five7kid

iTrader: (14)

You basically need a secure place to mount it vertically and where you can drain it when necessary (a hose on a petcock can accomplish that so it doesn't get into the frame or somewhere where it will become a problem under acceleration).

I would think you'd be better off with an electric in or back by the tank, with a return-type regulator in the engine compartment. I've used heat tape around fuel lines in the engine compartment or close to heat sources for years. Much better for preventing vapor lock, as a pusher pump will not vapor lock. And a cool can will go after the mechanical pump, which does nothing to prevent vapor lock.

skinny z

I'm thinking you may be right.
First though I'm going to give the QFT bypass regulator a try (designed to work with a mechanical pump) and see where that gets me. I've also been told that a more typical bypass regulator can be modified with a jet in the return line. I just need how someone has rigged that up. (It would operate just as the QFT 30899 unit does).

five7kid

iTrader: (14)

The main problem with a regulator after a non-return mechanical pump is the pump is self-regulating, so to get some return, you have to use the reg to drop the pressure below the pump operating pressure.

You could do the same with a non-return mechanical by putting a "T" in the line to the carb and using a needle valve to control how much returns to the tank. The key is to leave the return as open as possible and still maintain pressure to the carb under worst-case demand conditions.

The factory and M6626 do it a little differently by giving the pump more pressure capability and using a relief valve in the return to control output pressure to the carb.

skinny z

How do you think that might work with, rather than a needle valve, a restriction of a prescribed size.? I'm reading that a #40 Holley jet is used in the aftermarket versions. It wouldn't be difficult to tap a fitting (1/4-32 I believe) and install the jet inline with the return. Not unlike the restriction that's built into a leak down tester.

five7kid

iTrader: (14)

I've seen the needle valve used (albeit with an electric pump). Never known anyone to use an orifice, the trick again would be sizing it correctly so you maintain max pressure at the carb under heaviest loading condition.

loneroad

iTrader: (3)

I did install one. I mounted mine on the drivers side tray. right behind the headlights. I made a few passes, with or without ice made no difference. It is now a catch can for my kegerator. I was dead-heading my pump.

skinny z

I appreciate the input.
Seems my problems aren't likely to remedied by a cool can either.

After further testing (and more testing), and eliminating the possibility that any of my fuel filters were clogged, it seems that even after switching back to my Edelbrock pump (110 gph), my problems persist. Seems I'm outpacing the delivery capacity of my fuel system in general.
It looks as though the route to a remedy is via a electric pump and a bypass regulator (to ensure no vapour lock).

five7kid

iTrader: (14)

Last Friday evening a fellow racer at the track was having vapor lock problems. As he was telling the story, his mechanical pump failed on him the day before, so he installed an electric and eliminated the mechanical. I was about to say an electric back by the tank won't vapor lock when he said he put the electric in the engine compartment and just bypassed the mechanical. He acknowledged without prompting that the electric needed to go back by the tank.

That was a Monte Carlo. The issue isn't limited to our cars.