was duraspark Q's, now idle fine, driving is a no go help!

[Zorm]

Insalled one today. Had a choise between the MSD module or the factory one. I went the factory one. Anyway, all went ok, I do not have a timing light so I did the timing by sound for now. Once I got her close, the car starts right up and runs nice.
Then I attached the vac line and went fo a test drive, did not get out of the drive way, at idle she is great but as soon as I step on the gas with it in gear it wants to die. Could this be a vac problem? timing problem?
I took off the old metal line and put a hose in its place, the hose is a little bigger than the old line, could this be my problem? What has everyone else used for a vac line with this swap? I am still using the stock carb, its new but is the stock one
Loking for advice :

 

[bigfordsix]

If your carb has the spark control valve, then it will not be compatable with the newer dizzy. Others on the forum will be able to enlighten you further on this should that be your problem.

 

[addo]

Did you change the carb since it last ran OK?

 

[Lazy JW]

If it ran "ok" before the distributor swap then it may well be an advance problem. First, unhook the vacuum advance and plug it (both ends). This will remove it from the equation. Your engine should be able to run fine without it until the cause of stumble is cured. Then get the timing set accurately and go from there. Keep us posted.
Joe

 

[Anonymous]

You need to set the timing with a light, also it sounds like you have a carb with an scv and this is not a dood supply for vac to a duraspark. Straight man vac is not really good either as it supplies hi vac at idle which is a no-no also. I would think that the scv type carb (this has a metal vac line to the upper part of the carb) will supply too much vac and open throttle situations but might work ok at lower throttle positions, thus put a timing light to it first of all. also make sure if it is not a single vac port dist. use the out side vac connection there.

 

[Zorm]

ok answer to questions.
Yes this is the stock carb for the 200 in a 66 mustang. Yes it has a metal vac line which I reconnected today and used that for the vac advance, it ran a little better but still sputtered when pressing down the gas. And no, I need to aquire a timing light. I set the dizzy in with #1 at about 6 oclock position when standing on that side of the car, when I set the timing with the light, what should I try and set it for? Should I take the Dizzy out and try to get the #1 at about 7 or 8 oclock? then set the timing?
So I guess what I need to do is get the carb adapter from Clifford or Summit and get the 2bbl carb. Well, what about a stock 2 bbl from a 83 302 engine. I ask because I have that one in my garage, was going to put the 302 in the mustang but I like the idea of keeping the 6. I think the 302 is going in the 89 Wrangler.

 

[Lazy JW]

... Straight man vac is not really good either as it supplies hi vac at idle which is a no-no also...

Actually, quite a few pre-smog American made engines used manifold vacuum. Done properly, it can work quite well and a few folks on this board have reported excellent results using manifold vacuum.

I highly recommend changing only one thing at a time. Throwing a different carb in the mix will just complicate things. Get the base timing nailed down first (WITHOUT vacuum advance), then we can walk you through the rest.
Joe

 

[addo]

Around town, my experiments with manifold vacuum and an electronic dizzy proved fine. Plenty of pep, better starting, decent economy (when you didn't over-enjoy the extra pep ). That was on a 200 with SCV type carb.

Yes, I too agree with Joe. One task at a time and success is defined; locked in as a stepping stone.

 

[cfmustang]

The only difference between manifold and ported vacuum are at idle. Manifold vac us high at idle and ported is about zero at idle. They are exactly the same otherwise. I had a hard time with this till I read this:

http://www.gofastforless.com/ignition/advance.htm

and saw this chart linked to that article:

http://www.gofastforless.com/ignition/vacuum_chart.jpg

It really is interesting reading and it finally made it simple enough for even me to get it...

 

[MustangSix]

As cfmustang pointed out, there is no difference in the amount of vacuum, only in the way its delivered as the throttle is engaged. The difference is, on the examples he pointed out were with distributors with far less total vacuum advance available. Plugging a Chevy dizzy or a '68 or later inline dizzy into manifold vacuum might add as much as 10 or 12 degrees of advance, probably less, and is something many engines can tolerate. The base timing can be set as normal and the additional advance may actually improve the engine's idle quality. But when dealing with the quircky vacuum-advance-only Load-o-matic, the situation is different.

The problem with using manifold vacuum and a load-o-matic distributor is that some engines don't idle well with that much extra advance dialed in. Depending on the distributor, you could be getting as much as 26 additional degrees of advance with the vacuum diaphragm. If you dialed in the base timing of, say 10 degrees, with no vacuum, as soon as you plug into the manifold you would be at the full 36 degrees of advance.

So, to get the idle quality right, you cut back on the static advance. Then what happens is, as soon as the throttle tips in, the vacuum drops, your advance goes away, and the engine bogs from lack of ignition timing. If you have a load-o-matic, the problem is compounded because there is no mechanical advance to deliver more timing as speed increases.

The Load-o-matic carbs are designed with a spark control valve that references venturi velocity. As more air flows past the carb venturi, a greater vacuum is created in the carb itself. This provides some vacuum to the load-o distributor even at low manifold vacuum, such as when you are at higher cruising speeds.

Hot rodders have been struggling with this distributor design since the forties when it was introduced on the flathead V8.

Anyway, to answer your issue, you have a Duraspark, so you should not have those load-o-matic issues. I think you probably need to reset timing to reflect that additional advance.

