Dual carbs???

[amcervantes]

Co-worker of mine said he use to dual carb the first gens? I asked him how and he said they use have kits for that. Is this true? A dual carb MM would be awesome.

[Rahtid]

The dual carbs kits a hard to fine now but a lot of people are using motorcycle carbs now,
http://imageshack.us/a/img716/6572/s7uz.jpg (http://imageshack.us/photo/my-images/716/s7uz.jpg/)
http://imageshack.us/a/img842/5532/ws51.jpg (http://imageshack.us/photo/my-images/842/ws51.jpg/)
http://imageshack.us/a/img401/9096/bqaj.jpg (http://imageshack.us/photo/my-images/401/bqaj.jpg/)
http://www.youtube.com/watch?v=gFunG5Ku-fI
http://www.youtube.com/watch?v=4Zm7EecMZKs
http://www.youtube.com/watch?v=YHNAZqTAiLY

[amcervantes]

pretty awesome, hows it run? 2.0l, 2.6l?

[Rickdees]

I thought about this before buying a intake and carburetor but everyone said they’re hard to adjust.
That isn’t so, you can adjust the power band and get rid of that lag at idle to WOT.
To synchronize the carburetors you need a manometer to equalize the vacuum or you'll get a rich lean condition.
Great example, This guy made his and there are many more video's out there

http://www.youtube.com/watch?v=UXuvolYe93g

[amcervantes]

That's sweet, always wondered about ow to sync up carbs but never had to actually do it so I never actually looked into it. I think I will fab up a custom manifold for a dual carb set up eventually. For now I am just fixing things here and there.

[noahwins]

What are the advantages of dual carbs? And what size carbs are you using on that setup?

[amcervantes]

the idea is simple, more air more fuel more power. As far as what size carbs I don't know yet. Still brainstorming.

[Natedog]

I have a manifold for a dual carb set up for an Astron, I took the carsb and rebuilt them to use on my 1.6 in my Colt...

https://sphotos-b.xx.fbcdn.net/hphotos-prn1/936868_10201047422138599_497134470_n.jpg.

[BradMph]

If someone falls out of the sky with a duel weber compatible intake for a 2.0L G63B 4G63, Don't even post it. Just send me your paypal and we'll get that rolling. :grin:

[77amc]

If someone falls out of the sky with a duel weber compatible intake for a 2.0L G63B 4G63, Don't even post it. Just send me your paypal and we'll get that rolling. :grin:

I think CARBS UNLIMITED sells a throttle body set up for them.
You may call them to see if they sell just a manifold.
OR TWM. BOTH are kinda pricey though.

Otherwise, One could just cut off the top of the "Y" for each runner on the stock intake and weld on an elbow and utilize two Weber 34ICT's (down drafts)

E
I've been thinking of that for decades... Heck, if they can run a big inch VW, they can surely run a mitsu too.

[77amc]

Take a look-see at this kit.
Kinda universal. and PUURRRDY TOO!

http://www.carburetion.com/Products/ProductDetails.aspx?part=99600.021K

E

[amcervantes]

I guess the best bet is just have someone make me a custom intake... regret not taking the custom fabrication shop now lol

[Lon Moer]

I had a friend back in the early '80s that had a Dodge Challenger(Mitsubishi Sapporo) with the 2.6 4G54 motor that ran dual side draft Mikuni carbs.

It was actually the car that got me interested in Mitsubishi vehicles, and it was a pretty awesome ride.:)
I even got it up to 130+ late one night out on Hwy 1 between Half Moon Bay and Davenport.:devil:

[amcervantes]

my coworker said he had first gen MM with the dual side draft mikunis and he said the same thing actually, he also mention that since we had no rev limiter he would rev the crap out of it lol sounds like fun to me.

[Natedog]

http://www.rpw.com.au/shop/index.php?page=shop.product_details&flypage=flypage.tpl&product_id=1643&category_id=343&option=com_virtuemart&Itemid=1

Thats for the Astron, might look around the store and see what you can find for the sirrus and saturn, depending on what you need...

Originally the side drafts and down drafts were offered through Direct Connection, you could get all sorts of stuff for the 70-80's Colts for Rally Racing. The intakes pop up on ebay from time to time, thats how I found mine. Interestly the carbs for the dual 1.6 and 2.0 down drafts use the same spacing and linkage, although the manifolds are obviously different.

