[DeTomaso] WARNING: .050 may be the wrong kind of Bomb

[asajay at asajay.com]

Don't Panic...

until -after- the leak-down test and borescope inspection.

I don't think you introduced too much fuel.  I believe the others who  
have indicated you went lean, are most likely correct.  Rich would be  
black sooty plugs, not clean disappeared ones.  I believe you ran  
lean, and the WOT romps didn't help but you didn't know about the  
throttle plates.  Flattening out at 4,200 rpm is also an indicator the  
engine just wasn't getting any fuel.

It does sound like you have a problem with #5.  Let it sit overnight  
and test it again with no oil tomorrow.  It may be rings on that one  
cylinder.  I'm thinking worse case you may need to replace the piston  
and rings, hopefully no valve damage.

Yea, it's a pain in the rear, which is why I suggest waiting for  
results from a leak down and borescope.

Asa Jay


Quoting Dan Courtney <dfcex at pacbell.net>:

> I tried the compression test again on #5 last night, because on the   
> first test the other seven cylinders only took 2 or 3 revolutions to  
>  get a reading and it took me allot more on #5 (the cylinder with  
> the  most electrode damage).
> This time I could not get any reading at all.
> I pumped a little oil into the cylinder and it immediately   
> registered at 200 psi. After letting some of the oil escape it   
> dropped to 180, but still registers consistently, and immediately,   
> at 180.
> I believe this indicates the rings were not sealing?
> Sounds like I either have a broken ring or they got washed out.
> I took another look at the carb linkage. The rod the rebuilder put   
> in for the secondaries appears to be way too long and the linkage   
> bottoms out on a stop well before the rod can open the secondary   
> butterflies.
> I floored it a couple of times on the way back from Vegas for a 1/2   
> mile here and there and I'm thinking this made it go lean and caused  
>  detonation and/or washed out the rings with excess fuel. I never   
> exceeded 4,500 rpms and it was flat above 4,200.
> There is a nearby shop with a borescope so I might trailer it there tomorrow.
> I also have a mobile mechanic who can swing by tonight and run a   
> leak-down test.
> Or, I can just start pulling off the head.
> Here I go again, after only 800 miles on engine #5, which was   
> supposed to be a keeper.
> As you can tell from this email, I'm assuming the worst. If you   
> think I'm missing something please let me know.
> Unfortunately, it took me the 1 1/2 years to get this running   
> because I'm pretty fatigued about having to constantly get new   
> engines and I've lost allot of my enthusiasm for driving a Pantera.   
> What I really needed was a good year or so behind the wheel with no   
> blow-ups.
> Anyway, such is life.
>
> Dan
>
> Dan F. Courtney
>
> La Jolla, CA
>
> (858) 551-5455 Phone
> (858) 551-5456 Fax
>   ----- Original Message -----
>   From: JDeRyke at aol.com
>   To: dfcex at pacbell.net
>   Cc: detomaso at realbig.com
>   Sent: Thursday, May 28, 2009 11:18 AM
>   Subject: Re: [DeTomaso] WARNING: .050 may be the wrong kind of Bomb
>
>
>   In a message dated 5/28/09 11:10:02 AM, dfcex at pacbell.net writes:
>
>
>     Could impact from the domed piston to the plug tip crack the   
> electrode without breaking the tip? Although #5 is missing 1/2 the   
> tip, #6 has an intact tip but not much electrode.
>
>
>   Unless you're running side-gap plugs, first contact will be   
> between the piston dome and the ground electrode, essentially   
> shutting off that plug as the gap goes to zero. Busting up the   
> ceramic inside won't necessarily shut down the plug sparks, if the   
> ignition is energetic enough. I'm still thinking an over-lean   
> mixture at higher rpms causing detonation. Good luck- J Deryke
>
>
>
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