...preparations for DCOE 45's

[markmdz89hatch]

So it's finally time to let the cat out of the bag and admit that I just bought a pair of DCOE 45's in preparation for a carb swap.

The manifold fabrication is no problem, it's already taken care of. I already intend to build out an engine for these as well, which will include (but is not limitted to..) new higher compression Wiseco Pistons, shot-peened rods (or something else in that department), A20A3 head ported and revalved, A20A3 wild-grind cam, and obviously the carbs.

...now I need to know what else I'll need to be able to contain these big bastards.

...I don't want to detonate this engine, but I want to get everything possible out of this swap, so I need to know everything else that I should replace/upgrade in order to prevent any harm.

MOTOR: Would someone suggest something other then what I mentioned above for the internals? Should I worry about a stronger timing belt? I'd like to stay with power steering, but don't know if that's the best idea, any suggestions? Should I look into a custom cam gear? If so, any suggestions on the first place to look for that?

FUEL: I've been seeing a ton of talk lately about fuel supply (pumps, lines, etc.). Should this be something I should be concerned about? What should I do?

IGNITION: Should I use an aftermarket ignition control? I've already got the larger Accel coil. What wires, plugs should I use? Would stock suffice, or are there advantages in this application to using larger wires? Should I reuse the distributor from the A1 or just keep with the stock A3 disty.?

SUPPORT: I'm already contemplating buying new OEM engine/tranny mounts, but should I look to get some custom fabricated with a smaller bushing to allow for less play?

EXHAUST: The plan is to find a set of ceramic DC headers, but should I look into something custom to allow for a little less restriction? Or will these suffice for allowing only enough backpressure as needed for optimal performance? I know it's suggested to get 2.25" exhaust for a stock 3G, but should I consider a slightly larger diameter such as 2.5" or 2.75"?

TRANNY: I have a stock 87 LX-i tranny, and will be (thanks to Steve) be getting a 2G 'lude tranny. Between the two, should I mess around with the gearing, and make a combo of the two? ...or should I just toss one of 'em in stock? If so, which one? ...or should I look to pull gearing out of another tranny such as a 'teg? The main focus for this build is auto-x, so low gearing is prefferable, however I would still like to be able to drive the car on a regular basis on freeway and back roads alike. Driveability/comfortability is not really a concern, but I just don't want to be tacking about 8grand in fifth, at 90ish.

ANYTHING ELSE: I know that there are a bunch of things, or questions that I may have left out. If there is anything else that may be helpfull to me in this little journey of mine, please feel free to post it up. I realize that this is not a quick project, and it's one that will take a ton of research and learning to make it work, but I'm committed to doing it.

What sort of gains might this project yield? Torque? HP?

PS> Suspension is already being planned to be able to keep this beast on the ground and huggin' like a go-cart w/slicks on some nice warm pavement. (Thanks to some great info provided by Jim.)

[‹^› ‹(•¿•)› ‹^›]

Wow MArky!! Your hatch is gonna be one fast beast!! Your gonna be beating alot of Bseries guys out of the water!! Good luck!! If u ever need some man power just let me know!! i will gladly lend a hand!!

[79EK1]

It sounds like you have a great project going. For the motor, you can polish the rod beams, shotpeen, and install ARP rod bolts before resizing. That will reduce stress risers and strengthen the rods.

You can upgrade the fuel system by going to an aftermarket fuel pump, regulator, and high flow fuel filter. You won't need more than 6 psi for the pump, and the regulator should be set to 3-4 psi, as Webers don't like a lot of pressure.

The ignition could use an upgrade to a CD type. I use an MSD 6AL, and it's very reliable. The rev limiter keeps me from blowing the engine. After you get the car running again, think about getting the advance curve and total timing adjusted for max power.

The ceramic headers are a good choice, as they retain the heat in the pipes, maintain exhaust gas velocity, and keep the underhood temperatures lower. A 2.25" exhaust sounds about right. It depends on what you're going to do with the car. Larger pipe diameters decrease the exhaust gas velocity, reducing low end torque. Smaller pipes give higher torque, but are a restriction at higher rpm. You should keep it conservative if it's going to be a street car.

