Upgraded Camshaft and Base Timing

[GEDengineering]

Looking for personal experience and advice on whether advancing the base timing above 5 degrees helps improve idle with aftermarket cam shafts. I am running BC 272/272, idle set at 850 rpm and iac hovers around 35 steps at idle (ruuning Ecmlink v3 lite). The car doesn't stall and doesn't have surge put you can really feel the lob of the cams at idle. I am looking for ways to smooth things out a bit.

Thank you in advance,
Glenn

 

[tektic]

Degreeing your cam shafts may help. It is not advisable to blindly change your base timing.

 

[GEDengineering]

I have the ability to check the change in timing via a timing light and ECM Link, just would like to know what others are doing about the situation

 

[marvinmadman]

Raise idle? /ubbthreads/images/graemlins/dunno.gif

 

[tektic]

If you raise the base timing it will add that amount to your advance in every cell of the computer. If you have link you can try to add timing at idle. Check to see that the base timing is set correctly but leave it at 5.

 

[GEDengineering]

The base it set correctly at 5 degrees. I have look at the DA tables of link I think I am going to adjust those values a bit and also lean out the idle to see it I can improve things. If you have any other suggestions I am open to hear them.

Thanks
Glenn

 

[AllanL]

leaning it more at idle may make it worse...

as said, raising the idle may improve it a bit...

 

[swe_gvr4_1991]

I also have 272/272 and I idle at 1100 RPM to keep things happy.
If I idle at 850 the whole car shakes. These vibrations may look, feel, and sound cool but it will kill parts in the long run.
So +1 on raising the idle.

 

[GEDengineering]

Going to bump the idle a bit to see if it will help, cause the vibrations and shacking is really uncomfortable. /ubbthreads/images/graemlins/dunno.gif. Just to let you guys know that adjusting the timing some doesn't improve the situation.

Thanks

 

[strokin4dr]

Do you still have balance shafts? If so, are they out of phase?

BC cams seem to have poor quality control when it comes to alignment. Were the cams degreed when install? If not, you may want to do so. You are chasing your tail without knowing if everything is timed correctly.

My vr4 (built 2.0, no balance shafts, poly mounts x4) idles at 850rpms with comp 272s no problem. Minimal vibrations compared to my friend's completely stock vr4.

Not everyone degrees their cams. I did not for this car, but definitely would if I had an abnormality such as what you are describing. Being that they are BC cams, to me, makes them highly suspect.

 

[biglady112]

Raise the idle. 1100-1500. Problem solved. Degreeing your cams to zero according to what the manufacturer asks for will make a difference as well and put your timing events at the correct time.

 

[thecman02]

Do you have adjustable camshaft gears. Assuming everything else that has been said above hasn't helped; I've had good luck removing overlap to increase idle quality and even help on top end performance.

 

[AllanL]

^ as he said...

 

[ghostinthevr4]

Raising the idle will help big time with the idle before I fully built my motor I had BC280 intake and exhaust. I've read so much stuff about them I sold them for HKS cams first I had 264/272 then change my setup and went 272/272 HKS.

Didn't degree them in and slapped raised the idle to 1000rpm and it help with the vibration. Your pretty wise to understand playing with the timing will help with the idle. Verify that your are at 5 degrees by setting idle to 850rpms on link, yes it will idle like sh*t don't worry about it.

Then ground timing through link take timing light and verify a base timing of 5 degrees with your timing light. If it's out obviously adjust cam angle sensor till your there. Once you verified timing uncheck timing and set you idle to where you want it buy using the cells. What also helps is no idle problems like surging or vacuum leaks and make sure your TPS voltage is dialed in correctly.

Once all the above is done and checks out set idle to 1000 rpms and see if your happy with it. As long as the wideband is reading what you have calibrated you should be good to go. Then you can start advancing or retarding timing to help your vibration at idle track the cells to know which ones to change, you'll probably have to change the nearby cells of the highlighted ones to get it a bit smoother.

It's not hard to do just time consuming but the reward is worth it once done right.

 

[strokin4dr]

Most of these replies are sounding like bandaids for the real problem. No need to have the idle that high if everything else is set correctly. /ubbthreads/images/graemlins/dunno.gif

 

[GEDengineering]

I have verified the timing is 5 degrees with a light. I did a boost leak test and found a lot of air escaping from the valve cover and dip stick. I did a leak down test yesterday and I have about 10% across the board. I think the rings or guide are going bad. I have not done a compression test but I will once I get a functioning compression tester.

Let me know what you guys think,
Glenn

 

[biglady112]

Having a high idle also promotes better oil pressure at idle naturally. We have one car that idles quite high to maintain both hot and cold oil pressures as a "normal" idle from his engines see very, very low pressure at idle. We verified both with a mechanical gauge and his electronic gauge. I can deal with a high idle of it means not chewing up bearings prematurely.

So there are benfits to a high idle.

 

[marvinmadman]

Better voltage from the alternator as well

 

[JoeDaddy0]

I am using 268 cams and ER set at 900. I can't see a fairly smooth idle less than mine for a longer cam. /ubbthreads/images/graemlins/rofl.gif You should probably be at 950 for smooth idle.