vaccum timing advance

ok so usually i let my jeep warm up till at least the temp gauge moves before i go anywhere. today i only let it run a little bit being anxious to go home from work, and my jeep was back fireing and sputtering. i knew this was becuase the timing was off because of the vaccum advance. when the jeep warmed up this stopped and the jeep ran fine. my question is is there any way to get the timeing advance to come back, before the jeep is warmed up? im asking this not to do it all the time, but i also use my jeep for going to fire calls, and the station is not far. it is really unlikely i will be able to warm the jeep up before i leave. ( urgency of calls to get to the station). any info is greatly appreciated thank you in adavance. :driving:

 

On some newer cars the vac advance is temperature controlled, but on an old Jeep it should just have a hose from carb to dist. It sounds like you just need to choke it a little more.

 

what does the temp of the engine have to do with engine vacuum and therefore timing advance?

Are you talking about the choke? That would have an effect based on temperature.

Just trying to clarify

 

i just figured the advance had to do with the temp. because when the engine warms up the problem goes away without having to use the choke. but i did notice when leaving the station tonite, i jumped in and left the choke out and it ran fine on the cold engine. could my problem be a misfire on one of the cyl.s . do you think i should replace the plugs. i was planning on it any way. and just to verify the back fire is coming out of the carb and the exhaust i believe. carb for sure i definetly can see that one, and i can hear the exhaust.

 

backfiring through carb and exhaust points to two different issues. When was the last time that carb was thoroughly cleaned?

I think I'd start there and check the timing as well.

 

not sure when the last time the carb was cleaned. i plan on rebuilding it but at the moment its been my daily driver, cause my other truck is in the shop. i ahvent checked the timing yet but i will. this only does this sometimes so i think the timing is on or close because its not constantly doing it. only seems to be when the motor is cold.

 

I agree, use a bit more choke and leave it on a bit longer, there's nothing in these old engines that changes timing in regard to temp.

Which engine are we talking about and how old are you, as in, did you grow up when chokes were common equipment on cars?

 

Because it's not a consistent problem carburetor icing is also another possibility.

 

Isn't back fire out the carburetor caused by the intake valve not being completely closed on the power stroke?? I periodically have this problem. I've added cheap O'Reilys fuel injector cleaner to a tank of gas and it goes away. In my case, a tank is only about 4 gallons and I mix the cleaner rather strong.

 

i have the dauntless v6 oddfire and im 25 didnt really grow up with this type of equip. so this is all new to me. i do realize its definetly not the type of choke thats on the lawn mower R) .

 

ok heres the up date of what i did today. put the timing light on the jeep today after work and wow. according to the light the timeing tick was way out of wack. it was way above the positive i couldnt even see the timing tick a first. so i adjusted the timing and there is no real change. i guess it runs a bit smoother on idle but if i give it half throttle it starts to backfire. just to verify i do have the prestolite junk dist. so i have ordered a new delco dist. hoping that is the problem since i just put new point and condenser in this one. tonite i ran it home from work full choke and only half thottle it ran ok until i went to give it more gas and started to back fire. getting a bit frustrated at this point. i think i mite take the carb off and try and rebuild it tonite to take out some frustration. chainsawguy

 

It's really pretty similar. The choke enriches the mixture while the engine is cold to help it run. It's perfectly normal for the engine to require a little bit of choke as the engine warms up. Even on the coldest of mornings, I could take the choke off in less than a minute or so when I lived in Nebraska and it would be fine.

How long do you need to have it choked before it will run correctly off the choke?

 

it was off and on uptoo today some days it would run great off the choke and then some not. i usually run the choke the whole time im waiting for the jeep to warm up in the morning. ( bout a half hour ) is this bad practice?

the reason i do is because, my choke revs my engine up past idle and i was figuring the motor would heat up faster. and heat the cab up faster. when talking with the guy i work with who is a mechanic we were thinking that the timing advance mite be sticking. hence buying the delco dist. which should be here fri.

 

Running it on choke runs it rich and if done for too long can foul plugs. That could be a part of your problem too. Pulling the choke knob or whatever you have out slightly may raise the engine speed by engaging the fast idle cam while not actually choking off the engine. That's probably fine but if you're engaging the choke for that long again you can foul a plug. If the motor requires choke for that long to run right then I'd think you may have a problem in the low speed or idle circuit of the carb or the idle mixture could be way out of adjustment

 

ah ha ok i didnt realize this may foul a plug will pull my plugs tommorow, and check them and probably replace them. in just the starting phase of the engine i probably only need to run the full choke for 3 min and then i can release it. i was thinkning this was just reving the engine more than anything. tommorow when i start it i will i will back the choke off when i let it warm up.

when facing the carb from the front which screws are which when adjusting ( left right)

 

depends on the carb. If you can post a pic it will be easier to direct your actions. I'm not saying that it needs adjusting, just that its a possibility.

Also try the search function as there are lots of threads about carbs. May help you.

 

i looked back at my trusty fsm and found it. i have the rochester 2g. didnt get to rebuilding the carb tonite didnt figure i would ahve the time, mabey tommorow rite after work. at least if i rebuild it that will eliminate one possibility. this is the first time rebuilding a carb so i wanna make shure i do it right and take my time.

 

Just out of curiosity did you disconnect the vacuum line to the distributor before checking the timing? If for some reason it's running manifold vacuum that will advance the timing at idle and won't give you the base timing. Point gap also affects base timing.

 

no i did not disconect the dist. i will do that tommorow and recheck the timing. i did just set the point gap when i put new point in the other day but didnt have a dwell meter with me at the time. i did find one at the shop today but im unsure how to hook it up or where to hook it i belive it had three wires two for the batt. and one with an aligator clip on it.

 

As far as the dwell meter goes, red should probably go to the neg (-) side of the coil and black to a good ground.

Unsure about a third wire as all my meters have 2.


Red to bat, black to ground, clip to negative coil is probably how a 3 wire works