flathead fuel pump question?

i'm planning on running my stock model a gas tank with my flathead v8. do i still need to run the mechanical fuel pump or can i let gravity do the job?

 

I would recomend that you use a stock pump, or an electric pump(depends on what carb/inntake application)

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Taildragger&fenderless

 

Gravity will only work when the tank is full, the bottom half won't make enough pressure.

 

I ran the stock Model A gravity tank set up with the flatty in my 29 for about two years. It was fine around town and even managed to feed the dual 94's at interstate speeds but I don't drive the car hard. And I never let the tank go below half because the engine acted funny when I went over bumps if I did.

Unfortunately I was plagued with crap in the tank, was changing the sediment bowl filter every hundred miles because the the gravity feed set up couldn't keep up when it started getting clogged. I got tired of the hassle and switched to an early 32-42 style mechanical pump (more room at the back of the engine than later pumps) and kept the stock Model A sediment bowl on the fire wall.

In hind sight, I think the stock gravity feed is marginal at best for an engine as large as a flatty. Holley 94's require 2-3 psi supply pressure. At 14.7 psi for 30 feet, you can do the math. Even with a full tank, sometimes ten inches ain't enough

Regardless, if you keep the stock tank I'd replace the brass screen in the sediment bowl filter with a real filter. NAPA FIL3039 fits great and a Holley 4 barrel secondary spring works well to hold it in place. Keep an extra glass bowl in your tool box- don't ask me how I know...

 

wow gashog,thanks for the great reply.

 

grandpa told me that if your model a gas tank was low and you had to go up a hill you had to go up backwards or the engine would starve out!

 

I bet your Granpa was talking about a Model T. Some of them had the tank under the seat and the height difference to the carb wasn't much. A Model A has the tank in front and a low mounted carb.
The carb in a V8 is much higher than the updraft one on a stock Model A engine, I think the bottom half of the tank would be lower than the carb - it can't run uphill!

 

I tried to run my "A" with just gravity, with my 97 on a "banger". It would not go up hill, and would miss at less than half a tank. A low pressure electric pump solved the problem.

 

What pump did you use?