10-08-2020, 11:56 AM
We had a problem with the 1929 saloon. It ran well but started to develop a misfire if high revs had been used for long. Typically climbing hills in 2nd gear.
It was OK at higher revs but as soon as we changed up into top the car would stumble and not pull properly. This gradually got worse and worse and eventually wouldn't pull properly at all.
After trying everything I could think of I eventually removed the head and found that numbers 3 & 4 exhaust valves were sticking. On removing them found there was a build up of carbon on the stems which caused this. I cleaned everything up and reassembled it and all was well.
I think what was happening was that the exhaust valves were getting hot with the continuous high speed and had expanded more than usual hence not closing properly.
I adjusted the exhaust valves 0.002" wider clearance. No more problems.
It was OK at higher revs but as soon as we changed up into top the car would stumble and not pull properly. This gradually got worse and worse and eventually wouldn't pull properly at all.
After trying everything I could think of I eventually removed the head and found that numbers 3 & 4 exhaust valves were sticking. On removing them found there was a build up of carbon on the stems which caused this. I cleaned everything up and reassembled it and all was well.
I think what was happening was that the exhaust valves were getting hot with the continuous high speed and had expanded more than usual hence not closing properly.
I adjusted the exhaust valves 0.002" wider clearance. No more problems.
Jim