Gents,
Getting back some "free" time to actually do some work to the car after about a year and a half, and am going to start by fixing the oil leak(s) the car has. I have removed the old heat exchangers as I will be putting on some stainless ones.

My current project is attempting to replace the pushrod tube seals. I know there are many threads, but I have a specific question regarding the 1.7L engines. I was reading that there may be an "early" bore size and a "late" bore size. So this has me a bit confused now, and I don't want to order new seals until I can confirm which ones I need.

Also, I'm a little confused on whether I need to do all that TDC stuff when removing all the rockers/valves. I've never messed with the valves before or done an adjustment (still a "noob"). I do plan to do a valve adjustment after everything is put back together, but wanted to know if I needed to do anything special during removal, or if I could just go to town on removing everything.

ps: anyone want to show a noob how to do a valve adjustment? I pay with beer

Thanks!

I'm going to say "yes, you have to do all that TDC stuff". To be able to remove the rockers, they need to not be under tension, that is, the engine needs to be at a point in it's rotation that either valve, for the cylinder you're working on, is not being opened by the pushrods for that cylinder being on a lobe of the cam. It's like you are adjusting the valves for a cylinder, you want that slack or gap present so you can set the gap. It's not that you "can't" physically remove a rocker under tension it's just that upon reassembly, you want to be able to tighten the rocker mounting nuts properly which I don't think you can do if under tension. So for each cylinder, you need to rotate the engine to relieve the tension for that cylinder before loosening the mounting nut. Once the rocker is removed, you can then pull the pushrod tube about halfway out, don't think you can completely remove it, to change the o-rings at each end. I believe that the first 1.7's had the same size o-rings at both ends of the pushrod tube but a change was made early to different size o-rings which lasted to the end of the model production. You probably can figure out your sizes by comparing your engine serial number to the info in the Porsche PET for o-rings.

Edit: upon re-reading your post, I see you have a '73 which "should" be 2 different sizes of o-rings. I say should be because with a 40 year old car, anything could have been changed by a PO. I think the o-ring sizes changed 71ish but not sure but you have a 73.

Doing mine for the first time too.
I just ordered a push rod seal kit from AA - comes complete with instructions.
Hoping seals are correct size too - didn't have an option.

I just put mine back on and did the TDC stuff for the reinstall. I don't think you need to worry about it for the removal.

Just remove them. No need for tdc till you go back on with them. Rockers must go back on the same cylinder. Pushrods must go back in the same spot and same orientation. Same with lifters if you remove them.

I thought there might be an advantage to complete each individual cylinder before moving on to the next. I didn't like the idea of loosening the rocker nuts under tension; thought it's be a chance to bugger up (carry-over vocab from the Olympics ) the studs.