Change the disc type seats back to standard . They are ok for stock engines , they are either open or closed as the standard ones will allow fuel in as needed the 2nd. the float drops a hair it allows fuel in , the disc type does not . I am sure others will have their opinions on this as well , but think 1st. in depth of how the 2 are different in filling the bowls as needed .

+2

Not very fond of that design myself. They make a similar deal for the q-jet. I was sent one by a guy who bought my book and went into business building and selling circle track full race units. He swore by that type of needle/seat assembly, and wanted me to test one, which I did. The testing ended abruptly when I got a nose bleed.....from bouncing it off the steering wheel when the car nosed over at the top of first gear on a hard run! So pound for pound one of those isn't as good as the stock type high flow factory .135" seat at the same fuel pressure.

Never tried one again, but the rumor is they will take much greater fuel pressure than the standard type needle/seat assemblies, and may be something that could work for lower HP applications. Certainly not up to par for a Pontiac 455 making over 500hp using a Q-jet on it........Cliff

When you buy the car. Even if your current power levels don't require it, you have room to grow. And if you are truely a hot rodder, that won't be long. 1/2 inch lines and pickup should be part of that equation.

If you drive the car a lot, and in hot weather, I personally feel an electric pump with a bypass regulator is the only option. Recently tried to 'get away' with an 80gph mech pump and 3/8 lines in the clone, felt it would be 'fine' with 375hp or so. Not. Fell down top of every gear, and less after heat soak on hot days. (Was going to go to 1/2 line, pickup, and mech RobbMC 550, but after thinking about it gave up and am going electric route. Need to change my gas cap too).

Adding a pusher pump to a mechanical setup I feel is a waste. You are adding another failure point, and complicating troubleshooting. And for no real reason.

At the track, it's a real good idea to have no less than a 1/2 a tank of fuel if you're running the OE tank with no sump. In most instances, that will prevent the pickup from being uncovered. Pulling the sock off and extending the pickup slightly is a good idea.

Time for me is becoming more and more precious, and I want to enjoy the cars I have. I really don't want to have to address the same problem several times, not to mention the money. I've proven to myself (in the driver) that the setup I'm going to won't have any problems, now, or if I step up power, so not wasting any more time and cutting to the chase.

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I would love to go to an electric pump; however 1) the noise appears to be quite an annoyance, and 2) when it fails, you're dead in the water without a mechanical back-up. Over the years, I have used mechanical pumps. I have had one fail (and my brother had one fail in his '69 Judge about 20 years later), but we both we're able to limp them back home. He has went on the electric route once, and the noise drove him crazy. With all the talk of the electric units failing at 500, 1000, 5000, miles etc, etc., I don't think the track record is what one would call stellar. My soon-to-be installed engine should be be 500++ hp and I would like to have a set-up where I could run mechanical most all the time, and be able to flip a switch (activated by full throttle pedal, perhaps) to run as needed.

I hear ya, though keep in mind, all new cars use electric pumps. And there are new pumps out there that are quiet. Can't use a blue or red holley, have to be selective when it comes to pumps, and that usually means the 'cheap' ones won't cut it.

The driver has had the same pump on it for like over 85k miles, like 6 years.

Once I get the system in the clone, I will do a youtube vid for it, and try to figure out some way to reference the level of noise. That should convince most.

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From a pure horsepower supported stand point, with EFI, folks are running 800-900 flywheel horsepower turbo LS engines on 3/8th lines.


As for electric pump noise, 75% of the issue is how the pumps are mounted. The best ones I've seen (or rather not heard) are mounted to boards with rubber isolators then the board mounted loosely (nylon lock nuts) to the car using another set of rubber isolators. This was with an Aeromotive A1000 and you could barely hear it with the engine off when the key was on. Didn't hear it at all when the engine was running.

Also, my experience is that camera and phone microphones seem tuned to pick up electric motor whine's and usually record the noise at a higher level than what you can actually hear standing there taking the recording.

I will keep that in mind! Wonder if there's a phone app that measures decibles?

Yeah, 800-900 on 3/8 line. Guess you can overcome anything with more pressure! But noted. Think I set the driver to 7-7.5 psi, which I believe is too much for a Q-jet. Think those are what Cliff, 5.5 or so is what they like?

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There is and I've used them, but the issue is a frequency (Hz) issue rather than a decible issue. The buzz I think it picks up is more in a frequency range most of us don't hear but the mic does and shifts into an audiable range when played back.

Don't get me wrong, I can hear the electric pumps in my cars, but it seems ten times louder on every video I take, and I've heard the same thing on other people's video's.

"I hear ya, though keep in mind, all new cars use electric pumps. And there are new pumps out there that are quiet." My 200,000 mile Chevy Blazer is on it's third in-tank electric fuel pump. Everyone once in awhile it gets pretty noisy, then quiets down. I'll change it when it decides to get REAL quiet.

"Can't use a blue or red holley, have to be selective when it comes to pumps, and that usually means the 'cheap' ones won't cut it." Agreed.