With the advance disconnected and plugged, set your base timing to 10-14 degrees. Then plug the vacuum back in. Your timing light will now show all the vacuum advance, plus the initial timing.

 

[Zorm]

well, the stang was not running all that great before the swap but it had better power. When I first got the car, she died on me twice. I ended up replacing the carb, its only about a few months old.
After the carb replacement, she ran much better but still puttered when I stepped on the gas, and almost died on me once or twice. The fuel pump, and filter look brand new, that is why I leaned towards the D-II swap, besides my last coupe I swaped in the little pertronix thing or whatever that is called and did not see a great performance increase. I have also changed the voltage regulator, not because I needed to, I just had a brand new one laying around. Putting that on dindn't matter either way.
So I should have a timing light tomorrow and will start from there.
If she still dies or sputters after I get the timing dialed in, what might be my cause?

 

[MustangSix]

Too often people try to go after the carburetor when the engine misfires, but before any carb problems can be diagnosed, the sparks have to be working right. Make sure the ignition is good, then you can chase the fuel system.

Float level too low, blocked main jet, inop power valve, vacuum leak.....any of those could also cause your symptoms. But remember, ignition first.

 

[XFlow_Fairlane]

so you installed the dizzy without a light and wonder why it dies?

 

[Zorm]

turbo_fairlane_200, I did a swap like this on my 83Jeep cherokee, swaped out the old amc dizzy for a Chevy HEI, timed it by sound and by feel of the exhaust and have never had a problem since, thought I might try that on this one. I have the light and will check timing tomorrow, and just for kicks, I'll also check my Jeep to see if I am close.

by the way turbo_fairlane_200, I would love to see your engine and what you did to make it turbo, are you the one that was in Mustangs and Fords? White car with orange or red highlights on the engine?

 

[XFlow_Fairlane]

um yeah.....that was me yeah!!!

nah that wa will and kellys falcon with a 250 turbo


my car is a cobbled up pos with rust holes......that has turbo whine

 

[Zorm]

Ok, if anyone is following this thread, did the timing light. car was set to 8tdc or whatever the marks mean, before I moved it to 10, so my ear is a little good, might need recalibration soon.
Anyway,... so I attached the vac line and saw no change in the timing mark. I shot some carb cleaner on the vac line and found some leaks where it screws into the carb. patched those up and saw a little bit of difference, so I adjusted with the vac adv. on to 10 again. Was I supposed to do that?
Well, took it out and she still sputters almost dies when stepping on the gas.
Came back and looked around, I don't know if it makes a difference but I found a cable from the tranny attached to a bracket on the gas peddle assembly and it was way loose, I tightned it up, well took the slack out of it, and drove off again, no difference.
Brought the car back and noticed something on the carb. I didn't think it made a difference but the tube that goes from the exhaust manifold to the carb, choke side, is broken off from the manifold, it just hangs there. Well today I found out that there is a vac there. I did not know this, just thought it was a tube to send heat to the choke. Anyway, when I blocked it off, the idle whent down. So, I grabbed an old spark plug wire and blocked it off with the wire boot and checked the timing with the vac line to the dizzy conected, again I adjusted the dizzy to 10. I did not take it for a drive but it sounds a little better.
So, that peice from the carb to the exhaust manifold, that steal tube, should I get and ez out and try to get the broken peice out of the manifold then maybe get a copper line and push it back into the hole and conect it to the carb?
Would this line really make a difference? and as far as setting the timing, should I fix the broken line from the exhaust to the carb then set the timing without any vac connected to the dizzy? or can I plug the line from the exhaust, remove the vac from the dizzy then set the timing to 10?
Don't have a manual, trying to find one, so this is a ton of questions.
Thanks for any info!

 

[cfmustang]

Any update? Did blocking off that tube make a difference on the road?

I am not familiar with your carb so I am not sure about that tube. It sounds to me like a choke tube, but I wouldn't think that would have vac at all...

 

[ludwig]

That tube to the manifold is your choke pull-off. Don't worry about the piece in the manifold yet. You probably don't even need the choke where you live. Just plug the tube to the carb. It draws hot air that activates the choke plate. I would make sure that your choke is not drifting shut by turning the black cap all the way open and leaving it there. Then you can chase down the other vacuum leaks. Also check you fuel/air mix with the vacuum guage. You might be starving out the engine under load. With the guage hooked up, turn the screw until the engine just starts to die, then back the fuel mix screw off until you achive the highest vacuum you can. It should be above 18.
Once you have the car running well you can get the choke going. The only problem is that you can only do a cold start once or twice a day.

 

[JackFish]

Is your fuel pump in good condition?
If it's dying when you step on the gas that might cause it.

 

[Zorm]

update: the, I guess, choke tube, off the carb did not make any diff while driving. I did remove the vac advance, reset the timing to 10 and placed the vac advance back on.
Ludwug, Ill try that with the carb.
Jackfish, fuel pump is new, as if the fuel filter
cfmustang, I didn't think it had a vac either but this one does, its a rebuilt stock replacement carb for the 200, avail from a autozonediscountautonapachecker parts place
I also had another thought, since the car has been doing this since I bought it, and with every small fix, replaced exhaust manifold, replace carb, replace dizzy, plug wires and plugs, but it still sputters and hesitates when trying to drive. Although there is no knock or tap, could the timing chain be slack?