[Rahtid]

the motorcycle carbs would allow you use the stock intake after you modify it, here is the same videos i posted before of vehicle running
http://www.youtube.com/watch?v=gFunG5Ku-fI

http://www.youtube.com/watch?v=4Zm7EecMZKs

http://www.youtube.com/watch?v=YHNAZqTAiLY

[BradMph]

Take a look-see at this kit.
Kinda universal. and PUURRRDY TOO!

http://www.carburetion.com/Products/ProductDetails.aspx?part=99600.021K

E

Wow, that price for this could buy me a V8, installed. :grin:

[Rickdees]

Wow, that price for this could buy me a V8, installed. :grin:
cough, cough. Does this mean you get to keep the baskets the engine came in?
Building a aluminum intake wouldn't be that hard, but because of weld warpage you'd need it machined flat
You can set up your little mig welder to run aluminum, it's not just for steel, it's a welder. Just keep your whip straight as possible since aluminum is soft and it will jam. The cleaner weld area the better the weld, using a carbide rotary file not with a hard disc.
"Clean is, if it isn't shinny it's not clean"
Use some Preheat like a propane torch (it can't melt aluminum) and most likely you will get pin holes in your welds. (You won't if you have a tig welder). And yes your welds will look like crap, remember the rotary file? At work we call it weld profiling and weld repair.
They sell one pound spools of aluminum wire, A grade such as 5356 is harder so you need more heat compared to 4043 is a softer wire which needs less heat, as far shielding gas Argon or the higher grade mix.
O Snap, I've dam near built you one!

[pennyman1]

John Baker in the 80's sold the dual side draft setup for both the 2.0 g52b and 2.6 g54b motors. The 2.0 used 40MM Mikunis, and the 2.6 used 44MM carbs. The weber setup uses DCOE 45 carbs, which are slightly bigger than the Mikuni 44s, but the Mikuni - Solex carbs are work-alike carbs to the webers. Jetting will need to be changed to allow for other factors with the motor of course.

[amcervantes]

might just make my own like this

http://www.galantvr4.org/ubbthreads/showflat.php?Board=UBB11&Number=554229&page=2&fpart=1

[BradMph]

might just make my own like this

http://www.galantvr4.org/ubbthreads/showflat.php?Board=UBB11&Number=554229&page=2&fpart=1

Make 2, :lmao: I think I like one also...hahhaha!


Hey Rick, if you ever seen my welds...probably want to keep me away from trying to weld anything :rolleyes:. When I even use superglue for anything, I glue my fingers together.
Never got much training in the welding portion of high school, I don't have a welder or wire feed yet, but this is very high on my grocery list. My friend has a wire feed and said I can use it anytime I want learn the skills. I Use to do some braze welding in the day, but would like to try some aluminum someday as well.
I been thinking about this intake manifold thing also and would like to try a couple ideas I have. Most of my problem is just going out to the garage and burning up a reel of wire until I develop some skill.

[amcervantes]

I can't weld either so I will probably have some one do it for me. Lack the dexterity for steady hands. Will do this around tax season lol

[thillskier]

Ship it to me, I can weld it (except aluminum). Stainless, and even cast (use stainless rods:)hehe. Send return shipping and if only a few rods I have (pics before shipping), cost is nada to fellow members:)!

[amcervantes]

it will probably be aluminum though lol

[BradMph]

" cost is nada to fellow members! " Drops this line into my bag of Credits for future possibilities lol. Thanks :)

[yamahlr]

I still have a Mikuni sidedraft for the G54B. PM me if anyone is interested as I previously listed it in the for sale section. The 44s are what JB recommended in the day. I have a brand new Mikuni manifold and linkage kit that's why I'm selling the used one. The carbs can be had on EBAY fairly frequently buy a bit pricey The rebuilding kits and all other parts are available from Wolf Creek Racing in New York. Actually, we's the world-wide distributor for the PHH carbs. I have a number of articles from back in the day.The Mikuni carbs were generally thought of to be superior to the Webers because their mounting and ability to hold tuning and adjustment were superior.

