Electric Fuel pump-vs- stock pump

[B.Mac]

I'm getting advise to "chuck" my stock fuel pump (200/ 2.4 w/ relieved exhaust) and install an electric pump. I run 80MPH @6100 w/ a 28P ChopperII and I have'nt noticed any lack of fuel @ WOT with the stock pump but I'm being told I have minimal (1-2 lbs) fuel pressure at WOT and I should have more. It's also been suggested that I prop down to a 26P and spin up to 7000 and increase my speed by 5-8 MPH. To be honest, I'm just short of freaking out right now at 80 and I've always been told to run that motor under 6200 if I want it to last. I'm strictly a recreational speed freak and I need to make my powerhead last forever (according to my wife, and my wallet). Any input is much appreciated.....B.MAC

[Raceman]

First, if you're turning a 28 in the low 6's now and drop pitch it's very unlikely that you're gonna pick up top end speed. As a matter of fact, for pure top end it's more likely that you'd pick up speed with a 30. I've never been an RPM junkie. Again, it's good for acceleration, usually bad for top end, fuel economy and longevity of parts. How was it determined by the advisor that you don't have adequate fuel pressure? If the fuel pump is in good shape it's certainly capable of feeding 6100 RPMs. A carb motor needs one thing from the fuel pump: proper volume so the float bowls don't run low. All they are is reservoirs just like the tank on a toilet. As long as they stay full, it doesn't matter how much pressure filled them as long as it's suffiecient to pass fuel INTO the bowl and not high enough to blow needles off the seats. With proper volume, the pressure within these two ranges is irrelevant.

[Liqui-Fly]

Sounds to me like you're running pretty good right now. If you do decide to go with an electric pump a Holley Red pump might be your best bet. This is if you don't have oil injection. Some say to drop the pressure down to 3 to 4 psi's while others say 5 to 6. I'm running mine unregulated and it puts out 5 psi's just like it's supposed to from the factory. The only honest upside to running an electric pump is not having to pump a ball anymore. Your motor would let you know if it wasn't getting enough fuel. LF

[mercrazy]

i prefer keeping things as simple as possible. some people don't. they like to add all the bells and whistles and love tinkering with all the complexities of their creation. if you periodically replace the pump diaphram, eliminate all fuel line restrictions, and run the engine in the suggested rpm range, the stock pump should be sufficient. if it wasn't, mercury would have used electric pumps to start with like they do on the hi-performance motors. the diaphram pump can't pulse fast enough at high rpm. but now if you want to start tweakin on your motor and turning higher rpms to see what it will do, you should get an electric pump. you're going plenty fast in that boat already and the first time you hear that knock, knock, knocking sound, you and your wallet will wish you had left well enough alone. unless you're actually racing where every mph makes a difference, the risk isn't worth the reward. i've been there - done that.
darn, i must be getting old. after reading over my reply, it sounds like some old miser's response.

[jody]

I have a 135 Mariner I run a Holley electric pump I turn my motor from 6400 with a 28p to 6800 with a 25p. I run it a 4 psi and have had no problems knock on wood. Just my two cents.

[us1]

The stock pump is fine for 6100 if you are going to turn a lot more you might want to change. I have to agree with Raceman the smaller prop will slow you down. If you want that motor to last just leave things the way they are.

[B.Leonard]

hehehe ;) That's a first!

Electric baby! Holley red/blue pump all the way. (Many other brands as well w/ regulators)

For one, I have to also disagree with Raceman. It is more than just volume and pressure. It's also the way the fuel is delivered. Is it pumped in erratic spurts that cause turbulence and air bubbles in the carb bowls or is it pumped in a controlled laminar flow pattern like an electric pump does?

It's NOT that much more complex for the piece of mind. Also, I'd like to see you use the stock pumps to empty your fuel cell in minutes flat when it needs to be removed from the boat for whatever reason!

I raced with Quadrajets for years. One of the most advanced carbs ever made. Every ignoramus out there said the bowl was too small. Bologny! The bowl was perfectly designed to hold a proper level under all conditions, it just couldn't handle the "spurting" action of a mechanical pump. It needs the smooth flow of an electric and then it works awesome.

-BL

[us1]

Sure there’s always something better, but a stock motor at stock RPM should run on a stock pump.

[B.Leonard]

Actually I do agree.

