| Re: I was racing and saw this.....
It is pistons one and two, and two is the one with zero compression.
a well known Z motor builder told me that #2 frequently runs hotter than #1 and #3 due to the intake manifold design and I believe him. If you look down it from the bore the port to #3 is very open, #1 partially shrouded, but #2 is almost obsecured. The air/fuel mixture will be different in each one but leaner in #2 as the air and fuel has to make a relatively sharp bend and some separation will occur.
Add to that fact that this particular car has EGTs in #1 and #6, tuning for those cylinders, and you might have a lean condition in #2 at high RPMs. It was fine to 7k, but at this one track I was avoiding a 3-4 shift and riding 3 a bit to long, to about 7500 RPM. And I bet it got lean in that range. Bang.
You can bet I'll switch the EGTs to #2 and which ever cylinder on the back three has the more shrouded port when it goes back together. Block is out, engine apart, and will go to the machine shop guy (a good local Ford builder and racer). Another Z racer is going to loan us his torque plate so we can bore while torqued up.
Your white mark trick was just told to me by another dude about 2 days ago on the IT Forum - thanks for sharing that too. My front pulley is on the way out as the rubber coupling section, that thin part, is about gone and the pulley has a bit of wobble.
They are sort cheap - about $600 in parts with all new pistons, good bearings, etc. plus some other bits I don't need but am replacing anyhow.
Good luck with the 40 in the race, don't hold those gears too long. Is this with the new motor?
Ron |