# pontiac 461 fueling



## sameold01 (Jun 21, 2020)

Build a mild 461. Would a 750 qjet work or should I go with a sean murphy 800 cfm? Bigger mechanical pump for fuel or the regular one for now?


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## BearGFR (Aug 25, 2008)

Depends on what you mean by "work". Will the engine start and run, and the car be drivable and enjoyable? You bet. Will 750 cfm be capable of feeding it enough to get every last drop of performance out of it that it's capable of? Maybe. That depends on what "mild" means. 

Bear


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## solar68 (Nov 11, 2021)

I just had a fresh 461 built, the builder used a 650 quick fuel carb on it, their claim was that it made way more tq, i have having issues with the carb loading up if it idles too long- seems to make the right power (I’m still breaking it in) 

I have a Sean Murphy 800 Qjet he set up with my old 400 that has maybe 500 miles on it, I’m thinking about switching to that carb- I have 300 miles or so on the 461 so far (working to get 500 on it before i really bite into it) 

I’m feeling like the qjet may be the better call for me, but the 650 QF is working and dyno’ s with a great AF ratio and damn near 520ftlbs of tq


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## armyadarkness (Dec 7, 2020)

I have a mild 400 and I use an 800cfm Edelbrock carb on it. My advice is to use the biggest carb that generally is recommended for you cubes. IMO, I never heard any carb manufacturer claim that a 650 could ever supply enough for a 400, let alone a 461.

However, like bear said, what do you want to do?

It makes more sense (to me) to get a bigger carb and jet it down... but if you're not looking to do jetting, then yeah, you need to guess better.

The Qjet and Edelbrock shine in this area because both are better equipped to fuel a wide variety of applications, without jetting changes, than a Holley/ QF is. Those carbs need to be eaither matched out of the box or jetted for their app... or you run the riskk of way lean or way rich.


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## armyadarkness (Dec 7, 2020)

solar68 said:


> I just had a fresh 461 built, the builder used a 650 quick fuel carb on it, their claim was that it made way more tq, i have having issues with the carb loading up if it idles too long- seems to make the right power (I’m still breaking it in)
> 
> I have a Sean Murphy 800 Qjet he set up with my old 400 that has maybe 500 miles on it, I’m thinking about switching to that carb- I have 300 miles or so on the 461 so far (working to get 500 on it before i really bite into it)
> 
> I’m feeling like the qjet may be the better call for me, but the 650 QF is working and dyno’ s with a great AF ratio and damn near 520ftlbs of tq


I often hear guys complain about "loading up" when the car sits running... and in my opinion, that's the heat crossover in the intake manifold. Do you have one? Was it blocked off?


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## Lemans guy (Oct 14, 2014)

On solar’s quick fuel you can change the idle air bleeds, they are mini jets on top of the carb horn, They can lean the idle. Loading up often means the idle is too rich and as it sits and idles it just gets worse. The idle AFR is controlled by the idle mixture screws as you know, but on the QF the idle air bleeds are easily changed with a screwdriver and new idle air bleed mini jets. You can buy them on Holley’s QF website.

I like idle with today’s gas at 13.8 on 10% ethanol pump gas which has a stoic of 14.2 ….so just barely, .5 the rich side of stoich. Of course if you run straight pure gas all the time that can be a little higher (leaner) because stoich on pure gas is 14.7….so 14.2. Is good.

Power when accelerator pump shoots or power valve and secondaries are on 12.2 on 10%..

.5 higher on pure gas….say 12.7…..remember that you engine runs on the idle circuit up until about 2500 RPm’s, that is when the main jets deploy..


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## sameold01 (Jun 21, 2020)

Can i weld in an o2 fitting into the downstream exhaust and tune it that way. I will try the 750 first and see how it is. I just love qjets! Yea I might just add in an air flow meter to verify everything once I get this motor up and running. Thanks..


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## armyadarkness (Dec 7, 2020)

Yes. many of us here have AFR gauges in our cars. Quick Fuel and Qjet are both awesome choices!


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## Lemans guy (Oct 14, 2014)

If you combine the AFR meter with your old school techniques for idling and running, you can get a smooth powerful runner. So dismiss, the old it feels good, sounds good, has good vacumn etc…..but when all that matches with your SFR gauges it is nice…

AFR ‘s gauges let you dine tune it in. Yes like army and Bear I run a wide band 02 sensor in each exhaust with a Daytona digital dual display readout on the dash. Really helps make your mixture nice, curve your distributor timing and curve your AFR….for efficient and strong running


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## Lemans guy (Oct 14, 2014)

Typo…so “DON’T dismiss old school techniques….use them together with AFR gauges


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## sameold01 (Jun 21, 2020)

With how expensive Pontiacs engines are to build I want to make sure I have it dialed in right!


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## armyadarkness (Dec 7, 2020)

In another 7 days, I'll have been tuning my GTO for a year. I've spent the last 35 years working on cars, but mostly as a customizer, restorer, and parts swapper. By the time I got into performance, everything was fuel injected. So now at 50 Ive had to learn what I shouldve learned at 20.

Lots of trial an error, and the scene is not the same. In 1980 you got your info from Haynes, Chilton, Hot Rod Magazine, and your buddies on the corner. Now you get it from Youtube and a forum. Between bad information and good information, which was misapplied... you can easily chase your tail. Im on my 2nd carb, 2nd coil, 3rd dizzy, 2nd cam, 5 set of plugs... just in a year. I have no complaints.

Lots of time, lots of money... but now I control my own destiny. If theres something you want to try, do it. Take notes... AFR and timing curve, how it feels. There's no wrong answer... but youll easily find 100 people telling you that there is. Look what the Monkeys did to their 66.


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## BearGFR (Aug 25, 2008)

> Between bad information and good information, which was misapplied... you can easily chase your tail.


Truer words have never been spoken.

The best thing about the Internet is the vastness of available information.
The worst thing about the Internet is the vastness of available information. 

Bear


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## bigD (Jul 21, 2016)

There are 750 Q-jets running in the high 8's, on 2 different alum head 428 Super Stock engines. Also several of these engines running in the 9's. 

I ran home-built 750 Q-jets on all our low budget 455 bracket cars, without problems. Quickest one ran 11.80's. 

But, for anyone who has to buy a Q-jet, including the core, I'd buy an 800, correctly built by a good Q-jet builder. Can't think of a reason to buy a 750 instead of an 800, except to comply with racing rules.


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## solar68 (Nov 11, 2021)

armyadarkness said:


> I often hear guys complain about "loading up" when the car sits running... and in my opinion, that's the heat crossover in the intake manifold. Do you have one? Was it blocked off?



I have the Speedmaster round port intake, there is no crossover on this one-


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## armyadarkness (Dec 7, 2020)

solar68 said:


> I have the Speedmaster round port intake, there is no crossover on this one-


I tried to buy one recently, but I couldnt get the one I wanted, presumably due to the supply chain crap


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