Carb conundrum

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Captainkirk

Captainkirk

Old School Mopar Warrior
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OK, see...I had it all figured out.
I bought a nice used AirGap RPM last year for my 340 and had decided to use the original TQ by way of a spread bore adapter. Sure; it might take a little blending, no problem. And the choke linkage; well...a little constructive designing perhaps to change it over to manual. I have it figured out in my head, anyway. But now I notice this:
Air Gap RPM:
16480860613_d611c7cecb_z.jpg


Air Gap with adapter plate:
17006660137_84a3e1de01_z.jpg


On Top of Old Smokey: TQ, adapter and Air Gap:
17006672447_caefe81b2e_z.jpg


TQ base plate, bottom view:
29617531184_255c86bee0_z.jpg


Ruh Row. What do we see on the bottom of the TQ that could cause an issue, kiddies?
(hint: look at the stock manifold, then the base plate again)
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Ahhh...NOW you see it. The air bleeds and passages between the two sides need a gasket underneath to cover them. There is no plenum wall to support such a gasket.
What to do?
Yes, I could run the stock 50# manifold. I know they flow pretty good.
Yes, I have other carbs I could run, but I really had my heart set on trying the TQ.
Is there a simple solution I am overlooking, or is this one of those "not gonna work" things?
 
Port match the RPM intake to the large spread bore pattern? Got enough meat? Its not burning any bridges as itll still seal up to a Holley (except a 4010). Run a base plate if you need the sealing surface between the smaller bores.
 
I don't know anything about TQs but I've seen several used on open plenum intakes. The single plane M-1 and the Holley Street Dominator were spread bore so that a TQ could be used if desired.
 
Run the factory iron intake. Makes good power, bolts on with no adapter hassle. You will never see the weight difference in the performance. You run that air gap, with a adapter and TQ, it's gonna be pretty tall, better check hood clearance with you breather of choice.
 
Very tall, hole in hood in hood tall.
Weiand's Action Plus is TQ ready, minus choke well though, the Stealth might be OK.
 
I'll check it out on my particular Stealth in the morning.
IMG_0390.JPG
 
Well, this IS a conundrum!
The ideal situation (for me) would be to be able to run the TQ on the Air Gap. Best carb, best manifold for the 340. But...I also have the original TQ spread bore manifold. And then there's the original cast square bore manifold complete with Carter AVS. And then there's the old Holley 650 DP. And then there's a brand new (10 minutes running time) Edelbrock Performer 600cfm I bought from my kid, plus I have the X-type Torker from my early days, although all the recent testing says that pretty much sucks as a street manifold so I am choosing not to run that at this point in time.
With all these carb/manifold choices I certainly don't want to plunk down another 5 bills for either a new carb or a new manifold.
And yes, I am a little concerned about the hood clearance, although I am considering putting a Mopar dual snorkel scoop on so I could make room if necessary. Right now I'm more concerned with choosing the right combination.
 
Captainkirk said:
Best carb for the 340.
Click to expand...

Says who?

Is the 340 that unique of an engine? OR is it really that advanced of a design?

I just can't see reinventing the wheel for this. If you like that carb so much, stick it on a manifold meant for it. If you want a modern intake design, then run the carb it was meant to be used with.
 
roccodart440 said:
Says who?

Is the 340 that unique of an engine? OR is it really that advanced of a design?
Click to expand...

No, I s'pose not. But is anything new under the sun?
An Eddy Performer is just a AFB in a new dress.
An Eddy "Thunder Series" is just an AVS with new shoes.
All the new Quick Fuel, Demon, etc carbs are just Holley knock-offs with a few extra farkles.
All these designs are 30+ years old.
The TQ was a brand-new design in 1970 giving it the edge over all the earlier Carter designs as well as a lot of the Holley designs.
Same with manifolds...the Weiand Action+Plus doesn't look any different than the stock spreadbore manifold...just a little lighter...

roccodart440 said:
I just can't see reinventing the wheel for this. If you like that carb so much, stick it on a manifold meant for it. If you want a modern intake design, then run the carb it was meant to be used with.
Click to expand...
In the end, you are probably right. Maybe I'll flip a coin...
 
I say start with the factory manifold, first. You can use the factory choke and linkage. The air bleeds are not a consideration. I've run TQ's on all kinds of manifolds including spacers, no problem. You can always change manifolds later. There is not much hood clearance with the OEM manifold, TQ, and factory air filter to begin with.
 
Captainkirk said:
Rob, you're in the same boat with that manifold. You would need a spacer to run a TQ.
Click to expand...

(Slaps hand on forehead!)

Sorry, I'll be running an Edelbrock 650 AVS carb. I'm not into the headache of adding a TQ (electric choke or not!) onto a squarebore intake just to run a TQ.
You sure like trying to do things the hard way don't you!
 
rumblefish360 said:
(Slaps hand on forehead!)

Sorry, I'll be running an Edelbrock 650 AVS carb. I'm not into the headache of adding a TQ (electric choke or not!) onto a squarebore intake just to run a TQ.
You sure like trying to do things the hard way don't you!
Click to expand...
Why, yes (grinning)...why do things the easy way? This way is much more...interesting.
Otherwise, what would I have to talk about?
 
run the thermoquad with the adapter on the performer rpm! a gasket is not needed to cover those areas, many of us have run the thermoquad on the old ld340 and single plane intakes for decades.
 
plate is just a AL piece that has TQ cutouts. More for the gasket to sit on They are made to mount an AFB or Holley on a TQ intake but you could probably get cut for a spreadbore. I dont think the TQ even needs it.
 
I was not going to say anything in this thread, but I'm going to say something I almost never say.

I would use the stock CI intake and the TQ.

There isn't 5 HP difference in the manifolds. The TQ, if set up properly, is damn hard to beat.

Straight truth, I'm thinking of doing a little work to my Strip Dominator (I have already welded up the top and ported it square so I would have to undo what I already did) and doing up a TQ for it. If for nothing else, it just pisses people off.

OE intake and TQ is what I'd do.
 
Yr, ultimately, that's the best direction.
But this is Captin Kirk. I think his secret moto is, "The hard way or no way!"

Get a M1 single before cutting the SD back to normal. Maybe even trade. And yup, I'll run the same thing just for giggles. Then there's also to hear the Holley guys scream, squirm, boot and holla! Also the best question there is...

Wondering idiot car buff wanna be car guy;
"Hey! WTF is that thing?!?!"

Me;
OH! That is alien tach reverse engineered for Stone Age useage. I got it on my trip to Roswell! Psssssst, Elvis IS alive and doing wonderful on Chewlack!
 
The factory cast iron 340 manifold and TQ screamed for me every time I asked it to.

The late 1970s factory racing "direct connection" book noted that no performance increases were ever noted over the OEM intake manifold, save for weight considerations.I really, really like Thermoquads and AFBs.
 
Marcohotrod said:
run the thermoquad with the adapter on the performer rpm! a gasket is not needed to cover those areas, many of us have run the thermoquad on the old ld340 and single plane intakes for decades.
Click to expand...
What happens if those areas are left uncovered? Does anyone know?
 
Captainkirk said:
Perceptive you are...
Click to expand...
LMAO!

Captainkirk said:
What happens if those areas are left uncovered? Does anyone know?
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You mean the are under the carb itself?
Nothing.
The effect performance?
Probably a few extra rpm at best, a slightly better balance of the carb since the carb see's the entire engine.
Captainkirk said:
Where did you find those numbers published, YR?
Click to expand...
A lot depends on the build itself. Considering yours is a very mello build, those numbers are probably pretty accurate.
 
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