[77amc]

HEY... PM'd..

I've got several pairs of carbs and more on the way.

Errol

[Rickdees]

Ever wonder why Grand Nationals were so quick, Draw thru turbo, ol skool. Still works very well and simple as pie.

http://www.youtube.com/watch?v=ZZranViNa6I

[BradMph]

That V-Dub looks like it just swallowed a hummer and forced it down like a snake would, lol.

[Mandle]

In reading through suggestions, replies and posts, I think one major option is being seriously overlooked. It seems to me for the kind of money these people are spending, one could install a fuel injected motor mildy built, get better results and save money. Isn't this an insane amount of fab and expense to utilize antiquated technology?
I'm an amature mechanic. Maybe I'm putting to much faith in fuel injection?

[BradMph]

Computerized Fuel injection is better because it can adjust to conditions unlike a carb, otherwise new cars would still have carbs.

I think what your reading mostly is what people want to do independently with their modifications and what they are familiar with. You have old school and new school going on. Keep your faith and then make your own choices on what you like to do. You'll get good response either way you go I'm sure.

[77amc]

IS THERE ANYONE WHO SELLS MANDREL BENT ALUMINUM TUBING??

Son got permit and man.. I really thought that I'd have this truck running for him by now..
If I dont use that Dual intake manifold, I thought of a cheaper route by using stock intake and cutting it after it comes to a "Y", and use a mandrel "L"
to use a pair of single downdrafts sitting on top of that.

I've got a few sets of bike side drafts but for nothing over 750's though.

That Ol Rochester that I fabb'd to the Quest intake worked OK, just couldnt' get it to idle down under 1200.
I'll look at it more in a couple weeks.
E

[thehive]

The reason I went with the duel carb set up was purely for nostalgia, and to be unique.

[geezer101]

Don't get me wrong, EFI is the way to go if you're looking for a plug and play build. But there is something about old school carbies that has a craftsman aesthetic to it. A nicely built carby is a work of art in it's own right - and you don't have to have a wiring diagram and a degree in electronics to fix them...

[thehive]

Exactly, I could have DOHC Turboed my mighty max but that already been done, and quite a lot actually and I wanted to be different. And while I wont make as much power the WOW factor is deff there when you pop the hood and everyone sees multiple air cleaners

[noahwins]

As someone raised on computer everything, I like the old school look, too. Glad it's not another 4G63T swap.

Those dual sidedrafts will sound a lot better than EFI, too.

:layrubber:

[geezer101]

There is something about hearing those secondaries crack open when you're sinking the boot into the carpet (and you can feel the mid range torque band coming out to say hello to you when you hit it right) EFI doesn't have the same magic to it...

[boozehero]

I know this thread is ancient, but here ya go..

https://www.lynxauto.com.au/lynx-manifolds/mitsubishi.html (https://www.lynxauto.com.au/lynx-manifolds/mitsubishi.html)

https://www.dragtimes.com/parts/Mitsubishi-4G52-Dual-Weber--Mikuni-manifold-Galant-Sigma-Colt-L300-Dodge-Ram-50_200752525998.html

https://www.weberperformance.com.au/product_info.php?products_id=539

Not sure if these are still available, but I do know the Aussies are way into this stuff.

[dash]

no secondaries in dual sidedraft carbs
nostalgia is about all you get.
Crappy obnoxious loud induction noise, draw attention
.....while mom in her minivan full of kids, laughing while leaving the noisy pickup in the dust
Probably too much carb for a street 4
Duals guzzle gas too. My dual mikunis (even with their jetting/tunig kit) were a total waste
A basic starion 2.6 or the mildest of DSMs.... are on another level, of quality, hands down

[xboxrox]

Don't get me wrong, EFI is the way to go if you're looking for a plug and play build. But there is something about old school carbies that has a craftsman aesthetic to it. A nicely built carby is a work of art in it's own right - and you don't have to have a wiring diagram and a degree in electronics to fix them...
Some audiophiles spend tons of money on old electron tube components to hear the better sound quality tubes provide over what transistors micro chips can do ~ newer is not always better ~ did you know electric cars & trucks were in use long before combustion engines came to being !! Electric motors make better power than combustion engines ~ if you don't think so then why did trains go from steam to diesel to electric..?

