Putting Vortec heads on an earlier 350 block for a vintage truck that will be required to go to Home Depot occasionally in the winter. I’ve run enough SBCs with blocked exhaust crossovers to know the climate here and the laws of thermodynamics will require some heat to the carb November through March. The 7116 I have has the provisions to use either exhaust or coolant under the carb. I think I would rather use exhaust, but I would like to be able to shut it off in the warmer months, and I haven’t figured that out yet. Running the coolant under there is relatively straightforward, but I wonder if 180-190 degree water is enough to keep it warm, especially considering how the carb sits way above the plenum. Anybody have any experience with this?
Intake manifold heat is good for any street engine. I usually restrict the exhaust heat but not block it. All the aluminum manifolds I’ve used will get hot enough to help with atomization but will not retain the heat as cast iron will. Also exhaust heat is immediate where coolant heat takes longer and not nearly as hot. It’s your choice depending the type of driving you do. Good luck.
Will you be running an automatic choke? If so, does your carb have an integral choke (choke t/stat mounted directly on the carb) or a divorced choke (t/stat moumted in a cavaity in the intake manifold)? Will you be using stock exhaust manifolds with a heat riser? This may have some bearing on how you choose to heat the intake. If the carb uses an electric choke thermostat your choice may be a matter of a coin toss.
Electric choke Holley. No other choice. These manifolds never come with the provision for a divorced choke because Vortec heads have no provision for exhaust riser crossover. With very few exceptions all Vortec L31 heads came on engines with fuel injection, so no need for heat. Generally the people I talk to have put a carb intake on their Vortec truck and complain that it runs like crap in the winter. I ask them about carb heat, they look at me like I’m crazy because heat is “always bad” for a carburetor. End of conversation.
It you have access to something that can whittle out a hunk of aluminum, you could make a heated spacer. This sort of thing was not uncommon, think the Falcon-6. Imagine a 4-hole spacer, maybe 1-inch thick, with extra metal on the sides, so as square on the outside as it can be without the bellcranks hitting it. Horizontally drill three sides of it, all the way through, making a u-shaped passage. Tap and plug the extra holes. Put hose barbs on the remaining two.
Or: https://jetpumpparts.com/carburetor-spacers-water-cooled-water-heated-nos- Or Ford 390GT: http://mansfieldmustang.com/EngineFuelCarbp1.html
I am all about making parts, but I would certainly thing twice before I turned on the mill to save $65-$75, especially considering current materials prices.
The Jalopy Journal
