EFI to carb swap help!
12-15-2016, 11:17 PM
#1
EFI to carb swap help!
I have a running driving EFI to carb swap. Here is the kicker most say you can't do it but it can't be done. I AM STILL RUNNING THE COMPUTER FOR MY FUEL PUMP AND DISTRIBUTOR TIMING. It is still speed density. Only things I have hooked up are map sensor to straight manifold vacuum and and the distributor and coil hooked it up.
I have one issue tho I have been driving the truck for about 2 months now after complete rebuild now. Main Mods are:
edelbrock performer intake
Edelbrock 600cfm carb
mild cam (flat tappet version of an e303 grind)
professional products EFI to carb fuel pressure regulator with return to tank
Stock EFI distributor and ignition coil
The only issue I am running into is that I have no compensation for the load of my blower(heat) and my headlights so when I'm driving at night with the headlights and heat on it idles down lower than normal. And being that with EFI you set your base timing at 10 btdc the the computer advances it to around 20 or 22 btdc when the spout is plugged in. Which causes the engine to idle up furthur I have to compensate by lowering my idle speed back to around 700 rpm. Where it's got a good lope and good throttle response. When the load of the headlights and heater are placed on the engine it cause my engine idle to bog a little more loosing some of my vacuum I believe this is causing my map sensor to reject the timing back to base timeing vs the 22 btdc timing it originally had it really causes my idle to drop just about killing the engine if I don't give it any gas.to keep the idle up.
My question is is there a way to keep it from rejcting to base timing ( I know it does this because I have checked it with a timing light to see if that is what it is doing)?
If there isn't anyway, would it be okay to hot wire the fuel pump to stay on when the ignition is turned on with out hurting the fuel pump since I already have an existing regulator designed for it? I know that the EFI distributor turning is what signals the fuel pump to stay on vs staying on soon as the switch is on....So that I may run a hei distributor or duraspark setup with the existing fuel pump without issues later on.
Thanks...any questions on the swap I'm happy to answer. Leaving the computer has worked great for me so far except for the issue with a high electrical load and this is not all the time it only happens every now and then. Mainly in stop and go traffic and cold starts in the morning as if the alternator can't keep up.
I have one issue tho I have been driving the truck for about 2 months now after complete rebuild now. Main Mods are:
edelbrock performer intake
Edelbrock 600cfm carb
mild cam (flat tappet version of an e303 grind)
professional products EFI to carb fuel pressure regulator with return to tank
Stock EFI distributor and ignition coil
The only issue I am running into is that I have no compensation for the load of my blower(heat) and my headlights so when I'm driving at night with the headlights and heat on it idles down lower than normal. And being that with EFI you set your base timing at 10 btdc the the computer advances it to around 20 or 22 btdc when the spout is plugged in. Which causes the engine to idle up furthur I have to compensate by lowering my idle speed back to around 700 rpm. Where it's got a good lope and good throttle response. When the load of the headlights and heater are placed on the engine it cause my engine idle to bog a little more loosing some of my vacuum I believe this is causing my map sensor to reject the timing back to base timeing vs the 22 btdc timing it originally had it really causes my idle to drop just about killing the engine if I don't give it any gas.to keep the idle up.
My question is is there a way to keep it from rejcting to base timing ( I know it does this because I have checked it with a timing light to see if that is what it is doing)?
If there isn't anyway, would it be okay to hot wire the fuel pump to stay on when the ignition is turned on with out hurting the fuel pump since I already have an existing regulator designed for it? I know that the EFI distributor turning is what signals the fuel pump to stay on vs staying on soon as the switch is on....So that I may run a hei distributor or duraspark setup with the existing fuel pump without issues later on.
Thanks...any questions on the swap I'm happy to answer. Leaving the computer has worked great for me so far except for the issue with a high electrical load and this is not all the time it only happens every now and then. Mainly in stop and go traffic and cold starts in the morning as if the alternator can't keep up.
12-16-2016, 06:02 PM
#2
Junior Member
not sure how exactly to help you with your problem but i do know that speed density systems don't like a cam because it changes vacuum, that could cause a little trouble.