We have a 66 tbird with a 390. It has always pinged, but it started to get worse. We replaced the timing chain with a double roller and it seemed to idle and run a bit better but dad said it was still pinging. Then he replaced the plugs (which were rust colored when we did so) and retarded the timing so much that it had no power. Dad said that it still pinged, which I cant see how it is possible(I have yet to ride in it so I'm going by what he says). What would be some things we should check to solve this problem, we are running it on high test gas (97 I believe). New cap&rotor, pertronix points replacement, plugs & wires. Any help would be grately appreciated, we want to get that engine running good.

 

Check your plugs again. They should be light tan colored on the grounding strap, not oily, not rust colored, not fouled or carboned up. Let me know what you find.

 

Dizzy bushings could be wore out, dizzy may need to be recurved, possible carbon buildup in combustion chamber of heads and piston tops, engine temp. to high...

 

Its got less than 50,000 on it, but I dont know how long the bushings/dizzy shaft would wear out. W're afraid to drive it anymore because it was pinging bad, but the whole plug(electrode, grounding strap) were rust colored. Could the fuel not be high enough octane?? I believe that in '66 high test was 104. How could an engine ping if the timing was so retarded that the engine bogged and lost most power?? I've heard teh carb, gaskets and the sort might be bad. it had sat in a barn for a while and wasnt driven that much untill we got it (it was my aunts, al service intervals were met). ive heard anything from the carb needing adjusting (not the stock carb, not sure how) to varoius gaskets being bad. Just trying to make a list of things to ck and mark off. Thanks guys.

 

Is this new plugs, or old plugs? I know old leaded gas caused rust colored deposits. If they're that old, they probably needed to be replaced anyway. You should pull and read the new plugs, that will tell me a whole lot more. While you're at it, you should probably do a compression test. While not mandatory, it will tell us how much compression the enigne is building. I've read that about 165psi is about as much as you want to run for pump gas (per an article on Crane Cams' website). Plus, this will tell you a lot about the mechanical condition of the engine.

Are you sure it's a ping, and not another engine noise? Does it do it all the time, or only when the engine is hot? Under load, cruise, idle, when?

You might try a product called Seafoam. Use by running the engine with the air cleaner off, and slowly pouring it into the carb, at an increasing rate until the engine dies. Then wait 5 minutes, and restart, then go drive it. This should clean out carbon and lead deposits, reducing the tendancy to ping.

It could be that your engine was a "premium fuel only" 390. In which case, you might try aviation gas or race gas just to see if it goes away.

 

Marc, some of the early 390s had 10 1/2 or 11 to 1 compression. The thunderbird was more likely to get one of these 'Premium FuelOnly' engines than a galaxie or any of ford's other cars. If that is what you have, none of the currently available unleaded fuels is going to be enough, with the exception of Sunoco's GT100 unleaded. How about adding 5 gallons of Blue AV gas ( lowlead 100 ) or 5 gallons of leaded racing gasoline to the tank ? Then see if you still have the problem. Before the first gulf war, my everyday ride was a Boss351 powered mustang. It had 11 to 1 pistons and iron heads. Premium unleaded was not enough. So I went to the airport, put in 10 gallons of Blue, and then drove to the filling station and topped the tank with premium unleaded, giving me about a 50/50 blend. Never had a bit of trouble. When the war sent fuel prices skyward, I started driving a diesel powered escort. You're in New York, aren't you ? DF, spending his lunch hour at the boss' computer at work. He went home early today

 

Yep, I am in NY and I have thought of mixing the fuel as you said, but I dont know where that high octane racing fuel is sold, or how much it costs(prob make my cry when I see it). I'll ask my buddies that have racing quads, they run the stuff. The 93 pump gas is most def not enough, so maybe we'll try the higher fuel. Double cking the timing chain to make extra sure it is on right, not adv/ret at all. Thanks alot guys, hopefully we can get the 'ol bird straightened out. I'll post some pics next time we get 'er out!!

 

how about running a compression test to see where your at- run some sea foam down the carb to help clean everything and then get specifics on what's in the tank to know what your attempting to burn. If compression is over 160psi (?) and you got 85.5 octane unleaded ya might of found the problem etc.

(I'm just a back-yard flunkie but thats where I would start given the info at hand)

 

I had a pinging / pre-ignition problem that drove me nuts. I know how frustrating it can be. I tried everything to no avail. Finally, thanks to the suggestions of some of the guys answering my post on this forum, I found the solution.

I had the carb re-jetted by a carb expert who also took out the vacuum advance unit in my brand new distributor and replaced it with an adjustable unit and then he rercurved the distributor. Problem totally solved.

I don't know if this will solve your problem, but mabey something to think about.

Good luck,
Bill