Looks like there's NO camshaft for a 2.8/3.1 V6 that has been CARB-certified. Seems like places have just bothered to work on getting V8 cams certified... that sucks for me. New Jersey has the "new" dyno emissions testing. I'd rather not do a cam swap before every test, know what I mean?

Is there a way I can tell how much a camshaft will increase emissions? Is there any determining factor as regards what comes out of the tailpipe? For instance, here's some specs:
<table BORDER=3 CELLSPACING=3 CELLPADDING=3 >
<tr><td></td><td>Degr Durtn @ 0.050" I/E</td><td>Degr Advrt Duratn I/E</td><td>Lobe Sep</td><td>Gross Lift I/E</td></tr>
<tr><td>Stock</td><td>196/202</td><td>238/256</td><td>108</td><td>0.393/0.410</td></tr>
<tr><td>Crane 2020</td><td>198/204</td><td>258/264</td><td>104</td><td>0.401/0.403</td></tr>
<tr><td>Crane 2030</td><td>204/214</td><td>264/274</td><td>109</td><td>0.423/0.423</td></tr>
<tr><td>GM Perf 1</td><td>204/214</td><td>not given</td><td>112</td><td>0.420/0.442</td></tr>
<tr><td>GM Perf 2</td><td>204/216</td><td>not given</td><td>112</td><td>0.422/0.444</td></tr>
</table>

Do I have a shot with any of these? I also have a few more cams at home; is there anything I should look for? These all claim to work with the stock computer, but my bet is that won't help emissions.

Or, heh, am I completely screwed, and have to go after a stock camshaft? Is there a book or something I should track down?

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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
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[This message has been edited by TomP (edited January 09, 2001).]

 

Good question, I wish to know myself. The only thing I know of is if they print a 1,2, or 3 emission symbol next to it.

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Rob
'86 TA 305 TPI

 

I would think since they don't know for sure what cam is in the motor they can't fail you for a non-emissions cam. When I lived in california years ago we got some race engines past emissions simply because they ran clean. The sniffer only knows if the stuff coming out of the tailpipe is clean or dirty. It has no idea weather it is certified or not. If you have a computer controlled engine the emissions should be clean enough to pass. Think about it for a second, If your neighbor's 150,000 mile, bad rings, burnt valve, bone stock, 5.0 boat anchor can pass why shoudn't your mild cam, fairly fresh, V-6? Just make sure it can pass a visual inspection and give it a try the worst thing that can happen is you fail and then you'll know.

 

I'm more than sure that all of those cams will pass the "sniffer" test. If you don't mention it to the tech, it won't matter. What makes the cam not "smog legal", is the compatability with the computer and the other components in the engine. For instance, if you get a radical cam, one with alot of duration, then you'll have a larger overlap. That will reduce your vacum, which, in MAP sensor cars, the stock PROM will make the ECM go crazy 'cause it will think that there is a vacum leak. So you'll have to change the PROM. There are alot of things you can do, but it costs alot to experiment. But, the cams you've mentioned aren't too extravagent. Check out the specs on some V8 smog legal cams and compare them to the stock ones.

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'82 Firebird, dead stock, 9 bolt disc rear, over 200,000 miles and still going strong, more to come...

 

R.O.B, all of the cams I want have the 3 printed next to 'em- what a bummer. I have a feeling that since the 2.8 cam market isn't a big one, they didn't bother to get them emissions-certified.

87RS402, I think a worn-out engine's worn-down cam can pass emissions because it's not lifting the valves as high (or as long) as it originally did... which I'm also guessing leads to less air/fuel in the motor, which I'll guess once more leads to less emissions. But yes, I have no plans on mentioning which cam's in my motor, but I gotta pass that sniff test (done now on a dyno in my state)! You're right though, I guess the worst is, I have to do another cam swap. That would be a major pain though in the cold of January (my emissions test month)! You bring up a good point tho; I wonder how much "squeak" room I get for the test.

Stingerssx, thanks for that info on the cam stats. Do I have this right: So the higher the duration means the longer the overlap, and that means less vaccum, which could raise the emissions? Is that all that higher duration does? I have a MAF-equipped car, so my computer shouldn't be too picky if the vacuum's an inch or so low. Doesn't lobe separation also affect vacuum?

It looks like that Crane 2030 (the one I originally wanted, by the way) will only increase duration (at 0.050") by 8int/12exh degrees. Does that sound small enough to not matter... almost in the line of what 87RS402 was eluding to? Should I concern myself with lobe separation, or should I just worry about overall valve lift?

Oh and heh I know that duration @ 0.050" is the "standard", and "advertised" duration can be measured differently-- should I concern myself with advertised duration at all??

That's a great idea to check out TPI smog-legal cams to compare 'em. I'll have to do that tonight!

Thanks again...

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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
---Think your car could be pic of the week? Visit http://www.f-body.net for details!

[This message has been edited by TomP (edited January 10, 2001).]

 

While it's not exactly the same, valve overlap is determined by lobe seperation. The farther apart, the less overlap. The duration doesn't directly have as much of effect on this, but you would generally find more overlap, and less lobe seperation with longer duration. I have a sheet that you can fill out your specs. I got it when I was going to school. E-mail me, and I'll scan it and e-mail it back to you. It makes everything easier to understand. And never, ever, (unless your bench racing) go by advertised specs. They all are worthless. Always go off of the .050" lift specs.

 

I'd be partial to the GM performance grinds because of the wide lobe centers. That ususally translates into less overlap at TDC which would be good for street driving, high vacuum at idle and, the computer ought to be able to work with them.

Small lobe spreads usually mean lots of overlap. Lots of overlap is good for high-RPMs because the headers can more effectively scavenge the combustion chambers when both valves are open for an extended duration. Trouble is, is that the engine can breath and scavenge TOO WELL and raw air/fuel mix can sweep right on out into the exhaust. A combustion chamber cleaned of all residual exhaust gas gives you maximum power but you'll have sky-high HC and CO emissions. Lots of overlap in a performance grind also causes rough idle and once again, sky high emissions.

On the flip side, factory grinds with small lobe center numbers use that overlap to INHIBIT scavenging. The overlap is used as a built-in EGR, like the stock cam at the top of the list. Such cams can still produce smooth idles because of low valve lift and timing of the overlap with respect to TDC.

Those Crane cams listed may not be CARB certified because CARB certs are EXPENSIVE! A company like Crane is not likely to want to put itself through all of that agony. Even if the cam survives the testing and red-tape, Crane would then have a liability tail on that cam which would suck if someone failed a smog test and blamed Crane for it.

Those GM cams are more likely to have been tested but it stands to reason that GM developed those grinds to get the best overall performance from the V6 without regard for CARB. I'd take my chances with the GM Perf (1) cam, IMHO.

 

Jrr, thanks for the ideas. Crane actually makes that "Gm perf #1" camshaft for GM. I think tho that the GM site recommends the "GM Perf 1" cam for TBI use, not MPFI. I guess I could always call Crane! Funny how the Crane 2030 and "Gm Perf 1" have the same duration at 0.050 ...


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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
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