12 replies to this topic

[Madmax]

Hey guys!

I have searched the forum for about a day now with no luck finding any decent cam timing guides in laymans terms.

I have a DTI & stand, with timing disc and know basically how to use them, but does anyone have 2 seconds to just write a quick step by step 1,2,3,4 etc guide on the process with any handy hints or tips along the way just so i dont get tripped up!

Hopefully this will benefit many others along with myself.

I have an original SW5 and vernier duplex timing gears.

Really appreciate the advice

cheers

James

[Guess-Works.com]

There is one somewhere, wrote it about 4 or 5 years ago....

[Guess-Works.com]

Ta da....

http://www.theminifo...x...ic=3781&hl=

[Madmax]

GW you are officially a legend... that post was from when i was a regular on here so i cant believe i missed that haha

cheers mate!

[Pauly]

Dont you have to take into account the slight dweel ontop of the cam lobes??

Paul.

[dklawson]

Dont you have to take into account the slight dweel ontop of the cam lobes??
Paul.

Yes. You're supposed to.

Take John's instructions in the other thread and add the following steps both for locking in TDC and when looking for the max lift on the cam lobes.

With the DTI set up, turn the engine over watching for the DTI to reach its maximum value. Set the DTI to zero.
Now turn the engine BACK through perhaps 10 degrees and slowly turn it forwards, watching the DTI and stopping when it displays about 0.010" from the its zero position. Now look at the degree wheel and write the number down. Keep turning the engine forward until the DTI now shows 0.010" on the "other side" of its zero. Again, stop and record the degree wheel position. Repeat this at least 4 times (before and after the DTI zero). Average the numbers. That "average" number will be where the max lift point is, it will be the middle of the dwell you mentioned.

If you don't have a degree wheel, see here:
http://home.mindspri...egreeWheel2.pdf

[Madmax]

i printed one of your degree wheels out last time i attempted it DK, much appreciated

[Guess-Works.com]

I printed one onto a printable CD, almost the perfect size for the timing bolt

Here I could do them again with loads of advertising material on... he he

I digress, yes DK's right ( I'm surprised I didn't put that in the post but it was a brief summary ), to position accurately you should go either side of the LCA by a measured amount using the DTI as a guide and then averaging the two angles to get the actual LCA.

[Pauly]

Dont you have to take into account the slight dweel ontop of the cam lobes??
Paul.

Yes. You're supposed to.

Take John's instructions in the other thread and add the following steps both for locking in TDC and when looking for the max lift on the cam lobes.

With the DTI set up, turn the engine over watching for the DTI to reach its maximum value. Set the DTI to zero.
Now turn the engine BACK through perhaps 10 degrees and slowly turn it forwards, watching the DTI and stopping when it displays about 0.010" from the its zero position. Now look at the degree wheel and write the number down. Keep turning the engine forward until the DTI now shows 0.010" on the "other side" of its zero. Again, stop and record the degree wheel position. Repeat this at least 4 times (before and after the DTI zero). Average the numbers. That "average" number will be where the max lift point is, it will be the middle of the dwell you mentioned.

If you don't have a degree wheel, see here:
http://home.mindspri...egreeWheel2.pdf

Does it explain that method in the haynes?

Also does it have to be 0.010" could be any number as long as you stop on it on both sides?

Paul.

Edited by Pauly, 09 November 2009 - 06:03 PM.

[liirge]

Your also meant to take into account of the slight stretch in the chain (even in duplex chains) after a while.

Edited by liirge, 09 November 2009 - 06:05 PM.

[Madmax]

good relevant comment ref the chain stretch, this is why i was going to set it 2 degrees out from the recommended to allow for this

2 degrees sound about right?

[liirge]

good relevant comment ref the chain stretch, this is why i was going to set it 2 degrees out from the recommended to allow for this

2 degrees sound about right?

That seems excessive to me, i'l get back to you in a min or two with a rough idea, cant remember what i usually set them to

[dklawson]

I have also been told to set the cam about 2 degrees more advanced to allow for chain stretch. However, I didn't do that on my car... I learned about it too late.

The 0.010" number isn't magic, you can use a different value. The important thing is to keep it the same value each side of the apparent zero point. However, you want to keep the value fairly small on the cam lift. The reason to handle the cam a bit differently is due to some cams having an asymmetric profile (different ramp angles into and out of the max lift point). The smaller the increment before and after the DTI reaches zero, the closer you will be to a "real" value for the cam angle.