"Charles D. Sorkin" wrote:
> Besides the
> plugging up of the air injection ports and the PCV valve, what (if anything)
> is specifically different about the block?
>
> Was the actual block from the same casting in during that period?
The actual blocks were different in castings, not size.
The 67 block was of a thinner cast it had lots of excess slag on the
outside as opposed to the more refined 68 and onward 1275s.
Block numbers on 67s were 12cc, 68 starded with 12cd.
The 67 also had a nitrated crank (en40b) 68 had a tuftrited crank
(en16t)
67 had a cross drilled crank also.
None of this would account for any difference in horsepower just a
weaker block with a stronger crank. Some 67 blocks were also sleeved, I
have seen 2, I have owned 4. I have never seen an other sleeved 1275
other then 2 of my 4 67 12cc blocks.
The primary differences from 67 to 68 are;
1) centrifical advanced distributor
2) non swing needle SU carbs but still 1.25 each.
3) pollution stuff, air pump, gulp valve, air rail, charcoal can, etc.
To revert the 68 carbs, use the dashpots, pistons and needles from a 67.
also run a tube between the 2 air vents to close them off. (always use a
matched set of carb pistons/dashpots) The jets are the same.
find (invest) in a Cooper "S" dizzy centrifical advance only.
replumb the pollution stuff to eliminate the air rail, pump, charcoal
can, and gulp valve and install a Smiths PCV to the timing cover inplace
of the tube to the carbs.
IMHO the centrifical dizzy is where the power is. The pollution stuff
just robs power so simply removing it is a big help. (check local smog
laws first ;-)
The swing needle carbs were (I think) just a form of evolution and have
nothing to due with performance restrictions. However, the spring loaded
button valve on the throttle plate has to go. this is where 90% of the
fluxuating idles come from, a bad spring on one or both of these popet
valves will give weird idle settings. Solder up the holes after clipping
the popets.
--
Frank Clarici
Toms River, NJ
Down to only 3 Sprites, 1 Midget and an A40 Farina
http://www.exit109.com/~spritenut
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