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Old 08-23-2007, 10:09 PM
Senior Member
Join Date: Jan 2006
Location: La.
Posts: 2,890
Default ProComp Heads Update,

Ed and Curtis, you're gonna love this :lol:

Remember in the first post that i wouldn't sell a set of procomp heads to the person that had a 144 b&m blower on his 355, and was going up to 383"? (he bought them else where)
He called me last thursday and said he got it running, Sunday morning about 9:00am he calls me in a panic, said he's 1 mile from the house and got on it one time, went up to 5500 and the engine shut down. It would not restart :shock: He pulls a couple plugs and the tips are collasped and the engine turns over like it has no compression, my answer is that it probably doesn't.
He trailers it back home and he's got water/milk in the oil. He calls me later sunday and saids that he has the engine out of the car and the heads off, there's only 8 pistons busted, it pulled off 2 to 3"'s of the top of all pistons above the top ring. He pulls the pan and finds that there is JB weld along the inside of the block in spots where the local race engine builder cleared the rods too much (not always necessary with Eagle H beams) I then started asking questions about the rest of the assembly. It turns out the the short blk. builder recommended Mahle -16cc coated pistons, over $700.00. O'h and he put a new 871 blower on the engine (8lbs boost). I tell him his first mistake is the Mahle pistons and ask him to measure the end gap on the top ring and the piston to wall clearance. It's .028 on the ring and .004 on the piston Also only 1/4" of land between the top of the piston and the top ring, not enough alum there. O'k on the ring but not enough in my opinion on the pistons. O'h forgot it also bent most the valves, they donot like chewing up alum chunks.
Monday he takes it back to the engine builder. Today he calls me back, and the engine builder tells him there's nothing wrong about the pistons and he should have bought 76 CC heads instead of 64 CC heads and it would have worked just fine. Now the engine builder wants him to buy another set of heads and the same pistons.
This is where i come into the rebuild, he can't afford this. I had told him earlier that the pistons were totally wrong for his application, he needs about 3/8" land there and blower pistons not street pistons. So i tell him to call Tom at Arias and give him the imfo. that he gave me and see what they recommended.
He called me back a 1/2 hr. later and told me that Tom laughed at his application and there should be about .400 on the top land and his heads are just fine with the right pistons, which Arias will build for $110.00 with rings,pins,and buttons, but they have to bill them to me because i have an account with them. (no i did not call Arias first)
Bottom line he's out over $7,000.00 and can only use the crank (which now needs polishing), the rods and heads maybe!! because it beat up the heads around the seats and may have damaged the seats.
Ask me again should i have sold those heads to him? (NOT). Because some of this could have come back to me.
I've built lots of blower mtrs and a few nitrous mtrs. and as it has been said here they are different animals and have to be built accordingly.

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