I feel probably two separate issues. Engine is a Robin 244:
-Recently rebuilt (top and bottom)
-Converted to HEI ignition with new pulse coil
-Using Amsoil at about 80 to 1
-Governed down to well below the max recommended RPM
-The throttle/start limit are adjusted correctly with the proper spring on the cable
After it warms up good it has a knock at full throttle. Not a constant knock and it seems to change between engine loaded and unloaded (like if coasting down a hill). Hard to explain but it sounds like valve clatter. It did it before I rebuilt it but much worse. Seems I adjusted the governor to a lower RPM is maybe why not as bad now?
If the timing was causing a knock, would it be from being too far advanced or retarded?
Anything else that might cause the knock?
The other problem I have is that it blows the engine side diaphragm out of the fuel pump quite often. It will be OK for a while then out of the blue it will blow. It back fires occasionally but not continually. This weekend it seemed to blow before the engine even fired off. After I replaced the diaphragm it backfired a time or two but never blew again.
If timing was causing a backfire that blows the engine side diaphragm on the fuel pump, would it be from being too far advanced or retarded?
Any other reasons I might be blowing that fuel pump diaphragm?
I would rather fix the issue if there is one but is there any other options for fuel delivery on this thing other than raising the tank for a gravity feed (elec pump maybe)?
-Recently rebuilt (top and bottom)
-Converted to HEI ignition with new pulse coil
-Using Amsoil at about 80 to 1
-Governed down to well below the max recommended RPM
-The throttle/start limit are adjusted correctly with the proper spring on the cable
After it warms up good it has a knock at full throttle. Not a constant knock and it seems to change between engine loaded and unloaded (like if coasting down a hill). Hard to explain but it sounds like valve clatter. It did it before I rebuilt it but much worse. Seems I adjusted the governor to a lower RPM is maybe why not as bad now?
If the timing was causing a knock, would it be from being too far advanced or retarded?
Anything else that might cause the knock?
The other problem I have is that it blows the engine side diaphragm out of the fuel pump quite often. It will be OK for a while then out of the blue it will blow. It back fires occasionally but not continually. This weekend it seemed to blow before the engine even fired off. After I replaced the diaphragm it backfired a time or two but never blew again.
If timing was causing a backfire that blows the engine side diaphragm on the fuel pump, would it be from being too far advanced or retarded?
Any other reasons I might be blowing that fuel pump diaphragm?
I would rather fix the issue if there is one but is there any other options for fuel delivery on this thing other than raising the tank for a gravity feed (elec pump maybe)?