Good luck with the engine.

[markmdz89hatch]

^BUMP^

I can really use some help guys... ...really anything is greatly appreciated.

PS> 79EK1 --> Thanks for the info... As for the pump, what's the stock LX-i pump push? Would I just be able to use that? If not, I should get an external pump rather then an in-tank pump if I go aftermarket right?

Also, should I run a larger fuel line to the carbs? I would assume that since I'll be using the pump, that's mainly due to the need to feed the thirsty carbs.

Anything is helpfull here.

[Site]

First off, I'm presuming you've got a good DCOE book (like Des Hammill's) and have read it through.

"Should I look into a custom cam gear? If so, any suggestions on the first place to look for that?"
-Nah, I think you can make necessary timing adjustments with the distributor (turning it counter-clockwise advances the timing). Once the DCOEs are installed, start the car and let it get to operating temperature. Advance the timing until the idle stops increasing. It may seem like you're advancing it a lot. Then, adjust the idle mix screws to get the idle between 1000 and 1200 RPMs. After that, use a syncrhometer and adjust the idle mix screws slightly to match the flow of the carb barrels with the one that shows the MOST airflow when all throttles are closed.

Use this synchrometer:
http://www.webercarbsdirect.com/inc/pdetail?v=1&pid=794

"I've been seeing a ton of talk lately about fuel supply (pumps, lines, etc.). Should this be something I should be concerned about? What should I do?"
-An EFI pump will give too much pressure and too little volume. Get something like an Aeromotive Street Rod pump or a Holley Red pump. PhydeauX is upgrading his fuel lines for his 45DCOEs and has a post about it, check it out. I would look into a 2 port fuel regulator (Aeromotive, BG, Holley, Magnaflow, etc) to keep the pressure at 3-4 psi and give each carb a dedicated, equal feed. Get one with a fuel pressure port and get a gauge. PhydeauX has had problems with fuel pressure drop and leaning out while accelerating. Get a high volume pump and a good regulator!

"Should I use an aftermarket ignition control? I've already got the larger Accel coil."
-I'm using an Accel coil for now and am happy with it. I run Magnecor 8.5 mm wires.

"I'm already contemplating buying new OEM engine/tranny mounts, but should I look to get some custom fabricated with a smaller bushing to allow for less play?"
-Nah. Just check your mounts for wear and replace them iwth OEM if necessary.

"The plan is to find a set of ceramic DC headers, but should I look into something custom to allow for a little less restriction? Or will these suffice for allowing only enough backpressure as needed for optimal performance? I know it's suggested to get 2.25" exhaust for a stock 3G, but should I consider a slightly larger diameter such as 2.5" or 2.75"?"
-You'll be happy with the 4-2-1 headers like DC or Pacesetter. I have 2.5" piping, but with crappy bends, so it probably flows like good 2.25" piping. I'd go with good 2.25". Our engines have good torque, you risk losing it with piping that is too large.

"I have a stock 87 LX-i tranny, and will be (thanks to Steve) be getting a 2G 'lude tranny. Between the two, should I mess around with the gearing, and make a combo of the two? ...or should I just toss one of 'em in stock?"
-I pretty much know nothing about transmissions. PhydeauX has the hybrid Accord-Integra tranny setup with the Accord 5th gear and is very pleased. I plan on doing the same eventually.

"What sort of gains might this project yield? Torque? HP?"
-LOL - who knows? My car is faster and louder than before. Sometimes the DCOEs sound like they're gonna suck my arms through the firewall. Does that count as an expert opinion?

[doug]

only one person on this board that I know of that has even begun a DCOE 45, that's andy. I know he just got them the middle of december, I have not heard if he has it all hooked up yet. so you are pretty much the bleeding edge. sure some of the dcoe40 stuff will translate to your project, I'm sure you've done all the necessary searches of past posts as there is alot of good info already here to find. what it all boils down to is you're kinda out there on your own in that not many have done what you want to do, then again you'll have good experience of trial and error to share with us as you work to dial in the carbs to the rest of your engine.

