Help With Buying Spark Plugs For 65 Tbird

[rollsman44]

The engine was rebuilt appr 6 years ago and an Electronic Ignition was installed. I get a hesitation when driving It feels like the carb but I checked it manually and it seems ok. I am thinking the spark plugs since they were changed about 6 years ago and have about 8-10K miles on them. What plugs can you recommend I use? I will change the plugs and see if that works. Thanks Dennis

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[Gary Tayman]

What kind of hesitation? This can be a lot of things. What type of ignition? Pertronix? How do the plugs look?

As for changing the plugs, I don't know the specific part number but you can go to any parts store and ask for plugs for a 65 Thunderbird 390. But this is only part of the picture. Wires, coil, distributor cap, distributor itself (how's the spark advance?), fuel line and fuel filter. Were the wires/cap changed when you put in new plugs or are they old? How old is the coil - and what brand?

This is hard to troubleshoot without seeing the car, but all of the above is suspect.

 

[rollsman44]

What kind of hesitation? This can be a lot of things. What type of ignition? Pertronix? How do the plugs look?

As for changing the plugs, I don't know the specific part number but you can go to any parts store and ask for plugs for a 65 Thunderbird 390. But this is only part of the picture. Wires, coil, distributor cap, distributor itself (how's the spark advance?), fuel line and fuel filter. Were the wires/cap changed when you put in new plugs or are they old? How old is the coil - and what brand?

This is hard to troubleshoot without seeing the car, but all of the above is suspect.

 

[rollsman44]

I hear you. I will check the plugs first then go from there. Thank you very much.

 

[XWING1138]

Got Autolite 45s in mine. Starts every time.

 

[rollsman44]

Thank you. I wasn't sure if I should use these or different ones due to the fact the Motor was rebuilt 4 years ago and I have electronic Ignition in it. Does that make a difference with using these 45S plugs?

 

[XWING1138]

Nope. I got an electronic ignition and 45s and that part of it is fine. I also have a hesitation similar to what you've described but for me its a carb issue.

 

[rollsman44]

I took the car to a friend who is an old time mechanic and knows about older cars. He suspects a small air leak somewhere. He will check it out this week. I told him to change the plugs anyway. Will get back to you once I see what is causing my problem. Thanks

 

[Dwain]

The engine was rebuilt appr 6 years ago and an Electronic Ignition was installed. I get a hesitation when driving It feels like the carb but I checked it manually and it seems ok. I am thinking the spark plugs since they were changed about 6 years ago and have about 8-10K miles on them. What plugs can you recommend I use? I will change the plugs and see if that works. Thanks Dennis

 

[Dwain]

I use the autolite spark plugs. I have the electronic ignition as well. No issues. You may have a carburetor problem.

 

[64ZCODE]

Hi there Dennis

If the hesitation is fuel related, check out the accelerator pump. It may not be properly adjusted (the pump lever should start actuating as soon as you press on the throttle) or perhaps the pump diaphragm is cracked or old and stiff so you're not getting a good shot of gas. If all that is up to snuff but you still don't seem to be getting enough fuel off the line, you could consider changing the accelerator pump nozzle size. A larger nozzle delivers more gas from the accelerator pump in a shorter period of time.

Holley Street Avenger carbs are notorious for stumble off the line. It's due in most cases to accelerator pump linkage not being properly adjusted.

If the fuel related hesitation is more mid-range, then the power valve could be the culprit. The power valve lets additional gas into the carb throat when manifold vacuum drops to a certain point, and you can play around with different ratings of power valves. They have numbers and the rule of thumb is the correct power valve number is half of the manifold vacuum when the engine is at idle. So if manifold vacuum is 17 inches of mercury at idle, the power valve should be 8.5.

Doug