top overhaul

[Boydskyking]

I am a aircraft mechanic for many years and have performed many top overhauls on six and four cylinder aircraft engines. My 1980 SC which is a 3.0 engine , the valve guides are getting bad and needs to be replaces. I was wondering if I could do the same type of overhaul on it as I have been doing on the aircraft engines for years. Heres how I do the aircraft engines. Pull the jugs and reach through the hole in the case and and unbolt the rod and pull it out through the hole in the case. Replace the rod bearing and rod bolt and place it back on the rod jornal and retorge the bolt. Replace the rings, grind the intake valve, replace the exhaust valve , put the jugs back on the engine and button it up.The car only has 81,000 miles and has great oil pressure. This is an approve repair for the Federal Aviation Agency and would this be ok for the Porsche engine. Your comments are welcome

[E Sully]

If the car has Alusil cylinders, you want to leave the pistons rings and cylinders alone. Just do the valve guides and exhaust valves. If Nikasil, you may want to consider the rings.

[Bob Kontak]

I pulled two connecting rod caps off in my 81 back in 97 when I had the heads redone. About the same mileage (broken head stud) Bearings were fine. Replaced the bolts with two new factory stretch bolts on the rods.

Doubt bearings are going to be necessary but there has to be some value in doing it.

My exhaust valves stems were below tolerance.

I did nothing with my Alusil P&C's except clean them up and check bores, ring land gap, ring end gap. They were fine. Bores were maybe a half thousandth out of round.

Consider replacing the lower studs. Not sure if you can mix and match studs. I put raceware in top and bottom but they were "only" $500 back then. $375 for bolts and I got the fancy nut set as well.

I do remember they flycut the top of the heads six thousandths for a good seal seat. They stamped the machining dimension into the head which I though was pretty cool. I did some volumetric calcs and it took my 9:3 up to 9.5. An easy one or two hp. :-)

[Boydskyking]

Thanks fellows. I have always changed the rod bearing on overhaul because when operating under the Federal Aviation you do what they say.I dont see any reason not to do it , it cant hurt just be better.
Thanks again