Evening,

In a post couple weeks ago, I mentioned my lost compression in cylinder 3.
I got the head off today, and found a significant gap in the exhaust valve, it also looks as though the valve is bulged. Also, the top of piston three is bone dry, can I assume this is down to the valve problem and not something else?





On the plus side, the cylinder walls look spot on.

Ive never worked a head before, but Im fairly competent in the old spanner department.
Thoughts on my next step, should I,
rebuild with standard bits,
take the opportunity to port & polish and uprated (possibly out sourcing to a experienced builder )
source a ready uprated head (such as the NMS one in the for sale section).

Any thoughts and advice very welcome,

Cheers guys

Wayne

 

i take it the valve is open with the rocker/lifter removed? as in the cams not opening it? the bulge around the base of the valve looks normal??

 

No, the rocker and lifters etc are all still in situ. First thing I tried was torquing the rockers, but its still rattling slightly.
Engine was set to TDC, and the other 7 valves are sitting closed flush against the head. Only no3 exhaust is sitting like this.

 

turn the cam and see if it closes... also check the valve spring is still in one piece

 

Not sure if it's the pic
But the pic of the stem looks a little bent
Could be carbon build up tho

 

Ive turned the cam one full revolution, and the valve doesnt shut fully. It one point there was a 3mm gap. It looks like its def bent, but there is no damage to piston, wallls, bottom of stem etc.
Ive been through the history, there is receipts for a bottom end rebuild, but it looks like the head is still original. Time for a rebuild

 

Try taking the tappet out and see if it's any better first

 

Im gonna strip it this weekend, once my Supra guru friend has had a look at it.

I was searching around at the weekend, and found a company called CNCHeads, that do a fully gasflowed and matched head for 350 (inc exchange)

Anyone used them?