fastbackford351

OK. Here's the deal.

The fastback has been running like a poop lately, to the point of not being able to get out of its own way. 4k on the rebuild. SVO aluminum head, Holley 650dbl pumper, nice Crower bumpstick etc.

It is fine putzing around town but when I stand on it, blech. It is WAY less than impressive and not near where it used to be.

I put the timing light on it and see that the timing has crept up a few degrees from where I set it a couple years back but nothing grossly out of bounds. I usually run it at 14 initial with 38 total.

I backed it down to where it should be but it was still a pig. It sounded a lot better but still WAY down on power. I take it out and stand on it and about 2/3 of the way through the pull I would get a backfire through the carburator.

While I was setting the initial timing everything looked fine. Nothing unusual. When I revved the engine to check the total the timing the lite would 'cut out' momentarily. I moved the spark plug lead to several different plug wires with the same results (cutting out under load). I put the timing lite on the coil wire and there was no cutting out there so I am pretty certain that my distributor is getting good signal from the coil.

Now, granted, my ignition system is a DizzyII setup with about a bajillionty miles on it so if it up and died right now it doesn't owe me anything. I am running a Standard brand Duraspark box with the white connector (retards during cranking).

But I was wondering what was failing. Thoughts, comments, suggestions?

kalli

hiya ... it really sounds like you might have two seperate problems.
One thing you should try is to verify that your TDC mark actually is TDC (for your poor performance). I personally don't like more than 10degrees at idle on mine, but every engine is different

Ther other thing with temporarily cutting out sounds very familiar to me. I once had that as well. In my case it was a pertronix distributor where the vacuum advance was screwed to the distributor housing. This screw was as well holding the ground cable from the HEI module. So only when the vacuum advance was active it would could out temporarily. Bottom line. You might be lucky and it is just an intrenal ground issue from the HEI module inside the distributor to the distributor housing itself.

Kalli

fakesnakes

If the coil is firing properly, then the only thing in the way is the dizzy cap, rotor and wiring. The pick up and box are eliminated. If it's that old, replace the cap and rotor. That may be your only problem. I've also seen a rash of bad spark plugs lately. The set on my DAytona Coupe had only 1500 miles on them when the car started breaking up above 3500 rpm. I finally replaced the plugs out of desperation and it felt like it got 100HP back!

MBDiagMan

I think that fakesnakes is right on the money with his diagnosis. You are talking about a few cheap parts here, so it's worth trying. As he said, try the cap and rotor first and then the wires.