New AN barrel & Emglo Pistons

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Having read through this I can not understand why you didn't contact AN before posting on here
 
I don't understand what's so hard to see? In his very first post, it was clear that OP wanted to handle the problem himself, rather than bring the build to a screeching halt by going back to AN. Commendable, in my view.
 
Mr. Rick said:
I don't understand what's so hard to see? In his very first post, it was clear that OP wanted to handle the problem himself, rather than bring the build to a screeching halt by going back to AN. Commendable, in my view.
Click to expand...
If I were the vendor I would like to have known if there was something wrong with a product I had sold before reading about it on the web
 
baz said:
Having read through this I can not understand why you didn't contact AN before posting on here
Click to expand...

I posted, originally, because I was hoping that the pistons I had were abnormally short on skirt diameter. The measurements I made, initially, of the bore were not repeatable and, therefore, inconclusive; this is why I took the pistons and barrel to a specialist. Forum members confirmed that the pistons were of the correct skirt diameter, my specialist confirmed that the bores have a taper, .006 at the top, .004 at the bottom. Cleaning up the bores gives me .006, if I'm lucky, something larger if not, in either case the dimensions approach the limits of standard bore clearances, not the way I do business.

I communicated with AN and got an immediate response from Mr. Ashley Cutler, who wrote, in part:

"You will never achieve the clearance you are looking for with a standard
bore and the pistons you have - you will have to rebore. The reason why is
that the original bore 2.8746/2.8750 has a larger diameter than what we
currently bore to (73mm) 2.8740/2.8744'' Had we bored to original size the
skirt clearance would have been even greater irrespective of the taper. The
pistons you have are what I consider not fit for purpose as they would not
actually fit a standard bore that well with a skirt clearance greater than
0.006'' NOS pistons and copies will no doubt allow for the old clearance
required - clearances are as you know a lot less these days, with our forged
750 pistons using 0.003'' these are only 348g with the pin rings and clips".

As someone mentioned AN's piston offering is a better fit in their barrel, no surprises. I still like the idea of having my machinist cut new bores and finish hone them to a near perfect .0045" skirt clearance, so that's my plan. So, if you are planning on the purchase of a new AN barrel ether purchase their pistons or plan on doing the first oversize, pretty simple strategy, actually.
 
RoadScholar said:
baz said:
Having read through this I can not understand why you didn't contact AN before posting on here
Click to expand...

I posted, originally, because I was hoping that the pistons I had were abnormally short on skirt diameter. The measurements I made, initially, of the bore were not repeatable and, therefore, inconclusive; this is why I took the pistons and barrel to a specialist. Forum members confirmed that the pistons were of the correct skirt diameter, my specialist confirmed that the bores have a taper, .006 at the top, .004 at the bottom. Cleaning up the bores gives me .006, if I'm lucky, something larger if not, in either case the dimensions approach the limits of standard bore clearances, not the way I do business.

I communicated with AN and got an immediate response from Mr. Ashley Cutler, who wrote, in part:

"You will never achieve the clearance you are looking for with a standard
bore and the pistons you have - you will have to rebore. The reason why is
that the original bore 2.8746/2.8750 has a larger diameter than what we
currently bore to (73mm) 2.8740/2.8744'' Had we bored to original size the
skirt clearance would have been even greater irrespective of the taper. The
pistons you have are what I consider not fit for purpose as they would not
actually fit a standard bore that well with a skirt clearance greater than
0.006'' NOS pistons and copies will no doubt allow for the old clearance
required - clearances are as you know a lot less these days, with our forged
750 pistons using 0.003'' these are only 348g with the pin rings and clips".

As someone mentioned AN's piston offering is a better fit in their barrel, no surprises. I still like the idea of having my machinist cut new bores and finish hone them to a near perfect .0045" skirt clearance, so that's my plan. So, if you are planning on the purchase of a new AN barrel ether purchase their pistons or plan on doing the first oversize, pretty simple strategy, actually.
Click to expand...
Sorry I didn't know you had been in touch with AN you didn't mention that until now, cheers
 
We have only been in contact since last night so no surprise Bill didn't mention it up to now.

Everything seems to be cleared.

Joe/Andover Norton
 
Nice to see that the principals in this case are satisfied.
Are the rest of us not still left with the question of how the bores are (were) tapered as received? By how much? And whether this is intentional or not?
 
Well, probably yes. Some things we're just not meant to know :lol:

Ken
 
I had bought one of those new through bolt for 750 ,, from Norvil / Les Emery , 10 years ago (or more) and it was perfect,I just have to make it honed to get a 4 thou clearance for my Dunstall/GPM pistons, now on my Atlas, still running good.........don't know where Norvil have them made,but good work.
 
Mr. Rick said:
Nice to see that the principals in this case are satisfied.
Are the rest of us not still left with the question of how the bores are (were) tapered as received? By how much? And whether this is intentional or not?
Click to expand...

No question in my mind, that these bores were tapered as reported (know the players) and that it was not intentional (recip aircraft engine sidetrip discussion does not apply here). The "let's not talk about this anymore publically" is baffling, because, the madness will continue.
 
"my specialist confirmed that the bores have a taper, .006 at the top, .004 at the bottom. Cleaning up the bores gives me .006, if I'm lucky, something larger if not"

I'm confused, what is the total taper amount , 4 thou, ,6 thou ,2 thou or is it a double taper?
Glen
 
Fast Eddie said:
How is it possible to unintentionally machine the bores with such a taper?
Click to expand...
It takes years of practice, and highly specialized equipment.

Then, just do it like you don't intend to.
 
From what I have read it IS a double taper. Bore may be true at some point in the middle, but tapered at top and bottom! This can happen if you left a long hone stationary and walked away as it was hanging out of both ends. Just guessing at this point, a real mystery, but I've seen it on an align honed block.

Jaydee
 
If, as in this case, there is an issue with a part we quarantine the item in question until either a) stock has been checked again and found o.k. or b) the issue can be found with all these items on the shelf in which case some items (very few, but it has happened) are binned in toto.

Our Ashley is currently checking the barrels in our stock but so far has not found a tapered bore yet. I personally still find the incident hard to believe.

New barrels are being cast at the moment and we will make sure every single one will be checked when the goods come in rather than the random checks carried out up to now.

Joe Seifert/Andover Norton
 
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