Mechanical fuel pump for 383 ?
Thread Starter
Racer
Joined: May 2004
Posts: 288
Likes: 0
From: Tigard OR
Mechanical fuel pump for 383 ?
I need a mechanical fuel pump for a 383 with a 650 speed demon carb. Do I need a 80, 110, or 150 GPH rated pump? Do I need a fuel regulator?
This engine will have around 400-425 HP...
This engine will have around 400-425 HP...
Le Mans Master
Joined: May 2002
Posts: 5,086
Likes: 787
From: Lebanon Township New Jersey
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Every 2027 Corvette Engine Explained
Joe Kucinski
Designer Imagines A Corvette That Looks More Like a Corvette Than the Corvette
Verdad Gallardo
10 Ugly Corvettes That We Still Kinda Love
Joe Kucinski
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Melting Slicks
Joined: Mar 2006
Posts: 3,456
Likes: 102
From: Piedmont Va
St. Jude Donor '11-'12-'13,'19-'20
with the ! I have 383 ~425 and installed a new NAPA replacement pump for a 73 Corvette SBC with the vent. The vent works as designed and the motor screams! 
Melting Slicks
Joined: Mar 2005
Posts: 2,838
Likes: 10
From: Austin TX
Here's the pump you want for your rig. Lower pressure, higher volume. Plus it's rebuildable:
http://www.summitracing.com/parts/SUM-EDL21/
http://www.summitracing.com/parts/SUM-EDL21/
Le Mans Master
Joined: May 2002
Posts: 5,086
Likes: 787
From: Lebanon Township New Jersey
Here's the pump you want for your rig. Lower pressure, higher volume. Plus it's rebuildable:
http://www.summitracing.com/parts/SUM-EDL21/
http://www.summitracing.com/parts/SUM-EDL21/
Melting Slicks
Joined: Mar 2005
Posts: 2,838
Likes: 10
From: Austin TX
I don't know of a performace pump that has the return line provision. A "street" performance pump will flow about 80 GPH. A stock pump flows about 30.
LT-1 was a fine engine and I'm sure the stock fuel pump was up to the task.
But we're talking about a built 383. If the fuel pump was inadequate and she goes lean at just the wrong time, it could be catastrophic.
The pump I suggested above is only $20 more than a stocker.
Sure seems like cheap insurance and an inexpensive performance upgrade.
As far as the return line, I'd remove it entirely and plug the nipple at the fuel tank.
FWIW
LT-1 was a fine engine and I'm sure the stock fuel pump was up to the task.
But we're talking about a built 383. If the fuel pump was inadequate and she goes lean at just the wrong time, it could be catastrophic.
The pump I suggested above is only $20 more than a stocker.
Sure seems like cheap insurance and an inexpensive performance upgrade.
As far as the return line, I'd remove it entirely and plug the nipple at the fuel tank.
FWIW
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
I use no regulator on my 600+ 434 ci
Le Mans Master
Joined: May 2002
Posts: 5,086
Likes: 787
From: Lebanon Township New Jersey
As for the results of "going lean", an inadequate fuel supply at full throttle will cause the engine to suddenly die, and almost stall. It will instantly recover after you let off the throttle. No permanent damage.
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
The OP estimated 400 - 425 hp from his 383. My 383, with a stock type pump, isn't at 400, but its not far off.
As for the results of "going lean", an inadequate fuel supply at full throttle will cause the engine to suddenly die, and almost stall. It will instantly recover after you let off the throttle. No permanent damage.
As for the results of "going lean", an inadequate fuel supply at full throttle will cause the engine to suddenly die, and almost stall. It will instantly recover after you let off the throttle. No permanent damage.
I run my system at sub 5 psi and I used to use the bigger needle and seats used for alki burners. Just a little bit of thought goes a long ways. For the record I have had my foot on the floor for over 20 seconds, can you say that?
Le Mans Master
Joined: May 2002
Posts: 5,086
Likes: 787
From: Lebanon Township New Jersey
You would have to have a really ****ty system to accomplish a lean condition or you have to be a bubba mechanic.
I run my system at sub 5 psi and I used to use the bigger needle and seats used for alki burners. Just a little bit of thought goes a long ways. For the record I have had my foot on the floor for over 20 seconds, can you say that?
I run my system at sub 5 psi and I used to use the bigger needle and seats used for alki burners. Just a little bit of thought goes a long ways. For the record I have had my foot on the floor for over 20 seconds, can you say that?
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Something about 30 GPH not being enough. Another way to look at it in fuel needs is what kind of MPG do you get. Lets say that you drive for one full hour at 100 mph and you car has such a wide throttle opening that it only gets 10 mpg. So it took you 10 gallon of gas to go for one hour. Your pump puts at 30 gallons per hour so you are doing great.
Melting Slicks
Joined: Mar 2005
Posts: 2,838
Likes: 10
From: Austin TX
First, yes indeed, lean-out at high RPMs, due to fuel starvation, can blow a hole right through a piston. Ask me how I know.
Also, according to Holley, a stock fuel pump, which again, flows about 30 GPH, is good to 350 HP. More here:
http://www.holley.com/data/TechServi...ech%20Info.pdf
Using the formula found here:
http://www.fordmuscle.com/archives/2...reOfGetInLine/
...you can see that 30 GPH doesn't do the job, if you're 'exercising' your 400+ HP engine toward it's limits.
This book agrees with me:
http://books.google.com/books?id=lX5...age&q=&f=false
More here:
http://www.chevyhiperformance.com/te...tem/index.html
I could on, but the point is, once you're in he 375+ HP range, you need an upgraded (performance) fuel pump.
The pump I suggested is perfect:
http://www.summitracing.com/parts/SUM-EDL21/
It's about $20 more than a stocker, supplies 110 GPH at only 6 PSI, meaning you don't need a regulator and won't over-power the needle & seat of your Speed Demon carb. The pump's rebuildable and supports 550 HP.
Also, vapor lock shouldn't be a problem on performance engines. By definition, the fuel flows more quickly through the system. For instance, on first gen Camaros (67-69), Holley equipped cars didn't receive the fuel return line (Z-28's, L-78, L-89, and all the 427 COPOs). All other first gens were equipped with the fuel return line.
FWIW
Also, according to Holley, a stock fuel pump, which again, flows about 30 GPH, is good to 350 HP. More here:
http://www.holley.com/data/TechServi...ech%20Info.pdf
Using the formula found here:
http://www.fordmuscle.com/archives/2...reOfGetInLine/
...you can see that 30 GPH doesn't do the job, if you're 'exercising' your 400+ HP engine toward it's limits.
This book agrees with me:
http://books.google.com/books?id=lX5...age&q=&f=false
More here:
http://www.chevyhiperformance.com/te...tem/index.html
I could on, but the point is, once you're in he 375+ HP range, you need an upgraded (performance) fuel pump.
The pump I suggested is perfect:
http://www.summitracing.com/parts/SUM-EDL21/
It's about $20 more than a stocker, supplies 110 GPH at only 6 PSI, meaning you don't need a regulator and won't over-power the needle & seat of your Speed Demon carb. The pump's rebuildable and supports 550 HP.
Also, vapor lock shouldn't be a problem on performance engines. By definition, the fuel flows more quickly through the system. For instance, on first gen Camaros (67-69), Holley equipped cars didn't receive the fuel return line (Z-28's, L-78, L-89, and all the 427 COPOs). All other first gens were equipped with the fuel return line.
FWIW
Last edited by 73, Dark Blue 454; Jan 15, 2010 at 11:53 PM.