All valves leaking badly

[97egl]

Lapped all 16 valves and they all had a decent looking ring on both seat and valve faces after minor lapping. Slapped the engine back together and went to fire it up and it didn't even attempt to start. After doing all other diagnosis because I assumed the engine was good I finally ran a compression test and got 45-50 across all 4 cylinders. Verified timing and eventually pulled the cams out and did a leakdown test. Air blowing out of the intake and exhaust on every cylinder. I'm totally stumped here because while lapping is not near as good as re-cutting the valves and seats I'm just doing a cheap rebuild for a winter beater and I have lapped valves on at least 30 heads in my life and I've never had them leak bad as long as the valve and seat faces have a good mating ring after lapping.

Any ideas? This is on a 6 bolt

 

[Mello]

Could the guides be worn out cause the valve not to seat well (assuming valves aren't bent)?

 

[AWD-Tony]

Probably cheaper to find a used good head, lap valves and slap her on.

 

[Mech Addict]

Any chance when you cranked it over, the cam timing was way out, and bent all valves a little? I wouldn't think you'd even get 40psi compression in that case, though if they only bent a little??? I'm reaching here. I'd be better answering the question about the water main. Looks like you'll be pulling the head anyway, so re-inspect how the valves rest mate with the seats. It would take some serious guide wear to be that leaky. I've not heard of that problem with 4g63 heads, likely since they have such a nifty rocker arm design, with far less side-loading than, say, an sbc, or any motor with the pivot between the valve and the lifter/pushrod. The arc at the valve tip is fairly flat.