I spoke with Dave McLain about this. Here's what he said:
"Installing a sleeve will distort adjacent cylinders somewhat and you never
really know how much until the sleeve is in the block. Generally one at the
end will tend to only push one cylinder out of shape whereas one in the middle
of a bank will effect one cylinder on each side. It can be very little
distortion 1/2 a thou to more like .001. Honing slightly oversize can
generally get it back into shape without a massive increase in bore diameter.
If they are running a forged piston they probably won't notice any difference
in engine noise, blowby etc. I would give it a try."
Two batches of XE192540 iron race blocks were cast at the Geelong foundry in
Australia. The first batch of XE blocks were manufactured in 1975 and were
available over the counter, if you knew enough to ask for the right part
number and had the cash. They were listed under the catalog part number
D1ZZ-6010-T and were quite expensive for the time, about $1500 in 1976.
The blocks were completely machined, except for the cylinder bores which
were semi-finished, being rough-bored at 3.990". A number of these blocks
were shipped to Holman and Moody and Gapp and Roush. Holman and Moody used
to list these blocks under the part number D6HM-6010-1.
A second batch was commissioned when Ford (U.S.) decided to get back into
racing in the early 1980's with the formation of the SVO program. These
were manufactured during 1982 and 1983. There were quite a few of the second
batch that didn't meet minimum specs with respect to core shift and other
defects. Some of these blocks were subsequently transferred to the standard
machining production line and were sometimes fitted with two bolt main bearing
caps (depending on when they were discovered to be defective) for use in a
standard passenger car engine. The blocks that passed inspection were
originally listed in the U.S. SVO catalog under the part number M-6015-A3
with a price of around $900.
I've had one of each of these blocks. One had a 5M2 date code (December 2,
1975) and a 1975 in a circle and the other had a "24C2" date code which would
indicate it was cast on 24 March, 1982. Neither had Siamese bores but they
did have thicker, non-contoured main bearing webs, a thicker non-sculpted
block skirt (oil pan rail), beefier high nodular iron four bolt main caps,
and thicker (0.165 inch minimum thickness) cylinder walls. The only 351C
blocks that I've seen with Siamese bores were SK blocks which oddly had the
thinner lower end of a standard production 351C block. Both of my blocks
carried the XE192540 part number but I've seen XE182540 part numbers as well.
There were also XE aluminum blocks and SK iron blocks. The SK blocks
I've come across had thicker Siamesed walls but a standard sculpted lower
end. Kaase mentioned there were a very few XE blocks that were Siamesed
bore but most were not and, though the wall are generally thicker than a
standard 351C, it's not uncommon to see XE bores with a thin spot or two
so it's worth sonic testing. You can test for Siamese bores using a coat
hangar snaked in through the core plug holes. If it's Siamese, the cylinder
walls will touch and you won't be able to push it through the adjacent