wildstar

I have an '84 TA with an Edelbrock 600, The engine appears to be stock. I plan on this being my daily driver.

I just had the carb rebuilt and the shop owner (only shop in LV that rebuilds carbs) said I need to switch to a mechanical pump. He said that electric pumps deliver too much pressure to the carb at lower RPM's which can cause problems.

I like the idea of going mechanical because the existing pump is poorly wired and there is no return line. I also like the simplicity of a mechanical pump.

But I've also read that Edelbrocks prefer around 6 PSI and the mechanical pumps vary from 2 - 6, depending on RPM.

Which arrangement would be best for my setup?

Night rider327

iTrader: (13)

Edelbrocks do not like more than 5.5 psi fuel pressure. Over that and it pushes the needles out of the seats and floods out.

Mech. or elec. pump don't matter, it's all about the pressure and volume. I have had to put dead head fuel pressure reg. on with mech. pumps and eddy carbs in the past. Alot of the performance mech pumps put out 6-7 psi and again that's too much for the edelbrock.

What type of elec fuel pump do you have and where is it installed?

If it's one of those uni fit inline square pumps they are not very good, they do not have much volume. Most are under 40 GPH.

I recommend atleast a holley dead head reg. with all edelbrock carbs. It's just safer/better that away. I set mine to 5.25 psi

wildstar

My pump looks a lot like the Mr. Gasket style pumps that they sell at the parts store. It's cylindrical shaped inside a housing that is bolted to the wall between the seats and rear axle. I had the carb rebuilt because occasionally, fuel would pour out of the front float bowl. I figured it was debris not causing the needle valve to seat, but maybe it was fuel pressure like you said.

Based on what I'm hearing, I'm leaning on going mechanical.... If I keep the electric I'll need to install a relay (currently hard wired to the ignition circuit) and that's just more things that can possibly fail, not to mention more wiring and splicing.

I want this to be as safe and simple as possible. So even if the pump is rated below 5.5, you think I should install a regulator?

Joe Tag

iTrader: (4)

I use a Carter m6626 fuel pump. 120 GPH with a return like the stock pump an 84 would have come with.(you will need the return to keep fuel boil from happening) It runs as high as 6.5# so you will need a regulator. Using a Holley 12-803 deadhead with mine set at 5.8#. No fuel smell or flooding.
http://www.summitracing.com/parts/crt-m6626other
Some other parts that would be a good idea to have.
http://www.summitracing.com/parts/ctr-85-000 makes a nice connection to fuel line.
http://www.summitracing.com/parts/edl-9266
http://www.summitracing.com/parts/sum-g1532 Good for insulating from engine heat, which Eddys are very intolerant to.

Night rider327

iTrader: (13)

Get a fuel pressure gauge and check to make sure. Don't just base it on what they say the pump, pumps at.

You can get an actron fuel pressure/vac gauge for $20. Great tool to have around. You can check your fuel pressure plus engine vac with it.

If you have the pump that I think you do, yes get rid of it, go to a mech or even a better elec.
The type I think you have is like this http://www.summitracing.com/parts/mrg-12s/overview/
Those are only 35 gallon per hour volume. You should have at least a 50 GPH pump on any stock V8 engine, and if it's a performance engine or ran hard then you need even more. Common volume for a 350-400 HP engine is 90-120 GPH pump.

Now if yours happens to be like this one http://www.summitracing.com/parts/mrg-95p/overview/ it's fine to keep using. Just check your pressure and install a reg. if over 5.5 psi.

Do not use the cheap round with dail type mr gasket or spectra fuel reg. They are not as good. Use a holley deadhead like Joe Tag mentioned

wildstar

I bought a holley pressure regulator (4.5-9 PSI). It looks like this:

http://www.speedwaymotors.com/Holley...9-PSI,382.html

Very purdy.

Where is the best place to mount it? I was thinking against the strut tower wall. There's not much space for a drill but I think I can make it work.

I still have not found the right pump. It seems like there's not much middle ground. The stock pumps are rated at 23 GPH and the next highest are around 90.

Night rider327

iTrader: (13)

That's a good regulator. Pretty much the same one I run.

I have mine mounted on the pass. side strut tower. I'll post a couple pictures.

Are you looking for a mech. fuel pump for sure? If so then you got a couple of good options. '

1979 corvette 350 has a 55 gph mech. pump

Stock replacement for a 1970 or 71 camaro Z28 LT1 350 v8 is a great one. It's a stock 80-90 gph pump. It does have 3 lines though. You can run the return line or just cap it off.

I ran that 70 z28 LT1 pump on mine for a long time and done great untill I got in to the low 12's 1/2 mile. Then I added one of the small elec pumps with it to act as a helper pump and that done good down to like 11.70's or so at which point I was out running the fuel volume at the top end of the track. My pressure dropped off alot .

So then I went to a carter speedway series pump that's 172 gph free flow.

