mightyohm
Donation Time
Last weekend, my wife and I drove our 62 Sunbeam Alpine from Seattle to Sacramento for the 2015 Snowball Rally (http://www.thesnowballrally.com/). The Snowball Rally is an informal gathering of vintage sports cars (pre-1980) that starts in Sacramento and winds about 500 miles around Lake Tahoe and into Nevada before returning back to the starting line.
The freshly rebuilt motor in our Alpine performed very well. We had to drive about 800 miles just to get to the starting line, and the rebuilt overdrive transmission and driveshaft from Jeff Howarth performed beautifully. (I can't imagine making a trip like that without OD.)
We split driving into 2 days and drove to Ashland, OR on day 1 (about 500 miles from home or 2/3 of the way). Upon coming over a couple steep mountain passes and rolling into Ashland, I noticed the engine was idling low and rough. I checked a few basics the next morning and replaced a suspect spark plug, but didn't find anything obviously wrong. We pressed on, but by the time we arrived in Redding, it was obvious that the car wasn't running right - it was down on power. I pulled one plug wire at a time at idle and realized that cyl #1 was no longer firing.
I decided to pull into an Autozone and to check the valves and do a compression check. Bad news - cyl #1 exhaust valve had zero clearance. Fearing that I had burned the valve, I adjusted clearance back to spec and checked compression - cylinder #1 was 20-30 psi lower than the neighboring #2. More bad news! The car idled noticeably better with the new valve adjustment, however, and figuring that we had little to lose by pushing forward (the valve was already burned), we continued our drive.
The car performed admirably the rest of the drive to Sacramento. I checked the valves again the next morning at the start of the rally and found #1 tight again, a few thousands under spec but not completely zero clearance. I adjusted it again. The other valves were fine the whole time.
We drove through heavy rain, snow, and quite a few mountain passes, some over 8000 ft. We took it very, very slow over the mountains, often in 3rd gear (barely keeping up with the trucks), to try to give the motor a fighting chance at surviving the drive. I adjusted the valves again that evening. Cyl #1 tight again!
We pushed on and made it to the finish line and then the 800 miles back home (another valve adjustment at a rest stop in Oregon showed that the clearance is still moving, but more slowly now.)
Aside from the exhaust valve issue, the car had essentially no issues. I tightened a rear lever shock bolt once to stop a knock, and added fluids as necessary throughout the weekend. Not bad for what was by far the longest trip this car has seen in at least 25 years. Total mileage for the trip was 2182 miles.
I'm suspecting valve seat recession is the cause for the exhaust valve problems. I'm still fairly new to Sunbeams and older cars in general and wasn't aware that this was an issue before now. I had the head rebuilt over a year ago, but didn't have the valve seats replaced. I suspect that cyl #1 seat is failing. Should I have installed hardened seats? Any other theories about what is happening? I plan to test compression again and also perform a leakdown test before pulling the head off to inspect.
I attached some photos of the drive.
Cheers and thanks to everyone who has helped us make it this far. I could not have done the rebuild myself without the help of this forum and its members.
The freshly rebuilt motor in our Alpine performed very well. We had to drive about 800 miles just to get to the starting line, and the rebuilt overdrive transmission and driveshaft from Jeff Howarth performed beautifully. (I can't imagine making a trip like that without OD.)
We split driving into 2 days and drove to Ashland, OR on day 1 (about 500 miles from home or 2/3 of the way). Upon coming over a couple steep mountain passes and rolling into Ashland, I noticed the engine was idling low and rough. I checked a few basics the next morning and replaced a suspect spark plug, but didn't find anything obviously wrong. We pressed on, but by the time we arrived in Redding, it was obvious that the car wasn't running right - it was down on power. I pulled one plug wire at a time at idle and realized that cyl #1 was no longer firing.
I decided to pull into an Autozone and to check the valves and do a compression check. Bad news - cyl #1 exhaust valve had zero clearance. Fearing that I had burned the valve, I adjusted clearance back to spec and checked compression - cylinder #1 was 20-30 psi lower than the neighboring #2. More bad news! The car idled noticeably better with the new valve adjustment, however, and figuring that we had little to lose by pushing forward (the valve was already burned), we continued our drive.
The car performed admirably the rest of the drive to Sacramento. I checked the valves again the next morning at the start of the rally and found #1 tight again, a few thousands under spec but not completely zero clearance. I adjusted it again. The other valves were fine the whole time.
We drove through heavy rain, snow, and quite a few mountain passes, some over 8000 ft. We took it very, very slow over the mountains, often in 3rd gear (barely keeping up with the trucks), to try to give the motor a fighting chance at surviving the drive. I adjusted the valves again that evening. Cyl #1 tight again!
We pushed on and made it to the finish line and then the 800 miles back home (another valve adjustment at a rest stop in Oregon showed that the clearance is still moving, but more slowly now.)
Aside from the exhaust valve issue, the car had essentially no issues. I tightened a rear lever shock bolt once to stop a knock, and added fluids as necessary throughout the weekend. Not bad for what was by far the longest trip this car has seen in at least 25 years. Total mileage for the trip was 2182 miles.
I'm suspecting valve seat recession is the cause for the exhaust valve problems. I'm still fairly new to Sunbeams and older cars in general and wasn't aware that this was an issue before now. I had the head rebuilt over a year ago, but didn't have the valve seats replaced. I suspect that cyl #1 seat is failing. Should I have installed hardened seats? Any other theories about what is happening? I plan to test compression again and also perform a leakdown test before pulling the head off to inspect.
I attached some photos of the drive.
Cheers and thanks to everyone who has helped us make it this far. I could not have done the rebuild myself without the help of this forum and its members.
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