DUI installation troubles

[Anonymous]

Okay, to start off, this is in a 66 Mustang 200. I bypassed the ballast resistor, and wired up the distributor. I got it running and set initial advance to 12*. I then hooked up the vacuum advance to ported vacuum.

The problem is, the engine is running extremely rough, making a nifty throbbing noise at idle, that is shaking the entire car. Also, when I hit the gas in neutral, the engine almost dies on me. And, if I hit the gas too had too quickly, it backfires out of the carburetor.

It seems to do it a little less when I have the vacuum advance hooked up, but it is insignificant enough of a change that it may be purely psychological.

So, what could be causing this? Could it be something in the distributor? Even though it's new? Is there a way I can test it?

Thanks, this has me stumped.
-Chris

 

[FalconSedanDelivery]

and what was the initial timing before the swap , also try advancing the initial 18-20 degrees and see if it comes around ( only to test not a permanent setting ) do this with the Vac advance unhooked ( one thing at a time ) I have seen the outer ring slip and throw the marks off

 

[mugsy]

Did you verify that there is 12V at the DUI when its running? Check that first. If there is, then it sounds like the timing is way off, maybe too retarded. Ignore the timing light and move/rotate the dizzy until it smooths out. Rotate in the direction that the vac canister points.

tanx,
Mugsy 8)

 

[Harte3]

Try direct manifold vacuum. It may or may not make a difference but in the end, use which ever one works the best.

 

[AzCoupe]

Try manifold vacuum first, this will give you extra vacuum advance at idle, keeping your spark plugs cleaner over time. However some motors tend to idle too rough or too fast hooked up to manifold vac, in which case you should run ported vacuum.

 

[falcon fanatic]

wires in the right order? Sound like timing, though.

 

[Anonymous]

I had it hooked up to manifold vacuum initially, and that was worse than ported vac. For some reason, on manifold vacuum, I was seeing a timing retard when I hit the gas too quickly.

Also, the harmonic balancer is relatively new, and timing shows up correctly when I time the engine using my old dizzy.

 

[jamyers]

I had it hooked up to manifold vacuum initially, and that was worse than ported vac. For some reason, on manifold vacuum, I was seeing a timing retard when I hit the gas too quickly.

Also, the harmonic balancer is relatively new, and timing shows up correctly when I time the engine using my old dizzy.

Manifold vacuum will 'retard' (actually, it just quits advancing) the timing when the throttle is suddenly opened and the vacuum drops off momentarily.

I'd double- or triple-check the wires, I'm betting you got one or two out of order during the swap.

 

[grocery getter]

i'd start over, pull the valve cover make sure you're at #1 tdc with the intake just closing. point the rotor at the cap with cylinder number one wire. double check the firing order. you could be 180 off.

If youre absolutely sure you installed it correctly a bad ignition module or coil can do some crazy things.

 

[HighVolkage]

i was getting that when i was first getting my motor running, took it off of vacuum advance completely and it runs fine now. if you havent already tried that (could have missed something ) i'd give it a shot.

 

[Anonymous]

Ok, I fixed it. Jamyers was right. Even though I had already triple checked it, I had managed to pull a dyslexic moment and switched my 3 and 5 wires.

I'm running manifold vac now, and it seems to be working like a charm.

Thanks for all the help,
-Chris

 

[jamyers]

Ok, I fixed it. Jamyers was right.
...

Yay, I got one right!!!
(Even a broken watch is right twice a day.)

Glad it's going well!