G.M L-92 dual planes
#23
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The way I look at it if you are building up a first gen SBC with a set of AFR heads, you wouldn’t use the same cam and intake with 195 cc intake ports as you would with 225 cc intake ports. You would match the components to the flow capacity of the head or get a different head.
But I have to agree with the guys saying you need to be careful comparing LS motors to first gen any things. The better valve angle of the LS heads makes a lot of the old first gen rules no longer applicable. How many guys have come on here saying a 750 carb is too big for a “350” motor, yet how many guys run less than a 750 on the 5.7L and larger motors.
These engines produce so much more streetable power with so much less cam than the first gens. But most importantly, since they already make so much more low end grunt than similar displacement first gen motors, isn’t it worth trading a little low end torque, and from what I have seen it is only a little, to really take advantage of the higher flow capacity of the improved heads? Especially if you are traction limited at low speeds like my car. Even with the single plane you are foot pounds ahead of the first gen stuff.
#24
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I run a 6.0 w L92 heads, and a single plane vic jr, 850 double pumper, and a medium size cam(227-235@ .050).
I run a stick shift, and that allows me to lug the motor even MORE than an auto with a high stall. I will admit that the engine does feel a bit soft when the revs are WAY low, but I also know that most all theese LS motors seem that way because they come on so hard at and above 3000. And at that point, where the engine is happy all the way to 7000, that the dual plane will definatly be giving up power.
My next LS carb conversion project will be with a th 350 in my 65 Biscayne, and I will go single plane again, with 3.08 gears and a 2400 convertor, but probably a 220-224 cam.
I run a stick shift, and that allows me to lug the motor even MORE than an auto with a high stall. I will admit that the engine does feel a bit soft when the revs are WAY low, but I also know that most all theese LS motors seem that way because they come on so hard at and above 3000. And at that point, where the engine is happy all the way to 7000, that the dual plane will definatly be giving up power.
My next LS carb conversion project will be with a th 350 in my 65 Biscayne, and I will go single plane again, with 3.08 gears and a 2400 convertor, but probably a 220-224 cam.
#25
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I am all for the dual plane,in theory and past builds it worked better.$508 dollars for a intake is just not gonna happen.That is why no one (including me) has built a dual plane for all of us to compare with the single plane.John at scoogin dickey was right about G.M parts direct and the bullshit shipping charges.Looks like I'll wait for a performer R.P.M. or a magazine shootout between the single/dual plane intakes.There is plenty of interest in such an article.Magazine people are you listening???