I tried to use the stock pumps on my 2.6XP for that reason. When I found out they were bad and it almost cost me a destroyed motor, I weighed rebuilding the stock pumps and dealing with soft bulbs and silly plastic valves with the piece of mind of a Holley red pump that can feed a 400-500hp big block on nitrous.

The choice was clear.

-BL

[Raceman]

I don't know how quadrajets behave with pulsing mechanical pumps and they may very well have to have excellent flow if the size of the reservoir doesn't have much reserve in relation to the requirements of the motor. Merc carbs do not fall into this category when meeting the requirements of a 6000 RPM stock motor. Also, fuel doesn't hold aeration to the extent oil or other heavier fluids might. 5 lbs of fuel pressure won't do any better than 2 lbs in a merc carb if the volume is sufficient. Also with proper volume, the needles will cycle through open/closed even at full throttle. This in itself will absorb mechanical fuel pump pulses somewhat.

[Raceman]

And one mo thing......the reason I don't have any experience with quadrajets is that REAL performance cars all came with Holleys, HaHaHa. (I can't make myself type LOL)

[woodco]

On all my stock V-4 and V-6 OMC motors we always ran electric
pumps instead of manual.Never had a problem with fuel flow or efficiency ( what's that word ) , I guess it's up to the individual to make their own choice but one thing I did change was the bypass
of the oil injection pump.

[Techno]

One advantage is no more squeeze bulb, this is almost worth it all by itself.

Raceman, which 'Vettes came with a holley? The only one I can think of is the race version that was incorrectly listed as 430HP and actually put out around 650HP.
Notice that holley copied the spread bore concept.

[woodco]

Never found a Holley that was dependable.You could never keep them tuned. " Just my opinion " or should I say " Past Experiences " :p

[B.Leonard]

I knew that one was coming! ;)

The main disadvantage of the Quadrajet was that it was either on the primaries or wide open. Partial secondary usage is poor because the butterflys for the secondaries are so large they tend to redirect air flow at less than wide open positions.

It is true though that a larger bowl will give the fuel time to "calm" down.

-BL

[Talon2.5]

i run an electric pump it's a 7 psi one from discount auto parts but when i can i think i'll run the holley red pump, ive got a buddy with a canary yellow vector and he still has the stock pump running low to mid 6's on rpm, but says he can get 7 and hasnt had a problem.

personal prefference i guess, i like the electrics though, as b.leonard says it's nice to drain the tank with, and thats also where i get my weedeater fuel hahahahaha

later, skip

[Rickracer]

Holley Red, and no more da#$ bulb to deal with. :cool:

[B.Leonard]

The cheap crimps they use fail to keep a tight seel after the plastic/rubber starts to shrink a little. You can replace them with clamps to keep air out or to keep them from leaking but then the plastic fittings collapse and the valves come apart. I had one that came apart and the valve reversed in the bulb clogged the line completely. Had to dissable the thing on the water to pouring gas everywhere to get back. What a joke!

-BL

[Raceman]

Techno, you're right, the L88 was WAY underated at 430 HP. I've got a factory original '69 L88 that was a local car when new. After years of searching I found it in 1987 and restored it having it part of the L88 reunion at Bloomington in 1988. To answer your Holley question, Small blocks: all 350 and 365 HP 327's, LT1's, 64-67 300HP (not to mention 67-70 Z28's) Big blocks: 65 396, 66-67 427/390, 66 427/425, 67-69 427/435 (tri powers), 67-69 L88, 69 ZL1, 71 LS6. Also all the special high performance Camaro's, Nova's and Chevelles of every year made (396/375) 70 LS6 Chevelle, and some 325, 350, & 360, horse Chevelles too, but can't remember which years specifically without huntin' a book. Generally speaking, anything Chevy made with solid lifters after '63 had Holleys with the exception of the 409/425 which had AFB's up through the end of the run in early '65.

[Glenn]

I’m no expert to be sure but for what it is worth I’ve had no trouble since switching, on the advise of a few hear, to a Holley Red pump. One of the earlier owners of my boat/motor combo switched to an electric because he kept blowing the diaphragms on the stock pumps (I know this probably isn’t good). Unfortunately that electric pump was one of those diaphragm jobs and just wouldn’t flow over 6000. Incidentally, 6100 RPM as US1 stated is where the old pump I had would run out of breath. I’ve had no trouble and have been able to twist that motor faster without a hint of trouble since switching. I was lucky I didn’t blow the motor.

