Can hooking the vacuum on a distributor to the manifold vacuum port on a carb as opposed to the timed vacuum port cause the following issues?

1. Backfire during cold starts
2. Runs and dies during cold starts
3. Wont idle when cold and somewhat poor idle after warm
4. Rich idle
5. Severe plug fouling

I just realized my vacuum hose was on the wrong port on my carb but now its to short to reach the other port so it will be a few days before I can get a longer hose.. Meanwhile I would be curious to know if this was the main cause to most of my issues? Sure would be nice if it was..

 

My first response to your questions would be, "No, it can't". The idle quality might be a bit poorer on some cars (under the scenario you described), but I don't think it would cause anything as severe as you describe. Most of the time, moving a 'timed port' dizzy hose to a 'manifold' port will improve the idle. The use of the timed port is primarily for reducing hydrocarbon emissions during idle. As soon as you crack the throttle, a 'timed port' becomes a 'manifold' port.

 

Those problems sound like retarded timing or idle mixture screws need attention. I would look at the initial timing first and then go from there.

 

As already said, the advance should ideally be hooked to manifold vacuum, ported vacuum is an emmissions thing. I would leave it where it is. If this is all cold related, then surly it it the choke setup that is wrong ?

Jeremy

 

I cant figure out what else could of happened.. This motor was tuned on a dyno a few weeks ago.. After installing it and firing it up for the first time it seemed to run and idle great.. It even had a major lope to the idle too. I havent drove it yet because I'm still trying to work out the bugs in my new digital gauges and after starting it a handfull of times, the plugs started to foul out and then all the above mentioned issues started to arise.. So I installed brand new plugs (and verified the gap) thinking this would solve the problems but it didn't change anything.. I lengthened the vacuum hose because I wanted to route it differently and that's when I must of installed it on the wrong port (or maybe it came installed on that port, I just dont remember). I checked and re-checked the hose and there are no vacuum leaks so I cant figure out what else changed.. It doesn't even seem like it idles the same anymore either, almost like the timing is more advanced because the lope in the cam doesn't seem as extreme anymore. However, I didnt touch anything else, including the timming or choke.. Anyways, here's what my plugs look like after just one start, letting it get up to 190 degrees and then shutting it down.. While it was warming up I also shot a short video and as you will hear, the lope in the idle seems pretty mild now..

Video