Hello,

I am still looking for a used EGR Valve Volvo Part Number 1266363. That said,
my car, especially the engine and its accessories, has been completely restored to its factory original glory.

The Valves were adjusted to factory specification, I set the mixture with a shop's Exhaust Gas Analyzer to 2.0% CO, and I am using Mobil Synergy 8000 Premium 98RON Octane fuel, and the ping has disappeared, even on a hot 35 deg Celcius day.

I switched from Bosch W7DC Spark Plugs to W8DC, hotter plugs. The car seems to run better, around town. Bosch recommended the hotter sparkplugs. I tried W6DC, in NGK equivalents, but the engine was unhappy and they carboned up.

I have to admit setting the mixture is not an easy task, even using the proper slotted tool for the Zenith-Stromberg 175CD Carburetor and a commercial Exhaust Gas Analyzer. There is almost no feeling the Metering needle change and I am never really sure the tool has engaged the small tooth, at the bottom of the cylinder. Borrowing the shop's E.G.A. I felt somewhat rushed, because I did not want to inconvenience them, so it made it more difficult. As soon as I inserted the Piston with the Black Cap, the Mixture would change again, and I kept playing around until I got close enough to the 2.0% CO (Carbon Monoxide).

I pulled the W8DC Spark Plugs to check their color. #1 was slightly sooty, #2 was slightly less, #3 was cleaner, and #4 was clean. I was wondering if the car would run better with W8DC Plugs in #1 and #2 and W7DC Plugs in #3 and #4?Also, when changing Heat Range on Plugs, should I stick with .711 to .813 Spark Plug Gap? Is there a rule of thumb?

I am pleased to say that this carburetted B21A engine gets significantly better gas mileage than my former Fuel Injected B21E, though I dumped $4500 into various repairs over the years, especially on the Fuel Injection System.

The B21A always starts, with the Choke pulled out and a flick of the key, while the B21E was always difficult in cool weather.

Any thought on this?