Test and tune session at LeMons race. Car ran beautifully for a whole race in November and sounded great today, then started running poorly a half hour before the test session was over, sounding like it was down a cylinder. Pulled plugs to find the above. 1 and 6 are damaged, others look very good if perhaps a hair lean? Carb is tuned rich. When you let off the throttle you can hear the unburnt fuel popping in the exhaust. Runs very cool overall since we removed the thermostat. (I know, we can debate the wisdom of this later. It's ​on my list of things to remedy correctly.)

As I recall, we put these Autolite 63s in at a previous race because we were still having detonation issues and they were the only ones we could find at a local store that were cooler than stock.

Suggestions? I am thinking of driving all over Houston until I find some colder than stock NGKs, maybe two steps colder for 1 and 6.

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Somehow I ended up owning three 1964 slant six A-bodies. I race one of them.
Escape Velocity Racing

You may need to get a dashpot to keep the plates from wacking 100% shut after letting off the go pedal... or you will need to really richen up your idle circuit to make up for the lean out under load...

It is the damnedest thing I have ever seen in an engine.

We put new plugs in. Fired it up and it sounded good... but with the occasional pop or tick. Didn't sound like detonation, but didn't sound like a serious mechanical problem. Finally started pulling the new plugs just to verify. #1 was busted, similar but not as bad as 1 and 6 before. Inspection camera found what appeared to be something wedged in at the top of #1 cylinder. Pulled the head and found this.



Laying on top of​ cylinder 1 was the rounded and compacted remains of what we think used to be a nut from the air cleaner stud. The tops of pistons 1 and 6 look like the surface of the moon, but the cylinder walls look fine, all things considered. This nut must have bounced back out the intake valve of one cylinder, shot around the outer perimeter of the stock 2-bbl intake manifold, and entered the opposite cylinder. No idea how many times it did this.

As impressive as the unlikely ballistics of the nut were, equally impressive is how well the slant six put up with it. I've heard multiple stories of other engines that have holed pistons or thrown rods when exposed to abuse like this. Aside from the spark plugs getting trashed, I think this engine would have run just fine until the foreign object was battered into dust. We are currently waiting for a team member to get back from Houston's only 24-hour AutoZone with a new head gasket (because we are bad at planning), after which we plan to button it back up and race tomorrow.

This engine is getting torn down before the next race, but for now we'll see if it can finish the weekend.

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Somehow I ended up owning three 1964 slant six A-bodies. I race one of them.
Escape Velocity Racing

Or, what was in the #6 cylinder made it out the exhaust.............

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

Shot peened pistons will be the new fad at Le Mons.

I had a piece of a 4bbl carb (Edelbrock metering rod inspection door) come off and shatter into 3 pieces and bounce around in 3 cylinders once. I pulled the head at the track and fixed it. Engine never skipped a beat after that. I certainly did not run it that long, though! I was really puzzled by the plug pic and lean/rich until I read down to your head-off pic!!

I bet you can finish the race fine. Check for bent/damaged valves too. If a valve closed on one of those pieces, probably there are nicks in the valve/seat or maybe a bent stem.

Slant on!!

Lou

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Home of Slant6-powered fun machines since 1988

This is possible, but we know we lost the one nut and don't know where a second piece of debris would have come from. The damage between the two cylinders looks identical.

I think the engine will hold up fine for this race. We may have a little more blowby now, but It's been on track for three hours now and still running like a champ.

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Somehow I ended up owning three 1964 slant six A-bodies. I race one of them.
Escape Velocity Racing

Sorry i couldn't resist...
Was that driver or crew


I am sure you and the team will continue to forge on and have one crazy space car!


Greg

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http://www.youtube.com/hyperpack

The moment I saw the #6 plug I knew it was mechanical damage. A friend lost a Chevy 396 from someone dropping the air cleaner wing nut into the carb. Of course there is a lot less space above a 396 piston than on our 225s.

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Joshua

I stand corrected... that'd do it....luckily you're not running something 10:1 or better, that would have done a valve or piston in for sure....

I remember back when, if you really didn't like someone a few ball bearings down the carb bore would put your competition out of commission....

My buddy lost a carb nut down the bore in his stock slant, he shrugged and said if it blew up he'd replace it with a V-8.... he drove it that way for years... went to replace the exhaust and found the nut in the header pipe....

It is conceivable that the nut went in one cyl, was ejected back out the intake valve into the intake, then taken into the other cylinder. No way I can see a hex nut would break up, but maybe a wing nut? Did you have a washer under the nut?

Glad to hear it is running fine. When I pulled my 64 motor and re-ringed it, about 40k miles later, everything was fine except for the peppered piston tops.

Lou

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Home of Slant6-powered fun machines since 1988

No washers or other hardware were lost that we can account for. This (larger) air cleaner was newly installed for this race. My teammate used two hex nuts to lock the stud down to the carb, and two hex nuts with a flat washer and lock washer to hold the lid down on the stud. The air cleaner fell off during my last test drive Friday afternoon, and I put it back on while the last driver was belting into the car. The stud had come completely out of the carb, and the whole air cleaner was laying wedged against the inner fender with the stud still hanging off the lid. The top nuts stayed in place, holding the washers between them and the lid, but only one nut remained on the underside. Since I wasn't the one who first installed it, I didn't realize there should have been two nuts on the bottom...

We debated the likelihood of the "magic nut" theory for a while after we saw all the spark plugs, but in the end it seems plausible. Since then I've heard a few stories from other LeMons racers of similar events. I guess since the intake valve is bigger, it's more likely for a piece of debris to come back out the intake than to pass through the exhaust. It must have first gone down either the #6 runner during acceleration or the #1 runner under braking. Then when it managed to pop back out, either the opposite happened (braking/acceleration), or maybe the force of ejection just shot it all the way around the outer perimeter of the manifold.

To continue the harrowing story of unlikely engine damage, the car ran great for the first half of the Saturday session until it started to sound like it was down a cylinder again. It wasn't as bad as it sounded on Friday, so we kept running until the end of the racing session that day. Afterwards we pulled the valve cover and found the rearmost rocker shaft bolt had loosened, allowing the rockers on #6 to shift rearward, sliding up under the spacer and letting the pushrods fall free. When we took the rocker shaft out, we found it had cracked at the next bolthole due to the last section of the shaft being wedged upward.



We probably would have just bolted it all back together at an "away" race, but since my house was only 40 minutes away we sent a couple teammates to grab the spare head out of my garage and scavenged the rocker shaft out of it. The hold down bolts went in with blue loctite this time.

The car ran great all day Sunday with two exceptions. First, the chintzy chrome alternator bracket we've been using for years finally broke in half, probably due to alternator misalignment from a worn out bushing in the housing. We made a new one out of scrap angle iron in about 10 minutes. Then, about 20 minutes before the end of the race, the throttle cable failed. We missed the checkered flag, but we temporarily repaired it for the drive home with some bare wire cable I begged off a guy at the track garage. It's always something!

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Somehow I ended up owning three 1964 slant six A-bodies. I race one of them.
Escape Velocity Racing

Wow, that is one for the ages. I have seen various nuts dropped into engines and the hammered pistons that result but bouncing between #6 and #1. Thats nothing short of amazing. It must have hammered one piston and then shot over the the other. I can't imagine it bouncing back and forth!

Thomas, Mopar Mechanic at http://www.buchananautopark.com/

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SlantGeek