Weber carb and Thomas Head-How Much Extra H.P?

P

Phil Noonon

Member
Title about states it all. Was reading thread about touring cam and extra horse power, was wondering about this from anyone in the know.

Thanks
Phil
 
Not enough information as a touring cam means lots of things to different people..


FWIW, the original 32/36 Weber carburetor was used on Pintos & Vegas that had approximately 25% less displacement than a Model-A. Jetting was used to overcome the lack of fuel. Just by itself, this carburetor set-up is good for 3-4 Hp depending on whose dyno numbers you look at. To me, the limiting factor is you still have 1½ inch intake valves and a restrictive bowl area under the valve. Opening that up allows for additional air & fuel to enter the cylinder.

The additional compression of the Thomas (is it a 7.1 compression head?) probably adds 5-7 horsepower over stock HOWEVER it does nothing if it cannot get enough fuel & air into the combustion chamber to make efficient use of that extra compression. Volumetric efficiency is key here. This is where knowing what camshaft you have/want tells us more about the potential power it is making and at what range.

I guess it is all about combinations and each component performing properly to compliment the others. If the exhaust is restrictive, more compression does not add much benefit. If the ignition system is weak, the fuel does not make all the potential power. Dennis Piranio has some Dyno specs on his website offering comparison graphs. Maybe you would like to take a glance at those/
 
Phil, For a couple of "Free HP" Put the car on Jack Stands. Grab 1 wheel and spin it one time. Now Time how long it spins. 10sec not good,30 sec better. do the same to the other 3 wheels. Make Adjustments untill you get the max. spin time for each wheel. Make sure your alingment is dead on. Brakes adjusted. Remove any excess weight from car. Also Tire Pressure! Example take a wheelbarrow with 5lbs air in the tire and push it over a lawn with 50 lbs of weight. Now air the tire up to 25 lbs and try pushing it! Big difference.
Also dont forget the Exhaust,More flow into the motor has to get out of the motor.
 
i end up doing everything at once so i don't know which gives the best hp improvment
head cam valves intake exhaust and the one that some people overlook ignition
there is a website that has a breakdown of mods and what they ended up netting.
tk
 
So Wick are you saying that a 10 sec wheel spin is an indicator that the brake is tight?? Or axle nut is too snug?. This is all pretty new to me so forgive if questions indicate that. I understand the tire inflation and the exhaust concept.

Thanks!
 
Last edited:
Phil Noonon said:
So Wick are you saying that a 10 sec wheel spin is an indicator that the brake is tight?? Or axle nut is too snug?. This is all pretty new to me so forgive if questions indicate that. I understand the tire inflation and the exhaust concept.

Thanks!
Click to expand...
Overcoming rolling resistance. Don't neglect air resistance. Keep it waxed! The shape of these cars give them built in headwinds. In the 1980s, my father would make the drive up from Fla. He was an engineer and kept a lot of records of some rather mundane things, in this case, mileage. It was no problem getting a pretty accurate picture before and after. I waxed the 76 Ford wagon 351 eng and the mileage went up 1.5 mpg. Doesn't sound like much, does it? But when you consider it was getting 16 mpg previously, 1.5 mpg is almost 10%. Through various testing, we found that the higher the speed, the more effective and the more aerodynamic the shape of the car, the less improvement could be had.
Terry
 
With rolling resistance..a brake could be to tight or have a slight drag.Bearings too tight or a bad bearing or they need to be serviced. Yes the nut can be to tight.
Phil spin a wheel and see what you get?
 
You must log in or register to reply here.
Back
Top