wesmigletz

Just read the article and thought others might find it interesting. I wouldn't normally buy R&C, but the cover caught my eye. They started with a mild, but healthy 283, with an unknown hydraulic cam and early, stagger-bolt heads, and what looks like 2 1/2" rams horn manifolds. With a single four barrel cast intake, they made 290 ft lbs. torque (at a relatively low 3200 RPM) and 225 horsepower (4800 RPM) at peak.

They then swapped-in a Comp Cam 30-30 cam (p/n 12-107-3, 254/254* @ .050" and .485" lift on a 114* LSA) and a dual quad intake with WCFBs built and tuned by Chuck Smith. Torque peak dropped to 276 ft. lbs. at a higher 4600 RPM and horsepower peaked at 267 at 5400 RPM.

I thought the numbers were interesting. The 30-30 cam gave up a lot of low-end torque (as expected), but added 42 horsepower up top, which I found pretty impressive. I would have liked to see a comparison with the 2 X 4 set-up on the baseline engine before the cam swap. I think it would also have been cool to see how the 097, L79, and LT-1 cams would have performed for comparative purposes.

JohnZ

Further mods probably wouldn't make much improvement - those old 1.72/1.5 small-port heads are already strangling it.

SWCDuke

Yeah, I agree on the heads, but a set of nicely massaged 461s with some corresponding work on the inlet manifold will easily get it over 300HP.

Duke

wesmigletz

Duke, power wise, how do you think the 2 X 4 set-up would compare to the cast 4BBL? What about a low rise dual plane, such as a Performer? Wes

SWCDuke

I've recently had some discussions with an individual who is building a solid axle vintage racer that will see limited street duty. A 283 with 461 heads, and the old 2x4 setup is the basic configuration. I inspected an old 2x4 manifold a couple of weeks ago. Some ports are pretty straight and some have a weird twist. Looks like they can be opened up to nearly match the size of the 461s. Recall that this manifold was used on the early "medium port" heads with 1.72" valves so the runner cross sections are smaller than later manifolds designed for 461 and other big port heads.

I think this manifold with the two WCFBs can be made to work, but it will probably take significant doses of black magic, witchcraft, and other occult "sciences". I got some references for some 2x4 gurus who have apparently made the system work pretty well in vintage racers, but I'm not sure if they are willing to talk.

I recommended the 30-30 cam, and if the manifold can be made to work okay the 283 with well massaged 461 heads, good race headers and open exhaust should make over 350 SAE gross HP @ 7000, and could approach 400 is everything "clicks", but it rarely does.

I can't really compare the 2x4 setup to anything else because it is impossible to model for a simulation program with any degree of accuracy. All I can do is guess!

One "advantage" that the 2x4 setup has is that the manifold runners only average about 3" length versus about 5-6" for a typical dual plane four-barrel manifold. The shorter runner length will enhance top end power, but the combination of the 30-30 cam and short runners will really kill low end torque, however, since the primary application is vintage racing, that's okay. It will still be streetable, but definitely not a torque monster.

The mixture distribution will be a nightmare to sort out and I don't know how well WCFBs will take to 1g cornering loads, but I don't think they will like that kind of lateral force.

It would be much easier to "tune" this engine with a single four-barrel (and FI would be the best setup), but given the rules it has to be "vintage", so the only four barrel manifold that could be used is the medium port CI manifold with a WCFB that was on the base engine, and THAT setup would be VERY restrictive.

Duke

wesmigletz

Duke, thanks for the detailed response. I'm building a bored and stroked 283, and plan to make it look somewhat period correct. I had a pair of "clone" carbs done by Bob Kunz (Bob came highly recommended by JohnZ and others). He was a little concerned about the WCFBs if I were to be doing road course racing, but thought they would be fine for drag racing, unless I went wheels-up. I think your problems will be with the fuel sloshing in the turns.

Initially, I'll probably just gasket match the intake and may play with spacers to see how they help/hurt, but ultimately, I'd like to thoroughly re-work the intake. Thanks again, Wes

Desertvette

Ok I'm confused. I thought all 461 heads were 64cc and the original power pack heads on a 283 were about 57 or 58cc.
That being the case ,doesn't the compression ratio take a big dump thus requiring new pistons to compensate.
Straighten me out. Thanks
Bob

JohnZ

Yup, the head swap requires new domed pistons to maintain the compression ratio.