carter comp fuel pump
 

Im using the same mechanical carter comp fuel pump from probably the 90's. I bought a auto gage fuel pressure gauge and 4an line kit since I had no idea what I have for pressure. I started it up and it read like 8.75 psi. After I ran it for awhile it slowly crept down to about 7.5. Anybody using this pump and what do you have for pressure? I would think if the gauge was accurate i would have flooding problems if it were really 8.75 psi. I havent had a chance yet to go out and make a pull and see what it goes down to.

That's about right. Most of those types of pumps designed for use without a regulator will put out 7-9 psi.

I have one similar on another car with a mechanical fuel pressure gauge and on first start up it's 9 psi. As it builds a little heat it'll loose about a pound to a pound and a half and stay there.

Most decent needle and seats won't have an issue holding those pressures.

That's pretty much what I prefer to see on these mechanical pump deals. When you have a stock pump that only shows 5 or 6 psi you can imagine what it'll be when things get warm, and what issues that will cause.

OK thanks. Didnt know if something was up with the fuel pump or the new gauge but it sounds like its normal.

It's not so much a question of decent needles and seats it's the diameter of the hole in the seat.

The bigger the hole the less pressure it takes to open the neddle due to the increased surface area.

A small neddle and seat even through it flows less fuel per minute, will stand up to more pressure.

Another important consideration is that the less pressure you are able to run, the less airation will take place with the fuel as it's dispensed out of the needle, especially if the type of needle(s) that hang off the air horn of the Carb.

Fuel that has air in it will not only boil off faster out of the Carb, but at full throttle and high demand rates lean out your air to fuel ratio at the time when it can do the most damage to the motor!

Many times with a Carb when crazy rich jetting is needed at fuel throttle, yet the O2 sensor reads lean, this is the reason why!

Yep, the Summit high pressure and Holley high pressure pumps all show about the same thing that Carter Competition pump does. It'll work fine that way.

Its a 7040267 Qjet that Cliff did so I dont know if its a stock needle and seat or not.

At wide open what would you say you dont want the psi to go under?

As a point of comparison, I use a Mallory 140 in my race car with 9 psi at idle and it goes down the track at 3-4 psi at WOT without any hesitation or lean condition.

If it stays at 4-5 in most cases it would be fine. If it goes under that I'd probably look at things since you're running a Q-jet. I'm sure Cliff put a quality needle and seat in there and likely something that flows a little better than stock.

Even with that said, I know others, and AG just commented on it, they make full 1/4 mile passes with pressures down to 3 psi and not have a problem. A friend of mine had that going on not too long ago with a RobbMC pump and 1/2" lines with a large pickup in the tank. Running a Holley carb, which tends to mask the issue, and his car never laid over. But it's still concerning. He eventually changed the whole fuel system around.

Mine is 23 years-young, feeds two Carter 625 CFM AFB's at 7.5~8 psi.

Jon

I've used the Carter Hp mechanical in 4 motors and all work well. I have one in my brother's 464 with 530 Hp and it works great without any lean spots at WOT and using the stock 3/8" fuel lines.

edelbrock makes a pump similar to the carter, i used it in a 467 for awhile & it runs right at 6.5-7psi. worked great on the street at WOT but had issues at the track at upper to mid 11's with good traction. i converted to robb mc with big lines & pickup & it was much better but still has issues on some low 11 runs.

Mine would not keep up on my 455 with a Qjet running low 12s.

A little off topic but are the carter pumps clockable? it looks like it may but i want to be sure before i take a new pump apart.

I'm assuming the carter pump is manufactured the same as my old one which is clockable. I have a current 1100hp robbmc pump new in box and they don't come with the adjustment screw anymore...you have to use a regulator.

the 1100 isnt adjustable anymore? thats a nice feature to have, the FAQ section of the website still mentions that its adjustable & a reg is not always needed. but i do notice the current spec on the pump is 12psi, used to be 14 on the adjustable one.

No vapor return line on the carter so i put the robmc in.big improvement.

Yep patterned off the same Holley pumps, as mentioned Edelbrock makes one, and Summit also sells their brand of the same thing too that's relatively inexpensive. They are all rated about the same 110 GPH and 8 psi.

They are non adjustable now to keep the price down I was told but do come standard with 2 outlet ports where it used to be a additional cost.

I finally took the car to the track last night. Was very surprised to see the fuel pressure gauge not go below 5.9 to 6 psi at WOT. Made a couple of highway pulls on the way there,,,same thing, Im assuming the new gauge is accurate. Warmed up it idles between 7 and 7.5 psi. I guess the old carter HP pump, is doing ok.