Is this a good cam choice for 512

Building a a 400 to 512 to go in a 68 Charger with auto. I would like to see 600-650 HP and 700 torque. TF 240 heads, TF intake, 1 7/8 headers with 3 inch exhaust. Street car only, 3:54 rear. Super Sniper fuel injection with Hyperspark distributor and matching ECU. Car has power brakes so I need vacuum. Talking to Comp today and tech recommended a 23-712-9. I 236 and E 242 at .050 with lobe separation of 110. Comp recommended this cam custom ground with lobe separation of 112 and 4 degrees of advance built in. Comp says this is good 2500-6200 RPM. The second choice is Crane 689551, I 234, E 242 with 112 lobe separation. Crane says 2600-6600 RPM. I would rather see less HP and torque than to have to big a cam for the FI tune. Your thoughts

Cam it for what you’re doing with the car.

The power will just be what it is.

I'm sorry. This will be a street car. It will not hook up and its for fun not track racing

I think those numbers sound optimistic but they’re just numbers right? Unless you have an ET goal. I’m doing a street 512 right now too and I’m looking forward to having a little more HP amd a little less torque than my buddy’s worked gmc turbo diesel, but at 3000lbs instead of 6000.

Your car sounds fun! I already have holleys and tons of tuning parts that cost me no additional money but that sniper sure makes me jealous!

I run a 512. Some atreet use but mainly track. I run a comp cam. Part # 23-703-9. I dont run FI or PB but could easily and have considered changing over if I decide to drive it more around town. In gear I have 18" of vacuum. Idles very well w/almost no lope. Have ran a 4150 and 4500 Holley with no difference in drivability.

In comparison my brother runs the same cam in his 440. He has approximately half the vacuum(9-10").

I'm not as smart as many on here but I feel the extra cubes tames a large amount of duration. Youwill love your combo.

10 is what I would like to see with vacuum. Holley says 7 is minimum for the FI so I figured 10 would be good

236/242 should be fine. I run a 246/246 hyd roller in my 512 with the Sniper setup and it works just fine. Having the Hyperspark will allow you to add timing at idle and cruise so that will help a lot.

My cam is just a hair too big for freeway cruising with my 3.23 rear gears so you should be good to go. I have 15 inches of vacuum at idle with my cam so you should have more than that.

My 512 makes 485 at the rear tires which is probably around 550 at the flywheel. Here is a recent article from Hot Rod on my combination: https://www.hotrod.com/articles/holley-hyperspark-install-tune/

Someone here just recently dynoed a 505-ish motor with TF240’s, a hyd roller and a 6bbl.
The cam specs were something like 247/263-113.5.
He posted the cam card on the thread so you can check out the specs to be sure.

I thought he said it had about 9” of vacuum, so you can use that as a gauge point for the size of the motor/cam/vacuum.

We just dynoed a 492 inch Mopar today with TF 240 heads. CH28 intake with dual FiTech throttle bodies. Cam was hyd roller with 236/246 duration. Very smooth idle with plenty of vacuum, made 600 ft-lbs of torque and 540 hp. Pretty much done making power by 5500 rpm but that is okay with the owner. He wants an engine that he can cruise to car shows with his wife rather than a race engine.

I should point out that with a carb and a MSD distributor my 512 had around 11 inches of vacuum. Now with the Sniper + Hyperspark combo I'm around 15 inches of vacuum at the same idle speed.

Digital tuning allows you to dial the combination in faster. Since it is easier to tune digitally it is easier to find the "correct" tune. Pulling a distributor out and changing springs, weights, and bushings gets old in a hurry. Opening up the laptop and changing the ignition curve digitally can be done while you're watching a football game and drinking a beer.

assuming its a automatic,the torque converter will have a lot to do with rpm- vacuum when you pull in gear

That's good to know about the vacuum Andy. I went to manual brakes on my last car because I did not want to deal with low vacuum issues. I want to keep the power brakes on this car.

I'm starting to assemble another 512 C.I. low deck street bruiser to play with in the near future
It has a set of welded up used 440-1 heads, Indy 400-2 intake with a adapter for a 1050 CFM Dominator carb. 1972 400 block with a 4.250 stroke crank with a set of H beam Crower forged steel I beam BB Chevy type rods that are ,I think, 6.535 long.
A old NHRA SS solid roller grind Crower cam from bought from a member on here that is 261@.050 on the intake and 263 @ .050 on the exhaust ground on a 105 LSA, I'll install it from 2 to 5 degrees advance, if it will fit their okay.
I'm shooting for under 10.9 to 1 compression ratio for the local pump swill
I'm hoping this one will out perform my old Duster pump gas motor with the Indy SR M.W. heads that made 727 HP on Oregon Pump swill in Klamath Falls Oregon on a DTS engine dyno in the spring several years back That same short block made another 50 HP by swapping to a better set of CNC ported 440-1 heads within one week of each test

Headers or ex manifolds?

In my experience, aiming for a HP number has always left me feeling let down. Maybe because the engine builder I use has a dyno that doesnt produce the big numbers. I like Dwayne's take on it, that the power will be what it is. My car has a 505 with stock Stealth heads and a comp XE 284 hydraulic flat tappet. This car/engine was built by someone else and their dyno showed 550hp. Seems a little high to me, but im sure the previous owner felt good about that number. I'm replacing the Stealth heads with TF 240's and I would hope to see near a 50hp difference...but I would not expect to see 600hp on the dyno. Not on my guys dyno at least.

We used my 2 inch race headers on that engine although it didn't need them. Might have made better numbers with the smaller dyno headers.

I know it doesn’t really matter for what the owner is doing with that motor....... but that seems kinda low for TF heads and a hyd roller.
The tq number looks fine, so it must have been falling off pretty quickly.

It would have been interesting to try a “better” intake manifold and possibly a carb to see what kind of change that might have made.

Yep, torque peak was around 4500 rpm and it nosed over after that. I think the torque curve would have been stronger with a Performer RPM and a single throttle body. The CH28 isn't big enough to make good power on a 500 inch engine but it has a nice hot rod look. The owner wanted duals for the looks and he wanted a nice smooth cruising engine so he is happy.

I've seen the same results using stock type six pack intakes and carbs, peak torque between 4500 and 4600 RPM and peak HP between 5500 and 5600 RPM, I ended up learning at the track to shift those motors at the RPM that got the best ET which was above 7000 RPM with decent size solid roller cams
Test, test and test some more until your done testing and learning

Hi Frank
comp says 3:91 but with 512 cubes you will be ok with 3.54
but X2 what fast68Plymouth says
As andyf says (and he should know) 236/242 is too big
but .050 is worthless for cam selection-it's for degreeing in a cam
you need seat timing
problem with comp is you get a different answer with every tech
BTW all retrofits use Johnson lifters (if I'm wrong someone say so)
get a second opinion
http://jonescams.com/street-performance/
I like Jones inverse radius flank profiles
you can have shorter seat to seat duration or a fatter cam at the same duration or somewhere in between
get your head flows
cheers
you may not end up needing the lca squeezed as much giving more vacuum (less overlap) as the inverse profile can allow the intake to close earlier with a wider lca