Carbureted Fuel System
12-10-2008, 10:52 PM
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Carbureted Fuel System I'm sure this has been covered, but searching hasn't gotten me any results. I need to know all the parts and the process for setting up a carb'd Gen III. If someone could point me to a thread that already covers it that would be cool. I need to know what fuel pump to get, what pressure, line size, regulators, etc. whatever is needed. Thanks for your help.
12-11-2008, 12:03 AM
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I'm sure this has been covered, but searching hasn't gotten me any results. I need to know all the parts and the process for setting up a carb'd Gen III. If someone could point me to a thread that already covers it that would be cool. I need to know what fuel pump to get, what pressure, line size, regulators, etc. whatever is needed. Thanks for your help.
12-11-2008, 12:51 AM
#3
How complte is your engine already? lets just say fot starters, msd-6010, carb intake manifold, carb, and a low pressure fuel pump rated @ 7psi. Hope this helps! Also if you're looking to purchase the intake manifold then take a look at this thread,https://ls1tech.com/forums/lsx-parts...pp-intake.html
12-11-2008, 06:42 AM
#4
my system is a GMPP intake, BG demon 750cfm carb, aeromotive 350pump, aero fuel regulator set at 7psi. i have -12 feed line to filter, -10 filter to pump, -8 pump to regulator and twin -6 to carb, one line per float chamber. the pump body has its own return port in -8 to tank.
probably a bit ott for a street setup but in theory i wont have problems with fuel supply at any point as its a track car.
probably a bit ott for a street setup but in theory i wont have problems with fuel supply at any point as its a track car.
12-11-2008, 09:45 AM
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Thanks for the answers, when I look at fuel pumps they are all rated in Gallons per hour. How do I convert that into PSI? Would i be better off buying a high flow pump and then a regulator to reduce the flow?
12-11-2008, 10:28 AM
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Now you're giving us something to work with. There are some pretty exotic fuel systems out there, but my rule has always been, keep it simple. Don't buy a whole lot more than you need. My set-up is a blue Holley race pump (110 GPH, I think), Through 3/8" line to a Holley regulator set at 6-7 PSI, to a 750 carb. As far as the ignition, you can buy a distributor conversion set-up, but it is expensive and adds several inches to the length of the engine. Most people (myself included) prefer to use the MSD box, either 6010 or 6012. The box has to correspond to the number of teeth on the crankshaft reluctor wheel, 6010 for 24x and 6012 for 58x. You can tell which by color of crank sensor. Somebody else is going to have to jump in here cause I can never remember which is which. DON'T BUY the Edelbrock box as at least one of them CANNOT be programmed with your computer. Hope this helps. Ron
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12-11-2008, 12:01 PM
#8
I am running a Holley red 97gph and i know im over 500hp at the crank. I have no fuel starvation issues at all. think of it like this. there are 3.8L in a gallon. Most efi applications upgrade to 255lph pumps so thats more than adequate fuel. I am running 3/8" rubber braided steel hose all the way. The fuel pump is internally regulate to about 7.5psi feeding a holley 750 vac secondary carb with adjustable metering plates.
feel free to pm with any specifics. I have 1,000s of pictures of every step of my swap.
feel free to pm with any specifics. I have 1,000s of pictures of every step of my swap.
12-11-2008, 02:12 PM
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I agree. Magnafuel are some the only electric pumps rated for sustained use. Thats not saying the others won't live on the street, but magnafuels are built to last.
Definetly get a good pump and a good regulator. To figure how much fuel flow you need, you will have to know what kinda power numbers you are shooting for.
IMO when you build a fuel system for a car I like to plan for a little more than I need because I know that I will want to step it up more later on. No sense in replacing fuel system parts just because you set it on kill.
Definetly get a good pump and a good regulator. To figure how much fuel flow you need, you will have to know what kinda power numbers you are shooting for.
IMO when you build a fuel system for a car I like to plan for a little more than I need because I know that I will want to step it up more later on. No sense in replacing fuel system parts just because you set it on kill.
12-11-2008, 03:36 PM
#10
this link is a little conservative in it's esitmates, but does a good job of explaining everything.
http://www.centuryperformance.com/fu...e-spg-140.html
I was running a Mallory Comp 140 pump with their matching return style regulator. Use a 3/8 supply and return line then AN6 stuff from the regulator to the carb. Had a cheap Holley filter before the pump.
The pump destroyed itself after only 20 hours when some rust got into it. Very fragile (and expensive) pump.
I am getting the tank cleaned and sealed and switching to a different brand of pump. should get the tank back this weekend.
http://www.centuryperformance.com/fu...e-spg-140.html
I was running a Mallory Comp 140 pump with their matching return style regulator. Use a 3/8 supply and return line then AN6 stuff from the regulator to the carb. Had a cheap Holley filter before the pump.
The pump destroyed itself after only 20 hours when some rust got into it. Very fragile (and expensive) pump.
I am getting the tank cleaned and sealed and switching to a different brand of pump. should get the tank back this weekend.
