[steve25]

In none of the post that the OP has made in this string does he say that he has a electric pump to question him about.

[DaleO]

Originally Posted by steve25

Is your HEI new or used?

Another possibility for crappy running is if you have the super light ( most times silver colored ) advance springs in the HEI as they don’t even work right with very light advance weights , not less heavy stock ones!

The HEI is straight off NAPA's shelf and I honestly don't what weights and springs it has. Another great lead, thank you.

[78w72]

what happened to this post from "389"?? i got an email saying there was a new post to this thread but now its gone....

"Electric fuel pump is the worst way to go with this. After seeing a race car go up like it had a stick of dynomite from an electric fuel pump squirting fuel all over the place until it finally touched the fire.. Bad idea..

This is how I got my mechanical fuel pump to work really well. Sleeve every turn the gas line hose has with 3/8" steel tubing. Spray WD-40 inside the hose and slide the hose over it. This way the hose won't collapse when the fuel pump is calling for gasoline. Two 3/8" runs of steel tubing is better then one 1/2" run. When pulling fuel instead of pushing it the principals change, I don't understand why this works but it does. A guy who has a lot of knowledge in building engines for the last 60 years suggested I try this .. The best way is to run two 3/8" runs of tubing from a sump in the tank to a tee in the fuel pump.. You also need a 1/4" return line.. That car will feel like you just went from a 326 to a 455.. I tested my car on one of the steepest highways around and my car just kept marching up that hill. I was waiting for that sickening, out of gas feeling but it just kept going. I was so excited when I saw that speedo go past 100! It never would go past 50 before. I would ha ve to feather the gas.. The world was a wonderful place again!!"

[Cliff R]

Worried about an electric fuel pump when 7 out of 10 of these vehicles have a cut steel line between the mechanical pump and carburetor with an external filter and couple of pieces of rubber hose and clamps.

Not a single one of them took the time after they cut the line with a hack saw to put a bulge on it to make sure the rubber line doesn't slip off. I see that sort of thing all the time when folks bring vehicles to the shop for me to work on......FWIW.....

[Kenth]

I have found this pump suits a street performer (and occational strip runs) well.
Has served the 462 in my Judge for +20 years.

https://www.summitracing.com/int/par...a/instructions

And for electric fuel pump safety use an oil pressure switch:

[geeteeohguy]

Originally Posted by Cliff R

Insufficient fuel delivery (sucking the bowl empty).

It will not be anything else as it does fine when you nail it until it reaches 4800rpm's then noses over......Cliff

I agree. Ran into this years ago with my '67 GTO. Was a collapsed sock in the fuel tank at the pick-up.

[Joe's Garage]

Originally Posted by Joe's Garage

It wouldn't really be considered a 'bog' if it runs strong until it gets to 4,800 RPMs. That's a fuel starvation issue.

Check the fuel filter, pressure, pump, float level, etc.

Could even be a clogged screen in the tank or a leaking rubber hose between the tank and the metal line at the back.

The fact that it takes a few seconds to clear means it's NOT valves. They would clear immediately when the RPMs went down.

Good luck!

Whatever is the cause, it's lack of fuel.

[Old Goat 67]

I agree, lack of fuel.

[DaleO]

So I have replaced the fuel pump with a basic stock pump. I've learned from another thread they are probably made by the same manufacturer so didn't spend a lot of time researching for the best. I bought one from Ames. It hase "solved" a couple of problems.

1 -It confirms I am running out of fuel under hard acceleration. It did not totally cure the problem as it is still stumbling but is not as bad. This gives me confidence that when I can move to a superior pump this issue will be gone assuming the 3/8" line is adequate.

2-I was having a problem starting the engine after a lengthy time of sitting. I would have to either grind and grind with the starter which drove me nuts besides being embarrassing or pour a small cap of gas down the carb. The engine starts now like it should, I am back to giving three full shots with the peddle and it is starting right up after sitting for a couple weeks. I don't have a choke on the quadrajet,

[steve25]

So you have posted that the 3/8” steel fuel Line along with rubber and clamps from the tank to the carb are new, but what size is the tube in the new tank pick up you put in, is that 3/8” also?

[62posbonny]

Everyone here is right with the suggestion of fuel delivery. We ran into the same on a 9.2:1 RA4 cammed 455 in a 64 Catalina. Car stumbled at the top of 2nd gear and you could see AFR go dead lean. On top of that, AFR was lean throughout the range at around 14.5 @ WOT. Switched to an in tank pump and new lines, regulated to 6psi and initially ran vac line to the regulator. Carb was still lean but didnt run out of fuel. We then tried a flat 6psi with no vac reduction and the Cliff quadrajet hit 12.9 at WOT and the engine pulled far better than it ever had. We had to lean out the APT a little but with all of that done it's a beast and drives amazingly. he is running a relay box that primes the pump 3 seconds on key on then only runs the pump when it gets tach signal. whole system is great.

[DaleO]

Originally Posted by steve25

So you have posted that the 3/8” steel fuel Line along with rubber and clamps from the tank to the carb are new, but what size is the tube in the new tank pick up you put in, is that 3/8” also?

It is 3/8".