[uneasyrider]

I have a 461cid putting out 500hp and 562ftlbs. I’m looking for a new mechanical fuel pump for it. I can’t find the receipt for the old one so I don’t remember what brand it was and it worked great. It’s feeding an 850cfm Q-jet. Anyone have a suggestion on a good pump?

[1968GTO421]

I prefer the RobbMc fuel pumps. They are rebuildable. They come in two sizes, 550hp and 1100hp. The first link is the 550hp one , second link is the 1100hp one.

http://www.robbmcperformance.com/pro...ontiac550.html

http://www.robbmcperformance.com/pro...ntiac1100.html

Home for RobbMc---- http://www.robbmcperformance.com/products.html

[Jim Moshier]

I was thinking about running the RobbMc Gen 2 Powersurge so I can use the stock mechanical to supply the fuel and still be quiet.

[RocktimusPryme]

If you are dead set on mechanical I will second Robb Mc. If you are going to do any racing I would go straight to electric. I’m sure it’s beating a dead horse, but it’s so much less of a headache.

[TCSGTO]

The RobbMc 1100 is the highest flowing mechanical pump at higher output pressures made for a Pontiac bar none.

[AG]

My brother's car makes 530 Hp and uses a Carter 120 GPH mechanical pump with no fuel starvation issues.

[tom s]

I use the Carter street pump with no issue.Tom

[uneasyrider]

That’s why I will never leave this site, always get a good answer and usually promptly. Thanks guys! 👍

[78w72]

Originally Posted by AG

My brother's car makes 530 Hp and uses a Carter 120 GPH mechanical pump with no fuel starvation issues.

does he run the car at the track? what are the times? im about the same HP level & doing low 11's & the carter/edelbrock type pumps definitely had starvation issues at those times with a q-jet carb.

[78w72]

Originally Posted by tom s

I use the Carter street pump with no issue.Tom

on the street?

the carter/edelbrock pumps will be ok on the street at ~500hp, its when you get to teh track with good traction & get into the 11's that the issues can happen.

[tom s]

Is this not the street section?Tom

[tom s]

FWIW,the engine in my 63 lemans was a 550 HP 421SD and had no issues at the track with 2 750 AFBs with the street pump but was being pushed by a electric in the back.The electric was only used to prime or at the track.Tom

[Formulajones]

I haven't had huge success with mechanical pumps when approaching the 500hp mark.

Using bone stock pumps and fuel lines, I've gone mid 12's at 108-ish mph with a completely stock fuel system and ~400hp. But as the car makes more power it's not enough.

Using either a holley aftermarket mechanical pump or a RobbMC would get you by at 500 HP on the street but I wouldn't expect stellar performance at the track. I've done the Holley pumps and they are "okay". Friends have used RobbMC mechanical pumps to 11.30's at 116+ mph with bigger 1/2" lines but report low fuel pressure at the end of the track (less than 3 lbs.) Not ideal.

As mentioned, if racing in mind, even just once or twice a year, I'd recommend an in tank electric setup, even on a street cruiser. OEM reliability and excellent fuel supply under all conditions.

I recently went through 3 Carter stock replacement mechanical pumps before I finally got a good one that ran the car more than 3 miles from the house before it died on one of the vehicles here LOL So I'm liking the mechanical pumps less and less for reliability reasons these days, let alone WOT fuel supply. If I'm going to run one, it's definitely going to be a rebuildable unit, with a spare kit in the trunk

[rohrt]

This topic gets brought up a lot but the one thing I have not understood is it's really a flow issue or a suction issue. For me my car would sputter out pulling in 2nd gear with a stock pump and Q-jet. With the acceleration pulling everything back how do you know which one it is.
Does the RobbMc pumps or the carter pump do any better job of this over stock?

I wonder if a vacuum gauge could be put on the input line and be measured.

[RocktimusPryme]

Originally Posted by tom s

Is this not the street section?Tom

It is, but this isn't really like running a big snotty cam that could have some detriment on the street. An in tank fuel pump is going to be better on any kind of track obviously, but is as good if not better on the street too.

I wouldn't say my car is a race car, but it finds its way to the track a few times a year. Not very fun falling flat on your face.

[AG]

Originally Posted by 78w72

does he run the car at the track? what are the times? im about the same HP level & doing low 11's & the carter/edelbrock type pumps definitely had starvation issues at those times with a q-jet carb.

No track runs just WOT through the gears on the street with an AFR meter.

[78w72]

Originally Posted by tom s

Is this not the street section?Tom

yes it is, but lots of guys in the street section run their cars at the drag strip. was just curious if you ran at the track also... sorry for asking.

[Formulajones]

Originally Posted by rohrt

This topic gets brought up a lot but the one thing I have not understood is it's really a flow issue or a suction issue. For me my car would sputter out pulling in 2nd gear with a stock pump and Q-jet. With the acceleration pulling everything back how do you know which one it is.
Does the RobbMc pumps or the carter pump do any better job of this over stock?

I wonder if a vacuum gauge could be put on the input line and be measured.

To even get a stock pump to work well at the track for me, I have to do a lot of trickery to the fuel system for a good supply of fuel to help those stock pumps along, but even that only gets me mid 12's at 108-ish mph before I start to see signs of problems. I've done it with Q-jets. More power shows signs of weakness though in the fuel system.

On one car here, temporarily solved that installing a Holley mechanical pump with more GPH. So that was a solution at the time (1980's). The RobbMC is also a way to do that and in my opinion, I like those pumps better if you absolutely want a mechanical.

[RocktimusPryme]

FWIW, I do think the pumps will sometimes get blamed for otherwise deficient designs. I had all kinds of trouble with my RObb Mc 1100. Setup exactly how he wanted. But I think some of the issue could have been the basic stock replacement tank and running away from the sump.

When I went electric the tank came with baffles. Which may have been the real fix for me. Hard to say. The catch 22 of it is, if you are going to buy a baffled tank why wouldn't you do an in tank pump. A basic cheap and reliable walbro will supply enough fuel for a carb with a return regulator 5 times over. And be significantly cheaper than the baller mechanical pump.

[Skip Fix]

So my experience with a 78 Trans Am fuel system feeding a Q jet.Added a cam to the low cpmression stock 400 had fuel delivery problems with the factory mechanical. A small AC Delc electric pusher resolved it. 420 HP 455 needed better mechanical and an electric to solve it. Open header more HP and supply issues then a 1/2 line from 140 Mallory to carb and still a stock 3/8 pickup was OK.