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| Mechanical Fuel Pumps https://slantsix.org/forum/viewtopic.php?t=49678 |
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| Author: | 6pakattack [ Wed Aug 29, 2012 5:28 pm ] |
| Post subject: | Mechanical Fuel Pumps |
Can someone tell me if there are any aftermarket High Performance Fuels Pumps available for our slant 6's ??? |
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| Author: | SlantSixDan [ Wed Aug 29, 2012 5:36 pm ] |
| Post subject: | |
What is the performance deficit you are hoping to correct? A stock pump will feed a carburetor adequate for any but the hairiest slant-6 build. It is possible to build a high-volume slant-6 fuel pump -- you cannot buy a ready-made one -- but...why? Excessive fuel pump capacity (volume) will not help you at all. Excessive fuel pump pressure will make lots of problems. |
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| Author: | 6pakattack [ Wed Aug 29, 2012 8:09 pm ] |
| Post subject: | |
Wanting to be sure that my 11:1 Compression is kept from being thirsty because of too small a feed ! I've got 1/2" line from the sending unit to the fuel pump,was hoping to match the inlet on the pump to those lines for added insurance ! I should have stuck with the 3/8 I was going to use,but overkill is one of my downfalls !! It's a SS line,and I just don't want to trash it if I can avoid it !! |
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| Author: | DusterIdiot [ Wed Aug 29, 2012 8:27 pm ] |
| Post subject: | Why bother? |
Quote: Wanting to be sure that my 11:1 Compression is kept from being thirsty because of too small a feed ! I've got 1/2" line from the sending unit to the fuel pump,was hoping to match the inlet on the pump to those lines for added insurance ! I should have stuck with the 3/8 I was going to use,but overkill is one of my downfalls !! It's a SS line,and I just don't want to trash it if I can avoid it !!
It won't, I run more than that compression, a 600 cfm holley, and use a stock fuel pump with a 5/16" fuel line...3/8" would be the max, I don't think anyone racing uses much more than that. You can only use more fuel if you have the displacement to move it...225 is not a 440...-D.Idiot |
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| Author: | Dart270 [ Wed Aug 29, 2012 8:29 pm ] |
| Post subject: | |
It is possible for the stock pump not to keep up, but yes you need a serious buildup. Maybe tell us more about your engine and car? Lou |
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| Author: | ceej [ Wed Aug 29, 2012 9:20 pm ] |
| Post subject: | |
I run 3/8" from the fuel cell to a Holley Red pump mounted directly under the trunk, then 3/8" all the way up to the AFB. Was 11:1, bled that down to 10.7:1 since I was still street driving the car, and was experiencing detonation pulling grades under power. Now that the car is only rarely street driven, and I'm spiking the fuel with 110 Race Gas, it doesn't really matter. My fuel system is over-kill. 5/16" and a stock pump would feed it fine. E-85 or Methanol would rate the larger fuel system. Your compression is a bit low to take advantage of that though. 2¢ CJ |
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| Author: | SlantSixDan [ Thu Aug 30, 2012 12:38 am ] |
| Post subject: | |
A 1/2" fuel line will cause a lot of problems and solve none. |
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| Author: | Jeb [ Thu Aug 30, 2012 3:10 am ] |
| Post subject: | |
I was able to feed a 383 Chevy with a 750 Edelbrock and a 3/8 fuel line with no problems. 1/2 fuel line is absurd for a slant six. |
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| Author: | 6pakattack [ Thu Aug 30, 2012 5:25 am ] |
| Post subject: | |
From the sounds of it I may as well bite the bullet and go back to what I really should have done and that is "KEEP IT SIMPLE STUPID" !! Thanks for answering the question I should've asked in the beginning! |
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| Author: | terrylittlejohn [ Thu Aug 30, 2012 1:21 pm ] |
| Post subject: | |
ditch the 1/2 fuel line , there will be too much fuel weight in the line for a mech pump to pull! only use 1/2" lines when using a pump with 1/2" fittings. like other have said 3/8" is max, i have 2 x 4954 carters pumps pushing fuel to 2x450cfm holleys with a single 3/8" line with no flow problems. you can use a bb dodge carter mech pump just switch out the activation lever. i think doug has a artical on this site some were. they flow 120gph at 8.5psi but still have only 4.5 at idle so you will have no flooding issues,i have done two of these, one on my .030 over 9.5/1 stock valve 650cfm holley street engine. |
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| Author: | SlantSixDan [ Thu Aug 30, 2012 2:01 pm ] |
| Post subject: | |
Quote: ditch the 1/2 fuel line , there will be too much fuel weight in the line for a mech pump to pull!
Exactly this.
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| Author: | kesteb [ Thu Aug 30, 2012 7:29 pm ] |
| Post subject: | |
I'll interject here. The stock replacement pumps will not keep the carburetor full on my \6. I have tried three different ones. The last one I placed a fuel pressure gauge in the line, only to find that it pumps out 3.5 psi at idle. At 3000 rpms, it drops down to 1 psi. 1 psi is not enough to keep the fuel bowls consistently full. This weekend I will be trying a big block HP pump (440 six pack/ Hemi). We will see how that works. And yes they need to be modified to work on \6, and it is a stock replacement type of pump. It pumps out 5 psi at idle and drops down to 3 psi at 3000 rpms. I am only running 5/16 line at the moment. I am planning on 3/8 before the end of September. 1/2" fuel line is a little bit of overkill. But you can use an electric pump and end it in one of those canister style of filters and then run 3/8 to the carburetor. |
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| Author: | Dan-o [ Fri Jan 16, 2015 3:47 pm ] |
| Post subject: | |
Sorry to bring up an old thread, but I am having a small issue related to the topic covered here. Quick back story: We have a couple of REALLY steep hills on a commute I frequent. We're talking sea level to 4000ft in about 8-9 miles. So cruising in the Dart up the steeper sections at cruising RPM's (2450@70 mph) after 18 seconds, she'll start to stammer and cut out until I coast for a bit then resume at 2250-2300rpms. After quite a bit of diagnosis and trial and error I'd like to think that it's fuel supply/delivery related but don't want to add the unreliability of a Holley Red. So the long and short: Does anyone have a link to the fuel pump modification thread/page/post to put a BB pump in the car and test my theory? Or can I mod the /6 one? I'll be making the drive tomorrow, so it'd be an excellent time to try. |
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| Author: | Pierre [ Fri Jan 16, 2015 3:57 pm ] |
| Post subject: | |
There are plenty of electric pumps made besides holley's. You may not have a pump problem, the pickup in the tank may be starved if the hills are that steep. Have you tried the drive with a full tank? |
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| Author: | Dan-o [ Fri Jan 16, 2015 4:06 pm ] |
| Post subject: | |
I do and it's a foam filled cell. 40gal capacity. I can drive about 900 miles on a tank on cheap $1.85/gal Arizona gas! Sending unit is calibrated so the tank has 8 gallons even on "E" (cheap insurance so the wife doesn't run it dry) Fill up today before the trip to Cali was just under $50 bucks! |
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