Weber progressives and G63B: Need the nitty gritty details.

[Serius-Lee]

I'm having my doubts about the interest in non-turbo discussion/advice in this forum but I'll give it a go.

Hopefully theres some people reading that enjoy the "keep it simple" projects as much as I do...and dont mind reading my long-winded posts. I write for money so it comes easy and takes no time at all to fill a page or two.

I'm looking for in-depth information, specs, and research or any detailed discussion (past present or future) on Weber progressive carburetors, hopefully with some info and advice relative to NA 4 cylinder engines manufactured in Japan like the mitsus.

Why am I looking here?

Well theres a few reasons: Most of what is easily available online is info for "normal conditions" direct replacement, or super high performance ($$$)

Most of what I find is vague and often conflicting when it comes to all the variables that exist or COULD exist... like jetting configurations, psi operating ranges and requirements, effects on timing/spark delivery etc etc. and what little relevant info is available does not apply to the mitsu engine line I'd like to apply it to.

Why do I want that info?

I'm more interested in NA projects than anything FI and/or Turbo
I am currently rebuilding a G63B and rebuilding a 32/36 DG series to put on it. Hopefully with a slightly customized original intake that works as well as it possibly can with that "stock" engine and carb.

The SOHC engine will be rebuilt to stock specs with no mods or performance components other than quality direct replacement parts. Its just what I want to do at this point. Consider it a restoration to get it as close to original condition with one exception: No emissions, ECU or modern ignition components.

Remember when trucks were simple? If there was something wrong with it your first guess was usually right and you could fix it yourself with a buck knife and a pair of pliers?
Remember when you and a buddy could pull a V-8 on a Saturday morning with a hangover, rebuild it with the parts from your local NAPA...and drive it to work Monday?

Maybe I am part of a tiny subculture of boring enthusiasts who enjoy seeing cars and trucks that look more like they did the year they were built, bought and gently modified for performance/appearance, (by the kids on a budget who bought them)

But I'm not alone. Nothing bugs me more than seeing something like a 68 Malibu SS or a 61 GMC stepside with hacked suspension, 22inch after-market chrome wheels jammed up into the fenders, and sticking out the back is 3 inch chromed tubes clamped to no-name "glass pack" mufflers making noise.
While the whole time you can see 20 quarts of bondo through the $300 Maaco paint job, but only if you can focus long enough while the subwoofers in the car/truck loosen your dental work and massage your lungs.
Do people really think these things make a car or truck appealing...or nostalgic, or faster?
99% or those cars and trucks I see in my part of the country have a tired stock donor motor under the hood with 200k miles. Usually with a bolt on CAI and freshly rattle-canned valve covers to distract you from the 1/2 inch layer of 10w40 cookie dough covering the rest of the block.


OK rant over. Back to the subject. What I'm looking for is information and answers or at LEAST some educated suggestions/ideas as it relates to N/A and mitsus.
Maybe even specifically for G63B and a Weber progressive carb.

First is jetting. I've looked at the standard configuration from companies like Redline etc. But "standard" configs is where the details stop. Maybe because the internet isnt much more than a big freakin retail advertisement these days. 99% of it wants your money. Anyway...
Theres nothing out there I can find that answers questions like "What if I have a single intake chamber rather than the more common 32mm and 36mm holes on my manifold? Will the standard jetting on a 32/36 progressive still be capable of peak performance? Is the standard carb adapter such as a redline for a 2-port intake the most suitable for a single ported intake too?, if not do I need a single-hole adapter or do I need to ditch the progressive carb and buy either a single or a sync'd 2bbl? Can I synch the primary and secondary throttle valves in my progressive carb and expect good performance? If so which jets/valves do I need to change, do I need a different accelerator pump jet that squirts fuel into both the primary and secondary chambers if I synch this carb?" If I have the 2 chamber intake with 32mm and 36mm holes would I get better performance by milling it out to a single hole design even if the existing holes are steel lined?
What about the EGR ports? I've removed the valve and capped the hole but theres dead-end empty space there in that direction and into the motor now too. Anything I need to know? Are the ports on the side of the primary intake chamber just EGR or is something else involved that needs to stay intact?

Then theres the inevitable question of valve timing and spark delivery. Where can I find timing curve data or at least some reference material for proper timing belt adjustment and spark timing given the newly configured fuel delivery system? I CANT be the first guy to ever do this with the hopes of doing it right and getting peak performance as a result!

