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What went first?: 342 Bonneville mishap

3K views 27 replies 9 participants last post by  Sleeper CP 
#1 ·
So on the 15th run of the week the little 342" laid-over at 6,700 rpm at 185 mph at 2.5 miles of a 3 mile run.
the AF was 12.7 at mile 2. when it laid-over I checked the gauge and it was 14:0





the exhaust valve wacked the piston pretty good:






I'll be checking the valve springs next week. The protruded plugs will be coming out.

The engine will get a fresh-up, but I have a feeling the Mustang will be getting my 410" Windsor in it next year. 680-700hp vs the 550hp from the 342"...200 mph here we come.

So what went first? that's a lot of damage from the plug and what's left of it :idea:


S CP :mad:

(well I can't really be mad, this engine got a hell of a work-out from the crew (3) driving it. they put 12 of the 15 passes on it as they got their licenses)



Hey Bostick...you looking for something else to do?
 
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#2 ·
The plug started it.
Is that the only exhaust that hit? Plug electrode could have had a little to wth that as well.

Extended electrode plugs are bad news in extended high RPM, high compression applications. You can put one in a blown deal and lose it in mere seconds.



 
#9 ·
The plug started it.
Is that the only exhaust that hit? Plug electrode could have had a little to wth that as well.

Extended electrode plugs are bad news in extended high RPM, high compression applications. You can put one in a blown deal and lose it in mere seconds.[/QUO]

bob what do you recommend running in a blown alky deal??? my heads use this same style plug and i bought 7-10 on the ranges to play with but they are all extruded electrode style plugs..thanks for the help jeff
 
#5 ·
Oh yeah all had already gone to shit by the time I saw it.

S CP
 
#4 ·
Yeah it does. And if its an EFI, then the CPU starts throwing fuel at it and the thing starts running even worse, goes pig rich, the CPU backs up and it becomes a circle jerk.
If it carbed, you just get a LEAN reading and it holds. But its no real world indictation of whats going on in the other 7 holes.
AFs don't mean squat in anything less than a "hitting on all 8" engine.



 
#7 ·




car went 188mph in the timed 3 mile. Showed 192.4 mph on the gps (exit speed)
Next year we try for 200 with it. I think we can do it by pulling the C-4 auto and installing a G-Force 5 speed. But the 400+ Windsor sounds like a lot of fun.


S CP :D
 
#18 ·
CONGRATS on 190+

:))THumbsUp
Haulin the mail for that little 342 in fox body:thumb:
I have ran those same Autolite 3924 plugs in my 347 stroker SBF for years on the road coarse ussing Canfields 195cc without issues..
I dont think they are considered "extended tip" as the center electrode only extends out .125":confused:
on my Canfields the 3924 plug threads slightly extend into the combustion chamber which wasnt to my liking...
i have recently found out there is a denso plug that is slightly less then 3/4" reach and is suppose to match my Cans perfect and i will try them soon
 
#19 · (Edited)
:))THumbsUp
Haulin the mail for that little 342 in fox body:thumb:
I have ran those same Autolite 3924 plugs in my 347 stroker SBF for years on the road coarse ussing Canfields 195cc without issues..
I dont think they are considered "extended tip" as the center electrode only extends out .125":confused:
on my Canfields the 3924 plug threads slightly extend into the combustion chamber which wasnt to my liking...
i have recently found out there is a denso plug that is slightly less then 3/4" reach and is suppose to match my Cans perfect and i will try them soon

They are an extended tip plug.
There is HUGE difference between running on a couse that has you in and out of the throttle, up and down the gears, and keeping it pegged in high gear for 3 plus miles at max load for 3 plus miles.



 
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