Can the valve seals be replaced on the 1600 stock engine without pulling the engine in a Dune Buggy..???

There are no valve (stem) seals.

Would you be talking about the push rod tube gaskets?

Well, the mechanic now tells me that the #1 & #2 cylinders and only giving 135# and 140# respectively. The #3 & #4 and pushing out 170# each.  So now I have to take it back to the guy who rebuilt it a year ago. It has not been
driven except for 32 miles bringing it home the other day. Any ideas as to what could cause this. Does it sound like rings, or what?

If the motor only has 32 miles on it, it needs to be driven some more to break it in.  The piston rings need to seat in most of all. 

170 is pretty darn high cylinder pressure for a stock VW.  Is this a high performance motor?  Does it have bigger cylinders, raised compression or any such goodies?

As for the variation from cylinder to cylinder, that could be due to a number of things.  Some of the rings may be starting to seat and seal better than other already or the valves may be slightly out of adjustment.  Speaking of valves, if the pushrods were custom cut to length, the tip ends may be seating into the tube portion a little deeper now causing the adjustment to get a little slack.

If you can provide detailed build info we might be able to come up with more ideas.  No matter what, do not get discouraged.  These are very simple and pretty rugged engines.  I see VW engines all the time that "shouldn't" be able to last in the condition they are in or with the way they are (NOT) maintained but they keep on running.

My biggest advice to ALL air-cooled VW owners: Premium gas ONLY.  Remember when these cars were built and sold new the low grade fuel was 90-91 octane.  Inside the little gas door on 68 and later VWs said "91 OCTANE MIN." for a reason.  Gas has changed so now 91-93 is the premium stuff.  Part of the cost of driving a classic I guess...

I am trailering it back to the re-builder today. Maybe I can use thE information you supplied to give him some
direction if he needs it. He is an older fella, semi-retired, who now works with his sons.

He is also a former national VW race winner back in the day. He came highly recommended from a well-known engine rebuilding company South of here. So I trust he knows what he is doing.

I REALLY APPRECIATE THE ADVICE FROM YOU GUYS, IT IS WELL RECEIVED from this Old Timer, and not worry, I am not the type to get discouraged. I had a major heart attack, now have MDS and undergoing a Clinical Trial through the Cleveland Clinic for a new medication, so I don't go down without a fight. I WILL be driving the "Lil' Bugger" before ALL the leaves all fall to the ground.............

THANK YOU...THANK YOU............

Not knowing what parts were used in the rebuild and how in depth the engine work was done, it is very hard to say if it is an issue or some simple as the rings have not broken in and seated fully.

When it was rebuilt did the rebuilder provide values and demonstrate compression at that time, if so and your seeing a trend toward a major decrease then concern should be there. 

Ron, the builder did not provide values and I probably would not have understood them if he did. I did take the buggy back to him yesterday and as John said, he was not at all concerned with the variances in the cold compression numbers, saying that the rings need to seat. Thus Miles. So, I took the "Lil' Bugger" to our little rural town this morning in the fense fog and showed her off to the other old timers. It was great to have that feel of the buggy cruise.  There is no Health Insurance Policy on this earth that can sooth an old soul like a Dune Buggy.

The builder (a 200 miles round trip away) did reset the timing at 30 BTDC instead of the 10 BTDC it had been set at. He said to look for hesitation after down-shifting around corners. Well, there is hesitation, so I'm not sure how to eliminate that unless this is also something that will correct itself with rings seating.

Again to all you guys, thanks for the ear. It all helps..........