Hi Dave, Dennis and Listers,
Presumably Dave you have an early single breather PA block.
The fact that PBs and later PA blocks were bored out to 60mm doesn't, as I
see it, give credibility to the earlier PA blocks lending themselves to run
safely on a 60mm bore. The later blocks I'm told were cast with thicker walls
or, was this a factory ploy?
I would imagine one of the governing factors of over sizing, even within the
limits, is the condition of the water jacket deterioration. I'm sure there
are many of us who have taken that chance.
The site you referred to for pistons, Dave, would be,
http://www.jp.com.au/
Brian Kelly.
In a message dated 11/15/2002 5:15:35 PM Central Standard Time,
dmdwyer@optusnet.com.au writes:
> Dennis
>
> I think you're right at the utter limit for a PA (single breather) block.
>
> Our PA block was at +60, and with some fear and trembling we had it bored
> to
> +80 (ie 20 thou more than factory max recommended). It's run some 200 Km
> since then and hopefully will be OK for a long time, but the walls could be
> very thin in places. I much comforted to hear that early PBs had PA blocks
> bored to 60mm: ours is only 59.032mm!
>
> It's possible to test (I think ultrasonically) the wall thickness: talk to
> you engine man.
>
> We got our pistons and rings from J P Engineering Products in South
> Australia. Very helpful, knowledgeable and quick. Also sympathetic when I
> broke a ring (you need to be #very# careful to get the compressor evenly
> tightened) and supplied a replacement overnight. The +80 piston + rings
> listed at A$93 each.
>
> Phone: 61 8 8261 7222 Fax: 61 8 8261 9171 They have a web site but I
> can't find the address at the moment. Usual disclaimer.
>
> Regards
>
> Dave Dwyer
> J2 (yes, it's got a PA engine), TA, TC
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