Vacuum gauge for carb tuning
- Thread starter wm69
- Start date
Well, I spent the better part of the day covered in grease and gasoline. I hooked up the vacuum gauge and got about 21 at idle, so according to the Erman guy 21/2 ='s 11.5 11.5-2='s 8.5 so I need an 8.5 power valve. I discovered that my carb had a 2 stage power valve and of course no one in town had a 2 stage power valve in stock (NAPA and the other good store closed at noon AFTER I got started) so I thought I would try a single stage PV. More on that in a min.
My power valve cover has a vacuum hook up on it that was capped, so after a little googling I discovered that the power valve should be hooked up to manifold vacuum to keep it closed until the throttle is hammered and when the man vacuum drops the power valve opens up. Basically since I had that capped the power valve was staying open all the time. I T'd it into the PVC vacuum line, and I also hooked up another capped fitting on the accel pump on the front of the carb (T'd it into the vac advance line).
I found an 8.5 single stage power valve at Orelly's so I thought I try it. I discovered that a single stange PV will NOT fit in my carb, so I took the carb back off the Jeep (and dropped a nut down in the intake in the process; that was fun getting out) and put the original 2 stage PV back in (not sure what size it is as it is not marked) and put the carb back on the Jeep. Idles great at 500 RPM, still get a little puff of smoke if I gag it while sitting at idle, but not the cloud I was getting. I probably still need to get the right power valve in there but at idle it's not too stinky now so the 47 jets will stay in place. I'll have to drive it some this week and see how it does.
My power valve cover has a vacuum hook up on it that was capped, so after a little googling I discovered that the power valve should be hooked up to manifold vacuum to keep it closed until the throttle is hammered and when the man vacuum drops the power valve opens up. Basically since I had that capped the power valve was staying open all the time. I T'd it into the PVC vacuum line, and I also hooked up another capped fitting on the accel pump on the front of the carb (T'd it into the vac advance line).
I found an 8.5 single stage power valve at Orelly's so I thought I try it. I discovered that a single stange PV will NOT fit in my carb, so I took the carb back off the Jeep (and dropped a nut down in the intake in the process; that was fun getting out) and put the original 2 stage PV back in (not sure what size it is as it is not marked) and put the carb back on the Jeep. Idles great at 500 RPM, still get a little puff of smoke if I gag it while sitting at idle, but not the cloud I was getting. I probably still need to get the right power valve in there but at idle it's not too stinky now so the 47 jets will stay in place. I'll have to drive it some this week and see how it does.
