Low buck, home built dual plane HEMI intake

I am TRUELY impressed, both with the creativity involved AND the level of skill and workmanship....

 

DING DING DING DING!! WE HAVE A WINNER!! ...i think some people just don't "get it" my friend.

...for what it's worth i'd like to see the intake they have built from scratch, by hand for little if no money and without the aid of fancy computer models like the ones Vic Edelbrock SR. and Eddie Edmunds had when they started out.

 

you sure that'll work??? ...i'm just teasin ya. i love it. very cool. is that also on a HEMI?

 

the only question I have is...I looked at a bunch of other intakes very similar to the one you built...others have a tube going from one "log" to the other seems like some have it and some dont.....is that needed? what is its purpose?

 

Sounds like balance tubes, if one side needs more flow, it can suck some from the other side(someone can probably use fancier terms).

 

1 for a DeSoto was on EBay last week. If you going to go to a bunch of effort to make it look real, what not actually make it real?

 

we had discussed this but an inspection of a couple dual plane intakes sitting in the shop showed that none of them had any means of balancing between left and right. if it worked for them...

 

Oh crap... Yes, yes! Excellent point!

The original poster WILL want to make some provisions to have a ballance tube somewhere in the manifold if he wants to run it on the street.

The reason a ballance tube is required is due to a phenomenon called reverb. Basically, when an intake valve snaps closed, the air that was moving [at high velocity] towards the intake valve has a tendancy to "bounce back" and create a pressure wave thru the plenum.

On a dual plane manifold, if the pressure wave hits the bottom of the carb at the exact same time the other side of the manifold is *sucking* air, the momentary pressure wave will/can travel thru the carburetor. Once inside the carb, it can blow the fuel around inside the fuel bowl, causing air bubbles to make their way to the jets. This can cause low RPM stumbling and/or stalling.

That's why on factory dual planes, there's a small cut out beneith the carb that allows the pressure wave to pass from one side to the other without traveling thru the carb.

I hope my explination makes sense.

 

Great job! Who cares if it breaks any speed records. Its high on the Cool list. Damn, now I'm thinking about doing this to my Nailhead. Somebody PLEASE sell me a 3x2 manifold CHEAP and FAST.!

 

In a word AWESOME!!!! Im ready to go out and buy a 32 Ford coupe and a 331 Hemi
just to have him build a manfold for me

If anyone remembers the two 4bbl cross ram manifold of the early 60's Chrysler 300's;
the longer tubes made for a pseudo supercharged effect due to the tuned intake at
mid range RPMs. It worked well.

 

I'm such a Stromberg WW FREAK!

I have an old 3x2 linkage for Stromberg WWs that came from Dave's Mysterion leftovers...

~Jason

 

i've got an Edelbrock Performer RPM Dual Plane AND a factory GM 4 barrel intake and NEITHER of them has any such "cutout" (though i have seen them on manifolds before) nor do they have ANY way for the two halves to "balance". this was all well thought out ahead of time i assure you.

i offer for your examination exhibit A:

 

You speak of the "notch" milled or cast in the top edge of the plenum divider,yes?

 

Awesome thread Mike , you do my Dad some serious good here, Thanks

 

i've got a buddy that works in a chrome shop. we have discussed that option. problem is it would be hard to get the chrome in some of the nooks and crannies very well. we might still do it though.
i've got another buddy around the corner that does powder coating too, so that is not out of the question either... not that it matters. all of the arm chair geniuses of the internet don't seem to think it will work. ...but then if everyone listened to the nay sayers all the time we would be surfing the internet by candle light.

 

exhibit B GM Performance Parts dual plane intake:



Exhibit C factory cast iron GM dual plane intake (you might notice a very small notch on the top of this one between the primary holes. some type of balance device???):



exhibit D actual Rocket Science:

 

Hey man... Dont you know that Von Dutch used a steam powered TV?

Seriously tho, I went upstairs and dug thru my old tech manuals to research the reverb issue. I was right, but in this case, I was also wrong.

The reverb issue is a real one, and the pressure wave can indeed travel thru the carb, disrupting fuel flow and causing stumbling or stalling. The cure is either #1, to incorporate a ballance tube to allow the pressure wave to harmlessly travel to the opposite plenum and equalize, or #2, to increase the volume of the plenum to allow sufficent room for the pressure wave to disapate within the plenum without affecting or disrupting the carburetor.

The ballance tube also serves another function. That is to reduce noise. The intake charge is capable of exceeding the speed of sound when traveling thru the runners. [capable being the key word... read on.] When this happens, you get the "4 barrel" sound, as the "sonic speed" pressure wave snaps back thru the plenum. Having a crossover gives the sonic wave an opportunity to disapate before the "sound" escapes thru the carburetor. The sonic wave is more likely to happen at lower RPM's on a manifold with a smaller plenum/runner setup as the speed must increase due to the smaller volume. With a larger volume intake, it only happens at higher RPM's [hence, the "4 barrel" sound].

That means, a "performance" manifold [manufacturer] would not use a crossover on purpose to enhance the noise. Also, their manifold would not require one because the plenum would have suficent volume to allow the pressure wave to disapate before it affects the carb.

Since your manifold appaears to have MASSIVE plenum volume, a crossover would not be required. If you install one, the engine would/should run a little smoother/quieter, and the "4 barrel" sound would come in at a higher RPM than it would without one... But I'm guessing you actually want the sound.

