Ok, here goes. My 66 289 auto is acting a little wierd. It's done it ever since i got it. When you put it in drive or reverse, it runs ok, not like poor Harold, but when you punch it and let off real quickly it starts stuttering and the RPMs are going up and down. but most of the time it evens back out,but it stalled out yesterday on me, and took a bit to get restarted. About my timing, I have NO idea, because it doesn't even get close to running when i put it on 6 degrees. It shows it going off the the numbers totally when it's godd enough to run. Could my vacuum advance have something to do with it? Because i dont feel and vacuum coming off the port for it. When you rev it up you can feel a little, but not like the vacuum line for the tranny, it has alot of vacuum. Could this be the problem? I really need to find out because im taking my driving test in it tomorrow, even though everyone is telling me not too. I dont need it stalling out on me. Thanks for all the help

 

Power tuning is another way to set timing. Here's what you do:

Advance the timing until it starts to ping under load (like pulling a grade). Then back it off until it doesn't. Lock down the distributor and make sure when cranking over the engine it does not kick back against the starter (need to double check this when cold).

Something else to check:
disconnect the vacuum line to the distributor. At idle you should not have any vacuum. Then check to make sure you vacuum advance is working correctly. I had to add 3 shims to one advance to get the curve correct. It kept coming in too abruptly, and causing a stumble, but mostly on light acceleration lower rpms.

When in neutral, if you tap the gas quickly does the engine respond, or does it stumble. If it stumbles after you set the timing check your accelerator pump.

Good luck on your test tomorrow.

 

Thanks Scott, Advanceing it would be turning it clockwise right? I'll try that tomorrow. It only stumbles when it's cold, I think. How do you check to see if the vacuum advance is working? I popped the cap off, and with my hand pushed the advance and everything moved ok, it was just a little stiff, but im sure thats normal. like i said, the port feeding the vacuum advance doesn't feel very powerful. maybe it's not advancing right, but when driving on the street, i dont feel any power loss. i dont know, im getting frustrated with it all. Thanks again for the help.

 

You are correct, turn the distributor clockwise to advance timing.

If it only stumble when cold it could be the choke is set too lean. And you may also need to reset the fast idle speed.
However for your driving test you don't want to have a cold engine anyway.

Major burnouts and donuts are not good to do on a cold engine Just kidding, you don't want to give the poor guy a heart attack now do you.


If you are ever not sure you can look at the firing order and turn the distributor in the oposite direction. For instance the firing order for a 289 is 15426378 in a counterclockwise rotation, so the distributor turns clockwise to advance.

As for the vacuum advance it doesn't need a lot of vacuum to move the plunger. The diaphram is huge in comparision to the spring pressure.
To check a vacuum advance you need a handheld vacuum pump, a tachometer and a timing light, unless you've got a distributor machine handy. Connect the hose to the vacuum pump, and with the engine at a steady 1000rpm start increasing vacuum while watching the timing pointer with a timing light. Full advance should be about 10* depending on which distributor you have (could be anywhere from about 8* to 16*). Advance shouldn't start until after about 5"Hg and should progress linearly until max advance at about 16"Hg.

 

hahahahaa, Yeah, i know about the choke and everything. It's a long drive to the DMV, so it'll be plenty warmed up, but i still dont think i'll be doing burn outs, unless he starts talking trash about our beloved mustangs, then im going to make sure i scare him good. then i would never be able to drive though. As far as the advance, i sucked the end of the line, ( im definalty old school) and the plunger didn't think about moving. I was probably creating the same amount of suction as the port on the carb. at least i think i was. I will definalty try and get a vacuum pump. because i was about to have a stroke trying to do it myself.

 

Yeah, human lungs are good to about 3" of vacuum. Guess we were never meant to be Hoover vacuum cleaners.

Hope you get a cool tester who's into old school.

Well, good luck, and have fun!!!

 

I was gonna make a joke about a girl in high school, but thought better of it

 

Markstang Yeah, thats what i have been hoping too.

 

So How'd the drivers test go?

Are you now a legally licensed Lethal weapon (or as "special ops" would say, a LLLW)

btw: seeing as this is a "G" rated forum, I'm refraining from discussing anything that sucks...

like points off for agressive acceleration [sm=icon_rofl.gif]

 

YAY Yeah i passed. The car ran pretty good. I was very proud of it. It might because i told it, i would use a blow torch on it. Thanks for asking Scott, and thanks again for all the help.