13 replies to this topic

[Volvo5.0]

OK, so It's no secret that swapping in a set of NA cams is a worthwhile mod. Not sure how much they are worth as far as performance, but there is no doubt they have more lift and duration. So obviously they're better. The best part is, they are cheap and readily available.

Questions seem to pop up on most of the "NA cam" threads concerning the gears. Are the turbo gears needed or should the NA gears be used? This is what I have found and is only my opinion, so take it for what it's worth.

Basically, all of the gears are the same. NA or turbo, AND intake and exhaust. Look it up in Vadis and you'll see. NA and turbo are the same PN and there is a no separate listing for intake or exhaust. There is a listing for the gear with the quantity needed - 2. Part number is 3531523. How could the intake and exhaust gear be the same part # and have the alignment mark in different places? It can't, obviously the new gears are NOT marked when you buy them.

What I think happens is, when the motor is assembled, the cams are locked from the rear with the special tool. The crank is locked with the special pin tool. The gears are bolted to the cams with the bolts centered in the slots in the gears, then the t-belt is installed. After the belt has been installed, THEN the gear is marked with a hammer and chisel. Actually, probably there is another Volvo "special tool" used for marking the gear.

So what does this mean for someone swapping in a set of NA cams? Personally I would use the gears that match the NA cams. You can mark them to the cams, or simply put them back on using the outline left by the 3 bolts as an index. That will be a good base setting that will be in reality VERY close factory settings. From there you can adjust cam timing if you want. Obviously Lucky/ARD has achieved good results by altering the NA cam timing, so use his recommendations.

Here are some pictures of NA gears and turbo gears, so you can see the marks are fairly random....
NA gear.....


NA gear...


Turbo gear...


Turbo gear...


Turbo gear...

[lookforjoe]

If you're buying new gears, it's a non-issue. If you're reusing existing gears, I still think you want to pay attention to the existing markings. Every set of turbo gears I've seen are like your last pic, INT notch offset, EXH centered. It only makes a difference in terms of baseline reference if one is changing the base cam settings.

[Deimos]

I'm still confused why people ever completely remove the gears from these cams, there's no need to do so, as your research proves. If you're going to use NA cams, just leave the original gears on them...

[Simply Volvo]

I'm still confused why people ever completely remove the gears from these cams, there's no need to do so, as your research proves. If you're going to use NA cams, just leave the original gears on them...

I believe they only remove the gears on the 93 na cams because those gears use a different type of timing belt so therefore so gears arnt compatible.

[Simply Volvo]

I'm still confused why people ever completely remove the gears from these cams, there's no need to do so, as your research proves. If you're going to use NA cams, just leave the original gears on them...

I believe they only remove the gears on the 93 na cams because those gears use a different type of timing belt so therefore so gears arnt compatible.

[Volvo5.0]

I'm still confused why people ever completely remove the gears from these cams, there's no need to do so, as your research proves. If you're going to use NA cams, just leave the original gears on them...

Replacing the cam seals

I believe they only remove the gears on the 93 na cams because those gears use a different type of timing belt so therefore so gears arnt compatible.

Believe it or not, the '93 gears are the same as well. I think the deal with the '93 t-belt was, Volvo used a wimpy belt. They found out quickly that the belt was not up to the task, and redesigned it.

[Simply Volvo]

Replacing the cam seals



Believe it or not, the '93 gears are the same as well. I think the deal with the '93 t-belt was, Volvo used a wimpy belt. They found out quickly that the belt was not up to the task, and redesigned it.

Oh wow didn't know that! Thanks. I remember reading somewhere that the gears on the 93 cams were different.

[ARD - Lucky]

What continues to boggle my mind is that the marking made on the cam gear is relative to the notch in the plastic cover. Not exact precise if you ask me considering the plastic covers can warp and shift. Even new manufacturing tolerances could allow for 1/2 to 1 degree of variation easily, perhaps more.

Then again I've been known to over think things a bit

[Big Will]

These gears never actually wear right? I'm just trying to figure out the purpose of a Volvo kit for a set of the gears

[lookforjoe]

What continues to boggle my mind is that the marking made on the cam gear is relative to the notch in the plastic cover. Not exact precise if you ask me considering the plastic covers can warp and shift. Even new manufacturing tolerances could allow for 1/2 to 1 degree of variation easily, perhaps more.

Then again I've been known to over think things a bit

Lucky, what was the title of the thread you created when you did the NA cam for Nick Choy? I know it was something obtuse, and I can never find it when I want to....

These gears never actually wear right? I'm just trying to figure out the purpose of a Volvo kit for a set of the gears

I would never consider buying new gears - the bolts, yes - I have replaced mine several times to be safe.

[Volvo5.0]

What continues to boggle my mind is that the marking made on the cam gear is relative to the notch in the plastic cover. Not exact precise if you ask me considering the plastic covers can warp and shift. Even new manufacturing tolerances could allow for 1/2 to 1 degree of variation easily, perhaps more.

Then again I've been known to over think things a bit

Yeah, obviously it's just a mark used as reference when installing the t-belt, so it doesn't need to be exact. Seriously doubt Volvo had any thoughts of people dialing in the cams for performance

[sconeman]

Thanks for the info Jeff. This would explain why as Hussein and others have pointed out in the past that some gears don't even have marks. .. oops forgot that one, oh well.

[Deimos]

Replacing the cam seals

Well, obviously, but I meant in the context of going to NA cams on the turbo.

[ARD - Lucky]

Here's the thread LookforJoe was referring to: http://volvospeed.co...ker free zone

Edited by ARD - Lucky, 06 June 2012 - 05:36 PM.