TB discovered to be almost one tooth off perfect.

[txtorquemade]

For setting the tensioner you leave it loose as you rotate the crank 2 turns until you are on the marks again without rotating back and then tighten the tensioner, the spring sets the tension.

\

Since I did that, things should be good, yes?

[Rigmaster]

SUCCESS !!

The timing marks when I torqued the tensioner bolts were almost spot on. The crank dead on with the cam exactly in the valley next to dead on, but not onto the next tooth.

Sound about right? Anyone?

hmm, hate to say it, but it sounds like it might still be off a bit.


Every time I've done this (probably 10-12 times), if the belt is on correctly, the marks are dead nuts on both crank and cam.


Did you have the head shaved (milled) down?? I guess if the head was milled a bit that could throw the mark off by a hair, but otherwise it should be spot on.


Not saying it's not right, but this is something you want to make damn sure it's right before you put it all back together (I know, right???).......

;)

[SCapelo]

I say it sounds about right, a tooth off would make quite a bit of difference on those timing marks - a hair off should be fine. Like I said this was my first m20 TB as well and it worked out perfectly for me. And yes, I forgot to mention the spring loaded tensioner already places the correct amount of tension on the belt, all thats needed is to tighten the bolt once the spring and pin are mounted up (for future reference.)
Luckily I had my m20 out on an engine stand while doing this so it was MUCH much easier hahaha.

Start her up :up:

[nando]

each tooth is 7.5 cam degrees. that would make a HUGE difference in how the engine runs. An adjustable cam gear, for reference, shouldn't be adjusted more than about 2 degrees.

[txtorquemade]

Ok, well that sounds not so good.

I have the covers and dist/cap reinstalled. Can I mount the alternator and start the car briefly to check it out. How it's running, etc? Rather than mounting up the AC and PS too? Obviously, no coolant is in currently in the block.

If I do have to take the belt off again.... (I'd rather slam my *ick in a car door) how can I adjust the cam sprocket to end up dead on? Rotate it a tooth counter-clockwise, or clockwise?

Thanks for the truth and advice guys. I do want to get this right.

[nando]

no, what I'm saying is, if it was one full tooth off, you'd definitely know. if the car ran at all (that is to say, you don't bend a valve immediately), it's going to run really, really bad.

I've never had both of the lines line up exactly, more than likely your head has been machined at some point (mine has). if it's a hair off, that's fine, one full tooth off and then you start worrying. and if it's a hair off chances are that's as good as you can get, because there's nothing adjustable about the stock cam gear.

[txtorquemade]

Nando, so I should maybe just button up and give it a try? Im going to verify the amount its off. I will borrow a cam ( mines dead ) and post up a pic of how out it is tonight when I get home. If you might could check back then friend, I'd sure appreciate your time. As I always do.

I doubt this head has been milled, or serviced in any way from the amount of funk all about it. So I doubt that is the case, but I suppose I could be wrong.

[nando]

take a pic of the cam wheel with the crank lined up at TDC.

it's pretty easy to tell how many degrees it's off. From the center line of one tooth to the next, it's 7.5 degrees. 2 degrees off isn't ideal (it will shift your peak torque up or down) but it will work. 3 or 4 degrees or more, and you start having issues.

[txtorquemade]

Crank mark



Cam mark - straight on



Cam mark - Different angle. I think the picture angle is off on this one. The above was more dead on straight in the same axis as the marks, cam line, etc. This look fooled me last night. Looking at the above pic, seems I'm a tooth off.

Right?

Waiting on verification. Im planning on pulling belt and turning the cam gear 1-1.5 teeth CLOCKWISE from the mark on the head. Does this sound correct, to correct for the slippage when I popped the belt on?

[txtorquemade]

Ok....

Working off of commonsense and absolute certainty I was off one tooth I removed the belt. Advanced the cam gear clockwise 2 teeth, leaving it one tooth to the clockwise side of straight up 12noon on the head mark. Popped belt back on with the weirdass way described above and......viola. Dead solid perfect on both marks after 3 full revolutions of the cam gear.

I noticed a slip/pop "feel" when I was repositioning the belt from the inside/under the crank gear. I think, a tooth was bound up or not seated under there and it finally seated and the tension on the top part of the belt from cam to Intermed gear tightened up nicely.

All thats left now is buttoning up and installing my new radiator.

I think Im good. But Im going to post up some pics of my FINAL timing mark positions after torquing down the tensioner.

Thanks for all the assistance. Stay tuned for pics of SUCCESS!!

(yeah, Im being all dramatic... but damn, its my first time)

[txtorquemade]

Finally... got it to line up!!!

From SCalvato

I recently did my first m20 TB as well. I tried a couple different ways and finally ended up going this route.
- Line up Cam and Crank Gears to the marks
- Leave tensioner off
- Put on the TB on all gears MINUS the tensioner
- Put the pin on the tensioner and slide it into place with the bolt ready to get it in place
- Once I got the tensioner up and against the TB I left it loose then used a prybar to put the most possible tension on it to slide the tensioner spring onto the pin.
- Allow it to self adjust with the spring
- Tighten everything down
- Spin the crank 2 times over (1 complete revolution) and match up your marks for Cam and Crank

After removing the belt, again.... I followed the above steps...again, and the following are the final timing marks. I torqued the tensioner bolt, after 2 full revolutions.

I'd say, perfect....finally. Now to button it up tomorrow. Or, maybe by the weekend. Still lots to do!!

http://www.r3vlimited.com/board/attachment.php?attachmentid=36396&stc=1&d=1293685042

http://www.r3vlimited.com/board/attachment.php?attachmentid=36396&stc=1&d=1293684885

[Rigmaster]

Yeah, that first set of pics shows it 1 tooth off, the last post looks dead on.


Crank her up!!!!!!!


;)

[SCapelo]

From SCalvato

If I was hispanic...
Haha looks good.

[txtorquemade]

If I was hispanic...
Haha looks good.

ah. c r a p...well, I was close.

thanks for the advice friend!!

M

[recall]

Looks like you're all fixed up. Nice! Completing it the first time gives you a sense of accomplishment.

Here's how the cam mark sat when I got my car (I changed the TB within a couple hundred miles of getting it) while the crank was at TDC.



The car ran without issues like nando described. I fixed it so they were dead on, but I don't notice much of a difference now. How's that happen?