastle2]

the carbon buildup in the exhaust cross over can be hard as concrete, take your time with a chisel/screw driver and scrape it out best as you can, then have it hot tanked, most often you will find these passages totally blocked, and hot tanking won't work because it can't allow the slovent/cleaner to get inside those passages.the hot exhaust gas passes under the carb to allow the engine to warm up faster, and the flapper that was mentioned earlier helps direct the gases through there.
HTH,
Ben

[GRX]

^^ good advice. And again as mentioned above ... remove the heat shield. A good shop should do it for you and put it back on. Only takes a minute or two.