Hope some one on the forum can help with a problem a very experienced machinist and T mechanic has ran by me over the phone.
First, it's a full rebuild, ground crank, re-bore and ground cam.
Started checking an Anderson timer to see if within tolerance, each cyl was firing right at a few degrees ATDC for start-up, this is all being checked with the head still off but, this is the strange part, as fully advanced, the firing is now up to 1/2" difference across the 4 cyl's.
So the checks that have been done, cam is spinning true, front cover is aligned, no side play of the timers.
Next was to try another timer, a tiger, same thing, so I sent him a new TW brush timer to try, call today is still the same.
Any idea's on how it could end up with such a degree difference on advance across the 4 pistons?
I think your front plate is out of center or the camshaft isn't straight.
I think Andre is spot-on.
That looks like it hits the nail on the head, he did tell me that his aligner fits the seal hole as mine uses the timer one, so now, with out seeing it, I'm thinking the cover is a poor casting, a little of centre.
I believe the only proper way to set the timing cover to center is with the large diameter tool made for the recess that the timer actually resides in - whoever came up with the idea of producing a gauge to fit in the seal area was off-base.
with an anderson timer you can bend the prongs to compensate for an off center cover It migt make the unadvanced off but that doesnt matter as long as all pistons are hitting after top center.