12-11-2008, 07:22 PM
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Ok cool. I plan on running the MSD box and GMPP intake. I am trying to copy the build Car Craft did, they made around 550 HP at the motor. Thanks for your help, I will look for fuel pumps and regulators.
12-11-2008, 07:34 PM
#13
Without cylinder heads? 550hp was my goal on stock 241s but i dont think ill reach it although i think it will be close.
When you go to set up your carburetor its a little tricky on the ls1 with a single plane intake. I had to run a 50cc accelerator pump (vacuum secondary carb), a #35 squirter, and a clear red pump cam. A good base line to work with is 72 primary jets and 76 secondaries (if its a holley). a 6.5 power valve seems to work well even with my low vacuum cam. I have a 5.0 i put in there but it was running rich at idle some times.
For timing you'll want to start around 15 degrees and all in by 3000rpm about 28-30 degrees. If you run a MAP sensor, which i suggest you do, you can increase timing based on engine vacuum. The box reads MAP live for you but it messures it in psia. Not HG and its backwards from Hg. When you engine is off it will read 14.6psia or so this is atmospheric pressure. When running at idle mine reads 8.6psi. 8.6-14.6= - 6psi. the engine is creating 6 psi engine vacuum which is about 12hg (on my engine). You have to plot the timing advance map accordingly to your vacuum at part throttle cruising otherwise you'll have too much timing on acceleration. I have 10 degrees timing advance at idle so i have 25 degrees of timing at idle but when i stab the throttle it'll go down to 31degrees or so.
When you go to set up your carburetor its a little tricky on the ls1 with a single plane intake. I had to run a 50cc accelerator pump (vacuum secondary carb), a #35 squirter, and a clear red pump cam. A good base line to work with is 72 primary jets and 76 secondaries (if its a holley). a 6.5 power valve seems to work well even with my low vacuum cam. I have a 5.0 i put in there but it was running rich at idle some times.
For timing you'll want to start around 15 degrees and all in by 3000rpm about 28-30 degrees. If you run a MAP sensor, which i suggest you do, you can increase timing based on engine vacuum. The box reads MAP live for you but it messures it in psia. Not HG and its backwards from Hg. When you engine is off it will read 14.6psia or so this is atmospheric pressure. When running at idle mine reads 8.6psi. 8.6-14.6= - 6psi. the engine is creating 6 psi engine vacuum which is about 12hg (on my engine). You have to plot the timing advance map accordingly to your vacuum at part throttle cruising otherwise you'll have too much timing on acceleration. I have 10 degrees timing advance at idle so i have 25 degrees of timing at idle but when i stab the throttle it'll go down to 31degrees or so.
12-12-2008, 10:19 AM
#17
When you go to set up your carburetor its a little tricky on the ls1 with a single plane intake. I had to run a 50cc accelerator pump (vacuum secondary carb), a #35 squirter, and a clear red pump cam. A good base line to work with is 72 primary jets and 76 secondaries (if its a holley). a 6.5 power valve seems to work well even with my low vacuum cam. I have a 5.0 i put in there but it was running rich at idle some times.
12-12-2008, 10:27 AM
#18
Hmm well when i changed my timing curve to run 26 degrees timing instead of the 15 i had, it caused me to pull about 3hg vacuum more at idle and run a full point richer (12.4 AFR opposed to the normal 13.6). I swapped back to 6.5pv and it seemed to work. I dunno. Maybe i just had something out of adjustment in the carb it fixed it when i put it back together. I also had a problem with the acclerater pump arm pushing on the diphram and causing it to run rich and have since fixed that. I'm just a trial and error tuner lol. Thats why i run a dual wideband.
12-12-2008, 03:55 PM
#20
Really big 
. Mine purs like a kitten in a 5.7L. The videos in my sig were with hardley any timing, a carb leaking fuel and an engine that had sat for 2 years. You should hear it now . Carb setups due to the short intake runners, and 4 butterfly throttlebody can handle bigger cams. I would definately get one with more exhaust duration than intake as the L92 heads flow alot more on the intake than the exhaust as opposed to the standard LS1/6 style heads. For instance the stock LS7 is something like 211/230 or something. I would sugggest a cam around 238/248 on a 110+2 or so. I'm not sure how that'd work out with your PTVC but since it's going in a 6.0L it should be reasonably driveable.
. Mine purs like a kitten in a 5.7L. The videos in my sig were with hardley any timing, a carb leaking fuel and an engine that had sat for 2 years. You should hear it now . Carb setups due to the short intake runners, and 4 butterfly throttlebody can handle bigger cams. I would definately get one with more exhaust duration than intake as the L92 heads flow alot more on the intake than the exhaust as opposed to the standard LS1/6 style heads. For instance the stock LS7 is something like 211/230 or something. I would sugggest a cam around 238/248 on a 110+2 or so. I'm not sure how that'd work out with your PTVC but since it's going in a 6.0L it should be reasonably driveable.