advance/retard camshaft timing

[malice10985]

I was playing with desktop dyno, which has been giving me surprisingly accurate results.

My comp 200/206 cam is ground with 4 degrees of advance. As far as I can tell, this is hindering the potential of the cam. If I retard the cam back to 0 degrees, it will produce about 20 more hp. If I retard it 4 degrees, It will produce 40 more total hp. If I retard it more that 4 degrees, performance starts going down again.

Normally, if you retard a cam, you will gain power in the upper rpm range, and sacrifice power down low. When you advance a cam, you will get more low end power at the expense of upper rpm power.

My simulation showed that by retarding the cam a few degrees, I can increase power across the board without sacrificing low end power.

I am concerned about valve/piston clearance, but I can check that when I am putting the engine together.

Will retarding my camshaft have any adverse effects on daily drivability? Has anyone ever done this before?

[Zooomer]

I ran a 214/218 at 2 deg advanced and had pretty good results.

I now have the same setup but at 5 deg retard. I know it's a lot but I wanted to see what would happen.

Now some background. I ran desktop dyno and gained like 100HP by destroking to 3.4 liters from 3.8 and retarding the cam a ton. I know it has to be BS but I guess software is only good for so much...

The car feels like it lost a lot of bottom end and gained a small bit of top end. I'm going to dyno this weekend and I can report back the results. If I had to guess I think I'll end up putting the car somewhere between 0 deg and 2 deg retard when all is figured out.

[Lord_Verminaard]

If you're sure that the cam is ground with 4 degrees advance, I dont see any problems with dialing back the timing so that it's back to zero. Even retarding the timing a few degrees shouldnt pose drivability problems. You'd still be making more torque in the low rpm's than you would if it were stock.

Heres a question for you now: How did you get desktop dyno to give you realistic numbers? I've put in all of the stock figures that I can find, and the hp numbers are way off, like 140 or so when stock it should be making 200. What did you use for airflow values? I found some that someone posted on here a while ago and it still seemed low to me. Thanks a lot in advance, it's making cam selection hard when I dont have a good baseline to start from. [img]tongue.gif[/img]

Brendan
2000 Camaro L36 M49

[malice10985]

dominic sent me some realistic 3800 files a while back. I have just been tweaking them a little.

I can send them to you tonite if you want.

[WickEdSix9838]

you cannot base anything off of desktop dyno, that program does not have near enough entries to give you an accurate result, one of my friends has a program called Engine Pro that is really close, but you enter MANY values such as head flow, valve sizes, what size bore adapter you flow on, cross sections of the port, etc....

[AlienInv8r]

There's a link in this thread about halfway down for desktop dyno files that are pretty accurate. They're probably the same files, since dominic sent them to me also.
http://www.camarov6.com/ubb/ultimate...0;t=000009;p=2

[malice10985]

I just found out that if I want to retard my cam timing, I need a new $300 timing set :( So much for free HP.

Is there any chance that the machine shop will cut the new groove I need in my timing set?