Hurricanedt77

Hey guys, just figure'd I'd post up about a problem I'm having since I swapped my 351 Setup into my new 89. This completely has me stumped, I have no idea where to turn next. First, I'll tell you a little about the car and the swap and what I've done to correct the problem. It's a 89 LX 4 Cyl conversion, with a Carter Carb. fuel pump mounted in front of the tank. The fuel pressure is adjusted on the reg to 8 PSI. The only thing I haven't really done is hooked up a gauge after the regulator to see if the fuel input is consistant. The problem I'm having is that the car bogs down under normal driving. Low RPM Its pretty bad, first through 5th it tends to fall on its face but once you bring the revs up it seems to "Clear Out" and make good power. Now the weird part is that before I pulled the setup from my 86 I had no issues like this. The fuel pump I have is actually much more powerfult han the one that was in the 86, so I dont think fuel delivery is an issue. When I swapped the motor removed the dizzy, had trouble getting it back in time so I started from scratch. With the Vaccume advance unplugged from the dizzy I set the initial timing @ 14-A. Havent done the total timing yet, I'm a bit unsure on how ot do so. The carb's a 725 Demon w/ vacuum secondaries that was jetted last summer, it's right in and had great throttle response before the swap. I checked for vaccume leaks with car cleaner around the base of the carb and all on the intake manifold. I do have a PCV Valve hook from the valve cover to the vaccume tree. Another problem is that the car runs on for about 4 seconds after I turn the key back, fuel pump runs as well. And when I give the car gas it does rev which is weird. As stated before, I am at a complete loss and cannot figure out what is going on. Timed it, bumped the fuel pressure up a little bit, checked for vaccume leaks. I currently run an MSD Blaster coil 3, MSD 6AL & an MSD Pro Billet Distributor. Thanks in advance for the help, hopefully somebodys ran into some issues like this before.

aode08

The first thing is your fuel pump running after the key is off.

First thing, I would not let this get out of hand and frustrating, start with why your car and fuel pump is running with the key off.



Next, poor lower RPM issues and possible timing issue,

does your carb have a fuel filter built into the inlet port that contains a filter and spring, designed to regulate pressure? some do most dont and a fuel filter on the NEW Pump with an external regulator.

You dont want 2 regulators, 2 filters constricting volume.

2.Is this the right carb for a 351 with any mods you may have done, now that you have added over 49 extra liters of displacement?

some carb guys will chime in, and yes this is an extremely common problem.

Hurricanedt77

I've done research and found that the 725 if Plenty for my setup, as far as the fuel filter I replaced it yesterday. Its mounted in the engine bay before the regulator. The timing is @ 14+ during idle with the vacuum advance disconnected.

WhiteWindsor

8 psi is a little too much for carb. Normally the range is 4-7. I have 6.5 psi. I did not look in your sig to see if you are manual. Did the other car have a different tranny. Are the #'s of the cars comparable? I've had that problem before many times and it was mainly due to sec. being to open. Total timing should come in around 3000 rpms. Get the engine to that speed and check timing and that will show you your total timing. What PV are you running. Make sure there is no slack in your accelerator pump.