Fuel filter info...

[Longhorn Man]

I was just reading a back dated Car Craft mag, and they did an article on fuel filters. I normally skip over the simple tech stuff, but since we just had a few threads on this, I wondered if there was something we could all learn.
There was.
Fuel boils at a very low temp. Most of us know bout this...vapor lock bothers many of us in the warmer months. Well, placeing a fuel filter before the mechnical pump can aggravate this condition.
If you reduce the pressure on any given fluid, the boiling point is lowered. So that means that the fuel in the line, between the tank and pump, is already under lower pressure. Vacume produced by the pump is sucking it alon.
Well, if you place a restiction in the line....like a filter...you are increasing the amount of force required to pull the fuel through. This reduces the boiling temp of the fuel.
Acording to Car Craft, and there sources, you should not have the filter south of the pump.
It all makes so much sence when it is spoken.

[Lippyp]

I understand the physics of it, but surely the point of putting a filter in the line is to catchg any muck from your tank. The two items that need protcting are your carb and fuel pump, so a filter before the pump is to needed protect it. I guess what is needed is some idea of how restrictive your average fuel filter is and which makes flow the best. I have a filter before and after my Carter electric fuel pump and have never really given any thought to how well a fuel filter flows.

[JimKshortstep4x4]

Carcraft has some very good articles and the fuel filter article was timely. We make sure the pickup screen in the tank is good to protect the fuel pump and then mount an in line filter between the pump and the carburetor, We also, retain the factory filter that is built into the Q-Jets.

Jim

[crazy longhorn]

I have been running a filter before & after my elect pump, & havent had any vapor lock problems.....but have noticed that the pump works a lot harder when things warm up under the truck. That is interesting info.......it sounds like I may be removing a filter! crazyL

[Longhorn Man]

I know with my mech pump, I ge the vapor lock. I manage to keep it under controll...but with a very thin margin.
Maybe I should do my own testing like I normally do.
Ah hell, I'll probably forget all about this when the temps get over 70.

[crazy longhorn]

I thought about going to a mechanical pump, but that "little" aluminum headed Chev needs to run 195-200 degrees to run right......Im thinking that sticking the fuel pump on the side of the block might cause me problems. On a 100 degree day, I do have to dealwith heat soak on the carb....not as bad as the double pumper holleys I ran, but she just doesnt snap right off after sitting 10 or 15 minutes when good & warm. The insulator gasket helped on that, but I wonder if that RPM airgap would keep the carb a little cooler? crazyL

[Longhorn Man]

stop messin with combos and get some glass in that thing man!

[crazy longhorn]

Hehe! i hear you man

[bigjimzlll]

Im using an airgap(Dart kool can) same as the rpm air gap....I feel it helps, and it gets to 117degrees here
Jim