a little bit of cylinder head work this weekend to correct a coolant leak between cyl 1 & 2 on the exhaust side, there wasn't any fluid mixing and I didn't find any signs of cylinder leakage on the gasket when I got it apart
but before the actual work there is much prep. I sourced a Pick-A-Part 7MGE cyl head to prep so the whole job would be just swapping parts
after a thorough cleaning this is what I was left with on the intake side
originally I just wanted to smooth out the air flow a bit (take out some of the sharp edges by the valve seats, ect)but it turned into this with the help of my trusty Dremel
exhaust before
and after - the exhaust side was a PAIN because it's so much tighter
combustion chamber
valves all cleaned up and organized so they go back into the same holes
most of the power you can get out of an engine will come from the cylinder head, and being who I am, I pay attention to the details. after getting a cylinder head surfaced it will have these ridges or burrs along any opening . . .
which need to be cleaned, or it could lead to preignition from glowing hot metal fragments. I used 200 grit sandpaper. to give a nice round edge. the combustion chamber has "squish" all around the circumference, so I wasn't worried about undercutting the headgasket. I also cleaned all the head bolt holes and coolant passages
all back together and ready to go, the exhaust valve seats were touched up at the machine shop to remove some minor pitting but the valves were all perfect so I left them alone
this is kinda neat. the 7MGE cams and sprockets each have 3 holes and a removable dowell pin. when you get the head machined the distance from the crank sprocket to the cam sprocket is reduced, so if there is no cam adjustment the intake and exhaust timing actually become retarded. these holes are spaced slightly different from cam to sprocket and allow you to advance or retard the cam timing as needed. I didn't mess with it at this point because I lost my degree wheel . . .
I also found my vacuum leak, which I am pretty sure led to high NOx readings and my failed smog (likely did that one myself when I installed the EGR last year)
any repair is an excuse to upgrade, right? the 7MGe weakness is low head bolt torque (58 ft/lbs) with the ARP studs it is recommended to torque to 80ft/lbs using ARP lube or 120 ft/lbs using 10w-30 oil
the biggest pain of the whole job was valve adjustment. I had shims from 3 different engines to choose from and was able to get everything in spec except 1 exhaust valve (.001" too tight, all other exhaust valves are on the tight side). I'll need to go back through valve adjust again once everything settles in
I did have a problem starting it once everything was together, and I spent 1-2 hours going through distributor set-up, ignition, and everything else . . . until I saw the vise grips on my rubber fuel line that I had put there to prevent gas from siphoning out of the tank while I worked. After that though it started right up. a wide open throttle test drive up the I-5 Grapevine will have to wait till this weekend