Sorry to muddle up the conversation with facts. Sometimes I cant see the junkyard because all the damn cars are blocking my view.

 

I really kind of liked the idea that the ballance hole between the planes was to cope with Reverb, then I spent a while thinking about the valve timing and the firing order.
For easy of thinking firing order 1L 4R 2R 2L 3R 3L 4L 1R
which then if you take which plane the cylinders are connectted to ( U for upper L for lower ), goes L U L U L U L U so when an inlet valve shuts at say 65 after bdc, the pressure wave is going to be most use to the cylinder who's inlet is fully open and piston on the downward, and this works out to be one on the connectted to the same plane rather than the other with every cylinder so as a reason to link the two it kind of falls down.

I suspect the port between the two planes is there to try and equal up the resonance miss match.
Certainly looking at a cast one here on the floor the maker has gone to some considerable effort to make tubes which connect 180 degree pairs all very close to the same lengths, which seems to support the idea that pressure waves are very much a central idea in the design.
My guess is however that the fabbed up square tube will still work ok,
sure it will never be as good as one made by the guys with slide rules,
but that's not the issue here.

I know I could not weld up something like that and not have it warp so bad that it probably would never fit again, so best of luck.

 

no, that is actually very helpfull and i will pass that info along to Dan. i foudn it quite interesting to read. i do think your right and the plenum size is adequate to negate the use of a crossover... i'm glad you did that research. i did'nt know (and i'm betting Dan did'nt either) any of that. he was just goin by what he had seen done and imagined would work. he is'nt some high school kid just building stuff without thinking it through, the man is a thinker in the truest sense of the word.
we had many discussions about this thing as he was starting to build it. he just wants it to WORK, he is'nt concerned with it being some ground breaking design. it's just gotta look cool and WORK.


...you wnat to talk plenum size. you should see the one he built for a flathead Ford. he never ran it and i'm not sure he ever intended to. Dan just likes to build things and he's got the balls to do thing outside of the norm. who wants to be like everybody else anyways?

 

that has been discussed many times and it will be top on his mind as he goes about welding this thing together as it won't be possible to weld the entire thing together while it is bolted to the mock up engine.

...everything else you said before that made my head hurt.

 

I rode in a T-Bucket that was built in 1969 awhile back it had what appeared to be a blown 331 Hemi......he took me for a ride ,it would snap your neck if you were not ready once he mashed the throttle.....It had great throttle response.......We get back and he asks what do you think ?...I said it has some punch.......He then told be the blower had no rotors inside......I asked if he had built in some type of runners inside ?.....he said no its just all open inside..........so you just never now what will truely work........theory is always great...but its good to challenge it from time to time..........Littleman

 

Dan was just reading this at lunch and called me laughing about all the criticism. he had talked about running a blower on it and if he realy was worried about going "fast" that is what he would do.

like Dan always says "It's too bad that those who know it all can't DO it all.". if your going to think outside of the box, like he does, you gotta be able to take some criticism. both from those that know and from those that THINK they know.

it's all good though and we appreciate the comments both ways. it never hurts to have outside input. it just might get you thinking about something you may have overlooked previously.... you all enjoy the thread. i'm off to the shop to fix some cow damage on a 63 Chevy...

 

Well, I guess I am a "nay-sayer" now. Sorry for my ignorance and asking a question. Carry on and have fun. I'll go try to learn something on some other threads and keep my mouth shut.

 

What is wrong with the stockers?? Mabey it's just me but I aint diggin the square tube

 

The notch in the plenum divider on older aftermarket dual planes is to clear the big oval third butterfly on 3-bbl Holleys. I guess it provides some balancing effect between the two planes, but if you look at the old ads, Edelbrock sold a 3-bbl/ dual plane combo in the late '60s. CH-4B, P-4B, B-4B, etc all have the slot. A lot of factory Q-jet intales have little slots connecting the primaries for a manifold vacuum source.

 

Some years ago I saw a guy who had taken a stock 2 brl intake and machined it out to take a 4 brl square bore. He did weld a carb spacer on to act as a carb flange, but there was plenty of meat he told me.

This was a stock intake on a 354 hemi.

 

Forgot to add- that manifold looks killer!

 

Well now, square intake ports in the heads , valves are round, square runners means square to round air movement, round runners means round to square to round air movement, more is not always better, just because other people done it dosen't make it correct, I think? Now for the rest of the story, 6000 rpm ( or 5) , second gear, smoke everywhere, all crossed up, headed for the ditch, ready to grab 3rd, ---balance tube-equal length runners-square or round-thats not on my mind right now, life is about friends and fun and at 61 and still counting I really,reallly like how this has got allof you people thinking and talking and enjoying life, Dan

 

First: excellent work, daring, I never would have thought to use separate tubes as the banks.

With your permission?
Don't kill yourself over the perfection of the welding - sloshing some epoxy around will cure all of that. The vacuum can't be higher than 14.7 psi, so any sort of sealing compound will work (as long as not gas soluble).
You already know that the runner entry angle differs quite a bit between left and right - but it's a prob with stock manifolds too. What to do? See how it works.
If you can get in there - radius all joints, no sharp edges (duh).
You're going to have a potential distribution problem if you run progressive because the center carb "finds" the center pair of its H instantly vs. a stock 180° manifold. How much diff will it make? IKBA.