Can a Air Gap fit underneath a Ralleye hood for a 340?

[kawahonda]

I've not able to get a consistent answer from my research, so it's time to ask to prep for winter plans. And oh boy, I'm about ready to open a can of worms with these questions. Grab some whiskey and prepare yourself.

Preface: I work slow and plan well. I make no regrets for anything I've done. Replaced factory 14" Ralleyes for 15" aluminum magnums, zero regrets. Installing a tach into the blank-out non-ralleye slot, no regrets. All original parts kept in the attic, and I'm proud of every choice along the way because it's made the car better. I want to keep my A66 an A66. I don't believe it screwing things up, or making things look "modded'. "Updated" within reason is absolutely the ticket here with a professional-looking job since I'm a perfectionist. So let's begin:

1) Can an air gap fit underneath a Ralleye hood for a 340 w/ stock air cleaner and stock carb? Weight savings seem worth it. Better summer performance seems worth it. Cooler engine seems worth it. No boiling gas anymore for hot-starts. No 1" wooden heat spacer needed anymore to solve this "issue". btw, I have no hot start issues with the wooden riser.

2) What does one do since they loose their ability for the heat-riser AVS choke to operate properly w/out changing the carb?

3) Isn't blocking the heat riser better for today's fuel being that most people drive these cars when it's 50-100F? I don't know anyone who drives their muscle cars during freezing weather or snow anymore. Sure, we still need a choke, but do we really need hot gasses heating up our engines anymore?

4) Does the LD340 block the heat-riser ports? is it more "plug and play" vs the Air Gap? Worth the extra expense to restore?

5) What's the best way to paint an aluminum manifold with factory Chrysler period correct orange paint? Bead-blast a new intake + prime + urethane it? Not a chance I will replace my manifold without it having orange paint..don't want aluminum-looking stuff in my engine bay.

6) My assumption is that with an orange Air gap, if I keep my factory manifold in a container, I ain't really going to loose any points with purists.

7) What happens with all the other stuff that bolts up to the factory manifold? Throttle kick down stuff, etc. Anyone have an air gap that they tried to hook back all the stock stuff up and for it to still grow a smile on a purist's face? Basically, what additional planned-for troubles can I expect? Does the LD340 have less troubles?

The reason I'm asking these questions is because over the winter, I'm considering to upgrade my cam with something more modern, but on the mild side that rumbles. Keep in mind, my goal is to land in the 13s while still being period correct and stock-looking.

Great time to start to ask intake questions.

And hell no, I ain't replacing my 1970 HipO exhaust manifolds.

Curious on the responses.

[Chryco Psycho]

Question 1 - no
Q 2 - retro fit an electric choke
Q 3 - yes it is better to block the heat crossover unless you plan to drive in cold weather
Q 4 - the LD340 is an awesome intake & sits lower , you can stll make plates to block the heat crossover
Q 5 - clean the intake , you can use alum cleaner welders use , engine enamel / high heat paint
Q 6 - Who cares , it is your car
Q 7 - The LD 340 will work better , some minor tweaks are nessisay to make things work such as a extention bar from the end of the throttle cable to the throttle pi . extending kickdown rod

[kawahonda]

Awesome Chrycho, thanks.

Sounds like the LD340 is my only option for that stock look.

My heat riser AVS “sticks” right now. It’s very common for me to have to pop up the hood and “tap” the lever so that the choke plates close. Not sure why, but maybe old age? Seems like I can get a head start on this by doing an electric choke conversion right now.

Sounds like I need to be on the lookout for an LD340...

[Burdar]

Personally, I would verify by opening the hood and placing a string line across the fenders.  Put the string line over the tallest part of the air cleaner.  Then measure the distance you have between the air cleaner and the string.  Do the same thing with the hood.  Measure how much rise there is from the fender line to the bulge in the hood.  Finally, find out how much taller the Air Gap is then a stock manifold.

[kawahonda]

Cool! Would a ball of playdough do the same thing?

[Burdar]

Probably.  Playdough can be a little stiff.  It might push down the air cleaner a little if you place it out on the edge. (giving you an inaccurate measurement)  Just make sure that what you use is easily pliable.  Brand new Playdough might be soft enough.

[kawahonda]

Cool. Here's a good a-bodies post showing LD340 vs Stock intake height.

LD340 is pretty close to the stock intake in height. A little taller (about 1/2") but not much.

https://www.forabodiesonly.com/mopar/threads/ld-340-height.32120/#post-242228

Factory: 5" rear, 4 1/16 front
LD340: 5 1/2" rear, 4 5/8 front
Air gap is : 5.8" rear, 5.3" front, Center: 5.35"

Air gap seems big. RPM is same height as Air gap.

[Rdchallenger]

Why not use a drop plate for the air cleaner assembly to get that extra clearance needed?

[chargerdon]

Regarding point one...will an RPM Air Gap fit? 

