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setting up the fuel system for an LS1 conversion

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Old 11-08-2005, 03:01 PM
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Default setting up the fuel system for an LS1 conversion

HI:

I'm working on the install of a '99 LS1 into my 1957 Plymouth Belvedere (yes, it's driving the mopar purists up the wall- I love it!) anyways, I'm not too sure on how ot properly set the fuel system up. Thisis whatI have so far:

3/8" steel line roughly plumbed for the main feed line
-original 5/16" line to use as the "return"
- MSD #2225 fuel pump
-mallory adjustable fuel pressure regulator (andgauge)

every site online has a different way to do it. some suggestthis, others suggest that. it's making me dizzy!

what do I need to do and where is a good place to get the fittings to do it?

The LS1 is a '99 as it has the center bolt valve covers, but it looks like there are 2 fuel line tubes on the engine and some sort of vacuum regulator?? I'm guessing one is the return line. what about the regulator? should I trust this and not an aftermarket one?

Any help would be greatly appreciated.

Thanks,

-BV
Old 11-08-2005, 03:38 PM
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The other line beside the fuel line is the evap line. FPR and pump are normally
inside the tank. If you have externally mounted pump/fpr you need to have a return from the regulator to the tank. In my RX/LS1 swap I got a pump/fpr assy from a '98 Camaro and adapted it to the Mazda pump assy. All is in the tank.
Old 11-08-2005, 06:39 PM
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I used the Speed Inc. fuel rails, billet pressure regulator, 255lph pump, 1/2" fuel line, 3/8" return line, a large screen style pre-filter, a billet final filter just before the fuel rails that I got from Jegs, and a ton of Earls fittings. The Speartech harness came with a relay for the fuel pump. The setup works flawlessly. PM me if you would like some pictures.
Old 11-09-2005, 02:07 AM
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Pretty much you want to run 3/8" from the pump hi psi side to engine, 3/8" from tank to engine would be even better.

Pretty sure the MSD pump has 3/8" on the inlet and the outlet to engine is 5/16", if it was the other way around it would be perfect but you might find it to be a restriction.

You basically need a filter, a pump and a regulator and set it so its at 58psi, the reg always goes after the pump, ideally you want the reg after the fuel rails, but some regs are 3 port and allow the reg to be mounted before the rails, it just makes the pump work a bit harder as theres a slight restriction in its way.
Old 11-09-2005, 04:30 AM
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Lingenfelter has adaptors for the engines flex lines, however the threads were not what I am going to use. Will cut off and put on AN-4 (evap) & AN-6 (fuel feed) lines for a cleaner install.
Don't believe the regulator will make the pump work any harder as it will return the excess pressure back to the tank no matter what the demand is...
Old 11-09-2005, 01:59 PM
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Thank you all, this is very helpful!



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