I am in need of a carb recomendations, currently I have a 414sbc, 10.25cr, headers, Comp Roller 224/230@050 510/517 lift, ProAction 220cc heads & VictorJr intake. with a 700R4 w/2400 stall and 4.10 gears w/posi. I am thinking of the Barry Grant 750/825cfm Mighty Demon with mechanical secondaries?

I was originally running a Holley StealthRam setup but they dont work reaal well with raised runner heads, constant oil leaks & vacuum leaks, tried way to many times to resolve, I have tried other intakes only to have the same problem, the best duel plane intake I could get almost to work was the Edel RPM intake and it still leaked. That is why I am running the Victor Jr and it isnt leaking oil or vacuum leaks, currently I have a Jet Stage2 800cfm Qjet that with the other intakes ran OK and engine temp was OK, but after installing the Victor it appears I am running Lean, on a very light throttle my engine is runniing extremely Hot even under heay throttle, I even hot wired the electric fan on all the time and still runs hot even though the radiator is cool. So far nothing has run like the HSR and I should be able to do as well if not better. From a dead stop I can lay out 30ft with the carb, with the HSR all the way thru 1st & 2nd and the engine really came to life at about 4500rpm, even though spinning the tires in second at 4500rpm the vehicle came unglued and had to back off.

Any thoughts would be appreciated, Thanks

 

With a single plane intake, you will tend not to need as much carb; as the massive plenum averages out all of the individual pulses from the cyls, and creates more of a smooth flow rather than one with lots of "peaks" which the carb then must be up-sized for. That's why the Q-jet is lean.... it's expecting to see large "peaks" in the flow, which consequently cause it to deliver "peaks" of fuel; without that, its calibration is just all wrong. I would think you'd need no larger than a 750, a 650 might even do the trick.

The Stealth Ram has relatively long, skinny runners, compared to the Vic Jr. That's why it did a better job on the low end than the Vic Jr. There's no way you'll get that same bottom-end grunt out of the big single-plane intake, as out of one with runners nearly twice as long, and not much more than half the cross-sectional area.

IMO your cam and intake are a serious mismatch. You've got a cam that's basically going to nose over at around 5000 RPM, and an intake that will start working at around 4000 RPM. One of those 2 things needs to go.

If it was me, I'd tackle the oil leakage issue and understand why it leaks (since it obviously shouldn't), and run a Perf RPM and a 750 with the rest of that setup; I think that would be the best all-around match.

 

run a edlebrock 750 and youll be happy

 

I appreciate the feed back and dont get me wrong here by my reply, I have quite abit of lowend TQ with the VictirJR intake and even appears maybe a little more than the RPM manifold as well and drivability not knowing that it had a single plane intake you wouldnt even think it had one. The oil leaks and Vacuum leaks are due to the fact of the rasied runner heads. I ran the RPM manifold in which I had very minimalized both intake runner & oil leaks. For the average person this would have been very acceptable performance, with the HSR this engine was turning 6000+rpm (CompCams XM276HR) and I even had the ports on the HSR port matched to a 1206 gasket and the runners smoothed out as well (prfessionally), as far as the oil leakage & Intake vacuum problem I bet I have pulled the HSR at least 7 times & even pulled the motor to make sure it looked like it fully sealed and still leaked, I even pulled the RPM manifold 3 times before I finally got it to seal to some satisfaction. You had mentioned that the Victor Jr wont start working untill 4000RPM, according to edelbrock it actually starts at 3500rpm vs Holley's SR at 4500rpm where it begins to shine. If I am running lean with a 800CFM carb and how will switching out to a 650cfm resolve my lean issues.

 

I think you are fundamentally confused about the RPM ranges of intakes..... the Stealth Ram is a street fuel injection manifold, the Vic Jr. is a full-out racing piece. To think that a street piece has a lower limit to its usable functional torque band lower than a race piece, is absurd to the extreme. You're taking it out of context and coming up with something backwards from reality. When you quote the Stealth Ram ad copy that says "really begins to shine" starting at 4500 RPM, you should include the rest of the sentence, whether they put it there or not: "compared to a stock TPI". It's not at all the same thing as the Vic Jr's useful RPM band, which is designed such that its torque is below some fraction of the peak until the RPM reaches that point.

I think if you just look at the Stealth Ram for about 5 seconds, you will realize that you could port the ports where the intake meets the head, to whatever size you want; it will make no difference whatsoever to the flow of the piece AS A WHOLE. It is ultimately flow-limited by the part of the runner up by the plenum, not by the exit to the head. All you accomplish by "gasket matching" it to some inappropriate oversize gasket like that, is to create 8 little mini-plenums at the far end of the somewhat restrictive runners. Not a particularly productive exercise.

A smaller carb will always run richer than a larger carb in any given situation, because the "signal" at the venturis will be larger. One of the biggest myths in all of hot-rodding is that a larger carb will run rich. But none of that has anything to do with the Q-Jet issues; which is, that the passages in it are designed to respond correctly to the venturi signal typically produced by a dual-plane small-plenum intake (very strong individual pulses per cylinder) as opposed to the signal produced by a single-plane large-plenum one (more nearly continuous flow).

None of this has anything to do with learning to put an engine together so that it doesn't leak; or finding whatever faulty part it is that's making it leak. I would certainly not base the decision to use an otherwise inappropriate and mismatched intake on that reason.

If the runners in the heads are such that they will only seal to a large racing-type intake, then you are probably going to need to run a large intake. In that case you might want to consider losing the mild street fuel-injection cam, and putting something more nearly matched to the Vic Jr in it.