84TAProject

Okay, I run a CCC on my Trans Am, and am feeling the need for a new intake over my dated Holley 300-28Z with the 0-4800 powerband. I run the motor now up to about 5300-5500 rpm, and have traction issues now. I dont want to cut top end power, as next year I am seriously (meaning if I have the $$$) considering building the motor into a 383 with a larger cam. I have 487 casting heads with 1.94/1.50 valves. How is the performer RPM spreadbore? I need a spreadbore manifold, and would prefer not to run an adapter if possible. Is the rpm the best spreadbore out there? I have my EGR plugged now and it has no effect on anything, so EGR is not a major concern. How much willn low end take a hit from this?

F-BIRD'88

The Performer RPM will outperform your 300-28Z in the low end midrange and top end. You'll give up nothing and gain everywhere. The holley 300-z28 was an attempt to make a low rise single plane manifold with strong low end, at the expense of top end power. The result was that it didn't do well at any rpm really compared to other non compromised designs.
But at the time it was made, single planes were the hot street manifold on the market. Every one wanted to try one.
Others were Streetmaster, Accelerator, 360 equa-flow, Street Dominator (single plane).
You'll probabily really like the smooth torque and power of the Performer
RPM, not to mention the increased drivability that only a Dual Plane design can provide.

The Performer RPM manifold is a higher manifold than your 300-28Z but will fit under the hood with a decent size filter if you use the proper drop base air cleaner.

Search my posts for info a pics. It also fits the Qjet carb.

Search keyword= L-88

F-BIRD'88

84TAProject

Im about to search it out, but I should have no trouble with fitting it. I have a 2 5/8" cowl on it now, and currently run a 4 " filter on a 1" drop base with a domed lid. It may come down to a manifold swap every time before emmisions, but I think it only has to go through one more time.

F-BIRD'88

If having a functional EGR system is important, (emmisions test or visual inspection) you might want
to consider a EGR compatable Dual Plane manifold like the Edelbrock Performer EGR or a GM ZZ4 take off. With your motor combination I don't think you'll be giving up much in real world in the car performance with one of these manifolds over the RPM.
You can gain some of the top end power of the RPM by adding a divided spacer on top of these other manifolds. Makes it more of a "hi-rise" with a larger plenum volume. I wouldn't use an open spacer. It will outperform a single plane like the 300-28z at any rate.
When hooked up and functioning properly a EGR system
helps drivability and mileage while crusing by allowing more ignition advance without pinging or knock. At the same time reduces NOX emmisions. It does not flow at full throttle so it does not degrade full throttle power at all.
Lots of pluses, no down side. Something to consider.

84TAProject

Can I externally do the EGR? I thought Vortecs and Vette heads did that. I am willing to swap manifolds for emmisions reasons. The RPM IMHO looks better under the hood from what Ive seen, and by looking at the runner design on hte bottom it looks as if the runners have too sharp a curve to adequetely feed say a 383 a year down the road when emmisions isnt an issue. I dont use the EGR now, but on another thought. The car seems to run noticeably weaker at 220 than at say 180. Like 25 horse weaker. My EGR is blocked off. Could this be a potential cause for it? Connecticut currently only has the sniffer test. I dont know, I guess Im stuck wanting to build something old tech in a high tech world. Could the performer non rpm adequetly feed a moderate 383 (360 horse or so, built for a blower for the year after. I plan years ahead ).

copperchick

I'd love to not have to buy a new carb if that were possible and just rebuild the one I have. I just didn't think it'd fit with an adapter plate Any clue if it would fit? I bought the squarebore RPM from a friend because it was just too good a price to pass up.(i.e. hood clearance issues). I have a drop-base air cleaner.

Tracey

copperchick

You're in the same boat I was in with my 84 Z28. What I did was get that last e-test done ahead of time. The results are good for 1 year, so when your actual test becomes due, the results you get now will still be valid (unless your birthday is in Nov or December, then you'll have to wait a few weeks). Pass the test now and you've got all winter to mod the way you want. You could get pulled over for a spot check theoretically, but I have never had it happen to me (knock on wood). Just a thought.
Tracey

84TAProject

Thats a good idea, but what blows is there is no emmisions testing now until february of next year in CT when they change over , and Im due in february. I think my car is old enough after that so it will never go through again, which is when it gets stepped up to an aggresive cammed 383.

copperchick

OMG. That does blow. My condolences bud. And good luck with the mods!

F-BIRD'88

I think it will just fit if; you use a 1/2" qjet to holley square bore
adapter, and use the above mentioned GM Z28 L-88 drop base
air cleaner with a 2.5" filter element.

The drop based air cleaner that you have probabily is not the same thing. You can still buy the right one from various restoration parts companies like Ecklers corvette parts and
Year One. Search my posts for pics showing the difference.
Keyword= L-88
I could also see you picking up some hood clearance by custom welding the aluminum adapter right onto the intake manifold after milling down the bottom of the adapter and the top of the carb pad.
It would have the same height as the Performer RPM with the Qjet flange. +/- 1/4 inch.
If your really serious about fitting your Performer RPM intake with a Qjet carb under the hood of your Camaro give me a email and I'll advice you on some local shops that can do the nessessary mods (alumium welding and machining) for ya.

russ_q@hotmail.com