[Chris65LeMans]

All,

After my 435 blew up earlier this year, I ended up going with a freshly-built 461 from Kauffman. It it done, broken in, dyno'd and on a truck for the journey out to me now. (FOUR months ahead of schedule!!)

It dyno'd at 498 hp and 581 lb of Tq, The carb will be a Prosystems 780 HP.

The engine will arrive with a Fuel pump block off plate installed. Jeff recommends either a Holley 110 GPH mechanical pump or a 180 gph electric pump.

What sort of opinions are out there on mechanical vs. electrical?

Thanks, Chris

[steve25]

With that many cid and HP, either pump is a moot point if your tank has the stock size pick and also if the rest of the fuel line is the stock inadequate size going to the front of the car!

[78w72]

depends on what your plans for the car are, if drag racing or hard auto x'ing then electric is best, in tank electric is even better.

if only light racing/mostly street then you can get by with a mechanical. i would suggest robbmc over a holley any day though, or even the edelbrock 1713 over a holley. i havent tested a holley but did use the edelbrock on my 467 stroker that made 520hp on the dyno with no tuning at all, just a cliff built q-jet & sun tuned GM HEI. in a 72 firebird with stiff suspension the E-pump went 12.2 but had pretty bad starvation issues, edelbrock says it supports "up to" 600 hp but that is obviously standing still on a dyno. the robbmc 1100 i have now has ran a best of a high 11.2 but still has some occasional cut out issues but is dialed all the way down to ~7-8psi. both pumps had a 1/2" pickup & full 1/2" lines from tank to pump & pump to carb.

so really comes down to the cars purpose, if i had it to do over again from the start i would have went with a in tank set up & still considering that if i cant get the mech pump to work right.

[Tom Vaught]

Originally Posted by Chris65LeMans

All,

After my 435 blew up earlier this year, I ended up going with a freshly-built 461 from Kauffman. It it done, broken in, dyno'd and on a truck for the journey out to me now. (FOUR months ahead of schedule!!)

It dyno'd at 498 hp and 581 lb of Tq, The carb will be a Prosystems 780 HP.

The engine will arrive with a Fuel pump block off plate installed. Jeff recommends either a Holley 110 GPH mechanical pump or a 180 gph electric pump.

What sort of opinions are out there on mechanical vs. electrical?

Thanks, Chris

Could you explain why you need such a large electric fuel pump on your 500 horsepower engine?

For example a 200 GPH electric fuel pump from Holley (a Dominator Electric Fuel pump) will support 2100 carb horsepower.

https://www.holley.com/products/fuel.../parts/12-1800

That is over 4 times the HP of your Dynoed engine.

Please share why you need such a large (180 GPH) electric fuel pump.

Tom V.

The old Holley Blue Pumps were rated 110 gallon/Hr but that was FREE FLOW, (NO RESTRICTION IN THE SYSTEM) AND WAS
grossly overrated. The New Electric EFI type Pumps have far more fuel delivery capability.

[78w72]

Originally Posted by Tom Vaught

Could you explain why you need such a large electric fuel pump on your 500
horsepower engine?

Please share why you need such a large (180 GPH) electric fuel pump.

Tom V.

kauffman recommended that pump, hes just stating what they said.

[Tom Vaught]

OK Thanks. I would talk to a few Electric Fuel Pump suppliers like Aeromotive and
the Holley Guys for your street Carburetor application. Would not like to see a carb fire
from the needles and seats being over-powered.

If you stay with that pump get a very good fuel pressure regulator.

Tom V.

[Chris65LeMans]

Car will be street driven only. Good points on the fuel lines - we’ll have to look at them.

[tom s]

Carter street pump is all you need.Tom

[78w72]

Originally Posted by Chris65LeMans

Car will be street driven only. Good points on the fuel lines - we’ll have to look at them.

for street use only, a good mechanical will be fine, nice simple dead head set up & the E-pump & robbmc can be ran without a regulator on carbs that can handle ~6-7psi. the 1100 will dial down to ~7psi & the 550 is preset at 6.5-7psi.

the only real benefit of electric for a street car is easier starting after sitting for a week or so, but even with a mech pump i just need to crank it over for 3-5 seconds 1-2 times to fill the little q-jet bowl & it fires right up. probably wont be an issue with a holley though & less chance of starvation with the 2 big fuel bowls.

