[Formula jg]

Is it good practice to add a one way check valve to the fuel supply line?
If yes, what’s a good location near the tank or before the mechanical pump or between the pump and carb?

[TedRamAirII]

Your Fuel Pump already has check valves inside. What are you trying to accomplish?

[Formula jg]

I did not know this.
Had read somewhere it helped minimize cranking for vehicles that sit for periods at a time.

[pfilean]

To prevent long cranking after extended store time is especially a problem with the tri-power where there are three float bowls to fill. The check valve is done in parallel to an electric fuel pump at the tank so the electric pump can fill the carbs. This can also be done with switch over valves that are used in trucks with dual fuel tanks.

I use the switchover valve approach. After an extended storage time I run the pump 20-30 seconds, one pump to set the choke and it starts right up. No problem.

[steve25]

Why is it more of a problem with a tripower?

The 2 bbl has a much bigger fuel bowl then a Q-jet does, and the tripower only idles off of the center carb so that’s really the only one that needs to have fuel in it to get the motor running after sitting!

Also if sitting for extended times, and with how today’s gas falls apart into carb clogging crap so fast it’s better that the fuel bowls do go dry in a way!

Priming up any Carb that’s been sitting by means of pouring a small stream of gas down into the carbs fuel bowl vent slowly until the accelerator pump(s) are seen to work is the best way to gain a instant fire up out of the motor.

[Tom Vaught]

Originally Posted by steve25

Why is it more of a problem with a tripower?

Also if sitting for extended times, and with how today’s gas falls apart into carb clogging crap so fast it’s better that the fuel bowls do go dry in a way!

1) Tri-Power engines typically do not get driven daily like modern EFI Vehicles.

2) Tri-Power Carbs are made of Zinc material. Zinc Material from Rochester Products plant added to the carb castings to protect the zinc material. The bases are made from Cast Iron and were black oxide prepped by Rochester.

3) The carbs and engines sit in garages and the fuel over time slowly vaporizes into the surrounding air.

The white "Carb Clogging Crap" does not come from the fuel. It comes from the Zinc decay caused by years of use and by moisture in the gas from the engines sitting. The only way to delay that process is to have the carbs plated again with the Dichromate finish on the carb parts.

All of the old Pontiac carbs were made from Zinc except for the Carter AFB carbs which were aluminum.

That being said, I have posted about a fuel pump bypass circuit that allows the fuel to go around the electric fuel pump when the electric pump is not needed. Carter actually has a electric pump offering that uses that by-pass/ check valve circuit in marine applications. Just pay the money or rig up your own circuit. The Carter pumps are very durable. The Holley Red and Blue Vane pumps have a lot of issues with the vanes sticking if the vehicle/pump sits for any period of time. The red and blue small fuel regulators are barely adequate for stock use.

So back to the Tri-Power system. It is better to have liquid fuel around the inside of the fuel bowls vs have the bowls be totally dry (unless you had the carbs replated, the fuel shut off to the end carbs and the secondary linkage removed and the linkage only added for car shows. Basically you are then driving on a 2 BBL carb that you would like to have fuel in most of the time from daily driving. Aluminum carb parts can be anodized to protect their surface finish if done properly.

Originally Posted by steve25

today’s gas falls apart into carb clogging crap so fast it’s better that the fuel bowls do go dry in a way!

Again the "carb clogging crap" is not caused by the "Gas Falling Apart".

It is caused by the fuel (with water in it) attacking the Zinc material and causing Carb Zinc Material "Tooth Decay" which looks like a white powder inside the fuel bowls.

Tom V.

[steve25]

So no one but me has seen fuel break down into near clear Egg Yoke like gel in a fuel bowl before, because that is in specific what I was talking about.

[78w72]

Originally Posted by steve25

So no one but me has seen fuel break down into near clear Egg Yoke like gel in a fuel bowl before, because that is in specific what I was talking about.

does that happen in a couple weeks or ~a month that the OP is probably referring to when vehicles "sit for periods of time"?

if thats the case my cars should all have egg YOLK like gel in the carbs & fuel lines... some of them sit for 2-3 months without starting or driving & over winter storage they sit for 4-6+ months without starting... come time to start them they fire right up after a few seconds of cranking to get fuel into the carb bowl... been doing this for 10-20+ years with no signs of any gel in the carbs. just curious when/how this egg yolk gel happens in relation to cars sitting for relatively short periods of time.

i agree its a small inconvenience to have to crank them for a few seconds when sitting but i dont think a check valve will help much since its usually the fuel evaporating in the carb bowl &/or draining back to the tank in the lines before the pump.

[Tom Vaught]

Sorry but have never seen the egg yoke "gel" in the carbs.
Been playing with Tri-Powers since 1964 time frame.

The White Powder (like baking soda) powder is what I am referring to.
Maybe Jon Hargrove has seen that "egg yoke gel" in the past. Maybe he will respond to the question.

Tom V.

[Sirrotica]

Typically outdoor power equipment will get that gel being discussed during the off season. Usually takes 4-5 months to appear. One difference though is outdoor power equipment is typically a gravity fed fuel systems. The fuel float bowl is constantly wet.

If the carbs are pressure fed and the gasoline is shut off typically it evaporates leaving the white powder. If it's gravity fed it turns into a yellow gel that usually manifests itself in the float bowl as the gas ages breaks down, and goes stale. Any small orifices will be plugged up with the yellow gel.