Manifold vacuum question
Is there a predictable relationship between manifold vacuum and timeing?
The reason I ask is that I'm still looking at my 4360 FI unit and I wonder if the relationship between the 2 might be affecting the FI since it is so vacuum dependent. This unit has the single piston type enrichment setup which I understand GM junked early in the game. The car is a 250 HP Powerglide.
The unit runs fine when hot but poorly until warmed up. It functioned very nicely on a test engine which it was setup on but on the cars engine I have the cold start problem.
The problem is that the engine starts quickly and runs on the rich stop. After 1 minute the cold enrichment system sends vacuum to the enrichment diaphragm and the ratio lever moves to the lean stop and the engine stalls. I can remove the vacuum line from the enrichment diaphragm and warm the engine up with the ratio lever on the rich stop then connect the vacuum and the warm engine will run fine on the lean stop. At that piont it continues to run fine.
Most of the advice I have gotten in the past has told me to put my 4800 unit on the engine but I hate to give up and do that.
The reason I ask is that I'm still looking at my 4360 FI unit and I wonder if the relationship between the 2 might be affecting the FI since it is so vacuum dependent. This unit has the single piston type enrichment setup which I understand GM junked early in the game. The car is a 250 HP Powerglide.
The unit runs fine when hot but poorly until warmed up. It functioned very nicely on a test engine which it was setup on but on the cars engine I have the cold start problem.
The problem is that the engine starts quickly and runs on the rich stop. After 1 minute the cold enrichment system sends vacuum to the enrichment diaphragm and the ratio lever moves to the lean stop and the engine stalls. I can remove the vacuum line from the enrichment diaphragm and warm the engine up with the ratio lever on the rich stop then connect the vacuum and the warm engine will run fine on the lean stop. At that piont it continues to run fine.
Most of the advice I have gotten in the past has told me to put my 4800 unit on the engine but I hate to give up and do that.