[geezer101]

^I've got a friend who has built his own tube amps and they do sound different. Getting tube valves are the harder part - he had to resort to using military grade tube valves from Russia!

[xboxrox]

TUBE VALVE ~ we don't need no stinking badges..! Opps wrong movie he he ~ I dunno whatza tube valve :shrug:

google says: Same thing but how they say vauum tube in England ~ they say Tube valve

[dash]

On topic of: carbs vs efi..... newer IS always better. No comparison really

[xboxrox]

Does NASCAR still use carburetors..? If so, a simpler way of catching cheaters & equalizing or limiting the horsepower for a level playing field..?

Got my answer here ~ they use both but only manual transmissions
https://en.m.wikipedia.org/wiki/Fuel_injection_in_NASCAR

[geezer101]

Does NASCAR still use carburetors..? If so, a simpler way of catching cheaters & equalizing or limiting the horsepower for a level playing field..?

Got my answer here ~ they use both but only manual transmissions
https://en.m.wikipedia.org/wiki/Fuel_injection_in_NASCAR

There was but they found a way around it. They installed throttle plate restrictors in the 4 BBL adapter plates but smart asses made slide in cartridges so you could swap the restrictors out without needing to remove the adapter! :lmao:

[xboxrox]

FWIW ~ I onced owned a car with twin side draft carbs from the factory ~ 1972 Datsun Sunny Excellent JDM model that I owned a few years while USN stationed me near Yokohama, Japan ~ fun cool car became worth more than the nice new Toyota Celica only because they made very few of this top model ~ the engine was 1400cc same as the 240Z Datsun SOHC with twin SD SU (Stewart Warner?) Single barrel carburetors and 4 speed manual tranny ~ I bought a air manometer from JC Whitney to synchronize the opening & closing of both carbs ~ using throttle linkage adjustment and matching how high the ball went up the glass tube got twin carbs matched ~ the gauge had a foam base to put over the throat of the carbs ~ it worked to make smooth even power BUWAAAAH ;]

[Salteen]

there is such thing as too much carb. i think there may be too much carbueration going on. heres why:

first lets cover basics. head flow, camshaft, and displacement. exhaust system has some degree of effect but for simplicity's sake lets not include it, we know aftermarket exhaust helps power (it only begins to really effect when you have a moderate street motor and you have a stock manifold)

these motors are about 95% volumetric efficiency (higher if you install a bigger cam or a higher flowing head) and really wont rev out past 7 grand. they displace 2.0L or 2.6L which is about 122 and 158 cid respectively. so to formulate this we will take rpm x cid / 3456 x volumetric efficiency

if we do this, the 2.0 will require about 235 cfm of carb in stock form, the 2.6 about 300 cfm.

now with this in mind, 4 barrel carbs are tested at 1.5 inches of vaccum, 1 and 2 barrels are tested at 3 inches. so we multiply our result by 1.414

the ACTUAL CFM REQUIRED for a 7000 rpm motor (god forbid any street motor reach these rpm's) is about 330 cfm for the 2.0l and 420 cfm for the 2.6L

the average motorcycle carb flows something like 100 cfm for 200-300 cc single cylinder dirt bike engines. running 4 on a 2.0L may be slightly overboard but on a 2.6L that would be plenty.

now lets assume we never spin the engine past 6 grand (more reasonable). now our cfm drops from 330 and 420 to 285 and 365 for the 2.0L and 2.6L respectively.

also keep in mind having individual runner intakes will tremendously decrease low end performance for the sake of some top end power. probably not ideal to lose torque considering our trucks, it may be acceptable for a 2.6L. but a 2.0L will need some porting and a cam before it ever needs 400 cfm of carb (which if you wanted to use a 4 bbl, 400 cfm of single barrel carbs flows like a 282 cfm 4 barrel. so if anyone is looking to run a 4 barrel with vaccum secondaries on a intake with a shared plenum (ideal for intake scavenging and low end power) then a 300 cfm would be fine on a 2.6 engine.

also you can offset grind the crankshaft to a smaller rod size to increase stroke (although they are 45mm which is pretty small), and overbore the engine i beleive 1.5mm is the max and 2 is possible with sonic checking and you can resleeve it and go 3mm. 3 mm overbore would give you about another .1 L displacement. then youll need even more carb and a slightly bigger cam OR a ported head to offset losses in volumetric efficiency

to sum it up, its good for some hp gains but you could see your torque curve move out and drop low end power. if you put 4 100 cfm's on a 2.0l you could use a restrictor plate or port your heads / cam swap (ported heads i reccomend more as it increases power across the board, not just in one area). on a 2.6l you can do this fine and itll work out okay but you still have torque losses and the curve will shift further to the top end of the rpm's, which these motors were obviously not designed for.

