I need help sorting out some performance issues. The car is a 86 sc, LG4, carbureted, M5 trans., I bought it less than a year ago and all of the work I have done has been standard upkeep. I am ready to boost performance now, but I need help. The car had an Edelbrock 600 on it when I bought it. It had a 9"Open element setup that I switched to 14". O'Reilly says I need a vaccuum advance distributor to run the Edelbrock. I have no records showing a distributor swap and I was wondering how I can tell if it has the right carb/dist. setup? Cap is Delco Remy, but records show replacement in 98'. I need to find out if I can keep the carb or if I should go to a holley rebuilt q-jet. Any advice on how to tell if it is the right setup would help a lot.
Also I replaced the thermostat to a 160 degree. Afterwards I read on here that I need to replace the PROM. I have a Chilton, so if someone can let me know what to buy, and what system the PROM is a part of, I can probably get it switched.
I am open to any suggestions and thank all that reply.:hail:

 

many backyard mechanics have been known to replace the computer controlled carb with a mechanical one, but leave the original electronic advance distributor installed. car will run, but will have low fuel economy and not much power. if this is the case on your car, grab a mechanical advance distrubitor off a junkyard 305 equipped car or a rebuilt one from the autoparts store. if you go used, pay close attention to the advance weights, they often wear to an elliptical shape.

can tell what's currently installed on your car by looking at the distributor. if you see hoses running into it, its got a vacuum advance distributor. if all you see is wires, you've still got the original electronic advance distributor.

 

I checked the distributor. Nothing but wires coming in and out. You guessed my problems with low fuel economy and performance. I just wanted to ask what I would have to do different to install a vacuum advance instead of the electric advance distributor???

 

I meant to say mechanical advance distributor.

 

Non-computerized distributors use a combination of mechanical (RPM dependent) and vacuum (load dependent) advance. Computer-controlled distributors use neither. So there's no difference between a "vacuum advance" distributor and a "mechanical advance" one.

The bottom line is that if you have a non-computer carb on your car, the computer is going to be massively confused all the time as to its inability to affect the fuel mixture. It will end up with a "limp-home" timing curve, which is far from optimum. Worse yet, if you leave the computerized distributor in there and remove the computer, you will have no advance at all beyond your static advance, which is really terrible. Computer control is an all-or-nothing proposition.

Get something like a $100 Accel "blueprinted" distributor; or put the right carb back on your car. It will run a whole lot better. My advice would be to get a better carb than that Carter, and the non-CC distributor. I'd suggest a Holley 6210 carb.

 

changing the distributor isn't difficult, around the base of the distributor on the engine there will be a bolt to loosen when adjusting the timing. if the bolt is removed, the bracket will come off too, then lift the old distributor out of the engine and slide your new one in place, reassemble and place the spark plug wires on it.

vacuum advance port of the distibutor can be tied to any manifold vacuum source, just put a "T" in any existing hose and run a new hose over to the distibutor.

big thing will be getting the timing adjusted properly. you'll need to acquire a timing light for the job if you don't already have one.