Adjusting cam gear

[Travis Grant]

Hey guys. I'm looking at adjusting my cam gears a little. Cams were installed straight up at 0 tdc on the crank. Am I safe to adjust the cam gears 2^ retard or advance without a degreeing wheel on the crank. I've done some research and from what I understand they can be adjusted on the gears a minor amount without worrying about any damage due to piston contact. I Just want to get some opinions from somebody who has experience with this. Thanks !

 

[miliman13]

Possibly! assuming: many variables.
But the practical answer is NO .

Do it right or not at all. You have to measure ptv clearance a few degrees before and after tdc. And it won't be easy.

Lazy way will include a travel gauge and a Chrysler rocker removal tool.
Even then it won't be very accurate.


You first ensure you can in fact swing past tdc on the cam, while you degree; on the stand.



But since it sounds like you really want to..... aluminum pistons have deeper valve reliefs. If you don't have said pistons, then good luck.

 

[Kapok6]

http://my.prostreetonline.com/2013/08/16/how-to-tune-your-4g63-cam-gears/

 

[Travis Grant]

Thanks for the reply guys. so hypothetically speaking I have Manley pistons and eagle rods, 280 bc cams and their valves retainers etc, if I was to check valve clearance on a stand with clay, their would be a possibility that if a camshaft was degreed 1 in the advance direction that it could cause piston to valve contact. I guess I was under the impression if the cams were installed at 0 in relation to the crank there would be clearance left and right relative to the centre of the camshaft. I'm just trying to understand this a little more in depth .i have seen that kapok6 but thats what led me to believe they are adjustable "up to 4 degrees"

 

[miliman13]

Ok. No clay.
You use a travel gauge to check for example 15° 12° 8° 4° 2° before and after tdc.
Your tightest measurements are the closest that valve will get to making contact . That number has to be above 0.080/0.100 " to account for thermal expansion.

You can do this with the engine in the car..
It's more work but possible. This is made easier with test springs.

Honestly if you haven't removed much material of both mating surfaces and have deeper valve reliefs you most likely will be fine.
But the fact remains that your won't actually known for sure....


And your impression is understandable but no. Cams do not come zeroed out. That is the whole reason why you use adjustable gears to zero them.
Example mines are 2° and 4° retarded on the gears. But based on my geometry their actually zeroed based on those adjustments

Do this only on a dyno.
Otherwise your wasting time.

 

[GST with PSI]

Miliman13 has basically covered everything you need to know.

In summary, you should do three things to ensure you cam gears are adjusted properly.

1) Degree the cams: In most cases, cams are not a drop in mod, and for them to perform as the manufacturer intended, they need to be degreed 9 times out of 10. This will ensure all the valve timing events are sequenced according to cam manufacturer's specifications (cam card). Only then will the cam perform as it was intended.

2) Check PTV (piston to valve) clearance: Depending on your build, the tolerances created by machining, aftermarket parts, and cam lift can drastically reduce (or in some cases increase) your PTV clearance. You could even end up in a situation where you don't have the needed clearance to properly degree the camshaft. However, you won't know until you degree the cams.

3) Adjust on the dyno to achieve the desired power band: Once you know PTV clearance, you'll know your left and right limits for how much you'll be able to advance or retard your cam gears. Again, without knowing this, you're playing with fire, and an adjustment too far in either direction could leave you with a trashed head, motor, or worse. Once on the dyno, you can advance and retard each cam to achieve the desired power band. Keep in mind, cam gears don't necessarily create power on their own, they just allow you to use the power you do make more efficiently. The idea here is to shift the power band to where you need it most. For example, someone dialing in a drag build with a huge turbo would probably like more top end, whereas a road racer would tune the gears for better spoolup and low/mid range power.

 

[Travis Grant]

Ahhh I see your last paragraph makes sense now. And thanks for the step by step gst with psi. I'm kind of doubting the cams were degreed when I had it built. Is it possible to degree them with the engine in the car or is it just too tight?

 

[GST with PSI]

I suppose it would be possible, but definitely not easy. To be honest, I've never see it done with the motor in the car.

 

[Kapok6]

The advice given in here is the "Technically True" way to do it. I personally got all the gear and timed my last motor and the cams (GSC S2's) we pretty much perfect as they were, straight up.

I have talked to other old school DSMer's as well as a reputable DSM tuner and his opinion was that most of the quality brands are going to be pretty close to straight up when you drop them in and he personally never degrees them as they will be getting adjusted on the dyno anyway.

 

[ishnish]

I have a question regarding this. Getting new cams, I'm looking into the BC 268/272 cams. I know degreeing cams is ideal for our cars but I wanted to know if anyone has good experience Just dropping these on?