[doug]

often when you read the dcoe posts I see the values for
aux venturi
chokes
main jet
emulsion tube
air corrector jet
idle jet
accelerator pump jet

so what is your carb set up with? seems like a good time to get a thread going with the 45dcoe values compared to a 40dcoe setup.
I would think 36mm chokes at least, but then I don't really know.

[markmdz89hatch]

Originally posted by doug
often when you read the dcoe posts I see the values for
aux venturi
chokes
main jet
emulsion tube
air corrector jet
idle jet
accelerator pump jet

so what is your carb set up with? seems like a good time to get a thread going with the 45dcoe values compared to a 40dcoe setup.
I would think 36mm chokes at least, but then I don't really know.

All I know so far about these carbs is that they were ordered for a race application for a B18 all-motor monster. The Jet sizes, I have no idea of as of yet, but the chokes are currently 36mm.

[markmdz89hatch]

Site and Doug both...

...thanks very much for all that info. I guess what it comes down to is that it's time to hit the books. I've already got a book on weber carbs, and so far I've just browsed through it. I guess it's time to take the cover-2-cover approach.

Keep any suggestions, questions, comments, thoughts coming... ...I promise to listen to EVERYTHING that ends up in this post.

ANDY, where you at? I could use a 45 experts' advice on some of this stuff.

[Site]

Remember, if you start making changes to the carb jets you're most likely gonna end up needing to switch out several things. It's not usually a "change the choke size" and then you're done kinda thing. It's more like "change the choke, then the air corrector, then the emulsion tube, then the air corrector again" kinda thing. Infinitely tuneable comes at a price - LOL.

As far as 40DCOE and 45DCOE are concerned, for a 2L engine like ours, they're gonna be jetted very similarly. Either large jettings on the 40, or small jettings on the 45. "40" and "45" refer to the throttle plate size only. The air/fuel mix is controlled by the jettings. With the A20A, I'm not sure there will be any advantage having 45s over 40s. B20 is a different story, though (just ask AccordSi - he has a JDM B20 with 45s). If I were going to swap a JDM B20 in, I would sell my 40DCOEs and get 45s.

Originally posted by markmdz89hatch
ANDY, where you at? I could use a 45 experts' advice on some of this stuff.

Andy knows so much more about this stuff than me! Make sure you get his recommendations!

[markmdz89hatch]

Originally posted by Site

With the A20A, I'm not sure there will be any advantage having 45s over 40s. B20 is a different story, though (just ask AccordSi - he has a JDM B20 with 45s). If I were going to swap a JDM B20 in, I would sell my 40DCOEs and get 45s.

...hehehehehe... shhh.... that's the secret... ....after this is done, and I blow up a few engines in the process of tuning these puppies, it's off the B20 world for me, my 3G, and these DCOE's. But that's WAY down the road.

[doug]

Originally posted by Site

As far as 40DCOE and 45DCOE are concerned, for a 2L engine like ours, they're gonna be jetted very similarly. Either large jettings on the 40, or small jettings on the 45. "40" and "45" refer to the throttle plate size only. The air/fuel mix is controlled by the jettings. With the A20A, I'm not sure there will be any advantage having 45s over 40s. B20 is a different story, though (just ask AccordSi - he has a JDM B20 with 45s). If I were going to swap a JDM B20 in, I would sell my 40DCOEs and get 45s.


Andy knows so much more about this stuff than me! Make sure you get his recommendations!

do the same guides apply to 45 jetting as with the 40? I've read here on the board that main jet is linked to chokes size. choke x 4 = main, If I remember right. this would mean a 40 with 30mm choke gets 120 main and a 45 with 36mm gets around 145-150.
if this is correct then the jets either stay the same or get larger on the 45

[PhydeauX]

