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I have a set of 706 heads that will more then likely not run at this point due to boosting the car. I wanted the opinions of you guys on these. I bought them and they were freshly lapped and cleaned by the previous seller. When i unpacked them i saw this (right on the chamber edge). I researched a bit and you get differing opinions on the matter. Plus if I decide to sell them as is, i don't want to screw anyone over.
Looks to me like someone used a roloc disc to remove all the gasket material
HORRENDOUS to say the least.....there's so much more to milling a head than just the "make it flat" part
The actual finish quality (RA) is designed to "grab" the gasket material so as to seal but also move around a bit during expansion and contraction
That nic doesn't look too bad but I'd have those things disassembled and cut a few thousandths prior to selling or running...
Looks to me like someone used a roloc disc to remove all the gasket material
HORRENDOUS to say the least.....there's so much more to milling a head than just the "make it flat" part
The actual finish quality (RA) is designed to "grab" the gasket material so as to seal but also move around a bit during expansion and contraction
That nic doesn't look too bad but I'd have those things disassembled and cut a few thousandths prior to selling or running...
thank you for the input. I figured milling them was the best option. Appreciate rhe response!
You need to do some more research, some of the 706 heads were prone to crack.. used 706's are pretty cheap so milling might be point of diminishing returns. You didn't say what they were going to be used on but a trip to Texas Speed or some other shops for evaluation and their CNC porting and bigger valves and spring kit is pretty cheap. FWIW
You need to do some more research, some of the 706 heads were prone to crack.. used 706's are pretty cheap so milling might be point of diminishing returns. You didn't say what they were going to be used on but a trip to Texas Speed or some other shops for evaluation and their CNC porting and bigger valves and spring kit is pretty cheap. FWIW
This!!!!!
They will also pressure test fine as well, the cracks open when torqued. A pretty good way to tell if they are crack prone is to look for a double A battery cast into the head between the outside rocker stands. That means they are castech=will crack
If I see that on a cylinder head then I take a hammer and beat the head to death so no one else goes through the horror of leaking heads
02-12-2018, 04:15 PM
Knick on cylinder head 
