My 73 wagon has a crappy idle and no low end power. I finally got around to putting a timing light and vacuum gage on it. Vacuum was low and indicated late timing. I could see the timing marks on the bottom pulley but darned if I could find the timing reference.

To get the thing to run decent I had to advance the timing a bunch. brought the vacuum reading onto the lower Green region on the gage. It has a lot more bottom end now but a surge or miss at highway speeds that it didn't have before.  The whole thing made me think that maybe the timing belt had jumped a tooth so I set the cam gear up with the two holes parallel to the ground and timing marks on the crank pulley looked like they were at zero although I still didn't have a true timing reference. The distributer rotor was about 10-15 degrees behind the #1 index mark on the rim of the distributer indicating advance. I thought the distributer might be a tooth off but it only seems to want to sit in one place. Trying to move it one tooth either way resulted in it refusing to seat all the way to the block. I couldn't figure out why. I didn't see an oil pump key but maybe there is one.

The idle is much better but still not what I like and I need to figure out the highway surge but first I need to know where the timing reference is on the engine. The timing marks on the pulley were steady at idle not jumping around so I think the distributer shaft is probably OK although I didn't check them under acceleration.

I'm going to see If I can find someone with an old distributer machine to check out vacuum and centrifugal advance and bushings. The other obvious possibility is carburetor which has a new kit in it but could be sucking air through the throttle shafts or?. Sprayed some Starting Fluid around the shaft but couldn't really determine if anything was affected but that was when the idle was much worse. Will try again.

The car has 95.6K on it and seems to have been well taken care of. I've put over 1K on it since I bought it. I've been running regular gas but ran accross some specs recently for the engine that said Regular 91 Octane. Think regular might have been that high in the 70's. Can't remember but with the low compression these things have I can't see why they would need high test.

Comments please.

Timing belts generally do not stretch, they are made specifically not to do that. Rather, they shred or break out right or strip teeth off. I haven't seen a 'stretched' timing belt in 40+ years of working on cars.

Biggest trouble you'll have now is with unleaded fuel, that year used low lead, the difference between low and un is quite a bit. I could not keep valves from receding on pure unleaded, the max life on a fresh valvejob head was maybe 15000 miles. That was back in the mid nineties. Pull it down and the exhausts will be sitting in a 1/16" deep hole not there before. Could be your idle issue.

Harder exhaust valve seats to stop the recession..... .............. ......a ritual on older heads like these have. Somewhere in there they started induction hardening the seats on the iron head, you can see the blue heat marks on a really clean head if done. Maybe '75-76 models? Again, that is for low lead, I have no idea how long that would work on true 100% unleaded fuel.

I have the same trouble on Honda motorcycles of around '79-83, worse on them because valves are not cuttable, you replace only. Expensive at $20 a pop on a 16V head.

Even now on engines of today the exhaust valve seats will wear prematurely. All my zetec engines show it at around 80-90K miles, The intakes will be merely polished in but the exhaust seats will have noticeable dings and erosion from heat. You can go in and simply recut the exhaust seats and nothing more and motor picks up like 10% power instantly.

When I had my head redone, my #3 exhaust valve was D-shaped. $400 or so later, ran like a new car, and just keeps getting better all the time. Definitely try to find a shop that's been around for awhile and has experience with your motor, gave me some peace of mind that my baby was in good hands. Oh, and don't forget to send along the valve stem seals out of your head gasket kit when you send it in. No sense in buying them 2x. lol