[Fot] No vacuum after Spitfire engine rebuild

[George Harmuth]

Time query the collective again. My son and I just finished a rebuild of
his 72 Spitfire (1296, large journal) and I can't get it to run.  The car
will start up on starting fluid but won't even fire on it's own. Confirmed
fresh gas to carb, gas in fuel bowl, disassembled carb, cleaned and
inspected, looks OK and was working (rebuilt last summer) before engine
rebuild.

Think I've tracked it down to no vacuum, either from the vacuum port (flat
0 reading on gauge, no fluctuations ) on the carb or gross check, putting
my hand (or carb sync gauge) over the mouth of the carb. I've removed the
carb and intake manifold, gaskets etc all look good. Removed the valve
cover and plugs, verified ( multiple times) cam to TDC on cylinder 1
positions. The valves open in the correct sequence with respect to the
piston position, rechecked the valve clearance, are all set to .015.
Compression is a little low (1-4, 110.115,118,115) but the engine has less
than a minute of run time, I expect it will rise a bit as it breaks in.

The engine was working before the rebuild but it had low (ave 70Lbs)
compression on 3 cylinders. I found 3 broken top rings, I suspect the PO,
who had the car sitting for years, didn't do a proper job when he re fired
the motor before he put it up for sale and the rings broke. The block was
clean, looked like a recent (milage wise) rebuild on it but we replaced
rings, bearings, new valves and springs etc.. The cylinder bore was
inspected, measured and honed. The only parts not stock were a little
hotter grind on the cam, nothing radical and a Maniflow header to replace
the stock manifold.

Any idea where I screwed up or what I can check before I do a teardown?

thanks
mike



G. Michael Harmuth