For my third and last post of the morning I have narrowed my intake selection down to the GM hi-rise dual plane with a milled plenum divider, an RPM Air-Gap, World products single plane, or the Victor Junior. It seems I should go single plane with the 502 revving to 6000. Does anyone know if the Victor or the World Products fits under an L-88 hood or any other suggestions. Thanks.

 

I have a milled GM high rise dual plane and a victor junior intake single plane. I definitely like the Modified GM better. It would go to 7500. I thought the new single plane victor junior would be better but it was not.

 

The RPM Air Gap manifold out performs both open plenum single plane and dual plane manifolds.


[Modified by Cam Potter, 10:18 AM 11/28/2001]

 

Well it looks like I will go with the GM. Norval thanks for your information you have always replied to my posts with great information. How far down did you mill the plenum. Do you agree with Cam about the air-gap. Cam do you know the height of the air-gap, is it roughly the same as the GM. Thanks again guys. I do notice that the air-gap is cheaper. Incidentally Norval did the Victor junior fit under the L88 hood.

 

I was wondering is the 136 manifold still available the same manifold as the 198 on the L88 and ZL1 only without the plenum divider milled down.

 

I'm just guessing, but I would bet the intake on the 454/425 hp and 502/440 hp crate motors are the same as the old L72 intakes without the divider cut.

The factory GM hi rise is a nice piece. I've seen cars in the 9's with it in place. There was also an Edelbrock version.. the C396 (oval port) C427 (rectangular port 4150 Holley) and the C-454 ( rectangular port 4500 dominator flange). All of these ran great with slightly larger runners and very similar appearance to factory intake. One of them might be better to feed the 502. Without some work on the inside I believe the GM one will start to choke up the 502 at high rpm though. Remember it was designed for the 396 and just pressed into service on everything else.

We ran back to back tests with an honest 12.0 compression L-88 installed in a '70 Nova with a 4 speed and 4.10's. There was absolutely zip difference between the factory intake and an old Tarantula (twisted carb mounting) single plane at the track or on the street. At least nothing we could measure or feel. Granted the Tarantuala is a relatively small single plane by todays stds. This was a solid deep 11 sec. car.

If you are starting from scratch the RPM air gap seems to be an amazing piece also if you aren't concerned about original appearance. It just depends again what else you are going to do with it. Is it going to have to lug around at 1500 rpm or do you want to be able to pull hard to 6500? A 502 anything is going to have plenty of low end and mid range so you should probably concentrate on feeding it at the other end.


Jim

 

Jim thanks for your thoughts. I found a 163 intake for sale in the local paper for 160 that I am going to take a look at. If I don't buy this I will probably just get an air-gap. I am sure the 163 came with my motor but whoever did the install swapped in the LS-6 manifold to work with the stok BB hood.