<VV> To Ping or Not to Ping ? - "Premium" vs. "regular" gas

[Sweet, Bill]

All,

Back in 1997 I purchased a nice 1966 Monza 140 Convertible in the Bay area. I was very satisfied with it as long as I put 91 or 92 Octane into the tank and ran it on the flat land around the SF Bay area. But when I tried to negotiate Highway 17 to the Santa Cruz coast I found that the temp rose from my normal 350 indicated reading to over 450 with much pinging and a need to drop down as far as 1st gear. This was with the lower shrouds removed.
Even when adding a bottle of Octane boost to every tank of gas I had the same result. Timing and everything was set to the book.

In  1999, the national convention was scheduled for Lake Tahoe and I wanted to drive to the convention, but was fearful of the climb. Time to check the cooling fins. After removing the turkey roaster I found very little daylight showing through top to bottom, so got out my trusty keyhole saws, one thin with good set and one thick with good set I spent a Saturday afternoon "sawing my engine", as the neighbor said, and blowing the chips into the gutter at the curb. The jugs were all free of debris but were given a good soap and water wash before returning the engine room to an assembled condition.

After starting up and taking for a test drive I noticed that the temp settled out at about 250 indicated on the gauge. I then put the dog in the car and again headed for Santa Cruz, with the afternoon temperature about 90 F. T o my surprise I negotiated the mountain road with the temp climbing to only about 325 indicated and used only 4th and 3rd gear and no pinging. To say the least, a very relaxing round trip of about 45 miles. Since then I have ceased the 91 or 92 octane fuel and settled on 87 with no noticeable ping.

I made it to the 1999 convention all the way up US 50 with no pinging and temp no higher than 350 indicated on the same gauge.

That engine is still running strong. I do not know if the previous owner assembled it with an extra copper spacer at the heads to reduce compression, but have had no reason to do a tear down as the engine runs well. It is a weekly driver, and makes the trip to Palm Springs and back with no issues, about 1000 miles round trip. I drive about 4000 mile per year.

The opening of the cooling passages is sure worth the time to check and clean up, whether on the engine or on the bench.
I hope this helps those who have never done this, cause the rest of you know the drill.
I'll admit I have not gone to back to the higher Octane fuel cause I'm cheap/frugal.
Do you think I am asking for trouble after 11-1/2 years?


Bill Sweet
Silicon Valley Corsa
Office: 408-519-8754
bill_sweet at alliedtelesis.com