Rotary Valve timing on White 587 Engine, one carburetor

[Superca]

The shop manuals for the 1993 GTS and 1994 GTS are providing confusing information regarding the Rotary Valve timing for the 587 engine. Both years use the same engine and same number of carburetors, but in the 1993 manual, rotary valve opening timing should be 115 degrees and in the 1994 manual it says the opening timing should be 130 degrees. I have a 1993 doo with the engine replaced (don't know year of engine), timing is at 115 degrees and it would run okay, not great, just okay. When I set the timing to 130 degrees it started but did not idle smoothly or rev up smoothly, so I set it back to 115. Can anyone explain why there are two different settings for the same engine? Is this a shop manual error.

 

[mikidymac]

I would go by what the manual says for your year. Make sure you have the correct rotary valve as they made different degree ones. You also need to use a dial indicator to find exact TDC and a degree wheel to mark the opening and closing. Even then you might have to flip the valve to get it as close as possible to your marks. Flipping the valve will change its position about 1/2 a tooth.