AA 94mm Pistons

[mike]

While I have my 2110 motor apart, I've been contemplating an upgrade to 94mm pistons. Looking at the 94mm forged AA pistons set and been reading about how they need to be honed to spec to avoid any issues. Is there anyone local who is familiar with honing these cylinders?

I've also heard of some people machining down the barrels so they fit the 90.5 case register to maintain case strength around the studs. Has anyone here done that before? Is there also someone local that can do this machine work?

Thanks,
Michael

[Geoff]

I had High Perf Engines hone mine, It's about $80-$100 to do a set if I remember correctly.

[jim martin]

i do not use the AA cylinders .now mine were very early version and did not hold shape when honed. i would hope quality has improved .
at present i run a set of very well seasoned cima barrels that have no distortion issues when torqued .
its been a while but i seam to remember having less than 0.002" piston to wall clearance on my AA set out of the box . i would recomend
a min or 0.005" to prevent scuffing as well locate a set of wisco wrist pins and aluminum buttons from jc as the circlips seam to fold the
clip groove over .
also recomend high performance engines in bby for high quality engine machine services

[josh]

jim have you played with torque plates when honing? I have been thinking of making a jig to hone cyls when pre-heated to a couple hun degrees.......good yeh-neh

[mike]

I've decided to stick with my 90.5s for now. I'll save up my pennies for the 94s for next year with all the proper preparations.

Thanks!!

[jim martin]

jim have you played with torque plates when honing? I have been thinking of making a jig to hone cyls when pre-heated to a couple hun degrees.......good yeh-neh

played with a torque plate yes , while honing no .
the big difference is if you are honing at home with a ball or a 3 finger type hone there is no point but under a ideal situation torquing the jug down to the same torque you will be using and heating it would be the ultimate when used on real honing machine that actually makes a perfect circle and not just follows the shape of the jug.
if i remember high performance engines does a good job of securing the jugs correctly or at least as best as can be done .i do not know if there machine warm the fluid ,i would think not .
i remember when i took my first set of AA cylinders there i got a call and was told you have clover shaped jugs ,still have that original set which i have never used .
if you have a set of well seasoned cima jugs .use them .

[Bruce]

jim have you played with torque plates when honing?

I'd say clamping plates on VW cylinders is not as important as using a torque plate is on a water cooled block.  That's because the head bolts of a WC engine are effectively pulling on the sides of the cylinders at the top of the deck.  This causes a slight distortion.  Our cylinders are evenly clamped by two flat surfaces when installed.  There isn't a point loading on the side of the cylinder like a WC block has.

[GMB]

I've installed quite a few sets of A&As and have had to clearance the stud spiggotts to clear the studs properly. If this is not checked when you install the heads it kinda wraps the studs around the cilinders and I'm sure will cause distortion. Otherwise all have been good.

I've heard alot of guys say there's nothing to assembling an air cooled engine but with todays parts all made from different suppliers you sure have to be on your toes to catch the little things that could cause shorter engine life or failure!

Just the other day I was doing end play on an engine and the Customer had supplied a Scat chromoly gland nut. I usually don't use the larger headed nuts and so I had a new Brazillian gland nut to use instead. The Brazillian nut's threads lookes a little rough compared to the Scat nut and so I measured the thread diameter to see if there was a difference and there was a .005" difference between the two! the Scat one was the smaller diameter and when fitted into the crank The Scat gland nut was very loose..... The stock Brazillian was a perfect fit with hardly any noticible rock in the threads. I could imagine the Scat gland nut would have a way better chance of striping in the crank then the stock Brazillian when torqued.

If I hadn't checked this minute detail I may have had a nightmare on my hands!

   
     Gary.