Does the Chevy small block V8 mechanical fuel pump have the same mounting and actuation arm as the 250/230/194? I would like to get a higher fuel pressure than stock for a Holley swap.

No, they will not interchange.

Ok, am I correct in thinking a mechanical pump will make about 3 psi?

It depends on the fuel pump. If I remember right, the stock fuel pressure for a 194/230/250 is about 5 psi. You can get aftermarket mechanical fuel pumps for those engines that will put out more then 5 psi. You can also get a variety of electric pumps that put out anywhere from 3 psi to just about any pressure you want (using a regulator). Personally, I prefer electric pumps, but to each his own.

Having just bought a new pump from NAPA... The pressure varies from 3.5-5.5 psi, depending on the manufacturer. The 292 pump put out the highest, which is the way I went to help feed the turbo!

Dodgy, do you know the number of the 292 pump? I found a Carter M60406 that looks like it might have a higher free flow rate over the Airtex 6790 that I have.

Thanks for the info guys.

I know some people like to keep the mechanical pump for various reasons, like looks and originality, etc... and they work well...

But I'll throw in my $.20 in favor of electric fuel pumps. I lived in Florida before, and if I parked the car for a few days or a week, the fuel would evaporate from the carb and it would take very long to start the car, because the engine had to turn over to run the pump and bring fuel to the carb. This puts an unnecessary strain on the battery. If you also drove mainly short distances, the battery would not get charged back up, necessarily.

I absolutely love my electric pump, I just turn the ignition power on, and the pump primes the lines and fills the carb, and it starts instantly. Every time. I ran an electric pump in the engine bay at first, a pump that was designed to be near the tank (Gravity feed type). I just upgraded to a new pump, also gravity type, and installed it next to the gas tank, above the rear axle. Still works great. I picked one that said "For import 4 and 6 cylinders" and lowest pressure of the three available in the store, to match my future carburetor (Weber 38/38). https://www.amazon.com/Mr-Gasket-42S-Electric-Fuel/dp/B000BWE4RC Domestic sixes (by the product description on the box) were supposedly better served with the slightly higher pressure version. http://www.jegs.com/i/Mr-Gasket/720/12S/10002/-1

...just saying. I'll never go back to mechanic pumps.

There's about a million other choices out there too, these are the two we happened to carry so I picked one.

Back on the old continent people (and myself) used to swear by Facet pumps, my little beetle uses a Facet Red Top, these cheaper little pumps were just not enough to keep up with two dual 45mm Dells sucking it down, even after doubling the fuel line and fitting sizes Not sure how much pump a truly hopped up six cylinder would require.

https://www.pegasusautoracing.com/produc...CFYkehgodVW4BGA

Another option is to use both. I am plumbing for an auxiliary electric 'inline' pump controlled by a switch on the dash:

The pic is an Airtex.

This is perfect for the scenario that 70Nova paints. The car has been sitting = the carburetor bowl(s) is/are dry . . . just flick the switch and prime the system. Start it up and drive away on the mechanical pump.

Best of both worlds.

Should the mechanical pump fail one could use the electric pump as a backup - but you would likely need to plumb around the failed diaphragm - otherwise the electric pump would push fuel into the crankcase.

I tried using that Airtex electric pump but something wasn't right. I put it on a stock, tired 230 with a Weber 32/36 progressive carb and it would start up and run for a minute or two and then die because the fuel pressure went to zero. I mounted it vertically near the tank like the instructions showed...

I probably will go to an electric after getting my fresh 250 running. I just have a newer mechanical pump and I didn't want to have to trouble shoot the pump when I'm trying to break in my newly rebuild engine. I have an Airtex E84070N to try. It has a much higher free flow rate (which I know really doesn't matter)than the E8011 and a max pressure of 5 psi which should be good for the Holley and not need a regulator. We'll see.

That is exactly what I have done on several old Porsches (356), all hidden, for the same purpose, and retaining the original pump for original appearance and function. And just like you said, once it starts, turn the electric pump off and let it free flow fuel to the mechanical one.

Note that the MrGasket pumps I linked, do not flow freely, nothing goes through when they are not running. The airtex above flows through passively when not on.