A Simmons straight through carb runs lets say
29 cfm. A Model A carb runs say 63 cfm. Now, with a stock vaporizer intake manifold (just the runner), would a stock engine draw any more cfm from the A carb then 29 cfm or would the restriction of the smaller ID manifold limit the cfm to 29+/- regardless of carb? If I used a model A carb with a stock vaporizer manifold could I expect a greater cfm then the simmons 29?
Tyrone, I have both, but I have not tried them. I was going to use a Winfield intake with a Stromberg OE-1 carb, but a forum poster talked me out of it. He had tried the same carb and because it was used on large displacement six cylinder engines in the twenties, he said it was too much carb for anything but an all out full race engine. People seem to be using the Zenith and Tillotson Model A carbs on even stock engines with good results. So, since a Model A intake and exhaust manifold flow better than stock T pieces, I have convinced myself to use that setup on my "tour car", along with a Simmons Super Power head. I have a Rajo four valve head that I'd like to try, but don't want to have to worry about forgetting to lubricate the rocker arms and ruining the setup.
One more thing, Tyrone. I'm sure you are aware that you'll have to modify the vaporizor intake to mount a Model A carb, as it is an updraft carb and the Simmons and all other Ford supplied carbs were side draft. By the way, are you sure the vaporizor intake with its short runner length is going to produce the most "bang for your buck" with its exceptionally short intake runners. There must be something to be gained by having long intake runners as all modern car and truck engines have them. If you were around in the fifties and sixties, do you remember the Chrysler hi-po engines that had cross ram intakes with the left 4 barrel carb near the right fender and the right 4 barrel carb near the left fender? Something to think about . . .
Those Chryslers were in the 60s and I have a 1962 Chrysler 300 with them. Mine is a 413 with a factory 4 speed. Sorry for the drift.
When I build a speedster it is going to have a pair of side draft carbs, probably Stromberg OF's. I want to be period correct, using only parts available during T production.
The longer intake runs were an attempt to "tune" the intakes to take advantage of the pressure waves created by the opening and closing of the valves. At the optimum length the intake wave pressure will maximize at the next valve opening, in effect supercharging the intake charge. Of course this is most effective at a particular RPM. Exhaust headers also have been "tuned" to take advantage of the vacuum pulse to aid in removing the spent charge. With the Ts lower RPM range I expect the length of intake runs would be excessive.