Building a .030 over 396 using a 66 passenger car 2 bolt block. Forged pistons ,10.25 pop ups, 890 heads with 2.19/1.88 valves. Trying to figure out what cam to use. Going in a 68 Nova with either a 400 or a 700R4 and a 3.42 10 bolt positraction rear. Not gonna race(much wink-wink) but it needs to get out of it's own way. Don't want to run too much of a converter, maybe 1900-2100, but no more. Give me some thoughts. Also will have Weiand and probably a 650 or 750 carb..... What's everyone think??
I'll throw in my $.02 here. With that compression ratio on iron heads I would err to the side of caution. It's going to be literally right on the edge of pump gas. As a matter of fact my 454 comes out to 10.3:1 and unless I knock some timing out of it, it will NOT run on pump gas without problems. Now apples to oranges, I have a Lunati VooDoo 268 in mine but it's ground a couple degrees off of the "spec" cam card. And looking back I probably should have went up one cam size to help the pump gas problem or installed this cam a couple degrees late instead of degreeing it right to the as ground cam card. The problem I ran into is with the engine specs and the way it's put together, the dynamic compression is around 8.8:1-8.9:1 and its really above the limit of pump gas. Now to that effect I run Sunoco 110 and leave the timing and engine where it's happy. I don't drive it enough so the high octane fuel isn't that big of a deal.
Now, onto the cam of choice. Not all cams are created equal. If you start looking at the duration numbers at different points you will see that some cams are bigger or smaller than others when you start looking at .004, .050., .100, .200, .400, etc timing events. And some cams are better than others. Some have a lot of velocity and are very aggressive in their opening and closing rates. If I was going to buy a cam "off the shelf" it'd behoove you to look at similar cams from Lunati in their voodoo line. The same guy that designed the original XE cams for Comp is the same guy that went on to design the VooDoo cams for Lunati and he uses an updated profile on them with an aggressive opening rate but a slower closing rate than Comp and the cams make more power and are quieter than their comparable Comp counterparts. they open the valve fast but set it down slow. And most of the cam profiles are bigger throughout the range than Comp. But one of the standards for advertisement is to use the @ .050 numbers and most times things look "equal" when they really aren't. I'd look at a 262 (219/228 durations @.050) or 268 (227/233 @.050 but would probably be one size bigger than what you would want) voodoo from lunati. However, either way you will be quite happy! The Comp's just tend to be a noisier cam and I've had a few go flat over the years so I tend to shy away from them anymore. The local engine shop does too. But cams falling in those sweet spots for "street" whether its comp, crane, lunati, isky, etc. are what a lot of people use, because they've been proven and worked well for ages!
The other thing I would add, is if you're running any kind of performance camshaft with domed pistons, I would absolutely check your piston to valve clearance! Here's one area where you do NOT want to overlook. Especially with oversized valves and longer duration cams, you will get awfully close, and you'd much rather have to flycut the pistons/massage the reliefs before you assemble for the clearance you need as opposed to tuning 'er up on the throttle and the valves hits the pistons and trash the engine. Most off the shelf pistons have larger than needed reliefs due to the fact they try to account for those tolerances and build it into the piston but it's still an area I wouldn't leave unchecked.
No matter what you decide, I hope you have tire replacement funds allotted into the budget, because you will need it.
