bent my spark plugs today. Help!

[tankwilson]

Was on my way home from the Rust Revival sunday. Driving through Fort Madison and my 49 decides to floor itself. I tap the throttle but nothing, push in on the clutch engine runs full throttle for a second then I shut it off. Coast off the road and take a look under the hood. Whew my throttle return spring came off. Easy fix righ??? Well after i put it back on the car wont idle right. Play with the timing. Still not right. Pull the spark plugs and all but 1 had the gap pushed closed. Go to autozone and buy new ones, gap them and put the back in. Drive home. Still need to adjust my timing some but the whole ride home i wonder if i messing up my vavles and why would they hit the plugs????

Running R45TS plugs at .060" I have a langdon's HEI. Car has been running great this year up untill this??

Any Idea????

Car seems to be running fine after the plug change. Timing a little off but not bad.

Thanks

Matt

[Norm's Coupe]

I'm running AC45R. Whats the S for? If those plugs are too long (at the base) they will possibly hit the valves. You could do damage if thats happening. Maybe you should try just the AC45R plug, if its shorter than the ones you have now. Also, .060 is too big of a gap if the engine is stock.

[Jerry Roberts]

Are your plugs too long ? Compare one with an Autolite 306 .

[tankwilson]

i have been running r45t for the last few years. Changed to the S for a hotter plug running the Langdon HEI.

Put the HEI in the winter and the new plugs and the car has been running great up untill sunday. Why would the valves hit the plugs only at full throttle and not normal driving????

[Norm's Coupe]

Like I said, I'm not familiar with the 45TS. But........you said they were supposed to be hotter plugs. Hotter plugs are usually longer than the standard ones. So, that could be your problem.

As to why it would bend at higher speed. Not sure but will assume the valve really isn't going any higher, just faster. If the valve is hitting the plug, its acting like a hammer on the plug. So, if you drive slow the hammer is hitting the plug less and not as hard. When driving faster with higher RPM's its hitting the plug tip harder and much faster, decreasing the amount of time it will take to flatten the thing out.

Again, thats just a guess, but sounded good to me.

[oldmopar]

s is for extended tip see ac chart link below

http://www.acdelco.com/parts/sparkplugs/identification.jsp

[Plymouthy Adams]

The length of the insulator is the determining factor in heat range of a plug..not the length of the plug itself..it is the depth of the metal base from the insulation tip. hot plugs have deep base cuts for the insulator..cold plug will be shorter..extended plugs are special application in cylinder head by design to reach the combustion chamber. applcation by design of head still must be followed in plug design..another important issue is the length of threads..especailly in aluminum heads, I do not recommend thread extended below the thread in the aluminum due to possibility of carbon buldup and damage of thread on removal..increase this chance of damage if the head is hot..The gap of the plug is dependent on the ignition system and voltage delivered..if modified ignition then the deviation from stock specs IS mandentory

[Normspeed]

I bet it really sounded cool when you pushed the clutch in. As for damaging the valves, my theory is, if it just made enough contact to close the plug gaps, didn't shatter the ceramic around the center electrode, I think there's no chance there was enough contact to damage a valve. I have a couple Mopar valves laying around and they are pretty bulletproof.

[greg g]

No reason with a stock head to be using an extended tip plug. I would go back to the standard AC45 R's if you need radio noise suppresion.

The linked chart shows the normal plug at a .375 in projection, and the ts at .750.

Click on the matrix link to open a spread sheet scroll down to the 14.mm plugs and the plaie 45 under ac

http://home.att.net/~ngkaz/wsb/html/view.cgi-home.html-.html

[Don Coatney]

Have you installed a high lift cam? Have you milled your head severly? I measured my valve lift on my reground cam and measured the recess in the head to insure I had clearance for my plugs. Bob Criswell built a 41 Dodge engine with a radical cam and severly milled head. He had the same bent electrode problem. He doubled up on the plug gaskets to fix it.

[tankwilson]

Going to change my plugs tomorrow. What plugs are you guys using?? Especialy the ones running HEI???

Thanks

matt

[Frank Blackstone]

Isn't there a phenomenon at high RPM called a valve"floating"? Could that have caused the plug hit when it over reved?

[Don Coatney]

Isn't there a phenomenon at high RPM called a valve"floating"? Could that have caused the plug hit when it over reved?

Frank;

I believe valve float can occur at 7-8 thousand RPM's. If a long stroke flathead 6 were spinning at that speed the valves would not be the only thing floating.

[tankwilson]

Installed some autolite 306's set the gap at .060 and she runs great now. The second set of r45ts were bent too but not as bad.

[greg g]

Were the tips on the 306's shorter than the former plugs?

[tankwilson]

yep