I could tell you where I've been but then I'd have to kill you. You'll all find out soon enough. Anyway thers a buch of stuff to answer in there and I'm tired with a head ache. Any way the only major diferences between any of the dco series carbs (DCO, DCOE, DCOM) are the bore sizes. All they all use the same calibrated parts (jets, tubes, needles, etc). The reason for the diferent sizes are to tune the carb for the exact power band you want. Each size bore has numerous diferent chokes. Choke is queens english for ventrui and alot easier to remember how to spell, this has nothing to with the choke that helps you start the engine when its cold. The choke is actually what determines what rpm range the carbs will work best in. The carb meters fuel bases on how much vacuume is in the bore. The vacuume pressuer for a given air velocity can be changed by changing the size of the choke (I'm not going into any specifics on ventrui's princple). The smaller the choke the more vacuume is created. Also the smaller the choke the more restrictive it is. Yon need a strong vacuume at low rpm for good low end response, and you need as little restriction as possible for top end power. The choke size is a balancing act between driveability and all out power. The carb size determines what choices you have in choke sizes. The largest choke you can put in a 40 is a 36mm. 36mm is a pretty good choice for a built a20a. The jetting is very dependant on the motor. Multiplying the mand ventrui size by 4 will give you a good starting point. You'll be able to start the car and run it with those values. Thats not saying that it'll run perfect, only trial and error will get you that. As for the fuel system, put the carbs on and see what happens. The best way to find out is to just do it.

I've linked this countless times now, its a good read and tells you what each part does and how to tune it. http://www.lotuselan.net/publish/tun...oe_carbs.shtml

andy

[lostforawhile]

what ever became of some of these projects? if the info still exists it could be very helpful with my own project. the link is right above my signature. i'm especially interested in how the stock fuel line held up. deceiding if i should go to the considable trouble of bending new fuel lines and running AN from one end to the other. if the stock line is able to support the carbs with a different pump i will keep it. anyone who still has info on these projects post it up or post some of it in one of my carb threads. appreciate it y'all. these tech threads never die....just get reborn from other crazy projects.

[DDRaptor]

i would love to see pictures of this project finished

[markmdz89hatch]

i would love to see pictures of this project finished

Honestly so would I. So here we are more than 5 years later, and with the exception of the fact that I took my 3G off the road and retired it to my garage, I have made no progress on the carbs. It's funny how marriage, 2 kids, and a house can slow projects down a bit huh?

Anyway, still keepin the dream alive, and still have everything tucked away nicely on a shelf in the garage, patiently awaiting a time to be installed and bring the hatchie back to life.

Rather then a full motor teardown and internals & head upgrade I'm going to shoot for just bolting on the carbs on a bone-stock motor at least to get them on, and running. I've got 3 or 4 blocks, and as many heads in the garage, so one will be built while the car is at least driving for now.

I expect to have at least something worked out by the end of summer this year (hopefully).

[2oodoor]

OH man, you got me good, I started reading and was thinking wow more carb guys, yay, then I saw the date and went limp, then at the newest post I started reading and was like getting all giddy thinkin you were about to say you were willing to pass on the dcoe pair to a good 3geez member to keep the dream alive, then you say you want to put them on a stock motor and I went limp again, only for a second though..
Stock motor will be fine as long as you get those jetted right using AFM, and don't go crazy. I think the burden will be on the mains with the burst of dcoe' s but as long as you drive it like cool it should hold up a while, long enough to know if that is what you want. Keep in mind they use those carbs on all kinds of silly British and Italian crap cars expecting them to hold together... a worn A20 is much more durable than even spanking ass new Fiat or Brittney Ford.

[markmdz89hatch]

are you saying that the carbs could kill my motor if tuned improperly? I could see the scenario of running too lean, or rich, but if i get my a/f ratio set I should be able to push it throughout the entire rpm range without fail right?

EDIT: BUT, if I can find someone with 4 matching mikuni 45's or 48's and I can get all 4 for what I would be able to sell my DCOE's for, then I'm up for the swap any day. From what I understand, the flatslides are MUCH easier to tune than the DCOE's.

[2oodoor]

well yes, for one point leaning out at WOT will cause detonation and burning holes in your pistions and or head gasket or worse.I have seen F22 engines that had melted the CC area of the head.. now thats lean.
There is some good info in this thread already and Phydeaux link is still working !