Installed cams, but car sounds ummmm..... Kinda stock

[Chicken Patty]

The loping sound from a bigger cam is caused by the unstable vacuum drawing air into the engine, the unstable vacuum is caused by too much exhaust to intake valve overlap for the current engine rpm. You can't correctly call it Lobe Separation Angle because a higher duration cam with a wider LSA can create the exact same vacuum instability as a smaller duration cam with a narrower LSA.

When the exhaust valve is still closing and the intake valve has started to open it's called valve overlap. Overlap changes with physical camshaft timing (cam gears) as well as lobe duration (cam size).

When both intake and exhaust valves are open and the piston is approaching TDC on it's exhaust stroke, you may get some reversion of exhaust back into the intake port. As the piston passes TDC and starts down the intake stroke it creates vacuum to draw in air and fuel, and if the exhaust valve is still closing... well then, some of that exhaust previously pushed out can be drawn back in, some of that very precisely measured air mass and precisely corrected tiny fuel injector pulsewidth (*with your big injectors) can even sometimes travel out the exhaust valve unburned.

Both of these undesirable conditions usually occur with big duration cams and they work together to cause misfiring and random weak firing due to poor air/fuel charges. Hunting intake manifold vacuum levels are caused by the weak firings interspaced with good firings, because the ECU is working overtime adjusting things to correct the fuel trims and spark timing to try to maintain target idle speed.

As you increase engine speed, the loping effect will generally subside. This is due to the mass of air. It takes time for it to move, gaining momentum and achieving a velocity that drives the air/fuel mass through the valves in the correct direction, albeit sometimes partially overshooting and passing a little unburned through to the exhaust.

Some expert tuners will work around the lumpy idle and set constant or very narrow range idle speed timing correction and fueling, some will simply ignore it because they don't care to fix it and still others will try to make their car produce the sound just because they think it's cool.

I wouldn't be too upset or worried, but you might want to consider adjustable cam gears and scheduling dyno time to degree them in so they work the way you want them to.

Great post and thanks for the info! I am not going to worry for now, car pulls great, powerband seems really good and I really have no complains. I personally like the sound but it ain't the end of the world. I plan on maybe sometime by mid next year taking the motor out and doing a 6 bolt swap and once it's out go ahead and just build the engine from top to bottom. If I see in the near future that I will still carry on with this I will then just hold up until then and do it on the new motor while it's still out.

...also, I went ahead and dialed in the car since like I previously stated, I was sure trims were probably off some since the car was last tuned in the summer. Let me tell you, I love Speed Density! Trims were still almost spot on. Just mimor tweaks and trims are now +/- 2%. My car was never this consistent with a MAF.

 

[95talongirl]

^^ +2

Excellent post.

I have FP2's in my car, and you would not be able to tell. The car runs smooth. They were also degreed when installed and found to be about a degree off from what was advertised. Since this wouldn't really make that big a difference in the overall scheme of things, made the decision that the stock cam gears would be fine. It is a good idea to degree any aftermarket cam, despite being advertised as "drop ins" just to make sure. The adjustable cam gears then can help adjust for any errors. So yes, you can degree cams without the adjustable gears.... you just can't change them if you find them to be in need of readjusting.

Like you stated, I wouldn't worry about the car sounding "normal."

Also note the larger cams will cause the engine to pull a bit more vacuum at idle, as well.

 

[95talongirl]

...also, I went ahead and dialed in the car since like I previously stated, I was sure trims were probably off some since the car was last tuned in the summer. Let me tell you, I love Speed Density! Trims were still almost spot on. Just mimor tweaks and trims are now +/- 2%. My car was never this consistent with a MAF.

SD is next on my list. This MAF tuning is a pain! Glad to hear you got her consistent!

Here's a video of mine running for reference:
http://www.youtube.com/watch?v=gezISB73A08

Note: there was an exhaust leak from the downpipe to the mid-pipe there.

 

[Chicken Patty]

Yeah, I did notice from dropping in the cams my vacuum went from like 22 to 10ish.

...and yeah Speed Density is one of the best investments I've made for my DSM. Never going back to a MAF, ever!

 

[Chicken Patty]

Just to keep you guys posted. I went ahead and messed around with my ignition timing on the idle and cruising cells after reading up a bit on that, and I managed to get some better MPG's as well as a much better idle.

The idle now has more of a lobe, sounds more cammed but much smoother than before. Not like a choppy, camming, misfiring sound like it had before. Just idles and drives better. Overall super happy with the latest results. . Just thought I'd update you guys.