AN pushrods are not real expensive at £15.50 each, works out in UK at £100 a set.
http://www.nortonmotors.de/ANIL/Norton% ... 02&Part=14
So the decision to change two or four could be easy, especially if you are changing out a bunch of other parts and doing a thorough rebuild.
But you don't give much of the information you might need to work this out.
Is it a Combat motor? ( as a 1970 it shouldn't but who knows?
Or does it have an otherwise skimmed head or barrel face? We are looking to identify if a shorter or longer pushrod might be the right part for your build.
Remember that the Combat had standard length pushrods, but they should have shortened 0.040" to maintain the valve gear geometry with the 0.040" skimmed head, some owners over time will have know this and shortened the pushrods, maybe someone then repalced one with a standard length one.
But without an actual measurement you won't know.
Compare the actual lengths with the of AN supplied length of 8.15" (RGM has a whole range of other lengths available!)
Then take a good look:
Are the end pieces properly seated?
Pop them off, does the shorter rod show signs of having been shortened?
Difficult to see from the pictures, but is there any other reason to replace the pushrods apart from the uneven lengths?
If they are fine, and when you know what length you need, you may be able to just shorten the long one!
It is easy to just spend the cash, but without thorough checking you still won't know if the pushrod length is right for your motor
