Should I block the heat crossover on my 2x4. I know everyone says to do it on the spreadbore. Thanks Rick
Rick, You can block your heat crossover passages with no problem in your area. I heard some time ago it's good for about 10 more horsepower. You only would have a problem if you run into some cold weather then it won't run well till it warms up to operating temps. Good Luck, John :TU:
This is a weekender only. So if it does ever get cold, it most likely will not leave the garage. Thanks for the input :TU: , Rick
Stupid Question! I have a dual quad 66 with the Carter AFB's What is the heat crossover and how do you block it and why does it increase horsepower? I usually only drive it between Easter and Thanksgiving here in Connecticut. Thanks
The colder the fuel/air mixture, the denser it is. That is why racers cool the inlet fuel with ice/dryice. If you run hot exhaust through the intake, the warm mixture promotes easier idling when cold, and faster warm ups, but the mixture expands, and you get less btu's packed into the cylinders, so....less horsepower.
manifold heat I lived in Houston and ran a 401 with a 950 cfm holley 3bbl. I blocked the heat risers and the car did not run nearly as well. It bogged and did not respond to the throttle in all ranges, as well. The best combo that I found was to leave the heat in the manifold and pipe cold outside air to the air cleaner. This set up you could really feel in the seat of your pants. :Brow: I sat and studied this at length. Finally I came up with a theory. :Smarty: When the cold air comes into the carb, it is dense carrying lots of oxygen. Coming past the venturis it picks up the stream of fuel which makes it eaven colder and denser. The metal in the intake manifold is hot and causes the fuel/air mixture [in the vacume] to "flash" into a vapor. AN ENGINE WILL NOT BURN LIQUID FUEL, IT MUST BE VAPORIZED TO BURN. The cool,dense, oxygen laden air is already past the carb butterflys and cannot back up, it must go on down into the engine. The fuel must have sufficent turbulence,heat and time to completely vaporize before going past the intake valve. If it doesnt then that cyl will not run at peak efficency with any liquid fuel in it. So, in the real world, a compromise is the best. :Smarty: Buick says that a cold air pkg is worth 8% of the total horse power. Cold air to bring in oxygen/ heat in the manifold to vaporize the fuel. If you are running on the strip only and always at extreme rpm, maby, But for a street driven, carbed,car I have not found a better combination. Dont take my word for it, try it out and check it out. :laugh:
I'm not 100% sure on this, but I don't think there is a crossover on the 2x4 intakes. The steel gaskets are required on the single carb but not for the duals because of the crossover. Larry
Yeah, been following this thread and thought the same thing. This is the '64 2x4 manifold I bought from Bill Stacy. The channel is there but the ends are blocked, they were never open. o No:
Kevin, Has that intake been machined where the carb's mount? Did you know thath the 64 and the 65/66 2x4 intakes are different? I didn't until recently. I just swapped out my 65/66 for the correct one for my 64. For those that are wondering the differences are, the dash pot boss is a different angle, the kickdown bracket boss is different, higher in the rear on the 64, the coil mounting bracket holes are different, angled on the 64 to clear the kickdown switch/bracket. This may explain why I could never get my kickdown switch to activate and I had such a hard time adjusting the dash pot. None of this may matter if you are not using stock carbs and linkage. The `64 casting number is B 1357106 The `65-`66 casting number is B 1370316 B The alpha lettering may vary. Larry Larry
Never noticed it. Kevin I was wondering where that "worked" 2x4 went. Have one myself :Brow: No it's not on yet. :spank: My 316 B manifold is also not opened up for heat to cross over.
In the colder climates you need some heat to keep the carb from icing. As stated the air as it goes past the carb venturis speeds up the air, with it gets carried moisture from the air. When the heat is blocked completely the throttle plates will ice up. In extreme cases of moisture the throttle will stick. Not good if you need to stop with wet or icey roads. Of course most of us don't use our cars like that anymore, but the throttle can stick, the car can backfire just off idle until it gets fully warmed up. Not as much of a problem in warmer areas, but still can happen if you get caught in rain. I just leave the heat riser open or remove it completely. This provides some heat but not full heat. Just my .02 worth. Tom T.
