OK time to hear an answer, to a common age old question, from the 'big boys'...

Cam choices. I've looked over some old posts and looked through every online cam catalog, I also inquired with a local company that can replicate any cam profile I provide a profile for, for only $120 (that and the price I'm shelling out for a set of lifters thanks to rick, I should be able to do a cam swap for $150 or less... ).

Anyhow, I think the Hpak would like more bumpstick, and next year I think more gear would be in order too...

Here's what's in there now:
225 forged crank 20 over
9.2:1 compression
Stock Valves and springs and rockers
Hpak intake and dutra duals currently with 390 cfm 4 barrel, soon to upgrade to 600 cfm Vac. Sec. carb
A-833OD tranny with 3.55 sure grip rear end.

questions I'd like answered for a 'more educated guess' would be:

When is it necessary to swap to the 340 spring setup? what lift/profile?
This will be regular for street driving, but will see some time at the strip next year, a little 'lope' to the idle is ok, and the manual tranny is a bit more forgiving than having to tailor in a stall convertor into the mix.

I'm currently running a Comp Cams 252S, was thinking a 264, but am also thinking with a future gear change, etc...something in the 268 range would be good, but not sure about lift or if that would be too much for the stock springs.

Thanks for the info, am trying to line up 'the ducks' for the winter while I have time to do it, and dial it in before the March season opens up.



-D.Idiot

Well, I'm not sure I'm a "big boy," but here's my stab...

I think you will mostly be limited by your valve size and static compression ratio, and of course your "bumpiness" tolerance. You did some porting on this head, no?

With that gear and tranny combo, you should have no trouble with a cam that comes in around 2500 RPM or up, so you have lots of choices. I think most people would run a 225-230 @ 0.050" and 0.460-0.470", which is reasonably docile, IMHO. The Comp 264 or Isky 264 or MP 268 would fall into this category, and I've heard the best reports about the Isky. You won't get much power over 5000 with this setup.

Personally, I would run more static compression, maybe 10-10.5:1, and a bigger cam, like 235-240 @ 0.050" and 0.500", but that's just me... This will start in around 26-2800 RPM and pull to around 5000-5600. You should not really sacrifice much MPG (if any) if your static comp is high enough and your timing curve is set up right. You'll be fine with 92-93 octane with the correct timing settings on either of these.

I would guess you've read about my '64 motor, which has more cam and comp than I talk about here, and it runs fine on pump gas, gets 24 MPG hwy, and has a power band of 3200-6000+ (too chicken to go higher ). A little bumpier, and I've seen some rocker wear issues recently, after 20k miles with big springs/cam, but a pretty dependable and stout package.

My guess is that stock Slant springs would probably be OK with the Comp or Isky 264 cams, and the 340 springs should be OK with up to about a 0.480-0.500" cam.

Happy cammin',

Lou

_________________
Home of Slant6-powered fun machines since 1988

I kinda figured that 268 adv. would be about it with a lift around .46-something, the head is street ported.

My bumpiness tolerance is pretty high. I don't think with the gearing it has I'll ever see over the 4-4200 range....(I mean 3rd gear @ 4k = 100 mph...probably not in a 1/4 mile run....).

I figure, if I was going to go for more, I'll just build another mill and do it all 'right' instead of continuing to 'improve' this one.... maybe in another year or two...

That's exactly what I was looking for. Thanks!

-D.Idiot

You better rev that thing to 5000 in 1st and 2nd, or I'll be miffed...

Have fun!

Lou

_________________
Home of Slant6-powered fun machines since 1988

Lou you made me laugh so hard I almost ruined the keyboard, if I ever catch up to you in person I'll owe you dinner!


I'm trying to find Doc's 'street' cam profile he posted a long time back, juts to see what he had in mind, vs. the 'manf' grinds...I think it was 258 intake 26? exhaust, but I can't find the post any where. I noticed in one post he did mention a .904 lifter rise, soft lash ramp, 110-112 LSA (better idle), and limit the lift to .450....which puts it pretty close to the Isky 152116....


The funny thing is 2nd gear @4000 = 55mph... I can see why a close ratio tranny is every one's favorite...

time to go see if 5000 in 1st = 45 mph....


-D.Idiot