73 LS-4

I should be getting a hold of an L-36 intake here shortly for a 68 (aluminum) figured this would be somewhat of an upgrade from my cast iron LS-4 intake without having to change hoods or go to a single plane (I like all the low end) or get rid of a good Rochester. My question is, do these intakes take well to minor port work or am I wasting my time by trying it?, figured worst case scenario is I saved 20lbs of weight by switching.

:cheers:
Pat Kunz

trw

Which intake are you getting?

Rec port 793, 801 or the oval port 948, 067 I thought these were high rise intakes.

The only one that I thought would fit was the 569 with a Holley flange.

thanks for the info

Terry

73 LS-4

It's a 3919849 from a 68' 427, 390 horse. It's a large oval port Aluminum intake with a Rochester bolt pattern. It's considered low rise in most books i read.

:cheers:
Pat Kunz

mountainmotor

Not much can be gained in the way of porting that manifold but if you modified the center divider a little along with a cam change you can pick up some power.Not so much a larger cam but a newer design lobe and a LCA change for the better.I assume you have the stock cam ?Your sig did not say other wise. What rear gear ratio do you have?

trw

Pat

Let me know how it fits. I'm like you, looking for something that will fit under our hood.

That is the one that I did not see, until you gave me the number. Mortec just lists the three as oval port.

thanks

Terry

marky mark

I had mine port matched to my heads which opened up the intake openings a bit, but I'm not sure it made any dramatic difference, but it didn't hurt.

The main problem with these manifolds is they are almost flat and the runners are not equal lengths. The local Chevy guru said they stopped flowing well at high rpms so don't expect much past 5300 rpm. That being the case, don't pick a cam that makes max power at 6500 rpm for example. It's a good looking and streetable intake which helps more on the torque side than the high rpm horsepower side.

This is one of those compromises we make to keep from going the L-88 hood route, which doesn't help the value of a true L-36 engined car.IMHO.

Regards, Mark :flag :chevy

73 LS-4

Hi mountainmotor, the cam has been changed when the 2nd owner overhauled it, but the owner said it was stock specs and It's deffinitly mild, not much of a lope or high RPM rush, just a good steady pull to about 5000-5500rpm and then falls off. As far as gears, they are either 3.08's or 3.36's, it should be 3.36's with the M-21 but 3.08 was an option, as soon as I get it back from the body shop I'm going to check the axle code. In either case a 2.20 first with either of those gears isn't the best out of the hole so it needs as much low end torque as it can get and it does better then I thought it would with the setup but I'm looking at 3.55's in the future, unless it's got the 3.36's then I'll probably stick with them since i do take it on long trips occasionally and the difference between 3.36 and 3.55 I doubt is worth the expense.

:cheers:
Pat Kunz

73 LS-4

Thanks for the info Marky Mark, I really never planned spinning this engine much above 5500 anyway so that's not a big problem. If it helps the torque over the LS-4 intake that would be great, can't have too much torque in my oppinion a little extra hp wouldn't hurt either :D I may still go the aftermarket hood route eventually, but i think this may be a good compromise intake between the LS-4 intake and something like an Air Gap or Stealth.

TRW, I'll let you know how this works out

:cheers:
Pat Kunz