82 needs to pass CA smog - Mikuni problems - rebuild or buy rebuilt?

[DadsRed82]

[Duplicate post draft deleted by author request]

[DadsRed82]

I tried to post this last night, if this is a double post, Mods, please delete the earlier post and keep this one.
I need to pass smog ASAP - I'm well past the deadline and I can't PNO this truck - have to park on the street.

I've been studying this forum and learned a lot from that. Also I bought two new manuals - 1982 dodge FSM and Haynes 1979-88. Learned a lot from both but both are sketchy in places - need these forums, for sure.
According to the manuals the carb is a Mikuni 32-35DIDTA-80.

Two main problems actually, both narrowed down almost certainly to the carb. So after checking several things I broke down and finally pulled the carb out, which wasn't actually all that hard, and today this leads me to theorys on what's wrong on both problems.
First I will explain the problems, then I will give my theories and ask you if they make sense.
BTW I can provide photos of anything I describe below, if that helps.

OK,
Problem 1: Before smogging figured I'd check curb idle speed. Got idle adjusted perfect, then noticed the engine didn't seem all that warm even after 20-30 minutes of idling, bought a new thermostat, then pulled the old one and sure enough, it was stuck open. Now I adjust idle again engine full warm (choke working), idles perfect for 10-15 minutes, rev engine up back to idle all good. Now I go for a test drive, at first it's OK, but after a few miles, it suddenly starts idling too low, very rough, and it will die unless I keep the throttle open slightly. I will call the normal - good - idle "mode A". The low, rough idle is "mode B". I read the manuals and forums. Checked timing - good. Checked thermostat vacuum valve - OK. Removed and checked EGR valve (this is the dual EGR type) a bit dirty but both primary and secondary EGR seem to function OK. Now I am getting frustrated and desparate, so I just adjust curb idle so in mode A its a bit high. Then when it goes into mode B, at least it won't die (but still rough). I take the truck to get smogged, and the tech says the truck is so down on power it won't get to 15mph quick enough for him to run the test. That leads to problem 2.

Problem 2: Down on power, open throttle. OK, a few years ago I noticed the truck seemed down on power going up a hill, for example. But in past years the truck passed smog without much trouble, and I wasn't driving it that much and not on the freeway, so I could ignore it. This is much worse. So with the air cleaner off, looking down into the carb throat, I noticed even when I rev the engine pretty good the secondary throttle butterfly wasn't opening, at ALL. I checked the secondary actuator (called depression chamber in the manuals) like what
geezer101 said here: http://www.mightyram50.net/vbulletin...361-Carb-issue
(I recently acquired a vacuum tester for checking all the vacuum actuators, and glad I did). It seemed like maybe the diaphram was leaking so I pulled the actuator, but actually I think the diaphragm leak, if any, is so slight it would still work. But even with the primary throttle held wide open I can't move the secondary throttle at all. So now I start to think I need to rebuild or buy a rebuilt carb. And that led me to finally pull the carb, yesterday.

THEORYs and QUESTIONs.
Problem 1 theory: After I pulled the carb, I noticed that the sub-EGR valve will stick open sometimes - after throttle is opened pretty wide then returned closed, the sub-EGR plunger just stays out. It doesn't keep the throttle from returning closed, but the EGR is still active. Now I had watched the sub-EGR valve moving in and out when I was in the engine compartment adjusting idle, so one thing I did NOT do was the recommendation here:
http://www.mightyram50.net/vbulletin...alve-Servicing
But actually my sub-EGR plunger was so gummed up I could NOT have just pulled it out like described. With the carb out I had to really work at scraping/chiseling away deposits from the plunger, before it finally came out. So I actually had to remove the carb anyway.
QUESTION 1: If the sub-EGR value sticks open, could that/is that likely to cause a low / rough idle?

Problem 2 theory: This is no longer a theory - it's proven. Now that I pulled the carb, Problem 2 is definitely because the secondary butterfly shaft is almost completely seized. I mean it was HARD to even move it, slightly, with a wrench on the lever arm. (With primary throttle held full open). Well, that is going to restrict power, of course.
QUESTION 2: Have you seen/heard of a secondary throttle shaft completely seized, like this? If I hold the primary throttle open fully the secondary should be able to move freely, isn't that right?

QUESTION 3: What should I do? Should I try to fix/rebuild this carb or spend $300 and buy a rebuilt carb? Understand I'm in kind-of a hurry, and I've never rebuilt a carb before. As I mentioned the choke works fine, I think many parts of this carb are good - in "Mode A" it idles and runs just fine, so if my Theory 1 is correct, maybe just a partial rebuild would be enough. But I'm not sure the secondary throttle shaft is even rebuildable? Seems like the whole throttle plate assembly is intended to stay as a unit?

QUESTION 4: This carb looks almost exactly like mine:
https://nationalcarburetors.com/Chry...ack_p_659.html
Except, my carb has anti-tamper covers over the choke area, and the throttle opener/dashpot is different on mine.
I figure I can swap in my anti tamper cover to make it look the same. Either keep the rebuild dashpot or swap in my current one (which seems OK). Autozone (where I will actually buy it) says it isn't a california smog carb. But as I say, it looks EXACTLY like my carb with two minor exceptions. Should I risk it and buy the rebuilt carb?

Calling all Mikuni experts - you're on!

[geezer101]

Set your base idle when the engine is hot, then check/adjust your ignition timing. Kill the engine and let it cool off completely. Start your engine, then adjust your fast idle screw on the throttle linkage so it's at the recommended cold idle rpm. Let it warm up and see what it does, take it for a drive etc. The secondary throttle will not open unless the primary is almost fully opened - it acts as a lock out as the Mikuni is a vacuum only secondary carb (this is an emissions thing on Mikuni carbs...) This carb is a biatch to work on but if you follow adjustments in order, you won't accidentally introduce a running fault (e.g. trying to adjust your idle speed by using ignition advance instead of setting the throttle stop and idle speed adjustment screws first) Good luck. It's an art working on Mikunis but once you decipher it's dark magic, you can get back to driving this thing lol.

