Hey guys,

Before I do anything, let me list what I'm building...

Bottom end

-505 BBC (4.350x4.25)
-2 bolt standard deck block (arp studs, short fill to bottom of frost plugs, cylinders relieved to head gasket)
-blueprined melling standard volume pump, moroso pan, windage tray, crank scraper
-Scat 9000 series stroker crank (knife edging, lighting holes, etc.)
-Scat 4340 6.135 I-beam rods w/ 7/16 cap screws
-Ross 14:1 forged nitrous pistons (dome blended and bead blasted)
-file-fit rings (still debated weather to gap them loose for possible future nitrous use)

Top-end

-GM 049 oval port open chambered heads (2.25, 1.88 severe duty valves; bronze guides; chambers heart-shaped, equalized, polished and relieved on blow down side of exhaust valve; exhaust fully ported with roofs raised and guides profiled; fully ported intake tracks that are port-matched to a rectangle port intake and quickly taper back to the standard oval port cross-section)
-Team G rectangle port intake (fully ported with runner extensions added)
-Holley 1050 Dominator
-hooker 2" headers

This motor will be going in a 72 Nova SS with a TH400, and 3.90 gears in the rear. I want to eventually put this car in the high 9s.

I realize that my heads arent the greatest for what I'm doing, but I already have them and they have lots of high dollar port work into them. I will probably switch to a set of shiny aftermarket heads ;) in the future, but want to run what I've got now.

Anyways, the point of this post is to get some cam recommendations. Hopefully, UDHarold and some of you other Big Block guys will step up...

Thanks graemlins/beers.gif

BTW, I forgot to add that I want to stick with a solid flat tappet due to my budget right now. I also want to drive this thing on the street from time to time without killing valve springs.

I'm just throwing numbers out here but I was thinking ~.650" lift after lash is taken out, mid 270s @.050 on intake, low 280 @.050 on exhaust, and a 106-108 lob sep.??? let me know what you think guys..........

bump

With those heads, I'd sugest you try a Crane R274. It's an old as dirt grid, but will works well. BTW Ihere are some pictures of a 505 I built, but have not run yet. 505 pic's (http://bellsouthpwp.net/p/c/pcs0snq/505/)

Originally posted by Chris Hill:
-GM 049 oval port open chambered heads -Team G rectangle port intake Just saw this. Oval port heads and rect port intake???? graemlins/clonk.gif

Dont let it bug ya. Can you visualize the mixture gaining velocity just as it nears the intake valve head? I know, and why do we spend time gasket matching? While I've never done this rect/oval thing, I can see how it might work well ( except for low speed street cruisng? - that's what I'm going to try and see ).

Chris, the cam recommendation for a drag car is out of my league ( looking at the Lunati 402B4 )but even for the pros, a few questions might be

converter stall( the B4 will need all of 4K on the bottle and maybe more n/a!), you final static compression ratio, and it seems that 3.90s aren't enough gear for something that huge. It's a 7500-7800 rpm cam even in a 505!

Do you have a target dynamic compression, i.e. a specific octane requirement?

I have heard of decent results with Oval intake and rect heads but not the other way around like this. How can this work. It's like to worst flow match possible??? graemlins/clonk.gif

Posted by pcs0snq...
I have heard of decent results with Oval intake and rect heads but not the other way around like this. How can this work. It's like to worst flow match possible??? I didn't think an oval manifold would would work on a rect head won't even cover the intake ports will it?

Don't dwell on it. Rect intake to smaller oval runners is the only way it'll work, and it seems to.

gene, the converter will be chosen after the cam and final combo have been set. I will be running a 28" tire with possible future nitrous use, so a 3.90 gear will serve me well.

pcs0snq
As for the oval, rectangle combo........like I said above, the heads have been port matched to a rectangle port and then quickly taper back to the standard oval port cross section. There will be no flow problems. Many people run a rectangle intake on a oval heads without doing anything and it plain WORKS. Remember, racer1320 runs the rectangle to oval combo with great success...

gene, I forgot to mention that race gas is to be expected with no limit on dynamic compression...

The rect intake to oval heads works well with no crazy portwork to the heads to "make" them rect.
Ed "Racer1320"'s combo is like this with slight work to the intake.

I've also seen good working combos done as stated where the head was "rectangled" by porting the runner entry. Usually cannot be made perfectly matched but as seen in Ed's setup obviously isn't that critical.

