vannmike

So ive got the blueprint 396 getting ready to go in my 77. I'm going to buy a fuel pump with a return line because I've been told too use the return line. problem is this, blue print recommends a 80 gallons per hour pump, and the only fuel pump that summit offers with the return line is the stock carter that is 30 gallons per hour. is it time for me to plug this return line when I do my swap?

toobroketoretire

Are you sure about that 30 gph rating?

vannmike

That is what summit tech line told me.

Big2Bird

80 GPH is for strip.
I just installed a stroker, 450 HP, in a friends 69. He used a stock pump, and it has never starved for fuel.
According to my GM manual, a stock pump pumps a pint in 30 seconds. That would be 15 GPH. 60x2=120/8=15

vannmike

So by the sounds of it, this return line is a must have?

Big2Bird

Yes and no. It is helpful with preventing vapor lock. Vettes tend to get hot under the hood. The early Vettes had a return line from the filter. Later ones had it at the pump.(It is just another output line with a .070" orifice)
You could use an 80GPH mech. pump, and try it without a return. You could also plump in an early fuel filter, and use that return line.
A lot of guys use an electric pump, with a pressure regulator by the carb, and install a return line from the regulator.
Lots of options.
.

vannmike

Forgive me for the rookie question, but what is vapor lock

Big2Bird

When the fuel gets hot, it can vaporize from liquid to gas, leaving bubbles. The pump has a hard time sucking air, or pushing air.

Ibanez540r

You can also use an aftermarket pump w/o the return line and plumb a return with the use of a regulator.

Lars has a nice explanation and photos on a thread about return lines/vapor lock.

I think this is it... there are quite a few floating around

https://www.corvetteforum.com/forums...k-in-a-c3.html