Not only that, but is there any way to do this with the motor in the car? School and work will make this such a time consuming process for me and if this can be done with the motor in the car that would be great!

 

[miliman13]

I have a question regarding this. Getting new cams, I'm looking into the BC 268/272 cams. I know degreeing cams is ideal for our cars but I wanted to know if anyone has good experience Just dropping these on?

Not only that, but is there any way to do this with the motor in the car? School and work will make this such a time consuming process for me and if this can be done with the motor in the car that would be great!

You could in the car...
Its possible just very difficult......

And no straight in i was 2 and 4 degress of the crank.
Bcs arent known for straight drop.
Even then you have to test your range in both directions to find your limits
So you can know your limit for cam tuning on dyno.
Good luck. Dont rush.

 

[Vegas Smith]

I've heard from multiple reputable tuners that BC cams are the least likely to be spot on when installing.

 

[ishnish]

Thank you for your reply. Dang it that's actually a bummer. Is more worth it to pull the motor Just to degree your cams or just go try and Degree them while the motor is in the car? I've never pulled my motor (Just the cylinder head) and it Just sounds like a lot of work in order to Just degree some cams..

 

[Vegas Smith]

I would just sell them and buy a better quality brand like GSC or Kelford that have better quality control. Then, the next time the engine is out you can learn how to degree them. I have undegreed BC 272s in my car and I hypothesize that is causes my rough idle but I'm not certain.

 

[ishnish]

I would just sell them and buy a better quality brand like GSC or Kelford that have better quality control. Then, the next time the engine is out you can learn how to degree them. I have undegreed BC 272s in my car and I hypothesize that is causes my rough idle but I'm not certain.

Were you using their new 268/272 cams? Their website even says they should be a drop in affair..

 

[Vegas Smith]

Were you using their new 268/272 cams?

No.

Their website even says they should be a drop in affair

I'm pretty sure every manufacturer says that. I know they have attempted to increase their quality control, but who knows.

 

[keltalon]

Were you using their new 268/272 cams? Their website even says they should be a drop in affair..

In my experience i have gotten the best result out bc cams by doing exactly what they said , Drop them in and adjust accordingly. I use to spend a lot of time trying to degree a set of 4g63 cams and not only was i not getting an accurate reading with the factory hla I ended up changing the settings during the dyno session. To get them degree right IMO you need a set of solid lifter and most of us don't have solid lifters! IMO Degree a set of cams is only beneficial on our cars just to make sure that the cam is not so far off that the valve and piston make contact.

My method , I would start with both cams installed straight up at 0 I will then move the ex and intake cam setting in both directions with the engine at TDC, advance and retard until the valve hit the piston at this point I record the degree numbers on the cam gear this lets me know right off the bat how much adjustment i can make on each cam I then stay at least 4 degrees from this number to be on the safe side then I make a dyno run , look at the dyno sheet and adjust accordingly , If I wanted the cams to spool the turbo early in the lower rpm I adjust for that, if I wanted them to spool the turbo later in the upper rpm I would adjust for that and so on and so on until i have my car's power optimized for the modifications I have done, the intake i am using and the size turbo I have. Each time , using bc cams I was able to make some very impressive torque and hp numbers.

The consensus is this just because brand A (gsc) cam make more horsepower than brand B (BC) cam when installed straight up doesn't mean its going to make more horsepower when the final cam gear setting are made. This degreeing cams has been beat to death on the forums but what really matters is what is the car doing in the end. Everyone has their way mine has work perfect for me and those whom i have helped tune their cars. Here one dyno sheet running a set of bc 272 cams can't remember the settings but after I was done I was happy 500ft lbs of torque at 4850ish rpm is not to shabby! this was with the cyclone intake manifold. You can clearly see the car will pull to 8000rpm with the BC272s without breaking a sweat with minimal power loss in this case still above 600whp!

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[ishnish]

Very nice of you to chime in keltalon. Thank you very very much for the detailed information! I'll have to remember this for the future.

 

[keltalon]

Here's my 801 dyno sheet this time I changed turbochargers and switch cams from cyclone intake manifold to a JMF street from BC272 to Bc276 ,which IMO is one of the baddest cams on the planet. Also here's a video of what they sound like at idle after making all my cam gear adjustments. yes I had to change the setting because my setup changed even if I had degreed them they would have gotten changed again.

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Very nice of you to chime in keltalon. Thank you very very much for the detailed information! I'll have to remember this for the future.

Your are welcome! Anytime you need to know what I did just PM me I don't mind helping if I can!