Link and sync, now timing... just a check through

[9758JB]

Hello. I have a 1981 johnson 70 hp and now finally getting a manual I've done the link and sync and timimg. I found top dead center with a homemade piston stop tool and found the pointer was about 2 degrees retarded from where it should of been so I adjusted and measured, and measured and measured many times to make sure it was spot on

now to warn, I read alot of post saying that not to mess with it as its probably right from the factory. And at the lake I was really testing it for confirmation. As all the post on here about not messing with it could mess up your engine kinda worry me.

I got it to the lake and going wot it was reading 16 degrees, where it should set at 19. Now I bought this motor used, and its had its little things that didnt seem right like the spark plugs had been replaced with a much smaller plug and no crush washer. Stuff like that I found so its not out of the picture that this may of been messed with.

Anyways. Just want confirmation that I've done everything right and maybe stuff to look for that could have caused an error. After getting that reading I took it home and measured tdc again, and a few more times just to be sure. Really just any insite on potential mistakes.
thank you !!!

 

[jimmbo]

How exactly did you determine TDC? Did you rotate the piston past TDC then set the Piston Stop at a point where the Piston would contact Piston. With a slight backward Rotation of the Flywheel to ensure all clearances in the Con Rod Bearings is taken up. Record the Number read on Flywheel, then without touching the Piston Stop, rotate the Engine until contact occurs again? TDC will be in the middle/center of the Two Contact points

The only way for the Timing to be off, is someone was adjusting it. That engine did not use a Taper Seat Spark Plug,, get the Correct Plugs

 

[9758JB]

Yes. Spark plugs were changed long time ago, lol

I rotated the flywheel clockwise past top dead center, put in my piston stop tool, turned it counterclockwise untill it stopped. Markied it, then turned it clockwise again until it stopped. Marked it and measured

 

[9758JB]

It was stopping about 2.5 inches on each side of top dead center