Remember you can not have too much volume, but you can have too little. Having a 100 gph pump will not burn any more fuel, run any richer, or cause any probs.

Having too little of volume can cause you to run out of fuel supply to carb, and run lean

Here's 5 pics over the course of 8 years or so. 1st couple is with an edelbrock carb, and last ones are with a holley carb

Joe Tag

iTrader: (4)

Something to think about on plugging the return. In 84 the fuel supply lines to the pump are ridiculously close to the exhaust, much worse with headers. You will want a return of some kind to circulate more fuel to keep it cool. That's why they put them there. I would get fuel boil when it got above 80* ambient temp until I used the return. (tons of threads here about it too)OP lives in vegas? I foresee problems. The carter pump I linked has the return and no shortage of flow. Quality pump and dirt cheap at $20.

wildstar

Hopefully my last question. At the very top of the instructions, it reads in bold: "12-803 is not to be used with mechanical fuel pumps!" Should I be concerned about this?


Thanks for all of your help. I feel like I get a lot more out of this site than I put into it.

Joe Tag

iTrader: (4)

FWIW, I'm using that very regulator with the carter mechanical pump I listed with no issues for about a year now. You can spend $100 for the 12-704 holley recommends for a mechanical pump if you wish.

Night rider327

iTrader: (13)

I just looked to make sure. Mine is a 12-803 as well.

I 1st put it on in 2004. It was ran with the stock replacement 1970 camaro z28 LT1 mech. pump untill 2005.

Then I installed one of the small 35 gph elec. pumps in rear as a helper pump, along with the same '70 LT1 mech. pump

Then in late 2006 replaced the 70 LT1 pump with a carter speedway 172 gph mech. pump and have ran it ever since.

Same 12-803 reg. for 10 years with 2 diff. mech. fuel pumps

wildstar

(Sigh)

It seems like my regulator has a leak. When I pressurize the fuel system, fuel leaks out of the little recess by the adjusting screw. It even leaks when the locking nut is tightened down. What am I doing wrong?

Joe Tag

iTrader: (4)

Nothing you could be doing wrong to cause that. You should be able to remove the adjuster screw completely with no leaks. I would guess it's a bad diaphragm. Bum luck but sometimes stuff is bad right out of the box.

wildstar

So I emailed Holley's tech service to report the problem. I even offered to mail it to them, so they could have a look at it.

They said the same thing, probably a perforated diaphragm, and that I should just return it.

I was surprised at their casual response. Products that leak fuel could result in reputational risk and/or liability, esp. if the problem is systemic.

I'm tempted to open it up and look for myself.

Joe Tag

iTrader: (4)

With the amount of fuel leaking it's probably just a pinhole, you'd never see it. I believe there is a metal plate riveted in where the adjuster contacts the diaphragm and the spring on the other side, could be just a bad seal there. Open it up and you risk being refused to return it. Return it and get another. Odds are slim it will happen again.

wildstar

I exchanged my regulator today and the new one seems like a winner. I also got my Carter m6626 today. Promised the wife I won't do any work on Thanksgiving.

Is it OK to use elbows to better direct some of the fuel lines? I wanted to use one at the pump outlet, and maybe one from the regulator to the carb. I was concerned that the sharp angles might cause problems.

Night rider327

iTrader: (13)

Tight radius fittings are never great on a fuel system but it also depends on what you are 'feeding'

Stock or mild built 305 or 350 will probably never notice a diff in using even 90* hardware store fittings, but a 6500 RPM 450 HP engine would be a diff story all together.

Also never use tight radius elbows with a nitrous system

wildstar

I installed regulator # 2 and the mech fuel pump over the weekend and it seems to run pretty good. I settled on a Mr. Gasket fuel gauge.... the needle dances around a lot but I set it with an upper limit of 6PSI.

That's right, my carb is actually a Holley 600 - not an Edelbrock.... can't believe I was that stupid, ignorant, blind, _______, ......

I have a new problem though. I can't find an elbow to thread into the outlet port on the fuel pump, so I had to use a strait barbed fitting. So the fuel line actually runs around the outside of the lower coolant hose and dangerously close to the crankshaft pulley. I can't drive it in this condition.

I've looked all over town for the right fitting with no luck. It seems like it's slightly smaller than 3/8th. What type of fitting does it take and where can I find one?

Here's a photo of the plumbing.

F-BIRD'88

If you want to use a electric fuel pump on a carbed motor with a edelbrock carb,
Use the Carter P4070 pump. It does not need a fuel pressure regulator. its 5psi.
remove the in tank efi pump.. Use a common 3/8" fitting paper element in lime fuel filter
before the fuel pump. They run quiet if correctly rubber isolation mounted.
Use 3/8" fuel line and hose fittings.
rated 70GPH free flow. They flow enough at the working pressure 4-5psi to feed a 500HP engine
pretty simple