"The driver has had the same pump on it for like over 85k miles, like 6 years." Did it eventually fail? I could live with 85,000 miles. My mechanical is the original one for 1968 and is still running strong- about 100000 miles. It even ran for about 50,000 mile with a kink in it so bad that it would lay down after 100+ mph blasts.

"Once I get the system in the clone, I will do a youtube vid for it, and try to figure out some way to reference the level of noise. That should convince most." I'm all ears... and eyes. That would be greatly appreciated.

My experience is positive with a smaller electric pusher pump and factory 3/8" lines. Without the pusher (Carter P4070 electric....72gph) my 455 empties the qjet before I'm out of 2nd gear on a hard run. Flip it on and all is well as far as I've pushed things (deep into 4th gear). I rubber mounted it on a piece of aluminum angle that spans between my gas tank strap bolts....between the tank and the rear end. Yes, you can hear it run...off in the distance.....I have it switched so I can turn it off it so desired.
I installed it in May of 2008 and haven't had any issues with it. Miles? Somewhere between 10 and 15,000. In my case it seems like a better alternative than installing 1/2" lines.

The only q-jets that are fuel pressure sensitive will be those with the early float/fulcrum set-up, which means Pontiac, Chevy, and Buick units to 1968, and Old's/Caddy's to 1974. They will start to give troubles as early as 6 psi with the larger needle/seat assemblies in them. WAY better to run less pressure on those, down around 4.5 to 5.5 psi.

The later q-jets will take a lot more pressure, some Super Stock racers run 8-9psi, some even more than that by using smaller needle/seat assemblies.

In the 1975 and later Pontiac carbs, they are fine with a .145" seat to 7.5 psi, and that's using a float almost half the size that the 68 and older carbs use! That set-up will EASILY support upwards of 600hp. I've got a few customers over 700hp with that set-up, they all run larger fuel lines and at least 250gph pumps.......Cliff

tpssonic - That Holley HP 150 is still in there and running. It is a touch louder than it was when new, but it's still no where near as loud as any blue or red or black pump. It's quieter than the Mallory Comp 140 too. It probably needs to be cleaned well is all.

What I see kills in tank pumps is garbage gas, especially on work trucks that go on dirty work sites, like ones being excavated or something. And replacement ones, you need to be careful what you buy.

You can ask about the HP pumps, get other's who run them opinions. I swear they are the quietest pump I've ever heard (or not). I hear brand new OE pumps that make more noise, and those are in tank units.

I will do the write up, some folks over on the Olds sites could use some input on the subject too, sure they will appreciate it. I've done a number of these upgrades, so it doesn't take me long. I'm going to drill holes for the pump mount bracket, something I usually avoid, but for this car, makes sense. That's usually where the majority of the install time comes from, mounting the pump.

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The only vehicle that ever failed me on the road had an electric pump in the tank LOL!

That being said, out of 10 vehicles all the rest of them had electric pumps that worked just fine!

Tom V.

On the topic of pump noise, installing a bypass reduces the noise considerably. My Comp 140 pump is super-quiet with a bypass system, but got pretty loud after 15-20 minutes of operation when it was "dead-head". It also fried the brushes in a couple of months "dead-head". The bypass system was installed, and the pump lasted over 10 years before it needed a new set of brushes....FWIW.

In tank pumps seem to fail when the tank is very low/empty. I've had a couple quit in vehicles we've owned here, and every time the tank was pretty low....FWIW.....Cliff

Yeap There is a few aps out there for measuring db's

I've been thinking about doing this since my engine is on the edge. No problems with the stock system when running on the street, just at the drag strip. It launches fine and pulls hard through 1st but then gets soft in 2nd. I don't want the pump noise during normal driving (been there done that) and want to keep it looking stock under the hood.

But I don't want to hurt performance when the electric pump is not running, and a check valve in the bypass line would be an additional restriction. I've thought that a solenoid valve might be better since there would not be much of a pressure drop through it when pulling just with the mechanical pump. Or maybe enough fuel would also flow through the vanes so the check valve restriction is not an issue. Any thoughts?

I don't believe a check valve would restrict flow during normal driving. And having a throttle mounted switch that was only on during wot, you probably wouldn't hear the electric pump over the exhaust. And with this setup, the electric pump would only be on for a few seconds anyway

A proper check valve will have several times the flow area of a 3/8" fuel line and should not restrict the flow in any way. The sliding vane design on a Holley blue pump WILL restrict the fuel flow to the mechanical fuel pump if the pump is not turned on (unless you get lucky and the vanes are stuck in a more open position). If that happens then the pump does not move fuel worth beans. A blue pump is noisy as **** too.

Tom V.

I guess I could activate a relay through the downshift switch so that the pump always comes on at WOT. You are right that the noise would not be a problem then. And I would not expect fuel flow through the check valve to be an issue except when running hard.

Any recommendations on pumps and check valves for this sort of setup?

Check valve, I was thinking something like this:
http://www.summitracing.com/parts/sum-220193b/overview/

Not sure what you consider running hard, but at wide open throttle the check valve would be closed anyway when the electric pump came on.