Inliners International Forums General Discussion Hi Performance Street 292: headers vs. split manifold? Cam?

Hey guys.

I am going to be putting together a 292 for a 1964 chevy van. The van is a hot-rod, but also a daily driver. I will never drag race it, but will be having fun on the street with it. This includes burn-outs and impromptu traffic light competition. I sometimes haul heavy gear with it, but never tow. It currently has a 230 that is getting tired. The transmission is a ultra-wide ratio T10 column shifted 4 speed with 3.44:1 first gear and 2.56 rear axle gears for the freeway. It is effectively a 'poor man's overdrive'. Another way to think of my drivetrain is it is very similar to having a saginaw 3 speed 3.73 geared, with an 4th gear OD.

I plan to run a offenhauser 3x1 intake with three rochestor monojet carbs. The linkage will be progressive so the center carb is primary, and outer carbs acting as the secondaries. I will remove the choke on the outer carbs.

I have two questions I want to put out for discussion.

Exhaust: I have three options: Tubular full length headers, tubular 3/4 length headers or a custom 292 split manifold made by Kraig Sexton (splitz manifolds). I originally felt the manifold would be good to retain the exhaust heat under the manifold, but with the tight doghouse of the '64 chevy van, maybe the radiant heat from the headers would be enough to provide manifold heat. It gets quite hot in the doghouse, on that side of the engine.
How important is it to directly heat the underside of offenhauser intakes? Keep in mind I live in Western washington so our winters are mild compared to other parts of the country. It does get down to freezing temps here, but not very often.

I plan to upgrade the intake and exhaust. I plan to leave the 3927763 head stock, so figure on stock compression ratio. Probably 8:1 or whatever a stock 292 is. I would like to continue being able to run low grade 87 octane fuel in all conditions without knock or pinging.

I would appreciate receiving some cam advice and recommendation to take advantage of the planned intake, carburetion and exhaust improvements. I live in Tacoma, conveniently located to Delta Camshaft, who can regrind my cam to any profile I want.

In regards to this relatively mild street setup, I am considering simply leaving the cam stock, but I wonder if would there be any advantage to changing the cam profile from stock to take advatage of the intake/exhaust upgrades? If so, what new profile do you recommend? Please discuss duration, lift and LSA recommendations and why.

The van weighs about 3000 lbs, but sometimes I haul up to 1000 lbs of cargo, so we can figure on vehicle weight being 4000 lbs.

With my 26.6" tall tires and 2.56 rear gears, my engine is turning 2100-2300 rpm at freeway cruise speeds of 65-70mph. I want efficient operation during cruise, and want to retain the strong low end and midrange torque of the 292. Bottom end is stock, so I do not plan on revving it any higher than a stock rotating assembly can handle. I also understand the stock cylinder head will restrict upper RPM airflow, so I want to focus on having a broad powerband that increases streetable performance as practically as possible given the limitations of the stock engine and head. I figure redline of this engine will be 4500 rpm or 5000 at the most.

I do want a solid idle and a cam that is very steetable, but a little chop or aggressive idle sound is quite acceptable.