Car won't start but does sputter - carb problem?

[tbirdman]

Well I'm stuckin the house with about a foot of snow that fell yesterday so can't go out looking for a compression gauge.

[Friartuck]

Ken,

Since you have to make or find an adapter for the compression gauge, might I suggest you also set it up to do a leak down test. Pressurize the cylinder to about 60 pounds for that vintage and with a valve in the supply side, monitor how fast that pressure drops, with and without some oil in the cylinders. Will tell you health of the valves, rings, priming cups, etc.

[Richard Lichtfel]

I had a similar problem with my Mason. We tried everything but couldn't get it to go. We finally pulled the exhaust system and found that a mouse had built a nest in the muffler and it had broken loose and plugged the outlet. We cleaned it out and it started right off.

[tbirdman]

Making progress. Removed the carb and held a gas soaked rag up to the intake. It was sucking in gas and did fire. When we removed the rag, we noticed that gas was dripping out of the intake. Tried firing then and it caught and ran for a few seconds. Seems like me I got an issue with the carb.

[tbirdman]

It runs! First I readjusted the float level. It appear the guy who worked on the carb set it way to low according to my measurements that it should be 1/16-1/32 from the top of the casting to the float body. I took off the carb and adjusted the throttle valve set screw. The valve appeared to be shut all the way at rest. It started but idle was way to fast. Shut it down, readjusted the set screw and restarted it again. It again was idlling way to fast. However it did start and was running strong with no smoke or odd sounds. I figured that was a small enough victory to quit for the evening.

Hopefully I can get it to run at a decent idle and then see if I can find any other vacuum leaks or other issues.

[keiser31]

Congrats!!! It's a great feeling to hear them come to life.

[tbirdman]

Well I'm not out of the woods yet, as I need to work on getting the carb adjusted, but it is a relief to hear it run. It looks like nothing major is wrong.

I've learn quite a bit in the past months trying to troubleshoot the problem and I am very stubborn not wanting to send it somewhere to get it worked on. I almost feel that I've taken a semester course in auto mechanics. We'll see if I can pass the final exam

[tbirdman]

OK I think I have found the root cause. The pin holding the camshaft gear was sheared. However the gear was on there just tight enough that the gear would turn and then because of the valve spring pressure the camshaft would catch up. This was causing the snapping of the valves as the lobes were not moving smooth.

Everything I was doing was pointing towards the camshaft being the problem. Two weeks ago, for some unknown reason, the valves stopped snapping. Slowing turning the engine over by hand, I observed the valve timing and it appeared to be correct. I tried to start the engine and the snapping returned. Then I slowly again cranked the engine over and the valve timing it was way off with the exhaust closing and the intake opening not close to each other and the intake open occurring pretty far away from TDC. So I had low compression, valve timing was incorrect and it appeared the camshaft was not moving smoothly. Also the distributor on the left was moving smoothly which told me all of the gears from the crankshaft out to the left side of the engine were ok including the crankshaft gear. Also the ignition timing on the distributor was always dead on. Looking at the distributor on the right which was moving smoothly, told me that the crankshaft and camshaft gear were both engaged, but because of the jerky movement of the tappets, it indicated that the camshaft was slipping on the camshaft gear.

I though I was going to have to remove the camshaft to see and fix the problem. To remove the camshaft you need to remove the engine. So Saturday we took one last look at everything. We observed after removing the side covers from the engine, the jerky motion of the camshaft. Removing the timing cover it appeared everything was intact, but by closely observing the camshaft and the gear, you could see the slippage and then catching up. Because the gear didn't break clean of the shaft and just spin, it gave the odd motion which led to the snapping valves.

If it had broken free I would had found this quicker. Also the last time I had the timing cover off, we were not observant enough, and I was convinced to button it up and go back to the basics.

Luckily we were able to remove the camshaft gear without removing the camshaft. I should be able to replace the taper pin which are now on order. I hope this is the problem, and I should be running by next weekend.

[hchris]

Well done that is a freaky one, not many of us would have solved it for you.

I would have expected the cam gear to be at least keyed on the shaft as their is obviously quite a load as each cam lobe works against valve spring tension ?

Chris H

[tbirdman]

From my research. taper pins were quite common to install gears on shaft. I didn't even know what ataper pin was before someone told me that is what was type of pin needed.

[tbirdman]

Well turns out we apparently had screwed up the carb on the way to fixing the problem. After I got everything back together, all I could get was a backfire. I know everyone was saying your distributor 180 dgrees out. But I double checked everything. Even went as far as laid out all of the spargplugs on the block and slowly handcranked the engine to observe the spark and timing withthe valves. Everything seem correct. In fact one backfire caught some gas on fire on the floor that had dripped from the flooded carb. Can you say excitement? Anyway I put on a carb that someone had sent me. The car started right up. So I sent my carb to him about three weeks and just got back today. The car starts.

So now I need to wait for dry weather to push the car onto the driveway to adjust things as the tail pipe is stick in the garage the wrong way