6G74 VS 6G72 Cams and Cam gears

[Uniuno]

There's some decent discussion related to this going on in another thread, but rather than hijack it to post info and ask questions I'm starting my own thread. I have a couple timing jobs going on right now and I'd like your input on the best configuration for them.

One is a non turbo 74 that currently has 3.0 preset (+1 - 3) cam gears. The other is a 3.0 turbo engine.

Some background on the 74, I originally put it in my turbo car (10:1 and all) and used the stock cams with preset 3.0 gears. It made great power even on 9bs and sounded amazing (throaty gargle). I then bought a built 74 (with preset 74 cam gears) for my car and put the original 74 into a NA stealth. It had bad VSS so I swapped some fresh N/A 3.0 heads onto it and left the 3.0 preset gears thinking it would be the same setup.

It was a pain to get the marks to line up but didn't think much about it because I was ignorant of the difference between the 72 and 74 gears. That car doesn't feel like it makes as much power as it should and it doesn't sound anything like it did before. Had I known about the difference I would have used the 74 gears on the 74, duh..

Ok, now for my 3.0, since I had the preset gears from the new 74 laying around I threw them on just to see how they'd go. Lo and behold, the marks don't line up (pictures to follow).

We know the cam gears are different between the 74 and 72. They are marked a half tooth off from each other. I was hoping I could throw the 74 gears on the 72 and just use the marks on the tooth rather than the valley.

Here is a stock 74 gear (conveniently marked "G74D"):

http://i491.photobucket.com/albums/rr275/uniuno/Cam%20gears/DSC_0045_zps2slqza1k.jpg (http://s491.photobucket.com/user/uniuno/media/Cam%20gears/DSC_0045_zps2slqza1k.jpg.html)

If you follow the dowel hole out from the center to the teeth you can count 6.5 teeth to the left.

Here it is next to a stock 72 gear:

http://i491.photobucket.com/albums/rr275/uniuno/Cam%20gears/DSC_0046_zpskuvwfcrf.jpg (http://s491.photobucket.com/user/uniuno/media/Cam%20gears/DSC_0046_zpskuvwfcrf.jpg.html)

Tooth count is 7 teeth to the left.

Here are preset 74 gears that seem to be marked for 74 and 72 duty:

http://i491.photobucket.com/albums/rr275/uniuno/Cam%20gears/DSC_0047_zps8kfngs3i.jpg (http://s491.photobucket.com/user/uniuno/media/Cam%20gears/DSC_0047_zps8kfngs3i.jpg.html)

The following sequence of photos were taken without moving the crank. 74 preset gears on a 72.

http://i491.photobucket.com/albums/rr275/uniuno/Cam%20gears/DSC_0058_zpsa5gpnqda.jpg (http://s491.photobucket.com/user/uniuno/media/Cam%20gears/DSC_0058_zpsa5gpnqda.jpg.html)

Rear bank:

http://i491.photobucket.com/albums/rr275/uniuno/Cam%20gears/DSC_0059_zpskrsxwxtj.jpg (http://s491.photobucket.com/user/uniuno/media/Cam%20gears/DSC_0059_zpskrsxwxtj.jpg.html)

Front bank:

http://i491.photobucket.com/albums/rr275/uniuno/Cam%20gears/DSC_0060_zpsuwdhtzk0.jpg (http://s491.photobucket.com/user/uniuno/media/Cam%20gears/DSC_0060_zpsuwdhtzk0.jpg.html)


I find it odd that the front bank lines up perfectly with 3.0 marks while the rear bank lines up perfectly with the 3.5 marks.

I called my buddy with the 74 with 72 gears to drop his car off tonight. I plan on putting the 74 cams in it but I'm not sure what gears to use. Do the NA engines benefit from the +1 -3 setting? I'll take the gears off his and put on mine and use either the preset 74 gears on his or the stock ones, whichever make the most power.

Are there any pictures of anything people want to see while I'm at it?

[RealMcCoy]

In the above pic, I think your rear cams are off a tooth... I suspect it's being masked by the fact that the crankshaft is lined up slightly past TDC.

The gears with both sets of marks should work equally as well on either motor, you just need to use the correct mark.

The preset gears on a 74 are going to net 5 degrees total cam retard... Stock, the 72 has .75 degrees, the 74 has 3 degrees. That sounds a little extreme to me, but only dyno numbers will tell if it actually helps or not.

*Edit*: Those numbers are assuming the 74 has the same cam profile as the 72, as is the case on the Debonair FWD engine. ASA says the Montero uses a different exhaust cam, and I have no specs on that one...

[Uniuno]

What a pain it is to get these pictures with the engine in the car..

3.0 gears on a 3.5:

http://i491.photobucket.com/albums/rr275/uniuno/Cam%20gears/DSC_0303_zpsdtqrlkqu.jpg (http://s491.photobucket.com/user/uniuno/media/Cam%20gears/DSC_0303_zpsdtqrlkqu.jpg.html)

Rear bank:

http://i491.photobucket.com/albums/rr275/uniuno/Cam%20gears/DSC_0304_zps6smvtuhv.jpg (http://s491.photobucket.com/user/uniuno/media/Cam%20gears/DSC_0304_zps6smvtuhv.jpg.html)

Front bank:

http://i491.photobucket.com/albums/rr275/uniuno/Cam%20gears/DSC_0305_zpsc8fujtfq.jpg (http://s491.photobucket.com/user/uniuno/media/Cam%20gears/DSC_0305_zpsc8fujtfq.jpg.html)

Everything is lined up the same as if it has 3.5L gears, pointing at the valleys. I was contemplating not making any changes and leaving the gears where they are. Then I looked at the markings on the cams, the intake is marked with a "P" and the exhaust is marked with a "K".

According to the Ninja's site; "K" is a normal marking for a 2g NA cam. The "P" isn't listed. Does anyone know anything about this?

Ninja Performance Camshaft Specs (http://www.ninjaperformance.com/camshaftidentification.php)