[geezer101]

http://www.mightyram50.net/vbulletin/showthread.php/5114-Carbies-dark-magic-and-flying-lawnmowers

[SubGothius]

Well covered, Salteen. It's been conventional wisdom in my other Fiat-Lancia scene that -- aside from replacing their US-spec undersized 30/32 barrel carbs with their stock RoW-spec equivalent (twin 34 barrels) -- there's no point in upgrading further to dual Webers (4 larger barrels, 1 per cylinder) and/or hot cams, unless and until we've already rebuilt the block with high-compression pistons (going from US-spec 8:1 up to at least RoW-spec 8.9:1 or better) and maybe a bore-out, or else the better breathing of those hot carbs and cams just go to waste.

Plus of course, as you say, there's a tradeoff between low-end torque vs. high-end peak HP; what's good for one tends to be bad for the other. I reckon few of us will be doing any track time in our trucks where high-RPM peak HP would matter, and if we're using them for any sort of hauling/towing duty or just routine street driving, we'll use and notice and appreciate low-end torque a lot more. Torque is what we feel as that boot in our seat when we hit the gas; HP is how quickly the speed adds up at a given RPM, and a peaky curve that really only delivers when fully wound-out isn't much use (nor fun) on a working/street truck.

[Salteen]

http://www.mightyram50.net/vbulletin/showthread.php/5114-Carbies-dark-magic-and-flying-lawnmowers

i did a readup on this. some more thought has led me to think on how you can improve this system. a great way of improvement would be to basically copy the intake design of the crossram intakes on the old chrysler b and rb engines. they are a dual carb setup and the intake stretches out. i think theres a "short" 18 inch and a longer 32 inch intake not entirely sure. but its designed so that the intake manifold provides a supercharging effect at low rpm's and it makes pulses in the manifold each time the cylinder pulls its intake stroke. if you could manage to make a intake that turns up and reaches to the hood and then turns back across the valve cover, youd be in business but the crossram had half of each of its cylinders on a shared penum so i would build a "plenum box" at the end to help direct airflow, then mount your 4 carbs on. or dual webers or the such.

http://www.modelcarsmag.com/forums/uploads/monthly_2016_06/Long_vs_Short_Rams_Comparison.thumb.jpg.b0e8a85e11 5eb84924d2871b3781c14d.jpg

1960's chrysler crossram

[Salteen]

https://media.hagerty.com/media/wp-content/uploads/uscamediasite/images/story-images/2019/04/05/intake_cross_boss_bat20190405192809

autolite inline 4 barrel carb. there has to be another one like it, its basically just a couple 2 barrels stuck together. imagine how easy it would be to set up throttle linkage!

[geezer101]

Mitsubishi did change their intake manifold design. If you look at Astron I intakes, the runners were pretty short and unevenly matched compared to the Astron II. There isn't a lot of room to add a complex and long intake runner on a 4G5X engine, but EFI on the 4G64 changed the layout enough to have a 2 piece intake with long curved runners. If you can't alter the intake runners due to space limitations, use a longer intake pipe (something I've been recommending to do for ages) I still want to get the lower half of a 4G64 intake, lop off the remaining runner tubes and weld up some alloy pipes for bike carbs.

Salteen - what is that dual down draft set up from?

[xboxrox]

Chrysler's famous 413 engine long tube intake with dual quad carbs ~
https://www.hotrod.com/articles/engine-month-today-is-413-day-celebrate-mopars-max-wedge/

~ it went in Dodge trucks too ~ stop fiddling around 'n head to the junk yard for one of these puppies then make it fit :grin:

[SubGothius]

Basically, longer runners tend to improve low-end torque at the expense of high-end max HP, and shorter runners do the opposite (which is why some race cars have carbs bolted directly to the head or nearly so), but other factors come into play for determining the optimal length for each purpose, such as resonance and intake-pulse timing, etc.

