Bad head no compression??

[fortknox82]

Ok so i am revisiting this POS thousand dollar head i picked up. Please dont ask questions. All i know is it pulled good flow numbers.

The head is an 83 G-Head 4105445. It has stainless oversized valves installed. Nice springs with dampners. Overall the head is a nicely assembled unit.

What happened the first time i tried bolting this thing on the car was that i was having a compression issue. 2 cylinders had barely any compression and 2 cylinders had no compression. So naturally first thing that came to mind was that maybe the cam was a slider cam and i was using roller rockers. So i had a fuller roller setup on another head and swapped everything over to this head. Try it again. Same issue no compression.

So at this point yanked the head off and put it to the side to play with another time. I figured what someone did at this point was put swirl valves in a bathtub head.

Brings us to tonight. Dug the head up. Pulled the valves out. They all measured 112mm which is what they should be. DAMN!

Inspected the valves and the seats. As far as i can tell and as far as my dad can tell is that it looks like the valves have a 2 angle grind on them and then the seats only have a single grind. And it doesnt look like it ever had the valves lapped into the head. He said that could be a good reason why i had little to no compression if the cut is wrong and the valves were not lapped in.

So my question to the forum is what else should i check for??

Also, im going to cut a single angle grind on everything and was wondering if someone could tell me what the degree angle of the cut should be???

And im going to put two valves back into the head and pour some water into the chamber to see if it leaks out on a long shot as well. Any and all help is appreciated.

[TurboBaron]

I wouldn't go a single angle grind. That is technology for Ford Flatheads and other valve-in-block engines like Hudsons, Packards and lawnmowers.

Seriously, do yourself a favor and do a nice 3-angle grind. You'll never have to worry about burning a valve or having one stick again. There's a reason they came up with it.

If it's been ported.... double check the work. Too many times I've seen people cut thru the port wall and wonder why one cylinder is dead.

[NICK A.]

Here is another issure to look into that I ran into on a S60 head. Dropped a valve seat and had the machine shop put all new exhaust valves in. But after the 2 bad seats were changed the Valve TIP height was too high due the valve being sunken into the head and was hanging open 2 valves causing no compression in 1 cylinder and almost none in the other 1.

What you need to do is assemble the head with the cam in it and rotate the cam and see if the valves are staying open.

Nick A.