Cam advance on a L20B

[MF720]

I have come across a couple of mentions that there is 3 settings on the cam and that it is set at the middle for emissions. Is this true and if so what needs to be done to make this adjustment. Last but not least is it worth it? No real reason for me to do this but I sure want to just because it has peaked my curiosity.

[ggzilla]

Advancing the cam lowers the RPM band. So yes, it theoretically would make more power at low RPMs, but less power at peak RPM.

 

Here's what Car Craft magazine says:

Advancing the camshaft means that you are starting the opening and closing process sooner in the cycle. It generally improves low-speed torque and mid-range power while sacrificing top-end hp.

 

To use those three settings, you retime the engine (loosen the chain, and unbolt the sprocket, move it to the new hole and time it again).

[Logical1]

Advancing the cam lowers the RPM band. So yes, it theoretically would make more power at low RPMs, but less power at peak RPM.

 

Here's what Car Craft magazine says:

 

 

To use those three settings, you retime the engine (loosen the chain, and unbolt the sprocket, move it to the new hole and time it again).

 

Text Book Perfect Answer, +1

[ggzilla]

Now if only someone who has actually done it to L20B can tell us what difference it made...

[MF720]

Now if only someone who has actually done it to L20B can tell us what difference it made...

 

 

I was thinking that I might have to readjust the valves also? Still on the fence but want to try it. I don't really do much freeway driving and not putting it on a track so it would be nice to get up to speed now that sounds like my driving style.

[ggzilla]

Don't need to readjust the valves, as you are not changing the cam profile. That is no need unless you haven't done your yearly valve adjustment.

[DISLEXICDIME]

If you advance it to 3 with out neading it the rpm's will brake up after 4600-5000 ish it sucks.

[Sealik]

Now if only someone who has actually done it to L20B can tell us what difference it made...

 

Done it to a LZ23 and Z24.

Noticed both trucks could climb hills a little better without the usual drop in RPM and speed

New engine....so I haven't had it over 5 grand.....pulled strong up to that point though.

 

HRH has also advanced his cam I believe

[datzenmike]

To use those three settings, you retime the engine (loosen the chain, and unbolt the sprocket, move it to the new hole and time it again).

 

 

I would add that if you are not familiar with the L series timing chain you should research this carefully. The chain has a spring loaded tensioner that WILL pop out if you remove the sprocket and allow the chain to go slack. You need a wooden wedge driven in there to hold it in place. Failure to properly restrain the tensioner will result in having to remove the rad, crank pulley, oil pump and spindle and timing cover to get at and retrieve it and put it back. This should be avoided at all costs.