*if you beat it and it passes emissions, you can reset the engine tune and get some hidden power out if it (just remember to adjust it back next time it's going in for smog)

[pennyman1]

Since you are in commiefornia, you have to have the exact factory carb or it will fail the visual. rebuilding the Mikuni carb is not one a first time rebuilder should try - it is a nightmare to work on. Mike Warme knows of a carb rebuilder he uses since he is in California - check with him on where to send it to. The anti-tamper covers should pop off the screws, but then at the age of these trucks, they just might break. I can't believe they would sell you a non california carb- that is not good. also try Allstate carb for a rebuilt carb to match your vehicle.

[xboxrox]

DadsRed82

Contact Alan Bayeur of Carburetion Technologies in Tacoma, WA (253) 472 9667 email: abayeur@gmail com

He may be able to advise you if a non California Mikuni can pass the Calif SMOG

http://https://www.carbtech.us/

If your truck has an O2 sensor on the exhaust manilfold then the truck will have a feedback carb which the computer will adjust through an 8 pin harness sending signals to several selonoids on the carb

Calif requires the tamper plug on the idle air fuel adjust screw

Don't be surprised if $500 to $600 is the price range of a decent rebuilt carburetor

Honestly ~ YOU SHOULD STOP F_ing AROUND AND BUY A CARB ASAP WITH WARRANTY THAT IT WILL PASS SMOG

GETTER DONE BUBBAH

[DadsRed82]

Thanks everyone, lots of good advice, as I expected.
Not sure my question #1 was answered. My fault: my post was too long. Let me rephrase it:
Question #1: If the sub-EGR valve sticks open - either half or full open, stuck - what will happen? Will it affect idle?
Also keep in mind this is a dual-EGR truck - has primary and secondary EGR valves. The manuals say the primary EGR valve operates at "relatively narrow throttle valve openings". Does that include idle?

@geezer, thanks for the advice. I will certainly follow it as far as adjusting fast and warm idle speeds. You confirmed my idea of how the secondary throttle works. In my case it has nothing to do with the vacuum actuator, the problem is that the secondary butterfly shaft was seized. I understood that the secondary is mechanically prevented from opening until the primary throttle is open. What I discovered today is that if the secondary doesn't open AT ALL, another interlocking cam mechanism prevents the PRIMARY from opening all the way. Not sure why they would do that, but that's the way it is.

I will beat this thing! Thanks for the encouragement.

@Pennyman. Yeah, I was thinking a full rebuild is not a great idea in my current situation.
It's great to have a name, but how do I contact Mike Warme? (I don't do FB, perhaps you could PM me his email?).
Yeah, it has to look like the original. That's why I was talking about taking the anti-tamper shield off my original carb and swap it onto the rebuilt. I'm not sure every smog tech will be that thorough, but some might so I would probably take the trouble to do it.
No one is trying to sell me a non-CA carb, I just found the rebuilt available, in stock, and it is visually IDENTICAL to my carb except for a couple of things I think I could correct pretty easily.

@Xbox, it doesn't have an O2 sensor, this is not a feedback carb.
Thanks for the contact. That's what I need - someone who really knows these carbs, including California emissions.
Sure, if I can find a good rebuilt carb exactly my model, I will buy it.
I haven't seen anything online so I need the contacts of where to call.

UPDATE:
I am stubborn and I like to learn stuff. Today I couldn't wait for your replies. As I said the secondary throttle shaft was seized, hard.
I figured this carb was probably toast anyway and I can't make it any worse. So after a few hours of effort, with no guidance from any manuals or carb rebuild kit instructions, I figured out how to get the secondary shaft out.
(Partial disassembly of the primary throttle shaft was required).
I had to use a punch and hammer to drive the shaft out, little by little - it was that stuck.
But after cleaning shaft and bores, and a little grease, it turns smooth.
Might be able to save this carb, after all.

[geezer101]

Nice work. Hopefully the shaft journals aren't that badly ripped up and any vacuum leak you might end up with is minimal.

[xboxrox]

DadsRed82 ~ call Alan see if he has a rebuilt carb on the shelf for your truck OR ask him how much & how long to fix my carb and return it to me AND let him field your questions ~ he helped me greatly over the phone for free and he answered every question ~ ASAP or DIY ??
We don't always get what we pay for in time money or effort ~ I am certain a good percentage of rebuilt carbs are crap but if ASAP meant more to me than fun time DIY then I would be on the phone calling Alan first and every other ebay OReillys NAPA vendors to buy a rebuilt carb ~ yep !! If I had to rebuild another Mikuni again I would be on the phone buying that sucker with a good warranty ~ try talking to Alan is my best advice & like the others here we all wish you the best and enjoy the give & take here ~ George signing off 'n GETTER DONE RED

[DadsRed82]

Thanks again!
I will report back how this works out.

[xboxrox]

Thanks again!
I will report back how this works out.

If you contact Alan, you might let him know you are from the same online group as George in Hawaii & Happy New Year to him as well ~ FWIW Alan claimed to have rebuilt about 2,000 Mikuni carbs !! He has a FB page too

P.S. If not done already, make sure the PVC valve is clean and works correctly, it can greatly affect engine idle

Aloha & Best Wishes

[xboxrox]

DadsRed hope your able to fix your truck ~ perhaps you can locate a similar carb from Pick N Pull wrecking yard and cobble together one good carb from two parts carbs ? Hope we hear about your progress sometime soon respects George