Author Topic: I need the stock specs for a 17050213.  (Read 2350 times)

Offline Cadman-iac

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Re: I need the stock specs for a 17050213.
« Reply #15 on: November 18, 2025, 06:12:55 PM »
  Well, this carburetor runs rich from off-idle to 3500 rpm. It's not the timing.
  I noticed that this one has a  .016" smaller LIAB than the other 3 previous carbs, so is this the whole problem with the other 3, the LIAB's were just too big?

 And how would I get this one to lean out a bit in the off-idle to 1500rpm range? Enlarge the LIAB'S slightly?

 Something else I noticed is that the jet/rod combination in this 17080213 carb, (#72/49M), has a cruise metering area of 2.19 thousands of a square inch, yet runs much richer than two of the other carburetors that have a jet/rod, (#72/44 from Cliff), metering area of 2.55 thousands of a square inch, and the 3rd one has a metering area of 2.52 thousands of a square inch, (#70/41K). What's up with that?
 Does the LIAB's have that much effect on the AFR?
« Last Edit: November 18, 2025, 06:16:40 PM by Cadman-iac »

Offline 77cruiser

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Re: I need the stock specs for a 17050213.
« Reply #16 on: November 18, 2025, 06:53:53 PM »
Have you tried adjusting the APT on this carb? How's heavy part throttle?
Jim

Offline Cadman-iac

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Re: I need the stock specs for a 17050213.
« Reply #17 on: November 18, 2025, 07:20:45 PM »
Have you tried adjusting the APT on this carb? How's heavy part throttle?

 No, not yet, it was just getting dark when I got back from the test drive.  I do need to look at that, I didn't think about it being set too high.  I set it at 3 3/4 turns according to the specs I got from Kenth. I thought it was a bit much right off the bat, I don't usually run it up until I try it set at minimum first. But since I was trying to set this one up exactly like it left the factory I figured I'd try it and see how it works.
 I'll give that a try before I do anything else.
 But if this doesn't change it, would the LIAB's be a possible cause?

 The heavy part throttle is rich as well. I don't remember the reading, I forgot to bring my recorder for notes this time. But it's definitely fat from top to bottom.
 Im actually glad too, I was beginning to think I had some other problems with the engine instead of the carburetion. This just proved it.
 Thanks for the suggestion.
« Last Edit: November 18, 2025, 07:29:17 PM by Cadman-iac »

Offline novadude

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Re: I need the stock specs for a 17050213.
« Reply #18 on: November 19, 2025, 05:25:18 AM »
I think the LIAB could definitely be part of the problem with the other carb.  I've found that 0.062 vs 0.078 just seems to work better for off-idle.  As for metering area... I don't think you can compare SMAB carbs with DMAB, as they seem to behave different with regards to main system metering area.

I've shrunk the LIABs with an old accelerator pump ball and a punch, and cleaned up with a drill.  This doesn't always go smooth though, so be careful.

Offline Cadman-iac

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Re: I need the stock specs for a 17050213.
« Reply #19 on: November 19, 2025, 07:48:38 AM »
I think the LIAB could definitely be part of the problem with the other carb.  I've found that 0.062 vs 0.078 just seems to work better for off-idle.  As for metering area... I don't think you can compare SMAB carbs with DMAB, as they seem to behave different with regards to main system metering area.

  Novadude,
 The last carb was a SMAB, #17084226, and it had a larger metering area than this one does.

  I'll start with adjusting the APT, and if it doesn't work I'll make the LIAB's on this 17080213 replaceable with set screws, and try smaller ones until it gets into an acceptable AFR range. Hopefully it doesn't change anything else. The higher RPM mixture can be fixed with the jet/rod combo and the APT setting.

 The difference between these two is definitely confusing, but I'm gonna figure it out, it might take me a while, but I'll get there, (most likely with help from you guys).

