Is there a decent mechanical fuel pump for a 235 out there? The piece I have cannot maintain enough pressure to keep from vapor locking at altitude, 5000+ feet. Want to stay with a mechanical for safety reasons. I will install an electric with a low pressure switch if I have to.
Bill

I've never had that problem. Is it an old pump? Is there a replaceable filter? Could it be sucking air somewhere between the tank and pump? Could the be an obstruction between the tank and pump or pump to carb? Do you have multiple carbs? Is there a lot of heat near the pump or lines? See if the GMC fuel pumps have a different part number. Some will just because the have a vacuum pump side as well as fuel. But the 270-302 may have a higher volume. Let us know how you fix it.

I am at a loss and therefore am asking for help here. The car runs fine at sea level up to 5000 feet. I have a Wayne head with three Webers and it does get hot. I raced the car in Mexico which starts at 5000 feet and goes up from there. The pump is a new unit, no glass and produces the usual 3-4 lbs of pressure but when the atmospheric pressure goes down its not enough to keep it from boiling. I was thinking of a recirc line with an inline cool box.

My son and I had lots of trouble with his supercharged Studebaker vapor locking. The fuel pump is in front so the hot air from the radiator blows on it. We were have over heating issues as well and were driving a car we had just got together from Nevada to Texas. We had to make several attempts to pull the grade leaving Gold Field, NV. I found a hunk of fiberglass insulation and some wooden clothespins to hold it on around the fuel pump. As long as we kept the insulation wet all was well. So I bet a cool box would work. Later we put an electric pump on just to use when needed. A larger line with more volume might help.
Any pictures of the car? It sounds great. What kind if racing?

You might consider a Carter electric pump in the rear. They are a vane type that allow fuel to pass when not running and have a lower pressure that the webers can live with. Just switch it on when needed. Also, might check your mechanical pump to make sure your pump is using the bigger 3/4 inch valves instead of the smaller 1/2 valves

I used an Accel Chevy small block pump years ago with dual outlets, i am pretty sure it bolted right on.

V8 pump works off an eccentric on the camshaft.

Actually the V-8 pump is driven by a pushrod that runs off the cam eccentric....I think the mounting flange is the same but the pump drive "rocker arm" is different?

So it doesn't work off the camshaft eccentric?

Not sure that presence or the lack of a push rod changes the face of rocker arm on the pump. If there is a difference it escaped my eyes.

But I agree that a good solution is an inline vane type pump on the fuel line wired to a switch. You can turn it on when you need it - but in most situations the eccentric driven pump will suffice.

On my fastback the carb always had a tendency to drain back into the tank or just evaporate when parked. This made it nearly impossible to start without ether. I intend to use a vane type pump on a switch to 'prime' the carb bowls - so choking should be enough for starts (after the car has sit idle for days).

regards,
stock49

The Carter pump I was suggesting is not an inline, although an inline would probably work just fine. The one I have used is the traditional gold colored pump that sort of resembles a Holley. Been around since for many many years. Very durable and reliable.

Might you be talking about this one from NAPA, E84070 ?
Got one last summer - works great.

Exactly. Have run one of those fro many years, very reliable and works in conjunction with stock mechanical pump. Finishing up a redo of the 57 and will be putting it back on the car.

Not directly.......

the eccentric is the same it still works on mine with no mods. Just bolted right on made it nice to run 2 separate fuel lines.