A stock oval will not cover a rect head opening but some aftermarket manifolds will and can be used. Oval intake on rect head.

Generally it is better and easier to just use the correct intake for the head. However in some cases it can be used effectively.

Glad to see the guy's jump in here b/c I was gonna say maybe they would!!

AND please look Ed's combination over b/c you really don't need to go that wild with a motor like a 496/505 to get good times if you can get it to hook!!

Grunt and tires and gear will do it nicely without all that much CR. and high rpm stuff b/c Ed's combination does..

I even have a feeling that 3.73's may do nicely too as well as your 3.90's..

Build for max. mid to lower, upper range GRUNT and you will get there..

Guy's, please set him an upper CR. limit that will allow him to cruise the shows and yet meet his goals... I'm figuring at most 10.5 with a cam that will build grunt like I'm mouthing about???

pdq67

guys, compression is what it is and I can't change it now. I already have the pistons which will creat a compression just under 14:1 when its all said and done. Everthing listed above I already have or have purchased. I'm looking to make what I've got run as fast as possible.

I don't want this to be a high rpm motor either, I.E ~6900-7000 max rpm. However, I think I can run more cam and not be hurt too much due to the cudes and high compression??? The whole cam thing is still up in the air.

Chris, your shift points and trap speeds will be well below that rpm level. I should think something just a schooch bigger than the XR292 all the drag boys run might serve well.

Given the 3.90s and such, Harold's 288/296 would certainly fit the RPM range well, but not having ANY NO2 experience, I'm not sure whether I'd look at the drag version ( 107) or the street version (110). With 14:1, I'd opt for the street 110 I think.

Can't flycut those domes .200 or so??? Car might be just as fast and not nearly as finicky.

Curious question as to whether a large cam fit to the 14:1 will actually ET any better than a cam fit to the driveline and shift rpms, or ET worse.

Hopefully some guys with race expereince pick up the discussion at that point.

I would always pick the cam generally focused on the rpm range, which, of course, is dictated by the driveline. Then you can get out the 'vernier scale" and dial in LSA, lift, phasing, etc.

Plus, not for nothing dude, but oval ports on a 7000 rpm 500-incher. Sure they'll go there, but you're 1000 rpm out of the sweet spot.

yeah gene, I don't really want to be around 7000 on the shifts with a 4.25 arm out there. Was thinking maybe ~6500-6600 on the shifts and a little more through the lights.

The 3.90 gears aren't set it stone either... I can always swap them out. Its just what I've got now.

I want to keep the high compression though. Built the pump gas BBC's and want to do something different.

Hopefully some of the hardcore bbc racers will jump in here.

thanks for the responses thus far guys.. graemlins/beers.gif

Also, does Harold check tc much anymore? Whats his email? Might be best for me to just shoot him an email..

i like what your biulding but was wondering what made you decide on the short rod?

The 6.135 rods were purchased before I decide to go stroker.

I wish that I had a longer rod. This would allow me to use a crank with more counterweight. This definately makes things much easier when it comes time to balance.

If your building one from scratch, go with the longer rod.

Now this is just a suggestion again, but my copy of DRAG says my car should do something close to 130mph at 10.50 sec. if I can get it to hook per D2K, with my about 550hp, 9.8 to 1 CR. 496, M-20, 3.31's and good 26" or so tall tires combination.. (IF I don't break something???)!!!....

Before anybody gets excited about sim. programs, I will be happy if I get a middle 11's to even an 11!!

BUT what I am pointing out is that with such a big motor, you can run VERY well AND not be all that radical!!

If you are set on CR. and gas isn't a hang-up, then cam for max. DCR and thus "grunt" and gear and tire accordingly!!

There is a story in one of the mag's somewhere about a guy that had something like a 4.30 geared 427 in a light ride and later he went to something like a 555 or 556 and didn't run all that good. He ended up changing to something like your 3.90's and ran a lot better...

Please just use as food for thought..

Just tryin to help.. And I know I'm not helping much b/c I'm really out of my element here..

pdq67

If you want to stay solid lifter, I would probably not go bigger than the Lunati 402B1LUN. It is 296/304 at .020, 263/271 at .050, .630/.630 gross valve lift, and 108° LSA. If you want .650" NET valve lift, get a set of 1.8s(gives .667" gross, .651" net with .016" lash). This cam has gone over 100,000 miles on the street, it is very reliable. It should put you into the low-tens, without NO2.
Once you're there, we can work on the 9s....

UDHarold