Offline 77cruiser

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Re: I need the stock specs for a 17050213.
« Reply #20 on: November 19, 2025, 03:15:44 PM »
I dug one up in my stash, it pretty crusty inside must have had water in it.
Maybe I go through it & see what happens.
Jim

Offline Cadman-iac

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Re: I need the stock specs for a 17050213.
« Reply #21 on: November 24, 2025, 05:20:28 PM »
  It took me a while, but I've got it pretty close now.  The off-idle mixture is much better, and the high speed mixture is right where it should be.
 I had to increase the size of the LIAB'S to  .072" from  .062", and had to reduce the jet size from #72 to #70, keeping the 49M rods.
 I've still got to dial in the secondary airvalve spring setting, stock is 1 turn, but it works much better at 3/4 turns.  I need to get the secondary mixture right, i think it's gonna need a fatter rod to lean it out at WOT, it's just a bit rich yet.
 I'll post the specs once it's done, both where it was and then where it ended up.
  Thanks for the help in figuring it out.

  Rick
 

Offline 77cruiser

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Re: I need the stock specs for a 17050213.
« Reply #22 on: November 24, 2025, 06:55:47 PM »
How does it run? Are ya having fun?
Jim

Offline Cadman-iac

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Re: I need the stock specs for a 17050213.
« Reply #23 on: November 26, 2025, 09:18:27 PM »
How does it run? Are ya having fun?

 Weeeeellll, im not sure I'd call it fun, but I am staying busy.

 I think I've got the primary side pretty much dialed in.  Gotta do one more road test to verify that tomorrow. The tip in test I had to do several times to get it to react like Cliff suggests, but its right on the money now. Goes up about 60-70 rpm when I close the choke partially, and it didn't react when I pulled off a vacuum line.

 So here's where it wound up.

                  Stock.         Now
Idle tubes,   .038.        .038
DCR'S,          .054.        .054
UIAB'S,         .069.        .069
LIAB'S,         .062.        .070
Bypass air,  .105.        .105
Idle dschg,  .086.        .086
Float,         12/32.     12/32
PAB-Body,   N/A.        N/A
PAB-Horn,   .051.        .051
Noz. Bleed, .029.        .029
Main jets,    #72.         #70
Pri. Rods,    49M.        50M
P/V spring,  orange.   Blue
APT set,      3 3/4.      3 1/4
Sec. Rods.   DP.           DR
Hanger,         K.            K
SABT,s.        .026.       .026
Well holes,   .039.      .039
A/V spring,   3/4.       3/4
N/S asm.      .135.     .135

 Now anything with the secondaries is still to be determined by testing yet to be done. I'll update once I've got the secondaries dialed in.

 One thing that kept messing with me is that the AFR would fluctuate randomly like it had an internal leak, but multiple testing of the well plugs didn't reveal anything, and I kept remembering what Cliff says about these, "they seldom leak".
 But I've seen how the AFR gage reacts to a leaky plug and I swear it's leaking.
 Well after taking it apart after it sat overnight I noticed the pocket in the base plate was wet with fuel.
 And I kept seeing wetness on the primary well plugs too, so I removed all of them and threaded the holes and installed plugs and Marine Tex, now the AFR is definitely more steady and it sounds better too.

 

Offline 77cruiser

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Re: I need the stock specs for a 17050213.
« Reply #24 on: November 27, 2025, 05:21:35 AM »
Sounds like you did a great job.
Jim

Offline GSP7

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Re: I need the stock specs for a 17050213.
« Reply #25 on: November 29, 2025, 09:26:39 AM »
Whats the 17080231"C" ?

This is what i have on the 1980 350 HD Truck 17080213 Rochester and Carter units.
[/quote


« Last Edit: November 29, 2025, 09:40:04 AM by GSP7 »
Idaho

Offline Kenth

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Re: I need the stock specs for a 17050213.
« Reply #26 on: November 29, 2025, 10:55:38 AM »
C is the Carter mfd Quadrajet.

Offline GSP7

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Re: I need the stock specs for a 17050213.
« Reply #27 on: November 29, 2025, 06:31:04 PM »
I have a Rochester 17080213 that had 73 jets and 49 rods
Idaho

