heat or no heat for the intake

[gtxrt]

I have the heat blocked off to the intake on my 440 with a 1/8 to 1/4 hole for the exhaust valve reversion I don't think it is letting much heat in. sometimes the car will just chirp the tires and not pull very hard and other times it will go sideways and push you back in the seat running the 1/4 mile. runs better in hot weather for some reason. one time I tried 3 take offs off the line no power then the 4th time it came alive all within 5-10 minutes apart. i will have to open the heat back up which I hate to pull my intake off again. can anyone think of any other reason the power would change like that.

 

[Vertex_Jeff]

My experience in what has the biggest effect on power (in order):
1. Timing / ignition
2. Fuel / Carb Tune
3. everything else

Can't imagine blocking off the heat crossover making that big a difference.

 

[Cranky]

All the heat crossover does is heat up the carb faster but you also need the exhaust flapper valve to function properly for things to work well together. What are your coolant temps when the car doesn't perform well vs when it doesn't perform well. I live in a very warm climate and whenever I swapped the intake for something better, they either didn't have the crossover port or I blocked it if did have one. Never had an issue like you are describing unless there was something wrong with the carb, ignition or fuel.

 

[Dave6T4]

I blocked the heat riser on the 440 in my 1967 R/T, and have witnessed no driveabilty affects. On the plus side, the fuel does not boil out of my carb as quickly, and stink up the garage after a drive.

 

[MWbirdLOVER70]

I blocked the heat riser on the 440 in my 1967 R/T, and have witnessed no driveabilty affects. On the plus side, the fuel does not boil out of my carb as quickly, and stink up the garage after a drive.

Same here but running aluminum intake and the alum acts like a heat sink so it takes a bit to heat up before driving and playing with the car

 

[Dave6T4]

I have the heat blocked off to the intake on my 440 with a 1/8 to 1/4 hole for the exhaust valve reversion I don't think it is letting much heat in. sometimes the car will just chirp the tires and not pull very hard and other times it will go sideways and push you back in the seat running the 1/4 mile. runs better in hot weather for some reason. one time I tried 3 take offs off the line no power then the 4th time it came alive all within 5-10 minutes apart. i will have to open the heat back up which I hate to pull my intake off again. can anyone think of any other reason the power would change like that.

I suspect that your automatic choke is not pulling off as quickly, with the intake heat blocked, and your secondaries are not opening up. There is a "dog" on the choke linkage that prevents the secondaries from opening until the choke is fully open. You can replace this piece with a washer, and the secondaries will open at any time. Alternativelly, you can replace your factory choke system with an Edelbrock electric choke, which has its own heater, getting its power from the 12V side of the ballast resistor. I have this on both my carbs on my 440's, and they work well.

 

[khryslerkid]

Sounds like a timing issue as in vacuum advance not coming in.

 

[gtxrt]

it does have an alum intake maybe thinking it needs to have heat sink. it has an elec choke Edelbrock but good point I did check to make sure it was opening all the way and secondaries were coming in. that is how it feels when it's running slower like the secondaries are not coming in that is how much power it seems to lose. it has always been over 70* when i was testing and up to 85*. runs smoothly all the time without missing or surging. running a heat insulation sleeve around all the gas hose from the fuel pump to carb. The car runs 175-180 degrees.

 

[Cheapsunglasses]

I have a mild cam 440, factory electronic ignition, torker intake , manual choke edelbrock, electric fuel fuel pump. Depending on the temperature outside, it’s some times ready to rip, but sometimes I have to let it warm up a bit. I wouldn’t worry too much, you know how women are, sometimes they just throw something on , sometimes they have to pick out their outfit , do their makeup and their hair . Hopefully it helps , if not hopefully you get a decent chuckle

 

[PRHeads]

I think pretty much all the aftermarket aluminum heads for a BBM don’t have any exhaust heat crossover passage.

Nor do most of the “better”(higher hp) newer intake manifolds.

The intermittent lack of power being attributed to insufficient manifold heat doesn’t really make sense to me.

 

[Cranky]

Same here but running aluminum intake and the alum acts like a heat sink so it takes a bit to heat up before driving and playing with the car

If you have the carb set up a bit on the rich side, one can 'play' very shortly after startup....

 

[toolmanmike]

No heat.

 

[1967coronet]

Sounds like a timing issue as in vacuum advance not coming in.

Agree, weights may be sticking.

 

[AR67GTX]

Same here but running aluminum intake and the alum acts like a heat sink so it takes a bit to heat up before driving and playing with the car

I have noticed this also on at least 2 cars I have with aluminum intakes. The engines start and run a little rough for a while until the motor gets some heat built up in it. So I usually don’t block them completely off to help this speed up some.

 

[Black_Sheep]

If you’re running a divorced choke, blocking the crossover could be a problem. With an electric choke or no choke at all, I don’t see a problem. I have no choke and a blocked crossover, cold idle is a little erratic but drivability improves and the idle is fine within a couple blocks.

 

[toolmanmike]

The heat through the intake was for cold drivability only. Designed by the factory so people could start their car cold and within a min or two and drive away.It helped fuel vaporization during warm up. Helped prevent stalling and stumbles. Heat riser's were on production cars long before before emission requirements. Just an FYI there.

 

[Kern Dog]

The coldest that I can recall driving any of my classics was maybe 39 degrees. They all seemed to be a bit rough when cold but once the coolant gauge starts to move, the idle cleans up. I have 5 running and driving classic V8 vehicles here, none with operational chokes. None have heat going through the intake.
Mike is right… the heated intake was a cold weather aid or maybe it was to speed up the warm up to reduce emissions. A cold engine running at a 10 to 1 fuel ratio pollutes a lot so they tried to shorten the time that it ran so rich.

 

[gtxrt]

Agree, weights may be sticking.

I will put a timing light on it and watch the mechanical advance that is. the vacuum advance kicks out at wide open throttle so that can't be it. you do need some heat in the intake for the fuel to vaporize.