Skip: I forwarded this to my friend Chuck Brown in Wisconsin, who bought
his TC new in 1948 (second one sold in Oregon) Chuck was one of the pioneer
racers/engineers of TC's back in the fifties, and was racing it in SCCA
events back then, and still does, in vintage races. He's an extrordinary
engineer and received substantial publicity in those days for his many
victories and engine innovations. Back then, he was running two blowers on
his TC...a 15-lb boost Marschall Nordec (belt-driven), PLUS a 15-lb boost
rootes type out on the dumb-irons, linked as a two-stage system. I was
aware that he'd bored his TC quite a ways out there, so decided to forward
the recent dialogue about overbores to him, and get his reaction. Turns out
he's using a TD block these days, (his letter explains) to preserve the
original TC engine from potential ruin. I thought I'd pass his reply along
for whatever value or interest it might have:
Here are his two replies:
Sam,
The method of calculating the displacement of an overbore in the letter you
forwarded is incorrect...
After all, just do the math [as everyone says now] bore squared x
3.1416/4 x stroke x number of cylinders
Or, [ if squaring a number is a bit too difficult ] , bore x bore x
3.1416/4 x stroke x number of cylinders
Sam, my INITIAL overbore was to 0.132 over.
Then, as racing progressed, and various rebores were
required/&.or/honings , I ended up at an overbore of 0.168
Tsunami Pistons, of Tacoma Washington was able to supply me custom pistons
in step-ups of 0.004", by using patterns from the Lincoln V-12 of the '40's.
The only big change was when I had a set of magnesium pistons "light-off" in
the engine, requiring an Iffy .020 overbore to clean up THAT damage.
NOTE: still have 'souvenir pistons from that experience, not to mention the
crankshaft that broke, the 5 sets of differential gears, the valve that
lost it's head, spark plugs that shed the porcelain tips in heat of
battle,....
What I am thinking of now, is to pull the roller-cam, install TF-1500 rods,
have new bronze guides made for the Sodium-cooled valves.... which are in
the TC block, and have it sleeved back to a useable size for "just driving".
Then, put the performance parts into the TD block, install one of the
blowers, and have some fun again.
Would really shed a tear to damage the TC block, so the TD block is a
'little' more expendable.
Chuck.
> Gene:
>
> Most XPAG engines can be safely bored to .120 without a problem. You can
> also sleeve it and go out to 1500 CC, but it can be tricky.
> I like to run this engine at 9.3 comp. ratio. It really makes a
difference.
>
>
Skip........................................................................
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> At 02:56 PM 7/26/02 -0400, Gene Gillam wrote:
> >Any suggestions about the other two questions?
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