|Backfiring when transmission engaged ...
|Posted on Tuesday, March 27, 2007 - 12:27 am: ||
Well, with the new sailing season fast upon us, I decided to get serious about getting my P-60 running reliably again. Based on the great feedback from this group, I started by replacing Spark Plugs, Distributor Cap, and Rotor. Checking the plugs and distributor cap, I quickly found the plugs for cylinders 1,2, and 3 in terrible condition but the #4 plug looks almost new. The connection for the #4 cylinder plug on the distributor cap was totally corroded. All the rest were in reasonably good condition though. Any ideas as to why something like this might happen would be appreciated.
I have the Prestolite Distributor.
I used the following parts from NAPA and thought someone here might find the info useful:
NAPA AL133 - Distributor Cap
NAPA AL134 - Rotor
The rotor looks a little different than the one which was in my distributor previously but after doing some cross referencing and talking with the great guys at my local NAPA store, we came to the conclusion that the AL134 should work for my purposes. It does :=)
The next step was to replace the Spark Plugs. I was using Champion D15Y plugs last year. No one in the local area had those in stock this time around but my friendly Kragen parts guy suggested the Autolite 3116 as a possible alternative. These worked just fine too.
Finally, I was having a problem with a sticking valve in the #4 cylinder. I was able to access it via the spark plug hole and just push it down. After doing that, the engine started right up and seems to be running fine again though I am getting some backfiring occasionally. I notice the backfiring much more frequently when running the engine with the transmission engaged in the forward direction. The engine seems to run much more powerfully and smoother for some reason when the transmission is engaged in the revers direction. Any ideas as to what might cause something like this?
Is there an easy way to access the rocker arms and push rods in this engine? I am pretty new to working with engines but have been told that most engines have a valve cover plate that can be removed to provide access to the rocker arms without having to disassemble the engine.
Do you have an "exploded" diagram of the engine so that I can get a sense for what and where things are inside and how to best access them?
Post Number: 166
|Posted on Tuesday, March 27, 2007 - 08:57 am: ||
What color was the inside of the bad plugs? What did you use as a reference for your getting your cap and rotor? I have cap AL 134, rotor AL 150. Spark plug Autolite 3116 is industrial not marine as is Champion D15Y. Difference is the Champion is more corrosion resistant but the Autolites are cheaper and will run fine. Always use anti-sieze on the threads of plugs when installing them.
Are you sure that it is backfiring or is it misfiring (cutting out)?
The engine is a flathead. The valves ride directly on the camshaft. There is no rocker arm. There are valve cover plates on the starboard side of the engine block beneath the intake and exaust manafolds.
I have a Palmer P-60 engine manual and an IH tractor manual but Andrew sells both but I agreed not send repos from mine out of respect for his generous free use of this board.
Post Number: 25
|Posted on Tuesday, March 27, 2007 - 09:14 am: ||
Any time the engine runs better in reverse than forwards, I suspect that it is not firing on all cylinders. Forward is 1:1 while reverse is 1:1.3, so the higher gearing in forward loads the engine harder and makes any such problem far more apparent.
I am not an expert, but my first guess is that the valve is still sticking, and that you are getting no/partial/intermittent compbustion on that cylinder.
If the cylinder is not firing, and unburned gas is getting into the exhaust manifold, I can certainly imagine you getting backfires from the hot exhaust in the other cylinders!
What kind of prop are you using, and what is your rpm at full throttle in forward?
As odd as it sounds, you can sometimes free up valves in an engine like this with a dose of Marvel Mystery Oil on the valve head and stem, followed by revving the engine.
As well as the P-60 resources you find, you should also check out Moyer Marine. The A-4 is also a 60cid flat head, and many of the running quirks are common to the two engines, as are many of the ancilary engine parts (like the transmission, fuel pump, carb, thermostat etc.).
Richard A. Day Jr.
Post Number: 485
|Posted on Tuesday, March 27, 2007 - 09:55 am: ||
My concern is why is the valve sticking. I suspect water may be getting into the exhaust line from a rust through near the aft cylinder. Any sign of moisture on the spark plug?
Post Number: 26
|Posted on Tuesday, March 27, 2007 - 10:39 am: ||
I'd also consider a blown head gasket (not that a big deal with a P-60 - so long as you get a saltwater gasket).
Finally, I'd also check to make sure I have good spark in that cylinder.