Fuel pump contacting block

[msbaugh]

ok... What do yall recommend for electric pumps? ...

Also with 3/8" supply does the return also have to be 3/8"?  Will there be a problem having a 1/4" nipple return on my sending unit?

[734406pk]

You can get a new fuel sender that has a 3/8 supply connection with a 1/4 return connection and convert what you have. Then install a 1/4 tube/hose return with the factory style bypass filter. also insulate the fuel lines from the tank to the engine. That's about all you can practically do with the mechanical pump.

[734406pk]

I have a Holley "Black" electric fuel pump with a pressure regulator. It works great, but it is LOUD! Anybody have a better suggestion for a big block?

[Chryco Psycho]

ok... What do yall recommend for electric pumps? ...

Also with 3/8" supply does the return also have to be 3/8"?  Will there be a problem having a 1/4" nipple return on my sending unit?

 Mallory 110 , reliable & quiet

[roadman5312]

Running this on 2 cars, works great, very quiet    http://www.summitracing.com/parts/edl-1792/overview/

[msbaugh]

Ok... I am going to make ONE LAST attempt at stopping fuel vapor lock on my vehicle in the hot Texas weather.  I have a couple of plans that will require minimal investment, leaving the mechanical pump, but putting a 1/4" return line using a WIX metal return style filter.

I have a few questions.  Would some of you mind looking them over before I get started?  My main question is will my fuel pressure regulator work in the location shown here? Or should I put it before the filter/seperator instead?

Also what stops the flow of fuel into the carb from drawing fuel through the return line when the fuel tank is full?  Will I need to add a restriction or a one way check valve here on the return? 


Thanks in advance for glancing over my plans.  I will share my lessons learned to help anyone else wanting to make a mechanical pump work.  If this does not do the trick I will finally fold and buy the electric pump.

Matt

[cudabob496]

the tiny gauges on the carb inlet are very innacurate.
Should not need a regulator for a standard mechanical pump.
1/4 inch line seems too small.

Not sure, but can't you take air hose and blow back to tank, to unplug
fuel line from tank, if its clogged? I've done that, but went very slow with low pressure.

There's a stone like filter in Holley DP line, that should be removed.

to work right, would think gas tank needs to be vented well.

Regulator before paper filter may help things work better!

[msbaugh]

the tiny gauges on the carb inlet are very innacurate.
Should not need a regulator for a standard mechanical pump.
1/4 inch line seems too small.

Not sure, but can't you take air hose and blow back to tank, to unplug
fuel line from tank, if its clogged? I've done that, but went very slow with low pressure.

There's a stone like filter in Holley DP line, that should be removed.

to work right, would think gas tank needs to be vented well.

Regulator before paper filter may help things work better!

It's a high output pump so it requires the regulator, unfortunately! What would keep a steady pressure at the carb if the regulator wasn't right before it?

Good tip on the Holley float bowl filters I'll have to remove those. 

Didn't these come stock with a 1/4" return line? How is that too small?

Thanks

[734406pk]

Your drawing looks fine. You don't need a check valve or external restrictor when using the correct fuel filter. The Chrysler filter already has a restrictor (.065") built in. Make sure you get the right filter. 1/4" on the return line is the factory designed size for the RL back to the tank for the small amount of bypass fuel and is more than adequate. I hope this works for you!

[cudabob496]

It's a high output pump so it requires the regulator, unfortunately! What would keep a steady pressure at the carb if the regulator wasn't right before it?

Good tip on the Holley float bowl filters I'll have to remove those. 

Didn't these come stock with a 1/4" return line? How is that too small?

Thanks

You make some good points. I was throwing out some what-ifs.
was just thinking the 1/4 inch return line may restrict some return flow, thus allowing vapor bind.
1/4 inch may be factory, but factory did not have a high output pump.
The more flow, the less the gas line can heat up.
why have a highout putput fuel pump? I would assume one rated 6 to 8 would be fine. Anything
abouv that might cause problems.

My 496 has a 110 gph pump, 6 to 8 psi, and no regulator. I route fuel line away from headers.
and air coming from radiator. On 95 degree days, not vapor lock problem, but my hood is vented.

Maybe fuel before reguator is somewhat stagnant, being at a higher pressure, and is therefor
given a chance to heat up.  Regulator may be causing this vapor issue.

