so is there a hp gain when going with the air gap over the performer with stock ported heads (289)

 

i'd say with the right engine yes. I personally (and that's only my own experience) would use the Weiand 8124 with a 289 stocker. I did and it matches perfectly (only modification was a set of long tube headers back then)

 

Yea but i dont think mine would be called a stocker, the only thing not upgraded is the crank

 

Just another data point.

None of my SBC builds ever felt the need for more than an RPM. Most were 350's, steel crank, forged pistons, decent for the time iron aftermarket 2.02/1.60 heads, 220-ish @ 0.050"/maybe just under 0.5" lift hydraulic cam, 1.6 ratio RR's, various carburetion up to 750 vac sec. I'm not at all sure that I'd have put an RPM on a hydraulic flat-tappet 305 even if it had been available back when I had one of those things.


Norm

 

I don't know it all but, you need to choose a cam before selecting a manifold. The cam is the personality of the motor. The bolt ons are meant to complement that personality.

If it were mine, I would hire a custom camshaft guy I trusted to build a cam that worked for my motor. He will need to know your intake runner size, combustion chamber size, piston type and cc, quench, rod length and auto or manual tranny. Valve size and lift may dictate hoggin out the pistons for valve clearance.

Only after that can you determine at what rpm your engine is gunning for. Then you can select a manifold to complement your work.

But, don't shoot for highest horspower. Shoot for power where you will be driving it the most.(hard I'm assuming)

Yu misspeld secret in yur cig.

 

I would go with the air gap I just saw an article on a 351c and they were trying all kinds of intakes and the air gap blew them all away .i know it's also the most popular for the 350 for the chevy guys.yes it is a little rough on a cold day but once the engine is heated up you won't regret it.the air gap is what i will be putting on my 351c but i just got the car and want to see what the stock intake and heads do first.

 

Just keep in mind that the airflow demands of a 302 are somewhat less than a 351C . . .


Norm