Offline Cadman-iac

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Re: I need the stock specs for a 17050213.
« Reply #28 on: December 09, 2025, 08:11:26 PM »
  Well I've had to continue to calibrate this one, not sure why the results of the tip in test were spot on by Cliff's book, but on the road test it ran lean.
 It took multiple jet and rod changes to pin down the right combination that yielded good results.
 What's really weird is that with a 71 jet and a 44 rod it ran lean, but with a 72 jet and a 44 rod it ran rich.
 I ended up going with 70 jet and a 41 rod to get the afr into the correct range. The 71/44 combo gives a cruise area of 2.43, which apparently is not enough, yet the 72/44 combo with an area of 2.55 proved too much.
 So going through what I have on hand, I had a couple of options, a 69/40 giving me 2.48 cruise and 3.20 WOT, and a 70/41 with 2.52 cruise area and 3.31 WOT.  And since the 72/44 combo was rich at WOT as well, with 2.55/3.54, the smaller jet/rod combination brought the AFR closer to optimum.
  Even though it's running much better now, the tip in procedure is indicating that it's running rich.
 I may have to try another combination to see just how far it will go, but I'll have to order a couple of rod sets in order to find out.
 If I go with a 71/43, that'll give me a 2.50/3.42 cruise/WOT area,  or a 72/45, which gives a 2.48/3.52, but that keeps the WOT area too big and too rich.

 The other things I had to change were the air valve spring setting, that went back to 1 turn, and the secondary rods are now a pair of CT's instead of DP's. The WOT AFR is now around 11.0 at 3500 rpm.
  I also had to go to a  .067 on the LIAB's to get the off-idle mixture correct.
 I tried advancing the timing to 16° initial, but I think that's a bit much, I'm afraid I won't hear any detonation if it occurs, so I reset it back to 10°.

 On another note, I was getting a fluctuating AFR at idle still even after replacing the well plugs.  It was much improved, but still noticeable.  So upon disassembling it after leaving it sit overnight, I noticed that there was fuel in one of the small pockets next to the accelerator pump well, and the bypass air passage looked like it was wet as well.
 
 Looking at the air horn it had a slight curve at the front, so I filed it flat in the hope of stopping any fuel from leaking into the bypass passage.
  I haven't had it off and apart since installing order to check for leakage, but the AFR doesn't seem to fluctuate as much now.
 It was going from 13.5 to 13.9 and back at idle,  now the fluctuations are just like .2 instead of a .4.

  Novadude,  what is your AFR range when you're cruising at around 3000 rpm at light throttle? Mine runs around 15.2 to 15.5 and I'm wondering if it's still a bit rich.
  And at a WOT, just how rich should your AFR be? I've been shooting for around 11.0 to 11.5, but I really don't know if that's too lean, or too rich, or just right.

 My thanks again to you guys for all your help, Novadude, 77cruiser, Kenth, MCX, and Cliff.
« Last Edit: December 09, 2025, 08:25:25 PM by Cadman-iac »

Offline Cadman-iac

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Re: I need the stock specs for a 17050213.
« Reply #29 on: December 10, 2025, 07:08:21 AM »
  I wanted to share how I locked out the secondaries this time. Last time I used a wire to keep the secondaries from opening by wrapping it around the lockout lever and the shaft. The problem with that method was that it caused the secondary throttle shaft to move to the right side and not allow the plates/blades to close correctly, resulting in a vacuum leak.
 The wire apparently jammed between the base plate and the little pin that goes through the shaft.
 So to prevent that this time I made a bracket that bolts to the side of the carb where a rear pull-off would typically go, and it fits against the pin in the shaft.

 Another tip for locating an internal fuel leak is to use a blue Sharpie to color the surface around the suspected leak. If it is leaking, the ink will run showing the source.
  Since it's not possible to use a camera to actually see what's going on inside the carburetor, I figured if you could use something to cover the surfaces that would come off with fuel, that would hopefully show you where it's leaking.
 I initially tried this on the well plugs which revealed multiple leaks. So this time I "painted" the bypass air passages and set screws in the base plate, but I haven't taken the carb off and apart yet to see what is happening yet. When I do, I'll post a picture of the results.

 Another thing that I do to keep the idle mixture screws in "synch" is to paint the heads of the screws so it's easier for me to see. I paint one half of the screw head with a red welding marker and the other half with a yellow marker.
 Because I wear trifocal glasses it's sometimes hard to focus on the screws when I'm working on it in the evening, so this helps me see them better. If the red halves are both towards the left or right side, then I have them "synched". Its really easy to lose count of how far you've turned them, especially if your screwdriver slips off. I didn't think to get a picture of them though, but next time I've got the carb off I'll get one and post it.