CarburetorsCarb discussion and questions. Upgrading your Third Gen's carburetor, swapping TBI to carburetor, or TPI to carburetor? Need LG4 or H.O. info? Post it here.
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I was reviewing stickys/posts before diving ahead with an lt1 cam install, but read a little closer and noticed the lt1 cam doesn't have lobe for a mechanical fuel pump. I've got a mechanical fuel pump on my stock 305 plus a stock electric fuel pump in the tank. Obviously, the fuel pump needs to be straight before proceeding with the cam. Think I will need a Mallory 4309, but what else am I going to have to do?
Re: correct fuel pump setup in '87 lg4 with lt1 cam
The stock in-tank electric fuel pump is a "pusher" pump, intended to push fuel to the inlet of the mechanical pump. It isn't intended to provide pressure.
A good in-tank replacement like a Walbro 255 with a 4309 reg would be a good system to supply a bunch of poneys.
Re: correct fuel pump setup in '87 lg4 with lt1 cam
Quote:
Originally Posted by scooter500
for the suggestion!
Did you do anything with that yet? I discovered after I posted that that the carb in-tank pump is smaller than the EFI in-tank pumps, so mounting an aftermarket electric in-tank may be an issue.
Re: correct fuel pump setup in '87 lg4 with lt1 cam
I retained the in-tank and installed a 'holley' knockoff in-line pump near the rear tank (exhaust is welded in so dropping the tank would be an effort). The pump is designed for carb pressures, 7 psi I recall?, so I retained the stock plumbing to include the stock fuel pump mounted on the block. This allowed the mech pump, even though it's not pumping, to provide the means of fuel return.
Verified that I was getting adequate pressure and flow at the carb and that fuel was flowing through the return line. This setup saved the stock plumbing up front and the $ on a return style regulator.
Downside is the mech pump still absorbs engine heat and the fuel can boil back when it heat soaks. Fuel running through it while running keeps it cool enough then. This could likely be worse if I were relying on the mech pump alone, though.
Re: correct fuel pump setup in '87 lg4 with lt1 cam
gm still makes a "corvette" in tank fuel pump that came with the old "H.O. 350 kit" its like 77$ shipped i think i have to see if i can find the PN its what i was gonna do if i dont have enough PSi at the carb
i figured it was easier this way and i like to keep it simple, but im sure the other methods will work well also
http://www.gmpartsdirect.com/results.cfm <<---- 60$ plus shipping just put that part number in the search engine... ill be using this and a cheap holley regulator with gauge if my intak doesnt put out enough at the carb
__________________ u call it "drifting"? i call it a lack of proper traction, the fastest way around the track isnt sideways with the tires smoking (well, most of the time). oh yeah japan makes the best race bikes, but the cars are for transportation. and thats, your new opinion!
for the suggestion! 
and thats, your new opinion!
