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Took It To The Track (And Broke It)


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Went to San Antonio Raceway for Mustangs vs the World, and the car broke just before my 4th run. (I'm running a carbureted 427 Windsor backed up by a Tremec Magnum XL and 3.73 gears in a 2012 Mustang).

The three passes I was able to make:

13.2335 @ 117.8mph - 60-ft 2.4210

13.3929 @ 96.59mph - 60-ft 2.1076

13.2358 @ 117.6mph - 60-ft 2.4134

I suppose that ain't too bad for my first time at a drag strip since 1985 in a car that ain't setup for that kind of racing (on street tires no less). I think if I run drag radials next time, my 60-ft times will improve and I'll be down in the mid 12's or possibly high 11's.

I was lined up for my 4th run, and had started the car to move up when the car started backfiring through the carb. Car had fuel and oil pressure, so it doesn't look like the fuel pump died or a rotating part has gone out. Had to have the car towed home.

I checked the plugs (it looked like 3 & 4 were running leaner than the rest and otherwise they were okay, but I changed them anyway), and replaced the cap on the off chance that it was something simple. No joy. I also checked the oil and water to make sure I didn't have a busted head gasket or cracked head.

When I get home from work tonight, I'm gonna pull the valve covers to make sure a rocker arm hasn't broken, and then the distributor to see if I sheered the gear pin.

If anyone has any other ideas, I'll be happy to hear them.

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Verdict - Distributor gear is okay. The cause of the malfunction was that the lock-nut on the rocker arm on #2 intake was laying in the head, and the rocker nut had backed almost completely out. As a result, the rocker arm was floppin around like a sock on a clothes line. The pushrod is just barely bent, so I'm ordering another one. Dodged a bullet on this one.  

Of course, I *WILL* be inspecting all the rocker arms to make sure they're still tight.

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After closer inspection, I think I floated/bent the valve that is associated with the bent pushrod. I laid a flatedge across the valves on that cylinder, and the valve retainer is a little lower than that of the unaffected valve.


Potential Parts required if I did indeed bend the valve:


- Push rod (already on order)
- Valve
- Valve seal
- head gaskets
- intake gaskets
- header gaskets
- 8 qts oil
- 1 gal antifreeze
- spark plugs (already replaced)


Then there's labor and possible machine shop charges (replace the valve guide and replace and regrind the seat).


Hopefully, I didn't damage the piston too.


I'm bummed...

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