I have an Accel Gen vll EFI setup on a 59AB and plan on using a pressure regulator but it has a vacum inlet fitting. I'm assuming it's to allow for more pressure on acceleration. When the vacum drops more fuel will be allowed into the fuel rail is my guess. Does anyone know for sure?
Any ideas??


Jim

 

The vacuum reference keeps the fuel pressure constant relative to manifold pressure. The even pressure drop across the fuel injectors makes tuning easier.

 

The fuel pressure varies with manifold pressure so that there is always a constant pressure across the fuel injectors. If manifold pressure drops by 5 PSI, fuel pressure drops by 5 PSI. If manifold pressure rises by 1 PSI, fuel pressure rises by 1 PSI. So the pressure difference from inside the fuel rail to inside the intake manifold is always a constant.

 

Thanks guys for the replies,


I'm questioning this only for the purpose of learning, on my part. I haven't done any hot rodding since 1957 when I got married but before that was quite involved in drag racing. Flatheads were about the only thing around at that time other than the Jimmies that were actually damned quick for what was available at the time.
I use a 1" S. S. fuel log and did have four Strombert 97's but then went to the EFI and am using what looks like the old Moon conversion from about 100 years ago. I used the Stromberg needle and seat fittings so the old log fit perfect. At the end of the log are the pressure guage and I ran a 1/16" tube curled up and back to the feed end of the log and then back to the fuel tank. My theory was that with the end of the log open back to the tank and at a lower rate of flow that the carbureators would have enough fuel and the air would pass on back to the tank. If that is true I shouldn't need the vacum regulator now? I put a picture of the engine with the 97's and showing the log with the loop at the end. It was in the Build thread I started a fiw months ago and in the next frame on that thread is a picture of the engine with the Throttle Bodies replacing the carbs.


Any comments, good or bad?


Thanks for any suggestions and you won't hurt my feelings, so let it out.


Jim