Choosing a new cam

I have had a comp cam 268 duration in a 345 [i think it was a bit much for the truck], then I put a 392 in with a Schnieder 256 cam in. These were both in my 73 1310 auto with a 4.88 rear, Gear vendors od, and 235/85-16 tires. Headers and and Edelbrock carb as well. Engines were stock otherwise. I was happier with the Schnieder cam. A lot smoother and had a slight more lower end power. I also had a 392 with a stock cam in my "new" 75 200 one ton with a 4 spd. Drove that some for a year before I got another 392 IC that i built with an Isky split duration 256/262. The stock 392 was ok, but the Isky in the 392 definitely woke it up and I have been pleased with it so far. Mind you these results probably wont mean much for scout guys, as both of the trucks weigh about 9000 lbs "empty" [with all the tool boxes and tools in there] IMHO, a cam just over stock is great. If you have to smog it, dont try it.
Someone mentioned the timing too.. with all my cams the base timing was crap. I had to just keep advancing it until it started pinging and backed it off a smidge. All relative for whatever different things may be going on with the engine

 

I'm very curious about that last statement. Do you happen to know what that cam's actual effect is on emissions? I see you're in CA, so if anyone here might know, it would be you. I assume Palo Alto is a high-test region... though maybe not for larger trucks. I have no knowledge of their requirements.

BTW, I assume you are talking about this 256 cam, not the "256-2H" cam:
http://schneidercams.com/256HINThydraulicv8.aspx

 

Yes, you are correct... thats the cam I put in.
For smog, I dont have to deal with it thank god. I just remember when I was working at a shop years ago, had a couple people with mid 80's chevy trucks that had really mild cams that wouldnt pass. That was 10+ years ago, and I know it has gotten more stringent since then.. basically the cam makes it burn more fuel, hence more emissions...

 

Thanks. That confirms my long-time suspicion. I'd always dreaded the thought of going through the hassle of replacing the camshaft with an aftermarket only to find later it would not pass emissions. Right now my zillion-mile 345 engine passes smog at under the "average emissions" for its type, and WAY under the max allowable. So I do have a little room to play with, I suppose. But I still would not want to chance it. I guess this is another question to ask Schneider eventually: Do they know of any of their mild V8 cams passing emissions in CA.

OTOH, CA does seem to make allowances for smog equipment that's become unobtainable. And it's sounding like stock cams are moving in that direction, aside from having reground cams made. I wonder if that is an acceptable recourse, installing a mild cam in an otherwise stock and fully equipped engine. A question to be answered by the local Smog Referee no doubt.

BTW, @Darrell Tuxworth if you're still following your thread, hope you don't mind my asking all these smog questions. I assume your questions have been answered by now.

 

To follow up, in case anyone's interested. I just got off the phone with Schneider Racing Cams. Spoke with Kevin, their technical sales guy. He is plenty knowledgeable and was happy to help me out with my questions.

The answer to my question, do they still offer their IH cams: "Yes and no." They do offer and will be happy to sell them, but Schneider been waiting two years for new blanks to be made by the supplier. He said that's typical and their current order backlog is at sixty IH cams they are waiting to make. They have no plans to remove the IH cams from their catalog. The cams have just been slow to produce.

I asked about the duration thing, i.e. the reason for longer exhaust duration used with some cams. He just confirmed what everyone already knows. It's to account for the especially poor breathing on the exhaust side. Helps with scavenging. Especially with their milder grinds. I mentioned that the Elgin 'stock' cams are stated to have longer duration on the intake side. He found that to be really odd. I said I'd send him that information for his evaluation, just to get his take. He might have an explanation for why the numbers look like they do.

Regarding emissions and CA smog checks, for anyone who cares, he said, to no surprise, none of their grinds are CA emissions-approved. "I can't even do a stock grind and guarantee it'll pass." Legally speaking of of course. He did say that the milder grinds might/could pass smog if everything else is working well. Has a lot to do with oil blow-by anyway. There's a chance it would pass and he knows of a few engines that have, but the user would be taking their chances.

He did mention regrinds. As in, if I or anyone was rebuilding an engine right now, Schneider could easily do a regrind of the cam with a quick turnaround. Nothing wrong with regrinds. They work great. The obvious limitation there is if the cam's kind of warn down a bit and the user wants a bigger cam made out of it, that reduces the base circle noticeably and so longer push rods might be needed.

 

Good info.nice foot work. Good to know.thx

 

I Second this, very good info Pat!