I do not have the heat riser. I have a 440 4 bbl currently with the valley tray that has the heat crossover blocked off and my 4 bbl uses an electronic choke.

If I put a six pack on my motor, how will the choke work? Do I need to get a new valley tray so as to not have heat crossover blocked off?

Please explain?

Thanks, Rob

Do a search, a member posted what he did to overcome this issue. But you are correct the THERMOSTATIC choke which REQUIRES an open passage AND a properly working exh heat valve to operate properly. The member rigged up an electric heater similar to the one used in later cars to make his choke thermo work properly .

I have wondered if it's possible to install an electric choke on the center carb ?

This may be the thread mentioned above.

Do you drive your car in cold weather? If not you probably don't need a choke and can wire it fully open.

Although it is harder to keep running when cold, mine is wide open. The carbs are basically stock from my 1970 cuda. Normally I don't drive it when the temp is below 70 though.

A quick follow-on about this choke mod, I have about 1800 miles on this six-pack motor now without manifold crossover heat and a fully functional automatic choke. A couple pumps on the accelerator prior to crank, it fires up cold and goes directly to a fast idle of about 1400-1500 rpm’s for about 4-5mins. It can be driven right away without hesitation on acceleration or power valve blowing lean back fires.

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A quick follow-on about this choke mod, I have about 1800 miles on this six-pack motor now without manifold crossover heat and a fully functional automatic choke. A couple pumps on the accelerator prior to crank, it fires up cold and goes directly to a fast idle of about 1400-1500 rpm’s for about 4-5mins. It can be driven right away without hesitation on acceleration or power valve blowing lean back fires

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So you have a valley pan with the heat crossover blocked off and you also do not have a heat riser correct? Is it possible your choke does not come off completely once the engine is fully warm?

My buddy has a six pack on his 440, he does not have the heat riser but he does have the valley pan tray with the heat crossover NOT blocked off and his car runs great cold but the only thing I have noticed is his motor runs much hotter then my 440 4 bbl. I don't know if the two are related, I always thought his ran hotter because I have a new 4 core 26" radiator and he has a new cheaper 26" radiator.

Any thoughts?

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You should get a new valley tray no matter what you do to make sure it seals the new intake.

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Should the new valley try have the heat crossover blocked off or not blocked off?

Thanks, Rob

Hello Rob,
First be sure to read through my postings on the choke mod thread referenced above. It became rather detailed on why I needed the mod. In my case, I’m running Edelbrock Performer RPM heads which don’t have cross-over passages at all, also running headers (no heat riser). Remember the only reason for the cross-over and heat riser was is to attain acceptable drivability during warm-up. Not really a big concern for most of us today. The divorced choke system used on these cars originally depended on the cross-over heat for correct function/timing. A correctly functioning choke spring will never relax completely when the cross-over is blocked unless it is electrically heated. The heat riser flap/valve was designed to divert passenger side exhaust gases almost completely through the cross-over when first started to improve cold running drivability and relax the choke sooner. The bi-metal clock spring on the riser flap would relax as engine reached operating temperature. By mid seventy’s choke heaters/timers were used entirely and heat riser flaps/valves were omitted all together.
I have run many daily drivers back in the day without risers (headers), with open crossovers and had acceptable choke function with slight adjustments. If you block the crossover you will either have to disable the choke or figure out a way to heat it. You will find many opinions here on moparts as to why you would even need a choke at all. The fact of the matter is, in a basically stock configuration and correctly tuned for street use at operating temp, these things will be very cold blooded without a functional choke system. Hope this helps.
Good Luck,
Doug