Hi All,
New here but I've done a lot of lurking and reading on this forum, so it's much appreciated. I'm stumped on this one so thought I'd get some outside advice.
Initially I found that the hole for the sync screw on the third carb was stripped and screw/spring was missing. Because hole was stripped I had to invent a solution, but I did and it works. I was then able to balance the carburetors however I never could quite get the vacuum on the cylinder 1-3 as low as that of the 4th cylinder (bottom/lead cylinder), but I was able to get 1-3 even and only slightly higher than 4. So the engine would start and idle smooth, but the engine was still falling on it's face under load. I found that the o-ring on the fuel filter housing was inadequate and there was a huge vacuum leak. I replaced that o-ring and since then, the engine starts easy, idles smooth, and throttles up decently smooth.
BUT I still couldn't get the lead cylinder synced, and investigating further, I was able to establish that the cylinder has spark but doesn't appear to be firing. I did a whole bunch of swapping of coils, leads, and plugs (even put in new plugs) to establish that the problem never moves, so I'm satisfied that it is NOT a spark issue. Regardless of what I did, if you pull the plug wire or adjust the pilot screw on this cylinder while the engine is running, nothing happens, but it definitely does for any of the other three cylinders 1-3. There is periodically a lot of un-burned fuel in the exhaust, and when you pull the plug for that 4th cylinder (the bottom one) the plug is heavily fouled and wet with what smells like fuel. I also rented a compression tester, and all four cylinders were 110# +/- 5# so that seems fine. Not at all sure what to do next.
It seems like the options are the cylinder is being flooded with fuel, either due to carb or enrichener issue. Or it's getting flooded with water due to leaky head gasket, although again compression looked ok.
Thoughts?
Sconi
New here but I've done a lot of lurking and reading on this forum, so it's much appreciated. I'm stumped on this one so thought I'd get some outside advice.
Initially I found that the hole for the sync screw on the third carb was stripped and screw/spring was missing. Because hole was stripped I had to invent a solution, but I did and it works. I was then able to balance the carburetors however I never could quite get the vacuum on the cylinder 1-3 as low as that of the 4th cylinder (bottom/lead cylinder), but I was able to get 1-3 even and only slightly higher than 4. So the engine would start and idle smooth, but the engine was still falling on it's face under load. I found that the o-ring on the fuel filter housing was inadequate and there was a huge vacuum leak. I replaced that o-ring and since then, the engine starts easy, idles smooth, and throttles up decently smooth.
BUT I still couldn't get the lead cylinder synced, and investigating further, I was able to establish that the cylinder has spark but doesn't appear to be firing. I did a whole bunch of swapping of coils, leads, and plugs (even put in new plugs) to establish that the problem never moves, so I'm satisfied that it is NOT a spark issue. Regardless of what I did, if you pull the plug wire or adjust the pilot screw on this cylinder while the engine is running, nothing happens, but it definitely does for any of the other three cylinders 1-3. There is periodically a lot of un-burned fuel in the exhaust, and when you pull the plug for that 4th cylinder (the bottom one) the plug is heavily fouled and wet with what smells like fuel. I also rented a compression tester, and all four cylinders were 110# +/- 5# so that seems fine. Not at all sure what to do next.
It seems like the options are the cylinder is being flooded with fuel, either due to carb or enrichener issue. Or it's getting flooded with water due to leaky head gasket, although again compression looked ok.
Thoughts?
Sconi