I'm helping a buddy this weekend do the cam chain tensioners on his TC88. I'm quite sure I read somewhere that when the alignment marks on the pinion and cam gears are lined up, then one of the pistons is at TDC and when the marks are completely opposite each other, the other piston is at TDC. Please confirm if that is true and if so, which piston is it in each scenario. Thanks.

 

Just line up the two marks as pointing towards each other. Every rotation of the crank is one half rotation of the cam. So every other rotation the cam timing marks are 180° out. One more rotation and they're aligned again. There's no way to screw that up as long as the timing marks are towards each other when putting the chain and sprockets on.

Keep in mind the pushrods need to be out so that you are not trying to overcome the valve spring pressure.

 

OK, but I already knew all that and you didn't really address the question.

 

Don’t believe everything you read. Follow the manual.
Line the marks up properly or get someone who can.
END OF STORY.

 

I never said I was using that reference for the actual procedure. Just asking a question. END OF STORY.

 

No. when two dots face each other that's tdc compression on the rear. The front on tdc compression the dots look like this.

 

Not sure I understand the question; are you looking for TDC or verification of cam timing? Take a look at the attached images of the relationship between pinion and rear cam sprockets at TDC for each cylinder. The first image is TDC front cylinder #2, the second image is TDC rear cylinder #1.

I don't speak for Ohio but I think what he was tellling you was that if the timing marks on the inner cam sprockets are properly aligne, the timing marks on the pinion and rear cam sprockets have to be aligned; fool proof.

 

Thank you for an actual answer.

 

I think you're right but I don't have any concerns with how that works. Was just trying to remember if there was a relationship between the marks on the sprockets of a properly timed engine to the relative position of the pistons. The question has been answered. Moving on.

 

That's the case.

Common knowledge is that the two cylinders are 45° apart. So turning the crank another 360° will put the rear piston on TDC again. You have to turn the crank 45° from rear TDC to get front TDC.