I was helping my friend with his 89 Honda Accord, manual trans, and noticed the Vacuum advance is loose on the carb, is that normal? I am used to metal ones that fit snugly with no wiggle. In any case, I tested the ports and the one closest to the distributor will not hold vacuum but the other does. Is the one closest for typical vac advance function and the other related to emissions? I know that is how 80's Toyotas are but I am new to Hondas.

The car has been desmogged but neither of us did the work. It has a Weber on it, looks like a 32/36 but not 100% sure. Whoever desmogged it tied the Vac lines together and ran them to the carb base which appears to be manifold vacuum. In my experience the only port that should be hooked up is the one needed for advance (to manifold vac) and the other gets plugged. I found a factory manual for this car but it looks like both lines originally went to a control box so I am lost on how to hook these up. Does anyone have experience on what works best for hooking up a vac advance when when a Weber has been put on these cars?

Thanks for the help!

 

I'm more familiar with other carburetors (I had a 72 Datsun) so this is kinda general information.

That port on the bottom of the carb is probably a throat tap right at the throttle plate, and it starts making a strong vacuum just when you start opening the throttle. It's not the same as manifold vacuum because it won't create a strong vacuum at idle.

I'll try to do some digging, but I'm GUESSING(??) that the 2 ports on the distributor should NOT be tied together. One of them should come from that throat tap and the other should be the manifold vacuum. Tying them together might just provide a vacuum leak at idle.

 

Thanks JimBlake. I think you are right on the vacuum, I had to do a little reading last night to refresh my knowledge of vacuum and carbs. I have a couple carb'd Toyota's but everything is just in the factory location so I easily forget the ins and outs of vacuum.

The local parts store couldn't find a new vacuum advance so my buddy is headed to the junkyard tomorrow to hopefully find a working one. We may just have to do some testing with a vacuum gauge and trial and error to see what works. I will report back on what we figure out.

 

Got a MityVac? Open the distributor, disconnect both hoses, & apply vacuum to each nozzle separately. One of the nozzles should make the plate move in the direction of advancing the timing and the other should move in the direction of retarding the timing.

I'm pretty sure the throttle tap should connect to the one that advances timing and manifold tap should connect to the one that retards.

 

Thanks for the tip. I used the mityvac to check both ports and they both advance the distributor, but the one closer to the distributor body produces more advance, hard to say how much. My friend found a good unit at a junkyard but it was slightly different, we had to drill out the hole in the end of the connecting rod. It seemed to have the same range of motion as the one that was on the unit, although it was tough to tell since the diaphragm in that one was bad. In any case, we set the timing per the label and it obviously improved drivability dramatically. The port in the carb base is producing vacuum at idle and increases as rpm increases, some similar to ported vacuum. In any case, having it hooked up improved drivability dramatically obviously, had to say whether the total timing and advance curve is just right, but there was no pinging that I could hear so I think we are safe.

Thanks for the help, I may fiddle with it a little more but since it is the neighbors car and he seems happy I will probably just leave it alone.