[msbaugh]

You make some good points. I was throwing out some what-ifs.
was just thinking the 1/4 inch return line may restrict some return flow, thus allowing vapor bind.
1/4 inch may be factory, but factory did not have a high output pump.
The more flow, the less the gas line can heat up.
why have a highout putput fuel pump? I would assume one rated 6 to 8 would be fine. Anything
abouv that might cause problems.

My 496 has a 110 gph pump, 6 to 8 psi, and no regulator. I route fuel line away from headers.
and air coming from radiator. On 95 degree days, not vapor lock problem, but my hood is vented.

Maybe fuel before reguator is somewhat stagnant, being at a higher pressure, and is therefor
given a chance to heat up.  Regulator may be causing this vapor issue.

That is a good idea, I might try it without the regulator and see what kind of pressure I'm getting.   Unfortunately I'm still waiting on parts.

On another note where did you get that air cleaner assembly in your picture?  That seems like a neat idea of getting cool air to the carb.  I might try it if you think it would be worth while.  I might also get brave and cut out some"breathers" in the rt fiberglass hood scoops I have to vent some of the hot air out

[cudabob496]

That is a good idea, I might try it without the regulator and see what kind of pressure I'm getting.   Unfortunately I'm still waiting on parts.

On another note where did you get that air cleaner assembly in your picture?  That seems like a neat idea of getting cool air to the carb.  I might try it if you think it would be worth while.  I might also get brave and cut out some"breathers" in the rt fiberglass hood scoops I have to vent some of the hot air out

www.ramairbox.com

also, may want to search this site, as there is a lot of discussion on cutting breathers in hood scoops.

[734406pk]

The mopar filter is actually a filter/vapor separator. The RL sends fuel/vapor back to the tank so the carb gets liquid fuel. Also the fuel flow in the supply line (where the vapor lock occurs) to the fuel pump increases slightly to meet the demand of  the return flow back to the tank. This increase in flow has a slight cooling effect on the fuel in the line en route to the engine, hopefully keeping the fuel in a liquid state. Since you have a high volume pump, you can experiment with the .065 restrictor, increasing the size for more return flow. Just keep in mind that the supply line is only 3/8". You don't want to increase the vacuum too much or the whole idea goes backwards. A 1/2" line may be needed in that case. I would try the factory set up, keeping the tank on the full side in hot weather, slow cruising use. It might be just fine.

[734406pk]

You make some good points. I was throwing out some what-ifs.
was just thinking the 1/4 inch return line may restrict some return flow, thus allowing vapor bind.
1/4 inch may be factory, but factory did not have a high output pump.
The more flow, the less the gas line can heat up.
why have a highout putput fuel pump? I would assume one rated 6 to 8 would be fine. Anything
abouv that might cause problems.

My 496 has a 110 gph pump, 6 to 8 psi, and no regulator. I route fuel line away from headers.
and air coming from radiator. On 95 degree days, not vapor lock problem, but my hood is vented.

Maybe fuel before reguator is somewhat stagnant, being at a higher pressure, and is therefor
given a chance to heat up.  Regulator may be causing this vapor issue.

High volume pumps are great!  They have the potential to supply far more fuel than the stock pumps did. Most are rated at free flow. The actual flow in service is usually far less due to supply line restriction etc, but still more flow than stock. The fuel pressure regulator is designed to reduce the fuel pressure to a point that it doesn't overwhelm the carb floats needle and seat. This would cause unmetered fuel to "flood" the engine. Every carb manufacturer has a max pressure spec that is important to follow. 6-8 psi is fine if the carb can control it. My carbs lose float control over 6psi, so I keep it at 5.5 psi.

[msbaugh]

Ok... I've made some progress so far!! I had the bright idea of re-doing 80% of the fuel line. I found some fittings to adapt the 3/8" steel tube to 6 an braided ss hose. I'm using the flexible hose with heat/abrasion wrap around it to plumb inside of the frame all the way from the collectors up to the fuel pump! That will virtually eliminate heat issues. I also cut out the scoops on my fiverglass rallye hood to let hot air out/cool air in.

My fuel pump has 1/4" npt in and out! Is this a serious restriction with 3/8 line??? Should I buy a mechanical pump with 3/8" inlet and outlet?

-Matt