This may be a stupid question but....How do I adjust the cam gears

[carbonfire]

Ok I have Fidanza cam gears, and I dident get any directions with them, I understand you just loosen the bolt and turn it one way or the other, but what way is advance and what way is retard for the exhaust cam.... I know that sounds stupid but I think that towards the left would be retard and towards the right would be advance on the gauge, but It almost looks wrong to me some how... Let me know....

 

[CyberEye]

most adjustable gears have a little guide on it, with notches an arrow and negative/positive numbers on it to tell you what you are doing. If you're not seeing this, maybe you have them on backwards.

 

[carbonfire]

I dont even have them on the car yet, I was just checkin....

 

[carbonfire]

err mine just say 12 on either end.

 

[Injected]

Here's some good information. I hope it helps you.

Cam timing
Most cars have their cam timing set at the factory for minimum emissions; production of maximum power is a secondary goal. As we explained in the third segment of this series, most production camshafts are designed for minimum overlap with a wide lobe separation angle to reduce hydrocarbon emissions and to ensure a smooth and stable idle. If power is your priority, a few horsepower is usually available to those who are willing to spend a little time with tuning. Adding little bolt-ons like air intakes and headers can also change the optimal cam timing that your car prefers. VTEC-equipped Hondas and Acuras with their big duration secondary lobes and cars that have big cams fitted with headwork and lots of other mods can almost always benefit from some cam timing adjustment.

Another interesting fact is that almost all aftermarket and many stock cams are usually ground a degree or two off from the spec that they are supposed to be ground to. This is normal variation of tolerances in production. Dialing in the cam timing allows the tuner to compensate for these slight errors. Often there are a few hp just waiting to be unleashed by this alone.

As most sport compacts have DOHC engines, we will start with the assumption that your car has two cams. (If you don't know what DOHC is, please refer part three of this series in the June 2000 issue, where we discussed camshafts in detail.) To adjust your cam timing, you need to purchase adjustable cam timing gears.

While dyno tuning, if you progress in the adjustment orders listed below, you can usually get results with a fewer number of dyno pulls than proceeding willy-nilly. You don't necessarily have to go through the whole sequence of adjustments when tuning; if a series of adjustments starts to make good results, continue in that direction, do not go through the whole sequence. For instance, if advancing the intake cam moves the powerband to where you want it, you don't need to try retarding the cam as well.

The accepted way to dial-in a cam is to start with the intake cam, since most street-type engines respond well to having the intake cam advanced. Advance the intake cam 2 degrees at a time, testing between adjustments until the power falls off or the desired powerband is met. If the power falls off right from the get-go, try retarding the intake cam, although this is not likely to be the best solution on most street engines. After adjusting the intake cam, most tuners first retard the exhaust cam slightly. Try retarding the exhaust cam in one to two degree increments until the power drops. If the engine does not respond to this, try advancing the exhaust cam. Many engines seem to like having the intake advanced 4 to 5 degrees and the exhaust retarded 1 to 2 degrees. My take on this is that doing so increases overlap which, done in moderation, tends to broaden an engine's powerband. This also helps production-type engines with their more restrictive ports, intakes and exhausts (as opposed to real, race-specific engines) breathe better at mid and high rpm. As a warning, this is very general and must be verified on a dyno, as many engines will not like this either!

With SOHC engines, like the venerable D series Honda Civic engines, there is not as much flexibility in cam timing adjustment; you are confined to advancing or retarding everything, because the intake and exhaust lobes are on the same stick. This limits you to moving the powerband around, more than broadening and lowering the powerband or making the power peak higher and more narrow--options that you have on DOHC engines. When dyno tuning an SOHC engine, you should experiment first with advancing the cam, then retarding it. Two-degree increments usually make a big enough change to easily spot on the dyno.

When adjusting cam timing on the dyno, remember: It is better to go for an area under the power curve rather than maximum peak power. Having 4 more horsepower from 5500 to 7800 rpm will get you down the track faster than having 7 more from 7500 to 8000 rpm-- and less everywhere else. Adjust the cam timing to get the most power in the rpm range, where the car will be pulling the longest in each gear.

As a warning, piston-to-valve clearances decrease when advancing the intake cam. Usually this is not an issue in stock engines, but with a higher lift and long duration racing cam with milled heads or other modifications, it is possible to hit the intake valves on the piston and cause damage. In most cases, you can safely advance the cam on a street engine at least 6 degrees before you need to worry about contact; however, if you are not sure, measure the clearances before proceeding. A mistake can be costly.

It can be possible to see gains of up to and more than 10 hp by optimizing cam timing, although 3 to 5 hp across the rpm range is usually more typical. It is also important to remember that any change to the engine, especially to the intake and exhaust system can change the cam timing that the engine likes. It is also important to know the engine may like slightly different ignition timing after the cam timing has been set, so it might be a good idea to play with that again, after optimizing the cam timing.

As a final note, don't forget that many cars drive their distributors off the back of one of the cams, so a change in cam timing will also cause a change in ignition timing. If your engine has such a distributor, re-set the ignition timing after each change.

 

[Mr.Tao]

Dsm's are distributorless right? So adjusting cam timing, do I need to worry about ignition timing? If so, how would I adjust the ignition timing?

 

[suncad03]

you need the specs on the car and get a deg wheel and do it that way your car might not be the same as someones like mine
and do not just put them in you may bend valves

 

[Quasimondo]

Dsm's are distributorless right? So adjusting cam timing, do I need to worry about ignition timing? If so, how would I adjust the ignition timing?

I would say yes that you would need to worry about ignition timing since the cam angle sensor is hooked up to the intake cam. Altering the timing on the intake cam will alter your base timing as well. It could make for a tedious process, of adjusting the cam gear, than going back and readjusting your timing to compensate.

 

[carbonfire]

Wow, thanks Injected, that artical was really helpful.... now is it safe to say that with the FP2 cams 272's I should be able to retard my exhaust cam by 5 degrees and not have any contact problems?

 

[Mr.Tao]

Sorry if it feels like im stealing your post, So if I only mess with the Exhaust timing, I wouldnt have to worry about the CAS? ONly Intake right?