Detonation would "eat" the electrode and eventually the center with broken parts of ceramic. The bridged gap suggests to me mechanical contact with something. Even with 60 degrees of timing and 87 octane fuel, can a stock slant 6 detonate enough to cause harm?

if a lean condition occured it will over heat the tip first and while it is red hot the conbustion pressure will bend the electrode side ways, i have taken plugs out of my race car that look like these.

Got some Champion plugs to try out if the compression test looks okay. But I can't get that ring off. Any suggestions? I am not going back to those long plugs again, until I figure this out.

I clipped the ring off with a pair of wire cutters, and then twisted them untill they broke and came right off.

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'74 Duster 225 Super Six w/904
14" Cragar SS wheels

Are we supposed to take the gasket off of the plugs? I never knew that. huh. Now I know. Never had a problem with running a gasket before.

I just found out not too long ago. You only use them on the 60-62 heads. The 63+ heads do not use them. Your car will run fine, just not as well as it should, I guess.

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'74 Duster 225 Super Six w/904
14" Cragar SS wheels

Got the rings off with the wire cutter, and twisted them off. Thanks.

Tonight the compression test, and if that looks okay, try out the new shorter plugs.

Pulled off the head finally. No carbon buildup on the piston or valves that was too bad. I could read the .040 on all the pistons, except 3 and 6, which were the two blowing up the plugs. However, the top of the pistons on 3 and 6 are not smooth. I found a marble, that appeared to come from one of the spark plugs in cylinder 3. It was smaller than a pea. So I am glad I took off the head. But in no way are those plugs being hit physically with something that is obvious. Other than that marble in number 3.

My buddy came over, and looked at it, and was stumped. He said the valves look like they should, and the cylinder walls still look great. And told me I was very lucky, with how the block and cylinders look.

But he is stumped as well. His guess was predetonation. I showed him how I couldn't accurately adjust my timing, as was playing around with it, to try to find the correct timing. We took it to TDC, and the timing mark was in the 1200 position. My timing tab is at the 0200 position. And when I was at the Redding race, and watched a car being timed, I noticed their timing tab was closer to the 1100 position. If I try to adjust the timing with my timing tab, the car dies. So that leaves me with having to just time in by ear. Which not being a mechanic at all, you get the picture.


My buddy thinks I might have a bum distributor. Any thoughts on that?

Your balancer has probably slipped. Find true TDC and remark your balancer.

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David Kight
'62 Valiant Signet, White
'98 Dodge Dakota
'06 Jeep Liberty

Growing older is unavoidable but growing up is strictly optional.

I agree with David,also is the motor unmolested? How old is timing chain/gear set?Has it had any parts swapped like balancer,timing cover,timing tab?I also agree with earlier post that it's detonation going on here.I've seen "pinging"eat the top of pistons make them look like somebody took a hammer to them.That just might be what that pea sized piece is,chunk of piston banging around in there till it's round or even sucked up and spit out the exhaust.For sure one of lifes little mysterys,good luck.

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83 B-150 slant 6,4 speed. 79 B-300 360 pathfinder 4x4. 74 W-300 318 4x4 git-r-done 80 B-100 sl6,4speed

So, what is the "pea sizes" ball of material?... steel, aluminum?
FYI, any small chunk of crap that get's inside a cylinder is big trouble, I have seen a small screw that holds a carb's betterfly plate, "hole" a piston.

As for the timing mark, it could be a mis-matched t. tab to damper, there are two different set-ups with the marks in different places, in the positions you discribed.
DD

So far as I have noticed, if you have a 67 and later engine, you need to use the 67 later damper and tab to get it correct. Same goes for the 66 down engines. I tried swapping my 66 timing cover with bolt on tab, and its corresponding damper to my 71, and it didn't match up. The damper was still showing the mark around where the factory tab should have been on the 71. Not sure if this is an isolated incident.


You've got marbles, and I've got Gremlins...... hmmm wanna trade?

Good luck!

~THOR~

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Certified Auto Appraiser - RevItUp Classic Appraisals
Too young to be slow, too old for high speed.

Thanks - you have aced my problem I believe. As I picture that marble, it does have what looks like a screwdriver slot. So it probably once was a screwdriver head. So I look at the carb, and that is probably where it came from. That would make sense why 3 and 6 were impacted, if two pieces went in there. I got lucky with the little damage it did. Probably since once I heard the clicking I turned it off. And only turned it on to test to see if it was still there.

The timing tab on my car is bolted on the wrong side. I will find the place to bolt it on the passenger's side. Then my timimg issues should be over.

Thanks. Wish me luck with the Holley.

The problem with the 68 and up timing "tab" is that it does not bolt-on like the 60-67 tab, it is spot welded to the front face of the timing chain cover.

I have the correct covers and the correct dampers but for you, it may-be easier to find TDC and re-mark the damper you currently have.
DD

Agreed.

~THOR~

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Certified Auto Appraiser - RevItUp Classic Appraisals
Too young to be slow, too old for high speed.