GOSFAST

You need to concentrate (pay closer attention) on the cam spec choices when you're working with two different platforms. You'll need an entirely different cam profile between a 4.250" bore platform and a 4.500" one.

We have numerous 250*+ @ .050" intake lobes (hyd-rollers) peaking at 6100 with well over 700 HP and 700 Torque. We've been at 740+ with under 10:1 for years now utilizing the 4.500" bore on hyd-rollers. Most peak at 6100. We find the heads we use are the "key" part on these particular builds. I would expect a "shorter-stroke" build to be in the 700 HP area with a bit less Torque maybe!

On a side note, a good example of the benefit of using larger bore units began showing up back in the '60's when you had many mfr's using 4.300"+ bores with strokes in the 3.500" range and winding up with some serious Torque numbers back then. HP was good but the Torque was considered outstanding for back then. Gas mileage (at that time) was also a non-issue, but you didn't buy anything like these if you were interested in mileage still!

I'll say it again here, 4.500" bore platforms simply want AIR and FUEL, and a lot of both!

Thanks, Gary in N.Y.

P.S. Talking still "streeter's" here, if we lay out a program with any customer and "gas-mileage" does come up, we recommend NOT using the 4.500" platform, stay on the 4.250" bore, it will use less fuel in an "apples-to-apples" (so to speak) build.

Vortecpro

I have not tried those, but the extra lift would be a good idea if it revs. The voodoo test was 2.190/1.880 11/32 with several lifters including Comp short travel lifters. I will have to try those Crane lobes, thanks.

cv67

OP little more radical than you want...just to get ya motivated
http://www.chevelles.com/forums/13-p...er-idling.html
no low ent tq problems here

Jebbysan

Thanks Bruce.....
I tend to cam big on the large bore stuff because it likes it.....and of course this should only be done if the heads are sent out and had a program put on them......
You can cam these small as Vortec and Century say....but you are spending the money so why not make it nasty? These 4" stroke engines make torque everywhere anyway......
Two different schools of thought I guess.....the smaller cam stuff will surely be smoother on the street.......

FYI.....the Brodix BB-Xtra O (Brodix calls it the "race oval") is the baddest head I have ever screwed to a BBC.....I wonder if M2 has a Program to take the heads the OP has and make them into this....if it is even possible....

Vortec is correct about valve angles......they are critical for proper low lift numbers......

Anyway...it is your 509....do it how you see fit

Jebby

Neil B

Funny you guys should mention Crane.... I've always wanted to run a Crane Cam, but I never have. They have a few nice hydraulic roller lobes in the .359, .365, and .372 lobe lift range (.610, .621, .632 gross valve lift). The .200" lift duration numbers look good on these lobes as well. My understanding is that these lobes are used extensively by Mercury Racing in offshore boat engines and have an excellent reputation for being easy on the valvetrain. Even their shelf grinds with these lobes look pretty good. They make 110 and 114 LSA versions. I might opt to go a bit tighter LSA and and close the intake valve sooner.

Neil B

I looked hard at the 298cc RR BB3-Xtra O. Killer heads. At the end of the day, they really deserve a solid roller and a big single plane manifold. The other nice thing is the exhaust port is still very close to stock on these. I don't think the 'As Cast' Race Rite can be CNC'd using the Brodix in-house program. I think they start with a different casting.

Neil B

Man that thing sounds nasty. I might have to sell my Morel 4603s and get real with a solid roller.

Neil B

I like the way you think. I love de-stroked rpm motors. I took the 302 out of my '69 Z28 and put a 13.6:1 372 in it with a 268/274@.050 solid roller. It's a blast to drive.

centuryoldracer

Mine are in the .620 range for lift, and you have to run the expensive Howards cams roller lifters that don't collapse if you want to make power, also the lifter is light weight. You also need to have light weight valve train components throughout.

tt 383

no no, really thank you. Anytime some of you battle proven guys are willing to divulge results from testing you have performed its to our benefit. I know I wouldn't have the time or money to try and figure something like that out and be left scratching my head why it's a POS up top! I like the look s of that VooDoo too, for a shelf grind it's what I was actually looking too if I didn't have one custom ground.

centuryoldracer

Not sure what the end goal is here but I like to drive mine with the AC on and have reasonable rpm on the highway. I run 308 gears in the rear, and loosen the converter 400 rpms from stock if it is a automatic, and it will still destroy the rear tires.
If I was going for ultimate power with no regard to street ability and comfort, I would put a bigger hood on, so I could run a better intake, ditch my factory (ported) exhaust manifolds for headers, and run quite a bit bigger of a cam, but 600 fairly mild horsepower is a nice package, and it looks completely factory under the hood.

427Hotrod

It's a longer stroke combo with larger heads (555" and Dart 335's), but a few years ago I did a bunch of dyno testing with various carbs, intakes and cams......solid flat tappet, solid roller, hyd roller, hyd roller with solid roller lifters, dual plane, single plane, BIG single plane, 4150 carbs and Dominators. HP ranged from 740-850 with same shortblock and heads.

The hyd roller was a Crane 254/258 with a 112 LSA. It used 1.8 intake rockers and 1.7 exhaust. Seems like it ended up with .720/.680 lift. It peaked HP around 6300-6400 and rev'd clean to 6800 or so with Crane Hyd lifters. With a Dominator and Super Vic intake it broke 800 HP. 760'ish with a 1000 HP and a ported Vic Jr intake.

JIM

Neil B

I'm starting to think about camshafts for this build. I will likely go custom, but the Crane PN139781 hydraulic roller caught my eye:

Adv Duration @.004: 306/318
Duration @.050: 244/256
Lift (1.7 rocker): .632/.632
LCA: 110

Ideally, I'd like to close the intake valve a little bit sooner, but I don't think I want to add any more overlap by closing up the LCA with these particular lobes. This cam has very stable lobes and is well-proven in endurance marine applications. The intake/exhaust duration spread is about where I want it for the Brodix heads. This grind comes standard with a cast-iron distributor drive gear as well. What do you guys think? If I go custom, I'd probably shorten the intake duration a bit and put the LSA on a 107 or 108.

centuryoldracer

I think it is a decent compromise of having some street manners, while still making a lot of street horsepower. The cams I have been running are about 10 degrees less on the duration with similar lift, but on a 4.310 bore. I can't wait to see some numbers on this bad boy once you have it running.

centuryoldracer

I saw a video of you running a very low 9, that thing is pretty awesome.

Neil B

I stopped by the machine shop today and they had bored and honed the block, balanced the crank, hung the pistons, and fit the new rod bolts. Next is to check deck height and deck accordingly.

Jebbysan

Lookin good....how did that crank balance out for you?

Jebby

Neil B

It turned out nice I think. I decided to leave it external balanced. I've got an expensive external balance flywheel on my 468 that I really wanted to reuse. The new SRP pistons are lighter than the old TRW/Manley pistons and they had to remove just a bit of material as a result. The picture shows the two new balancing holes towards each side of the counterweight. I'm trying to keep the budget reasonable in this project and I'm ok with external balancing with the target HP and RPM range this thing will get used in.

Jebbysan

That is great....with your target RPM you should be fine....I do recommend a premium balancer on this setup though (ATI)....just a lot of weight in there spinning around....
Kudos to you....nice build.

Jebby

ajrothm

My **** is old ***** now....

She still runs though...

Hell it has been 8 or 9 years ago we did that thing.