Measure point for fuel pressure

[dandascott]

I am currently doing the plumbing for my 427 side oiler. It has 2x4 arrangement. I have a Holley "HP-125" electric pump at the fuel tank pushing fuel thru a 3/8" stainless line. This terminates at a Carter Mechanical pump at the engine (inlet is 1/4" NPT). From here it splits into the 2 carbs.

I would like to add the functionality to measure fuel pressure but I am not sure where is the most useful location. Is it right before the inlet into the mechanical pump ? or perhaps before the outlet from the mechanical pump splits into two ?

Suggestions ?

[priobe]

I am sure others will chime in.

I dont understand why you want to run 2 pumps. The rating on the Holly should be more than enough supply for the carbs. If you are running them in series the mechanical pump will restrict the Holly pump.

If you are running them in parallel then they should be the same exact pump.

As for the pressure reading I would measure the pressure right before the carb. You should be interested in how much pressure the carb is getting.

If you put the gauge before the mechanical pump you will only have a reading from the Holly pump.

[Danr55]

Aren't you asking for trouble by using two fuel pumps? That doubles the opportunity for failure. If one of them fails, the other will be useless anyway. The electric won't push fuel through the mechanical and the mechanical won't pull fuel through the electric. What's the point?

All of that aside, I agree with Priobe. Your main concern should be fuel pressure directly in front of the carb.

[dandascott]

Thanks for the input. I am far from an expert on fuel plumbing. The logic was that the electric pump would keep the mechanical pump supplied with a more than ample fuel supply, the mechanical pump would only need to distribute the flow at a hopefully even pressure.

I am sure what you have described will work fine, what I have is probably overkill.

Thanks,

[patrickt]

The liquid filled fuel pressure gauges (such as my Russell pictured below) are notoriously unreliable when mounted on the engine. The pressure change inside the gauge, because of temperature fluctuations, will give you inaccurate readings. The first time you experience this it will throw you for a loop, but the FordFE Forum is replete with liquid-filled gauge stories and, once you get used to it, it's not so bad ... and best of all it still looks nice. Seriously though, after a while you can kind of figure out why it's reading what it's reading and now you'll know why your engine seems to be running just fine with no fuel pressure whatsoever!