This is the principle behind variable-length intake manifolds (https://en.wikipedia.org/wiki/Variable-length_intake_manifold), such as the OG Ford Taurus SHO V6 with that "nest of snakes" intake (https://en.wikipedia.org/wiki/Ford_SHO_V6_engine) having a pair of differing-length runners for each cylinder that would switch over above a certain RPM.

[Salteen]

Mitsubishi did change their intake manifold design. If you look at Astron I intakes, the runners were pretty short and unevenly matched compared to the Astron II. There isn't a lot of room to add a complex and long intake runner on a 4G5X engine, but EFI on the 4G64 changed the layout enough to have a 2 piece intake with long curved runners. If you can't alter the intake runners due to space limitations, use a longer intake pipe (something I've been recommending to do for ages) I still want to get the lower half of a 4G64 intake, lop off the remaining runner tubes and weld up some alloy pipes for bike carbs.

Salteen - what is that dual down draft set up from?

yes a longer pipe would help tremendously. use some rubber hose and you can tune the length on a dyno till its about right, then build your intake from that.


Chrysler's famous 413 engine long tube intake with dual quad carbs ~
https://www.hotrod.com/articles/engine-month-today-is-413-day-celebrate-mopars-max-wedge/

~ it went in Dodge trucks too ~ stop fiddling around 'n head to the junk yard for one of these puppies then make it fit :grin:

yes, and the B383 and a select 361 engines had them too! (not the RB383, that was a crossover engine for the 413. theres 2 383 engines the B383 was the one in cars like the charger, road runner, etc the RB383 was in the windor sedan of the late 50's)

a big issue arises in junk yard searching. no one has these intakes at all. but paul here has hoarded some very rare and classic car parts, such as a 429 SCJ, 3 462 lincolns, a couple 400B engines, a cast iron 4 speed ford T18, a zf5, a 1970 460, and tons of intakes and carbs, factory headers and manifolds. among my collection i have a 413 long runner intake. i dont want to cut this peice up and i know damn well it wont fit. so if i ever tried to make it fit i would have to mount is in a "slant six" fashion, bend up a new shifter, and then maybe i can fit a long tube intake on. sounds like fun, maybe ill find another dodge 50 with the 4 banger and swap my 2.6/ 5 speed in, and then ill build it up like that.

its nice to talk but i need to plan it thorough. however i have engine simulation software so in the mean time, i can formulate how much power it should make and where.

[Salteen]

oh another thing. chrysler big blocks have paired ports for the intake that "snake" around the pushrod. so you would have to make an adapter of sorts if you ever hoped to mount that bad boy up and youll need to cut a section of the truck out. by then its best to make a copy of it.

maybe someone could try a ford inline 4 carb? that would be wicked, its 850 cfm total flow though so someone will have to have a serious engine possibly forced induction before its necessary. still would be cool to see that.

put a long tube efi system on my 3.8? now that would be sick!

[xboxrox]

wow that is one strange piece..! (the Autolite inline four barrel carb)

[SubGothius]

Looks like that carb was made to loophole a "single four-barrel carb" rule in SCCA Trans-Am racing at the time:
https://www.stangnet.com/mustang-forums/threads/cross-boss-intake-anyone-ever-seen-this.862697/

[Salteen]

Looks like that carb was made to loophole a "single four-barrel carb" rule in SCCA Trans-Am racing at the time:
https://www.stangnet.com/mustang-forums/threads/cross-boss-intake-anyone-ever-seen-this.862697/

indeed it was. but it still works great!

4 40mm motorcycle carbs flow 667.2 at 1.5 inches vaccum and 943.138 at 3 inches. extremely way too much carb. if you want throttle response you could run dual single barrels from a straight six like a dodge 225, ford 300, or a chevy 292. of course shared plenum and long runner to help torque.

875 and 943 are way too much carb (although the autolite inline 4 was rated as a 2 bbl, it actually only flowed like a 618.8 cfm. there is a boss 429 version too, and it had larger venturies, dunno the cfm)