Do I need to regap the plugs and/or the pick-up sensor in the distributor?
Is my OEM Nipondenso vac advance distributor suitable for the change in fuel delivery hardware and altered plug gap? If not, whats a cost effective solution?
I'd prefer points/condenser/coil for its simplicity but I've heard its dinosaur technology that doesnt perform nearly as well. True or false?

Hopefully I'm not the only one interested in researching these things and maybe theres people here who've been successful with NA mitsus getting peak performance out of their unmodified engines. Please share your wisdom!

Some other questions I have maybe someone could shed some light on.

When the new carb is installed, obviously I'm going to want to get rid of as much of the emissions components as possible, and remove the ECU and wiring completely.

First question is: What the hell do I do with the existing return fuel line other than cap it? I havnt looked but I dont think the fuel tank is configured with a return pump. True or false? Is capping the line my only (jerry-rig) option?
As far as I can tell the Weber isnt configured to collect and discharge surplus fuel...true or false? I'm sure its true because the things runs on 1-4 psi

The weber has a 2 port fuel inlet and has a wire strainer inside a tiny makeshift catch-basin. You choose a port for supply and cap the other.
Maybe the vapor port is capable of discharging surplus fuel? Does it? Can be set up on an anti-purge system to control both liquid and vapor? Or maybe I'm so far out of touch with reality....

Obviously the removal of the cat is another concern. Its gone already. Nice and tidy. Pulled the exhaust manifold, buffed it clean inside and out and gave it 6 coats of high temp primer inside and out thinking it might cook and have at least a little glazing effect over the rough surface for better flow. Probably wont have any measurable effect but I was bored.

Plugged the holes left by the removal of the exhaust gas recirculation tube and the oxygen sensor, replaced the gaskets and hardware, reinstalled. The question is this. With the slightly better flow as a result of removing the cat and exhaust gas recirculation pipe which will direct 100% of the exhaust through the muffler now, do I need to take that into consideration when selecting new carb jets etc? And what effect is the increase in flow going to have on exhaust valves? anything to be concerned about? Is there any reason I would have to reset either intake or exhaust valve clearances with the obvious change in timing that will take place?

Is there any emissions components to consider leaving in place for use in some other capacity aside from the charcoal canister such as the 5 port vacuum valve in the bottom side of the intake? Theres only one vac port on the carb and its reserved for the distributor. Actually theres one for the EGR that will not get used. But I'm just wondering if theres any reason to leave a few of the vacuum components such as the vacuum control switch for future use in some other capacity? Otherwise everything can go right?


By the way I got this weber DGAV with electric choke conversion from the junkyard for $50 off a 74 BMW 2002 series motor with a new K&N filter on it. Found a Redline adapter plate kit hanging on a hook in the back of a huge discount autoparts store for $19 clearance price. Its close enough to the right design that it will work just fine with a small mod to the carb base. But its so poorly made I cant use it until I deburr it, buff the mating surfaces flat and grind out the extra material in the port chambers. I'm also going press some rod stock into the pre-cut holes and tap nicely pitched fine threads into them because it looks like the existing coarse threads are molded NOT cut! I'm sure the alloy is poor quality too but what can I do? Not equipped to machine one myself other than with a jigsaw and a diegrinder which would take forever. The weber redline rebuild kit I got was $8.99 Just gaskets and o-rings. I hope the existing accelerator pump and float bowl diaphragms etc are good. Nobody has replacements in stock.

So the intake manifold has 2 water ports on the carb mount surface. The OEM Mikuni is cooled with water for some reason and has nothing to do with the Mikuni choke which already has both a vacuum cutoff and electric element choke control.
The issue I have is this. The redline adapter isnt going to cover them so my first thought was to make a plate out of 1/8 aluminum to fit over the carb mount surface on the intake. I can oversize the bolt holes, cut the fuel inlet chambers and just use a gasket under it. A new one made for the mikuni I'm removing should work fine. I sure the two ports are designed to channel water from one to other but I dont know if that flow is required for any other reason somewhere downstream? It wont be rocket science to figure out but if anyone knows please share it with me!

Maybe just plugging those two water ports with aluminum rod and filing the plugs flush will be easier and more suitable but if the plugs ever dislodged and made their way to a cylinder I'd be in a world of sh*t.

So I'll end this novel. Hope to hear from those in the know.

If your reading but your not a member and want to offer me some knowledge shoot me an email sixdsix at att dot net