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saw this on mod-depot

mike tymensky put up a pretty good post in response to a guys question, here is the reply:

1) Pay ZERO attention to the "Advertised Duration"! It will only confuse you more than you already are.

2) You MUST degree the exhaust cam first! If not, you will/could cause yourself serious or even damage to your engine!

The duration #'s that you need to pay attention to are the 228° @ .050" lift.

1) Remove the follower from the intake valve.

2) Install your L/A and Follower on the exhaust valve.

3) Set your Timing gear to the "0" position.

4) Take a wrench and position it on the flats on the cam and lightly maintain CCW pressure so you remove all slop from the timing gear assembly and torque the cam bolt to 25 ft #'s. (The Mod-Camponents timing gears can have as much as 6°-8° of free play that will cause your timing #'s to be skewed).

5) Set-up your dial indicator on your valve and zero your indicator on the cam base circle. You will be reading your timing positions @ .050"lift. Start by having your crank position atleast 60° before the valve begins to open (this will remove all areas of slop in the timing assy. Rotate the the engine slowly untill the valve lift reaches .050" lift. STOP! Note your timing position on the crank wheel. How far is it from your cam card specs? In your case it should be @ 52° BBDC ± 1°-2°(Before Bottom Dead Center). If you are not in that range Do not continue rotating the crank! If you are at say 61° BBDC that means your cam is 9° advanced. This will require you to retard the cam the 9°. Slowly back the crank up till the cam is back on base circle. Loosen your cam bolt and remove the washer. Put a wrench on the cam flats and pull the pin out of the timing gear. Put the pin in the corresponding hole for the direction you need to move the cam, the rotate the cam till the pin falls into place. (Retard= rotate the cam CCW, Advance= rotate the cam CW). Once you have repositioned the cam restart this procedure.

6) Once you get the opening timing to the acceptable range you can then procede to the closing event. Rotate the crank thru peak lift and back down till your valve is @ .050" lift before closing. Note you results. Do this procedure until you get the required specs. Once you have completed this and have the results that you want. Torque the cam bolt to spec and move to the intake cam and start the whole process over.

The intake side is much more prone to PTV contact. Once you have completed this on the one bank, you can then move to the second bank and restart the entire process.

This is a very tedious and time consuming process.

Have fun.


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Michael Tymensky


and the link to the thread: http://forums.modulardepot.com/showthread.php?s=&postid=624680#post624680
 

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4-valve tech, but THAT's what I call DAMN fine tech. Nice link.
 
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