PS: As far as what Vettes came with Holleys…. I could be mistaken but didn’t all of the mid year (63-67) Vettes come with Holleys? Flat Out…correct me if I’m wrong…


Glenn

[Way2Fast]

You took the words right out of my mouth !!! I was just getting ready to answer the Holley question.....and I read your reply. You answered it for me. I might add that the only car I have seen that performed well with a Quadrajet was a buddies '67 442 Olds. He gave my '66 350hp Vette a run for the money. However, if I remember correctly he had modified the carb.

[B.Leonard]

I like Holleys.

I need to switch to a square hole carb on my 427 Galaxie. It's setup for a road course and spread bore carbs don't cut the mustard there. You can't feather the throttle enough out of the turns.

Spreadbores are made for primary use and then WOT, nothing in between. They make good carbs for drag racing/street. I need to switch to something like an 800 dp.

The nice thing about Quadrajets for street is that a few years (mid to late '70s) they were made with externally adjustable main circuits. You could adjust the mains up or down 2 jet sizes without opening the carb.

Also, the primaries on those models have up to 5 stages for more precise mixture control. Very hi-tech for a carb but then again only on the primaries. Mercedes Benz even copied the design to use on their cars back in the 70s.

-BL

[Techno]

Not to go completely of the subject, but WHAT?
Mine runs just fine at any throttle setting. But like any 4 barrel if you open it up it usually isn' t part way.

And to bring it back to boating.
The reason I got my boat was whatever I did to my car the speed limit kicked in too early.
Not a problem with the boat.

And in the time it took me to write this I'm way down the list.

I guess my modified Q-jet don't count. adjustable primaries like you said but bored to 800. I suppose a little overkill.
But on the other hand my caddy runs fine with it(stock Q-jet), The loudest noise it makes is through the intake- and it has a muffled intake with a lead lined cover.

was the L-88 mecahincal cam, no vacuum advance, lower hp,and higher compression? The other 427s didn't jive with what that one had, and at a "lower" HP.

[Raceman]

Glen, the 63's didn't have Holleys. The 300 HP and 340 had AFB's. The Fuelie was rated at 360 that year. I can't remember what the 250's had, I've never owned one. Presently have a fuelie roadster and 2 340HP coupes. In 64 they went to Holleys and the big solid lifter carb motor was 365 for the first time and 375 for the fuelie. Actually the 63 motors were the same as the 62's, the first year for the 327 in the Corvette. There were more differences than just the carbs. The 365's had different camshafts, and bigger valves than their 340HP predecessors.

[Way2Fast]

The '63 Vette 250hp had a small AFB. I don't recall the cfm. I had a Sebring Silver split window coupe with 250hp, wide ratio 4 speed. 308 rear. Was really great on gas but fell on it's face when you hit 2nd gear.

[Talon2.5]

ok since the car thing has arisen, i finally get to post a pic of my old flame before the boat thing hooked me, as usual built it myself and re-did the car to in the next post

skip

[Talon2.5]

heres the car, the color was mixed out of stuff my friend had laying around and then clear with blue pearl was shot over it to give it the final color, at this point in time i did not paint the car but did all the body work and welding and re-assembly, i guess i should have kept it but life goes on :(


skip

[Raceman]

Damn, I LOVE 55's Skip, and it's one of the few cars I've always wanted that I've never run across the right one. That front pan's cool too. You're right, you should've hung on.

[B.Leonard]

I can't believe you let that go! Sweet lookin car!
I'll never sell my Galaxie. My boys will get Dad's car and I'm sure they'll find a big oak tree for it sooner than I'd like to think ;)

-BL

[Flat Out]

They will all work well when used properly. Too big is worse than too small. Having the correct linkages,fuel lines, ignition system all need to be right. I had a Corvette restoration shop for 5 years.Still have a '65 Convertible w/327/365 hp motor. When we rebuilt carbs they were flow tested and adjusted. The right carb on the right motor worked like magic.327/250s had Carter WCFB carbs. Carters, Holleys and Rochesters are all good. So much depends on how well they are set up and how well the rest of the motor is.The 'Chester is probably one of the most undrated carbs.With the right carb you can feed a hungry big block they will flow 800 cfm.Old cars are lotsa fun too.