Stingray1973

Guys - Need help on an intake/carb set-up that will fit under the factory 73 hood.
Seems like there is no definative answer on this question with others posts. Some say the air-gap or RPM's fit while others say not. I need some advice before spending $$$. I have a local machine shop rebuilding my 350 and I'm thinking of going with an Edelbrock Air Gap Intake or Performer RPM with a Holey 750cfm.
Will this combo fit under the factory hood??????

Going with flat top pistons, cro-moly rings, comp cam, Iorn Eagle Heads, 9:1 compression (driver car) and a Holley 750 to fuel it! Don't think the Holley 650 will fuel enough.
Any suggestions?? My first Corvette and first build.

BigBlockk

Get a '78 to '81 Corvette intake manifold. No problems getting under the stock hood.

BigBlockk

Later.....

Ganey

The Performer Air Gap should fit easily w/ a Holley & aftermarket drop base filter. 650 would be fine for 350.


The RPM incl. Air-Gap fit the similiar 76-79 med. rise hood on SB w/ aftermarket dropbase filter & Holley & have the needed about 3/4" clearance over the vent tubes.

Stingray1973

Cool - This seems to easy! Wonder why eveyone says they RPM or Air-Gap will not fit. Even Edelbrock is trying to sway me from the RPM or Air-Gap b/c of clearance problems.
So...650 cfm? My builder and others are telling me to go for a 750cfm...working towards a 350/350 Hp and folks think the 750cfm will be needed to properly fuel the car.

rcread

650 cfm should be plenty for a Holley

Bob in Dallas

The biggest problem for power increases is not matching the parts used to the application properly. For a 350 HP 350 CI engine, very mild streetable parts easily provide this power level. You should look for performace pieces rated for the RPM range of most use. On the street at this power level that should be from 1000-5000 RPM.

With your anticipated use, the Performer RPM or Air Gap are overkill. Thier performance ranges are from 1500/2000 to 6000/6500. The suggestion of the 76-79 intake (L82 aluminum only) is a good one. The proper Edelbrock is the Performer.

A 750 Holley is capable of supporting about 450 HP and is again, overkill for your application. The 650 Edelbrock is a good match for the Performer manifold.
Under no circumstances use a double pumper Holley for this mild engine.

With the parts for the basic engine you describe, you will not be happy with the driveability of the car with the larger carb and higher RPM intakes.

Your biggest thrill will be from the torque available from about 1000 to 4500 RPM. With the milder intakes and smaller carb, you should have easily 400 lbs/ft torque at about 3000/3500 RPM with minimal drop off (about 50 lbs/ft)until about 5500. If you can maintain greater than 350 lbs/ft at 5200, you have 350 HP at this fairly low rev range.

Don't forget a good set of headers and a freely flowing dual exhaust. All of the intake side work on the engine must be matched by the size and efficiency of the output allowed from the engine.

Listen to other people on this board who have built torque motors for the street. They are the ones who did their homework, matched the parts to the task desired and they are completly happy with the result and very seldom have problems with their engines performance or reliability.

Good Luck with your first project. Be careful to not get into the "mines bigger than yours" or you will be dissapointed in the end.

Stingray1973

Great feedback - sounds like the best advice/set-up at this point is the Performer manifold (which will easily fit) with a Holley 650 cfm. THANK YOU!
Why not a double-pumper?? Whats the disadvantage of a double pumper?
I do have a set of Iorn Eagle 165cc heads ( the machine show did some light work to improve flow) with upgraded springs and roller rockers and hope that the Performer manifold/650 cfm will feel right and always on the dual/right size exhaust.
The guy building my motor builds sprint car motors so I'm sure he learns towards the overkill side.

63mako

The 1970 454 450 HP LS6 with 11:1 compression used a 780 Holley. A 750 holley is TOO BIG for a 350 350 hp. Check with a different engine builder.

Stingray1973

Thanks guys....650cfm it is....SOLD!

2th farmer

The Edelbrock RPM air gap and a Holley 750 will NOT FIT if you want to run any kind of breather at all. I managed to close my hood with the threaded rod in the center out and it is bumping the underside right now. Mine is a BB 73 and I am going to cut the hood and attach a L88 scoop from Ecklers when I am done.

VETDRMS

I have both the RPM Air-Gap and Victor Jr. on my 406 with my stock hood and a 1/2" phenolic spacer using a Moroso Drop Base aircleaner and 3" element.

I will be listing my RPM Air-Gap for sale in the for sale section soon, barely used (less than 1000miles).

Ganey

He is asking about a SB 350.

Nevertheless the first sentence describes the situation w/ the SB RPM intakes & the 68-72 SB flat hood ...
& the 68-72 BB RPM intakes w/ BB hoods. (not L-88)