Finished pulling off old heads, a few questions... - The 1947 - Present Chevrolet & GMC Truck Message Board Network

lukecp · 06-12-2003, 09:03 PM

I just finished pulling off the cylinder heads on my 350 so i can bolt on my double humps. When i pulled them, the tops of the pistons had quite a bit of carbon build up on them. It wasn't very thick, but it was flaking off a little bit. How should i clean it off? I was thinking of dousing all the pistons with some carb cleaner, but would that mess up my bores any (which are in excellent shape

).

The pistons said .060 on them, so i that means my 350 is really a 360. Oh well, more cubes=more power, and it dosen't run hot or anything.

Also, i found out why my truck falls on its face after 4500 rpm, the heads only have 1.72/1.50 valves. I put the smaller valves into desktop dyno, and it only said 260 horsepower, instead of the 277 i thought it had, lol. Now i'm sure my 2.02/1.60 heads will make a HUGE difference.

One more, how much are my old heads worth? They are casting number 462624. Mortec.com says 75-80 350, 76cc chamber, and they have 1.72/1.50 valves. They arent cracked, and were rebuilt 22k miles ago along with the rest of the motor. The truck didn't smoke at startup, so the valve seals are fine, and none of the valves are burnt. I was thinking, maybe $150 tops???

Thanks for any help

*Piston* · 06-12-2003, 09:30 PM

continually soak the carbon with transmission fluid, this will soften the carbon enough to allow you to carefully use a wire brush. No need to clean the pistons completely though, just get the large chuncks off. These will cause detonation when warm.

The old heads? smog heads won't bring much. used heads won't bring much I'd bet. Those things are a dime a dozen

jef5150 · 06-13-2003, 05:26 AM

The .060 on top of your pistons means," 60 thousands" overstock bore diameter,,usually .030 is bored off the cylinder walls {.015/per side}in the first major rebuild,,,,,,so either your motor has been rebuilt twice,,or on the first rebuild,the cylinder walls were really bad and the walls didnt "clean up",so they took it up to .060

06-12-2003, 09:03 PM	#1
lukecp Formerly yellow72custom Join Date: May 2001 Location: Austin, TX Posts: 7,531	Finished pulling off old heads, a few questions... I just finished pulling off the cylinder heads on my 350 so i can bolt on my double humps. When i pulled them, the tops of the pistons had quite a bit of carbon build up on them. It wasn't very thick, but it was flaking off a little bit. How should i clean it off? I was thinking of dousing all the pistons with some carb cleaner, but would that mess up my bores any (which are in excellent shape ). The pistons said .060 on them, so i that means my 350 is really a 360. Oh well, more cubes=more power, and it dosen't run hot or anything. Also, i found out why my truck falls on its face after 4500 rpm, the heads only have 1.72/1.50 valves. I put the smaller valves into desktop dyno, and it only said 260 horsepower, instead of the 277 i thought it had, lol. Now i'm sure my 2.02/1.60 heads will make a HUGE difference. One more, how much are my old heads worth? They are casting number 462624. Mortec.com says 75-80 350, 76cc chamber, and they have 1.72/1.50 valves. They arent cracked, and were rebuilt 22k miles ago along with the rest of the motor. The truck didn't smoke at startup, so the valve seals are fine, and none of the valves are burnt. I was thinking, maybe $150 tops??? Thanks for any help __________________ '72 Chevy C10 Mild 350/TH350/3.07. Ochre/White. Old high school ride. '70 GMC C2500 '62 327 4bbl/SM465/4.56-geared Dana 60. White/White. Project or parts truck. '97 Saturn SL DD. 1.9/5-speed. 40+ highway mpg

06-12-2003, 09:30 PM	#2
Piston Account Suspended Join Date: Oct 2002 Location: Olathe, KS Posts: 2,300	continually soak the carbon with transmission fluid, this will soften the carbon enough to allow you to carefully use a wire brush. No need to clean the pistons completely though, just get the large chuncks off. These will cause detonation when warm. The old heads? smog heads won't bring much. used heads won't bring much I'd bet. Those things are a dime a dozen

06-13-2003, 05:26 AM	#3
jef5150 Inline 69 Join Date: Apr 2003 Location: valleysprings,california Posts: 1,018	The .060 on top of your pistons means," 60 thousands" overstock bore diameter,,usually .030 is bored off the cylinder walls {.015/per side}in the first major rebuild,,,,,,so either your motor has been rebuilt twice,,or on the first rebuild,the cylinder walls were really bad and the walls didnt "clean up",so they took it up to .060



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