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Old 10-09-2012, 09:01 AM   #1
94cobra69ss39694cobra69ss396 is offline
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Join Date: Jun 2008
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Default Time For The Cobra To Get A New Engine - The 347 Build

What started this build is when I broke another rocker arm and bent another pushrod on the Cobra. With 90,000 hard miles I figured the cause was weak valve springs. So I pulled the heads and and while I had them off ported them. I then took them to Pacific Engine (well Guy did) and had them machined and a valve job done. While doing so Guy discovered that AFR had way too much spring pressure and that some of the springs only had .500 lift before going into coil bind. My cam with 1.7 rockers has .530 lift so surprising they lasted 90,000 miles.

While the heads were being done I started cleaning the carbon off the tops of the pistons and noticed a nick in one of the cylinder walls. With that discovery I really didn't want to just slap the heads back on so I started looking into the cost difference of rebuilding the 302 compared to buidling a 331. The cost diiference was going to be very little so I'm building a 331. I've been saving up to buy the stroker kit from Coast High Performance and will likely be ordering it this week.

This weekend I pulled the shortblock from the Cobra and disassembled it to see what caused the nick. What I found is that two studs that hold a splash shield on the intake manifold had come out and fell into the pan. They must have been in there for a long time. There were nicks on the bottom of the pistons, cylinder walls, crank, rods and one lobe on the cam. Here are some pictures of the worst piston.





Before I discovered the damage this weekend I was planning to sell the pistons and cam to help offset the rebuild but now I don't know. The threw the cam out but I'm still considering selling the pistons. They've obviosly held up fine in the Cobra pushing 11-12 psi and the only damage besides the nicks on the bottoms is the wear marks on the skirt of the one pictured above. What do you guys think? Would you buy pistons with nicks like that?
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