Finally got time to let this twin SU-H6 B20B in my '69 144s run for a good long time, following R&R of the choke cable to recover the chafed sheath which was grounding out to the steering column support.

The entire time the engine ran (30 minutes), even after warm up, there was a steady stream of white, steam-like exhaust.

I could not attribute this to the mild, humid weather, as my other cars were not showing similar exhaust.

My concern is coolant in the combustion, as I was always told white smoke/steam indicated cooolant leaking into the block, cylinders, or a bad head gasket.

(I now have marked the coolant resevoir bottle to watch for coolant loss)

After shut down, I got these results on a check of engine compression:

In order of 1-2-3-4

155 - 160 - 155 - 145

Just in case gas was washing the cylinder walls by the time I did #4, I added a little oil and retested #4 at 153 psi.

Aren't these reading too low for a B20B? Haynes says it should be 170-185.
-28 psi is said to be bad, so, #4 is borderline at -25 psi.

Further, this is not the original head. It looks like an early carbbed model, but I don't know for sure. Could be from a 70-71 FI which has its injector holes bolted closed. It is definitely not a later FI unit.

Is the white exhaust and low compression telling me there is a problem? Or, could it just be low compression due to the different head and, maybe, a too-thick head gasket?

Or a head that is supposed to give compression in the 150-165 range?

Also, the plugs, which I had just cleaned, are dry fouled (black soot)