347 Hood Clearance

[Drivunn]

Putting in a 347 and need to know what intake manifold, spacer, carb and air cleaner combos fit under the GT hood/scoop ?
Anyone have any height measurements - already pulled motor so cant measure myself
Any recommendations on dual plane intakes ?
Thanks Steve

[Foxy 83.5]

Back in the day I had an 1983 GT with an Edlebrock Performer, 1 inch spacer, Holley double pumper and low cleaner. It fit under my hood with the scoop cut out. I should have put convertible motor mounts then I wouldn’t have had to cut it. It only stuck out by about a half inch in the front.

[ashley roachclip]

It is a 302 , what ever fits on a 302 , fits a 347.
I have a 347 in my 84 .
Performer intake , 1/2 nitrous plate , 650 dbl pumper , and still the original dual snorkel air cleaner fits fine .

[Drivunn]

I know a 302/347 is same block. Its about what fits under the hood scoop so I tried to clarify 347 so no one would ask.
And an Air Gap fits a 302 but I have no idea if it fits under the hood/scoop of an 83 GT.
So far the tallest "stack" seems to be a performer with a one inch spacer under a Holley?


Would the Air Gap fit - Holleys site lists both Performer 7121 and the Air gap at the same pad height of 4.90 which seems odd.?

Performer 2121 max pad height 4.12
Performer RPM 7121 height 4.90
RPM Air Gap 7521 height 4.90
Wieand Stealth est. height 4.5

[85MUSTANGTGT]

The combo in my signature below fits under stock '85 hood with factory dual-snorkel air cleaner, barely. It does rub a bit on insulation pad. Instructions for my intake list height as being 4.12". Currently only running an insulator gasket (3/16" thick) under the carb. Also using Energy Suspension engine mounts.

[Hissing Cobra]

I've got a 347 in my '79 Cobra and it's got an Edelbrock Victor Jr. intake manifold, 1" spacer, Holley 650 double pumper carb and an aftermarket air cleaner with a 3" filter and if fits just fine. However, my hood has the factory cutout for the Turbo 4-cylinder and it fits underneath the '79-'82 hoodscoop without any issues.

[Drivunn]

Thanks guys..this is the kind of info I was hoping for...Keep it coming.

ill have no hood So cut out is open into the hood scoop.

[Drivunn]

Ill have no hood insulation, so open to scoop.

[Broncojunkie]

There's a guy on here who fit a 460 under the factory hood (with the cutout). Shouldn't have too much trouble with a 302.

[wraithracing]

Performer RPM and Performer Air Gap are essentially the same intake. The Air gap has openings between the runners for less heat build up and cooling (AIR GAP) otherwise its the same intake in regards to design/height, etc. Good Luck!

[mustangwolf]

I see some guys are running the factory dual snorkel and some an open air cleaner. Any consensus on which is better horsepower/airflow wise?
Building a 347 for my '83 GT and plan on using the Air Gap.

[85MUSTANGTGT]

The dual snorkel air cleaners were originally designed for 460CI engine applications and are capable of flowing plenty of air. They also obviously draw cold air from the fenderwells instead of the hot, underhood air of an open element air cleaner. Couldn't find them right off, but seem to remember seeing CFM or HP numbers floating around here on the forum.

[Drivunn]

Thanks all for info. I’m going forward with the air gap . Had thought the edelbrock website in error as on chevys the air gap adds at least an inch over the the rpm. I’ll be running an open filter inside a strut bar.

[cb84capri]

I don't like the Performer RPM Airgap, seemed like a gimmick in my experience with it. It fit under my hood without any issues but caused me all kinds of carburetor heat soak issues that didn't exist to that extent with the Professional Products Typhoon it replaced. Much larger ports for the Professional Products intake too, and a rear coolant crossover to liquid cool it and help further regulate manifold temperature - nobody else does this. Tried to put an American made intake on my American made car, but in my opinion the Chinese Typhoon intake is better, hence why I went back to it when I built my 347. Both fit under my Capri's hood without a spacer. Both of these were about the same height, also use the stock dual snorkel air cleaner, and Energy Suspension motor mounts. The Airgap ports are better suited to an engine with stock heads, the Typhoon is a better choice with aftermarket.

Cale

[Drivunn]

In terms of horsepower loss, the Air Gap has become my least worry! No versions of BluePrint's 415 hp 347 are available for at least 3 months..maybe more...as the supply of cores has dried up due to covid. Considered a 408 but 450 tq would really exceeds the stock T5 tranny/7.5 rear end. So got Summits LAST 370hp 306 BP out of Nebraska ! BP has no other 306s in stock...again due to core supply.

At least this will be the same hp output as the original Pop Hot Rodding motor , although there is no data to compare with the BPs 350 tq rating which still exceeds the non world class T5.

While there may be a potential horsepower loss on the drag strip, down in Georgia heat/vapor lock is my enemy in street use. Switching to an Air Gap really helped deal with the heat on my 383 66 Vette. And its been good on my 408 Challenger as well as my daughter's El Camino. All have successfully survived 100 degree heat and Hot Rod Power Tour's infamous 1 -2 hour lines. I'll be using insulators and a regulated return line as well.

[Hemlock]

I'm running a 347 in my 84 RS Capri with a stock no scoop hood with no insulation, a RPM Air Gap manifold, Holley 4447 650 double pumper, a NOS sniper nitrous plate, Energy Suspension motor mounts and a duel snorkel air cleaner. I had to change the air filter to a thinner element to get the air cleaner to not hit the hood. It was literally touching and would push up the hood in the center a little when revving the motor until I changed to a thinner K&N element. When I did my UPR tubular K-member, I got the Maximum Motorsports K-member drop kit that was suppose to drop the motor down about a 1/2" in the bay, I haven't checked the clearance with clay yet but the motor does look a smidge lower in the engine bay with the drop kit installed.

Hope this helps,

Robert

[KevinVarnes]

Weiand Stealth is another good intake to look at. I think it is comparable to the Performer RPM. Might be a little shorter. I have one on the 351W in my Crown Vic. No Air Gap version, but that didn't bother me.

[306gt]

My GT350 uses a air gap and 650 D.P. with a dropped base 14" air cleaner. Fits under the stock hood (No scoop). On my 85 G.T. I run a Victor Jr, 1" open spacer, 650 D.P. and a 14" Dropped base air cleaner. Hood is cut out and 82 G.T. hoodscoop is used.