bragging sometimes backfires

[kenparker]

I have bragged on the engine in 'le coupe for ten years. Engine was built ten years and 20,000 miles ago. Never a seconds trouble. Run like a spotted ape and always start when I told it to.

On way home from The Great Texas Flat HillClimb Saturday afternoon she began running on very poorly - missing and very little power --- then sphoosh - a great cloud of smoke - then running on three cylinders and missing one of the three. We limped home, about 15 miles at 15 mph and barely making it up some of the hills.

Sunday I pulled the head and discovered the worst. Pulled the engine and removed the offending piston.

Years of running too much advance had done it damage. Predetennation.(sp) Moral of the story is keep a better watch on your timing and keep bragging to a minimum.

The repair will be a patch job, 'cause a new engine is already in the works. The new one is still several months away.

[barkleydave]

Ouch!

[Tom Wesenberg]

Must be the Texas heat that melted that piston.

When you have preignition it doesn't take long to do some serious damage.

How's the rod babbit?

[burner31]

Which piston are we seeing here...1,2,3,4?

[burner31]

Would this help make the case to install a Mallory dual point distributor with centrifugal spark advance?

[larrys40]

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Originally Posted by burner31

Would this help make the case to install a Mallory dual point distributor with centrifugal spark advance?

No!!!

[C26Pinelake]

You can still brag that 3 out of 4 pistons work well! Wayne

[Patrick L.]

Thats a shame, too bad. Its pretty ugly.
I'm wondering about driving technique. Was full advance used often ?
Any sign of detonation/ spark knock ?
Any sign of pre-ignition or after-running ?

[Lona]

Sorry, Ken. However, your misfortune helps to remind ourselves about proper ignition timing and spark lever position. Thanks for sharing.

Glen

[HoarseWhisperer]

Hey, Ken. Curious if this engine was running a hi-compression head?

[kenparker]

Ok. Follow up and answers to questions.
Patrick, There was never any predetention knock - always very quiet. I have an 26% Od (F150 OD) and only used full advance when running on the highway at 55 or better. Yes, the OD does put more load on the engine. And yep, I drive the bejesus out of that coupe.

And just for the record it is a stock Model A distributor and probably will stay tht way - just timed different.

Went to my spare parts stock pile and found a partial set of .080 pistons. .080 is wahts in the engine now. One of the partial set was within 3 grams of the weight of the three that were still in the engine. Tiny bit of grinding and polishing and all four are within 1/4 gram of one another.

Burner31, The messed up piston was #4. #1 and 2 two were the two that keep running and were clean. #3 was oily from missing - I think fron a blown head gasket as a result of the messed up piston but has no damage.

See, some things work out OK. ken

[kenparker]

hoarse wisp. Running a Brumfield 5.9 head. Been on the engine since 2005 - all 20,000 miles.

[rf900rkw]

Last year I was chatting with a gentleman (not a club member) at a small local car meet about driving an A, as I was hoping to take the FiL for a last ride or two in his Sport Coupe. the rides never happened, but I was told the timing was easy, full retard to start, then shove it to full advance and leave it there. Sounded wrong to me, but what do I know about 4:1 motor dynamics?

If you need a used piston, I have a bucket full.

[HoarseWhisperer]

Thanks, Ken. I've had to run significant less spark advance with a 5.5 head in addition to reduced spark plug gap.

[Patrick L.]

Originally Posted by kenparker

Ok. Follow up and answers to questions.
Patrick, There was never any predetention knock - always very quiet. I have an 26% Od (F150 OD) and only used full advance when running on the highway at 55 or better. Yes, the OD does put more load on the engine. And yep, I drive the bejesus out of that coupe.

And just for the record it is a stock Model A distributor and probably will stay tht way - just timed different.

Went to my spare parts stock pile and found a partial set of .080 pistons. .080 is wahts in the engine now. One of the partial set was within 3 grams of the weight of the three that were still in the engine. Tiny bit of grinding and polishing and all four are within 1/4 gram of one another.

Burner31, The messed up piston was #4. #1 and 2 two were the two that keep running and were clean. #3 was oily from missing - I think fron a blown head gasket as a result of the messed up piston but has no damage.

See, some things work out OK. ken

Timed different ? OK, that has me curious.

[700rpm]

I always understood that too far advanced would damage the rear main. I hadn't heard about piston blowout. Apparently that is also a risk, but is it true with a stock head as well? How's the main look?

[Patrick L.]

Originally Posted by 700rpm

I always understood that too far advanced would damage the rear main. I hadn't heard about piston blowout. Apparently that is also a risk, but is it true with a stock head as well? How's the main look?

Lots of info. Just look into detonation and pre-ignition.

[Tom Endy]

Could you relate what the ambient temperature was when the piston failed and if the car is equipped with a thermostat.

Tom Endy

[Tom Wesenberg]

Even a stock 4.2 head can have detonation. My temporary engine with no more than 2/3 advance sounded like a popcorn machine with the slightest throttle, until I flushed out all the junk in the cooling chamber and got rid of the hot spot.

[kenparker]

Tom Endy. The outside, ambient, temp was in the low 60's and damp. It had been raining two hours earlier. The Motometer on the radiator cap showed normal temp. She had/has a 160 degree thermostat. Normally runs as the thermostat says to - 160.

Good questions guys. thanks. ken