No I'm not an expert why I mentioned just contact Mike jones you can't do any better then him. But the man is at 7000 ft not the 500 ft I live atin the dfw tx. How can a man at 7000 ft cram to much air in that he needs to worry about his exhaust system. Not going to happen unless he puts boost to the engine. Harvey crane is credited for first pushing up to 10 degrees more exhaust duration back in the early 60s. He had a logical common sense reason for that most people in that time period were running around with exhaust manifolds and no more then a non mandrel bent 2 1/2 pipes and the restrictive factory mufflers at best a small percentage added headers to the car and even the factory heads did not have good exhaust ports. So now heads have changed exhaust systems are mandrel bent and no less the 2 1/2 pipes and 3 to sometimes 3 1/2 and nobody in that time period I remember had anything like a 3 or 3./12. So now there is no good reason to use extreme duration on the exhaust.. I came on here to help not deceive and I'm told by using a tight lsa I'm trying to put some one in a totally ridiculous ****** thumper bull **** cam that has say 17 degrees of extra exhaust duration. Bottom line all this stuff now makes more power with little exhaust split or even none. And again the OP has a 7000 ft intake air problem not exhaust. That's the reason for the cam duration and lift jones speced he also did not ruin the man's car with a high duration cam. I used a 248 .050 LTI cam in both 327 and 350 with more compression then the 0P has and I sure as hell was not at 7000ft. Both engines were a dog to at least 3700 rpm anyone tells you different is lying to you. The OP wisely thought of the cost of that high duration mess at his altitude.

 

Where is all this coming from? I know a lot of cam specs are dicated by a lot of things. People look at head flow for one. There is also the cam specs, valve sizes, and exhaust size/length. Larry Meaux has a good program call PipeMax that helps figure out exhaust length and size in relation to the variables above. This software can help find the optimal exit for the exhaust pulse. Not having everything optimazied would impact the midrange torque output of the engine.

 

...and where is it going?

 

lol I ment this to go on the high altitude cam thread.

 

Agree you can only do so much wtih an NA motor at altitude.
Increase cubes or better yet stick a weiand street blower on it.
When I moved from Tuscon back to LA felt like I picked up 50hp

 

Many years ago I had a back then high hp motorcycle for the time period of 120 hp which is nothing today. So I rode it to pikes peak 14,000 ft. Carburated I got maybe 10,000ft it started
having a to much fuel problem but I did make it to the top. But I'm not kidding that 120hp felt like 45hp honda 450. Lol