Poor Performance

[goodnigh]

The problem being the engine runs poorly, Most of the time.

It usually starts up smoothly but sometimes has a hard time

turning over, like a bad battery. New battery and starter did

not fix the issue. It idles smoothly, Most of the time. It will

hesitate then surge ahead when I accelerate. Sometimes it

accelerates smoothly and sometimes it pings. I could run

diagnostics on the dizzy, but I may catch the engine in a good

mood and find nothing wrong. The engine has less than 4000

miles on it so I doubt a problem with the balancer. The dizzy

came off the old engine. My finger is poised on the "BUY" button

at NPD, just another excuse to get a new part I guess.

Has to be the dizzy, can't find anything wrong with the fuel

system and pulling 18 inches steady vacuum.

mike

 

[wwhite72]

Check the distributor gear? You got a roller cam ?

 

[Don65Stang]

Are you running points?

If yes, then I think that may be the problem.

If no, then I still think it's a timing issue.

Maybe a worn gear as mentioned above.

Rotor button and cap fairly new?

Plug wires good shape?

What plugs are you using? autolite 24? Gapped at .035?

What is your initial timing set at?

What is your total timing at 3000 rpm?

 

[goodnigh]

Check the distributor gear? You got a roller cam ?

No roller, stock Cleveland.

Good question about the gear.

Does act like it jumped a tooth.

mike

 

[Don65Stang]

Does act like it jumped a tooth.

mike

Put the light on it.

 

[goodnigh]

Does act like it jumped a tooth.

mike

Put the light on it.

I'll get back to you.

mike

 

[wwhite72]

Pertronix modules go bad also, if you happen to be running one.

 

[goodnigh]

New Module, bad dizzy.

Put the light on it and advance read 50

no matter where I turned the dizzy.

Could rotate 45 degrees with no effect on the engine.

mike

 

[Don65Stang]

New Module, bad dizzy.

Put the light on it and advance read 50

no matter where I turned the dizzy.

Could rotate 45 degrees with no effect on the engine.

mike

Before we conclude bad dizzy, define Module. As in Pertronix I, II, or III?

I think bad "new" module if a Pertronix.

Take the cap off and turn the rotor button by hand clockwise. Should rotate 20 degrees or so then spring back to original position.

Either way, bad dizzy or bad module, want to go Duraspark II? I did this swap recently and a huge difference. Eric (mister 4x4) did a good write up with part numbers that you can get at the local parts store except for the wiring harness. You could easily make one, it's just running 5 lengths of wire from the battery area to the distributor and coil. Nothing hard about that at all. I can provide pics if needed.

Just mentioning another option.

Or could order a MDS distributor and spark box for plug and play.

 

[wwhite72]

Dizzy gear look abused?

 

[goodnigh]

Are you running points?

If yes, then I think that may be the problem.

If no, then I still think it's a timing issue.

Maybe a worn gear as mentioned above.

Rotor button and cap fairly new?

Plug wires good shape?

What plugs are you using? autolite 24? Gapped at .035?

What is your initial timing set at?

What is your total timing at 3000 rpm?

New Pertronix HEI coil and Ignitor module in dizzy.

8mm Taylor wires and Champion 3025 plugs both 4

years old (2000 miles).

The rotor turns maybe 20 degrees counter clockwise

but does not exactly "snap" back.

Don't know what shape the gear is in, have not

pulled it. Other than the power steering pump, the

dizzy is the only other part that came with the car

when purchased 7 years ago. Everything else under the

hood has been replaced. A dizzy is on the way so we shall

see. This rebuild will come with points. Since I don't know

how to use the new light, a distributor will fix the problem :angel:

mike

 

[Don65Stang]

Cool Mike. What dizzy did you order? If stock replacement you'll need to do some minor disassembly to see what plate they put in it to know The mechanical advance limits. Hopefully it will have 10L stamped on it but i doubt it.

Give me a call later if you want to discuss. I recently went through all this with the 71M 4spd car so it's still fairly fresh on my brain.

BTW, that timing light is one of the best tools you have for tuning your car to run great. I recommend you play with it a lot to understand how it works. It's pretty simple after you get the hang of it. The important thing is to mark your damper at the 0 degree line with a thin line of paint. "White out" works good. The rest is just up/down buttons to get the timing readings. Read when the zero white line is at the pointer and the display tells the rest. To set the timing is just the opposite. Punch in what degrees you want on the light then rotate the distributor until the zero line up with the pointer.

 

[goodnigh]

Cool Mike. What dizzy did you order? If stock replacement you'll need to do some minor disassembly to see what plate they put in it to know The mechanical advance limits. Hopefully it will have 10L stamped on it but i doubt it.

Give me a call later if you want to discuss. I recently went through all this with the 71M 4spd car so it's still fairly fresh on my brain.

BTW, that timing light is one of the best tools you have for tuning your car to run great. I recommend you play with it a lot to understand how it works. It's pretty simple after you get the hang of it. The important thing is to mark your damper at the 0 degree line with a thin line of paint. "White out" works good. The rest is just up/down buttons to get the timing readings. Read when the zero white line is at the pointer and the display tells the rest. To set the timing is just the opposite. Punch in what degrees you want on the light then rotate the distributor until the zero line up with the pointer.

Will do, Thanks. The dizzy is a stock rebuild from NPD.

Learning how to use the light.

mike

 

[wwhite72]

http://www.performancedistributors.com/fordduraspark.htm

 

[goodnigh]

http://www.performancedistributors.com/fordduraspark.htm

One of the issues is my distributor has dual vacuum ports and

the carb vacuum is ported.

mike

 

[wwhite72]

think you need a dual vac advance can? one is to retard timing at startup in believe. ever try just pulling the retard hose off and running the main hose to manifold vac? you may find your engine runs better, especially if you have some cam. my Holley has both manifold AND ported vac connections. are you sure you only have ported? also, most non-racing intakes have a tapped hole for a hose fitting. My 72 factory intake had the fitting just back of the coil mounting bracket location.

 

[Don65Stang]

http://www.performancedistributors.com/fordduraspark.htm

One of the issues is my distributor has dual vacuum ports and

the carb vacuum is ported.

mike

Easy fix; only use the outermost vacuum port, cap the inner port, and remove that vacuum line from your engine capping off where ever it originated from.

The purpose of the inner port on the vacuum advance is to retard the timing which keeps the combustion chamber/exhaust temp and overall engine temp higher. Higher temps means burning off more emissions. But where does the heat come from? Not from the timing alone...it takes an energy source to create the heat and that source is the fuel in the tank. It takes more fuel to create more heat to burn off the relatively few things the EPA deems a pollutant.

 

[wwhite72]

Mike, on your Ultra 770 the full manifold fitting is on the front, near the base, right next to the PCV fitting.

btw, you did pull/plug the hoses when you put the light on you engine and were moving the dizzy, correct?

 

[72HCODE]

disconnect the vacuum advance for now.

Inspect mechanical advance on distributor. check it has springs and the mechanical advance moves free and does not bind.