[78w72]

Originally Posted by tom s

Carter street pump is all you need.Tom

im sure the carter is a good pump, but when i was researching mechanical pumps what i didnt like about the carter is its states "stock flow" on summit & doesnt say a real GPH, do you know what its rated at? id imagine its listed on carters website but i didnt get that far when using summit to compare pumps & picked the edelbrock that states GPH of 110 & a claimed HP rating of up to 600hp. both robbmc pumps beat that number by a pretty big margin.

https://www.summitracing.com/parts/c...SABEgKxVPD_BwE

& after looking at robbmc site they compare the 550 to the carter, looks like carter is about the same 110gph as edelbrock, but the 550 beats it pretty bad in free flow & even worse at 4.5psi.

https://www.robbmcperformance.com/pr...ontiac550.html

[tom s]

my 434 with a pair of 750 NASCAR AFBs has never had a issue with the Carter street pump.I have a elect on a switch from when I raced the car and it comes in handy for priming after the car sits for awhile.I have NEVER turned it on with street driving.FWIW,Tom

[i82much]

this carter:

https://www.summitracing.com/parts/c.../gto/year/1970

is rated at 120 GPH and keeps up with no problem on my 505 with street tires through third gear. Add slicks, a good launch, and keep it up for a full 1/4 mile, maybe not. But I have driven the car hard on the street and the Carter has been great.

If I were going electric, I would use a gerotor pump just for the noise factor.

[389]

Sump the stock tank or get a 15 gallon RCI aluminum fuel cell put it in the trunk. Then run another 3/8" line next to the existing 3/8" line. If there's no return line I would put that in too. Run 1/4" for that. Connect both 3/8" lines to the sumps two ports and run them as close as you can to the fuel pump, then run hose between the tubing and the fuel pump with a three way tee screwed into the fuel pump. The Carter mechanical fuel pump is amazing, that is once you get it fed. A engineer friend I know suggested this over one 1/2" fuel line. He said the rules change when your pulling liquid as opposed to pushing it.. The two 3/8" lines would be perfect...
I did this to my old 64 Pontiac and wow what a difference!.

[421mike]

Times 2 on the Carter. Mike

[Tom Vaught]

This might help to understand the carter fuel pump by-pass circuit.

Tom V.

[mchell]

Originally Posted by Chris65LeMans

All,

After my 435 blew up earlier this year, I ended up going with a freshly-built 461 from Kauffman. It it done, broken in, dyno'd and on a truck for the journey out to me now. (FOUR months ahead of schedule!!)

It dyno'd at 498 hp and 581 lb of Tq, The carb will be a Prosystems 780 HP.

The engine will arrive with a Fuel pump block off plate installed. Jeff recommends either a Holley 110 GPH mechanical pump or a 180 gph electric pump.

What sort of opinions are out there on mechanical vs. electrical?

Thanks, Chris

Heat soak and vapor lock are real when using mechanical pumps…and I’ve done a lot of monkeying around with mechanical pumps.

There are plenty that swear they have zero issues with mechanical pumps. Just not me.

If you can’t stand the noise an electric MAY NOT be for you.

I choose an electric ….

[Skip Fix]

Assuming the Prosystems is a Holley type, dual bowls dual inlet?

Pushing that same in HP in my Q jet powered 455 I could not get any mechanical to feed it , but that was before RobbMcs came out.

[59safaricat]

My opinion is to use both.

Electric fuel pump to fill the carb(s) prior to starting for quick starts, cold or hot. External electric fuel pumps inherently have very short lives so using one full time isn't advisable.

Mechanical pump for the street. The electric fuel pump can be used as a backup if the mechanical fails but you'll need to add an adjustable fuel pressure regulator....which isn't a big deal.

I'd also vote for a return line to eliminate any vapor lock issues. Some A/C cars came equipped with them and you'll need to source one of those sending units that comes with an extra port for the return.

[AG]

Originally Posted by 421mike

Times 2 on the Carter. Mike

This X3, it's all you need.

[Tom Vaught]

The Only Mechanical Fuel Pump (that might have had that flow capability) IN MY OPINION) was the Ken Crocie 6 valve chevy fuel pump modded to work with a Pontiac Eccentric Arm.

And that was written up years ago in a magazine.

Tom V.