I have a 74 Challenger with the 360 and the engine (built by a professional engine builder) it came with the Air Gap intake manifold, and Edlebrock 600 CFM carb (1406), and Mopar Performance Valve Covers and Air cleaner.   A nice looking package.
The car has the "standard" non rally hood.   After installing the engine, and slowly trying to close the hood i realized...darn...it wont close.   So, i began my assault to make it fit.

First, i re-engineered the air cleaner base plate, (basically made it into a drop plate), and then remeasured I think i gained about 3/4 of an inch.   Close..  The air filter itself was 2 5/8 inch tall...my Napa dealer found me a 2 1/8 inch air filter saving another 1/2 inch.
The hood would then close, BUT, i found that in WOT from about 4500 RPM up the engine didn't pull well.   To verify i made a run with no air filter and it pulled great.   I researched some more and with NAPA help found a 2 3/8 inch air filter.   With it on i got enough air so that WOT runs over 4500 rpm still pulled well.   However, the top of the air filter was rubbing the structural webbing on the bottom of the hood.   I was able to "grind off" the edges of the structural bracing under the hood and it no longer rubbed !   So, at least with the standard hood you can make it fit. 

But, i wanted to install the factory looking underhood padding...  I tried and darn it squeezed the padding so much that the back of the hood was popping up a little....DARN>>DARN.   Well not wanting to take off the padding i thought...  Jack it up just a little.   I had some steel plating .25 and .3 inches thick lying around in my garage, so i drilled some holes in the plating and put them between the K member and the bottom of the frame...   The .3 towards the firewall end and the .25 in the front.  There are only 4 attachment points and this was easy to do, one side at a time.   That gave me the rest of the clearance i needed for the padding.   In driving the car i notice zero differences in handling so i don't think the geometry has been affected.  The front of the car of course sits .3 inch higher but that can hardly be noticed, and i could always adjust the torsion bars to lower it back down..   


To recap to make mine fit with standard hood, and Mopar performance Air cleaner:
1) Turned air filter base plate into a drop plate...  (summit sales drop plates for 14" round but mine is a 13").   You cant see the plate at all anyways with the air cleaner on. 

2) Used a 1/4 inch shorter air filter.  Tried 1/2 shorter but didn't get enough air with it.

3) Ground off the down bracing on the standard hood bracing where it goes above air cleaner.

4) Put in .3" "jacker plates" between K member and frame. 

Oh, and i had no real problem with the gas and auto kick down rod with the Air Gap...  Simply lengthened as much as i could with the cable adjustments. 

[Dynamo]

Good conversation Thanks for the help! I am currently building a 410 stroker to go in my 72 & looking at the air gap intake and didn't think clearance was this big of an issue

[Chryco Psycho]

What you have to weigh out is this ,
The LD340 is still one of the best performing intakes ,
With the air gap you have to run a drop base air cleaner ,
As Don found out restricting air with the air cleaner will cost power,
So do you make more power with an LD340 & a 3" air filter , or the RPM & restricted air flow ?? 
My bet is the LD340 & larger air fliter !
Don,t get me wrong the RPM Air Gap is a great intake but !! I wounder if you could mill 1/2 off the top of the intake where the carb sits , I would look at that before shimming the K frame 

[kawahonda]

Alrighty. I should be on the lookout for an LD340.

Hard to trust what's on eBay 

[GoodysGotaCuda]

I ran a drop filter an a performer rpm intake [same height as an air gap] on a -flat- hood.

Does the challenger hood have bracing in the way? I know my rallye hood has much more clearance than my old flat hood.


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[chargerdon]

Psycho Chryco...i did some test runs with and without the air cleaner on, and it feels the same, they way i have it set up...  so..its getting enough air..   I love it the way it is...

Look, if i were starting from scratch id maybe do things a lot different.   But when i bought the car that is the way it was set up...  Air Gap, eddy carb, and a flat hood.   Once you take the time to make the drop base its no big deal...  at least with the Eddy carb, maybe it wouldn't fit on other carbs, but, i'm sticking with the Eddy.   If i had a spare $700 sitting around maybe id buy the Ralley hood as i suspect it has a lot more clearance than the standard flat hood...  and if i had $1200 laying around, the Ralleye Hood, Proform carb, and if...oh you get the idea, these cars are a constant drain of cash...if you let them.. 

My next big project is to overhaul (do the work myself) the A518 4sp overdrive i have and put it in.   That is going to cost me $200 for the overhaul kit and fluid, around $200 to have the drive shaft cut and re-balanced to fit, and another $400 for a decent locking torque converter.   That comes before the Ralleye hood !

[1 Wild R/T]

Raisin bran hood will have plenty of room.... I have a 383, Performer RPM, currently a FiTech TB & a dual snorkel air cleaner... Only thing that ever is a problem is the passenger side snorkel if I don't position the air cleaner right...  The center area where a 340 air cleaner would live has over an inch between the hood & air cleaner....