Why TDC on belt change

Steve, I suppose you really don't have to align the markers as long as none of the pulley/gears move when removing the old belt

and it stay exactly where they are when installing the new belt.

 

I don't think you need to if all you're doing is swaping belts. You'd just need to mark each pulley (all three per bank) with a corresponding mark to the old belt, then accurately transfer the mark on the old belt to the new belt, install new belt by matching up the marks, release tensioner, hand turn 2-3 revolutions just to be sure valves and pistons are not playing tag, tighten tensioner, button up. I think the TDC thing is important to see where your cam marks line up and if you're going to degree the cams.

Having said all that I TDC'd mine when I changed them.

 

I have a chain, but if I was doing a 7 year belt change (like I would if I had such a car) I'd also be checking the cam timing just to be thorough. So as a matter of course I'd have the #1 cylinder at TDC on the power stroke before I dug in. If you do 3 year changes I seriously doubt you need to worry about it every time. Like valve clearances....check them, but a broken in engine will not need adjustments every 3-5 years, or more. Mine were spot on after 7 years....YMMV but probably not.

Ken

 

Steve,

I think the real issue is what do you do if one or more of the cams move while you are doing the job? If you don't have the flywheel and pistons at TDC/compression stroke, you have no prayer of realigning everything quickly and easily. Having the engine at TDC/compression allows you in a pinch to reset the cams based on the factory marks and then go from there. IMHO, taking a chance and depending on the cam lock as your only backup is taking a big chance. I'd rather have the engine set in the right position and know that if I have a problem, I can easily fix it.

Regards,
Steve

 

Why would you not want to do the full job?

check valve clearances tensions etc. etc. Seems just freezing the cams for a belt change with engine out isn't worth it on a 348 [sorry, but the Mondial T is always stuck in the Mondial section when it should always be included in the 348 section].

 

Ah, "engine out". That's a whole different ballgame!

Ken

 

I know, but like I said, when the Mondial T is in a lump with ALL 70-80's Mondials then I have no choice: Mondial T's are to be in the 348 section period.

They have more in common with a 348 in mechanics, suspension, trany, even some interior than older 3x8 or [non T] Mondials.

but I dribble on such......

Still wondering why someone might not want to check all components while belt was off, to make sure. Or is the goal only to rely that all is well, and replace the belt.

 

I agree.

 

+1. When I had my 308 engine out, I did the whole thing. If I just wanted to change the belts with the engine still in the car, I'd use the cam lock. With the engine out, it is silly not to do the whole job.

 

The valves just don't need adjustment that often. Since most of us don't drive anywhere near enough to need to check the valve clearance at every belt change, it doesn't make sense to tear open an engine that isn't leaking and doesn't need cam seals and cam cover gaskets, etc. just because the belt is due for a change due to age. As long as you know your timing is right and valves were checked during a previous major not too long ago, I see no reason not to just do the belt change. It's better than NOT doing the belt change!

Birdman