Author Topic: Carb recommendations  (Read 26130 times)

Offline Stewart G Griffin

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Re: Carb recommendations
« Reply #30 on: February 12, 2018, 09:53:21 AM »
Stock Non-CCC quad off 83 1/2 ton:






i can't help with where to connect the thermac----until next weekend IF we're lucky.   But i don't think that is causing your driveablility problems, so it's not urgent.
« Last Edit: February 12, 2018, 10:46:02 AM by Stewart G Griffin »

Offline bd

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Re: Carb recommendations
« Reply #31 on: February 12, 2018, 11:15:32 AM »
What's the carb number, Stewart?  The secondary air valve link is installed.  Can you post some clear pictures of it next to a ruler?  A new link could be fashioned out of some appropriate diameter welding rod.  The green Teflon coating isn't important.
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline Stewart G Griffin

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Re: Carb recommendations
« Reply #32 on: February 12, 2018, 12:44:31 PM »
Will get on it asap, but very busy.

Also, apologize for the dirty table---that's not me, but again----very busy.

Offline Monkey Uncle

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Re: Carb recommendations
« Reply #33 on: February 12, 2018, 02:21:11 PM »
Thanks very much, Stewart.  Those pics are very helpful.  From what I can tell, all I'm missing are the secondary air valve link and the idle stop solenoid.  I don't think I'm having any dieseling issues related to the missing idle stop solenoid, so I'm not too concerned about that. 

This might be the secondary air valve link: https://quadrajetparts.com/auxiliary-vacuum-brake-rod-fits-1980-3057-p-150.html

Sorry I haven't followed up on this lately.  The truck is still in the shop awaiting the replacement rocker arms.  Hopefully I'll get it back later this week.

I think my first order of business will be to do as bd suggested and check for vacuum leaks.  No point in going any further if the castings are warped and leaking. If that checks out o.k., next step will be dealing with the fuel seepage, and if I can get that taken care of, check timing, re-check choke function/adjustment, tune the carb, and replace the secondary air valve link.

Offline raf2330

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Re: Carb recommendations
« Reply #34 on: February 16, 2018, 08:23:49 AM »
Just my .02 cents here, I would stick with the Qjet. Seems you are leaning that way. These other guys have given you some good advice, IMHO, and I know blazer74  helped me out when I was doing the build on my Qjet for my 454 using Cliff Ruggles forum and his book. I had previously tried switching to an Edelbrock 1407 & 1806. All gave minimal performance and really poor gas mileage. Tried a Qjet a couple of years ago from Nat. Carb., terrible experience. Sent it back within 3 days. You have a 1708 casting pictured, in my experience these rarely warp enough to cause problems. Those later carbs are somewhat thicker with a different bolt pattern up front than the earlier ones. From one of your pics of the front of it, warping seems very minimal to nonexistent. I have a couple 1708's in my garage, none warped. My orig. carb is a 1705 casting and was warped bad, but did not cause problems. I fixed warping just so it wouldn't get worse. Your wet air horn gasket tells me that the float level is to high and that alone can be causing your drivabiity problems, that and the APT may need adjustment also, but if the float is wrong it will be hard to get anything else right. It's a great carb., it just needs to be tuned for your engine if not the original. After learning about it, and taking some time to set it up with new good parts, mine runs great. Good luck.
Working, & working, & working on dad's (now mine) 73 w/big block.

Offline 75gmck25

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Re: Carb recommendations
« Reply #35 on: February 16, 2018, 11:24:52 AM »
My very late reply to a question MonkeyUncle asked -

The carburetor I found on an mid-80's Chevy 1 ton pickup was the 17080213 M4MC, which is one of the last models with no electric or electronic controls.  The truck had been owned by a local commercial company, and it looked like they had kept up all the maintenance.  However, I am not sure if the carburetor was original.

I added an electric choke to replace the hot air choke, and also drilled and tapped it so that the APT could be adjusted externally.    The rebuild kit I bought from Cliff Ruggles worked well, although I still ended up replacing a couple additional parts (choke pull-off, etc.) that appeared to not work correctly.

Bruce

Offline Monkey Uncle

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Re: Carb recommendations
« Reply #36 on: February 17, 2018, 04:57:22 AM »
Thanks for the info, raf2330 and Bruce.

Raf2330, how did you fix the warping?

Offline raf2330

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Re: Carb recommendations
« Reply #37 on: February 18, 2018, 07:51:12 PM »
I built a jig out of steel plate to mount the sections of the carb. onto. Applied pressure evenly in strategic places, as best you can, and put in the kitchen oven that I had set at about 250 degrees. Did each section of carb separately. Put the piece in for about 15 minutes to heat up, then would apply a little pressure to the bolts in very small increments as to not bend the parts to quickly and crack them or cause warping in a different area. Took a little over an hour per piece as I recall, air horn and main body were both real bad on mine. Trying to attach pics for reference. Hopefully it works.
Working, & working, & working on dad's (now mine) 73 w/big block.

Offline Stewart G Griffin

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Re: Carb recommendations
« Reply #38 on: February 18, 2018, 09:53:15 PM »
17083224
1873 FKA





Side closest to 2 goes to choke flap, side closest to edge of ruler goes to vacuum can.


2) Also important is that we must all fully understand and acknowledge that i normally don't keep such a dirty table;  That was inexcusable and not my norm.  Also, i don't drink that much Monster energy drink(which is also a bad habit), but i'm working nightshift now.  :)

Offline Monkey Uncle

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Re: Carb recommendations
« Reply #39 on: February 19, 2018, 05:11:46 AM »
Raf - wow, that's a pretty impressive fix.  Unfortunately I don't have the fabrication skills or tools to pull off something like that, so if I do have warping issues, I'm probably looking at swapping out the carb.

Stewart - thanks for the photos.  That's clearly different from the part that I linked to on quadrajetparts.com.  Looks like their part is the link that goes to the choke, despite the web site saying that it is for the secondary air valve.

Offline bd

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Re: Carb recommendations
« Reply #40 on: March 01, 2018, 07:12:44 PM »
This is the air valve link on the carburetor imaged by Stewart (#3056 that replaces OEM #17062369 according to the Quadrajet Parts website).  Perhaps if you call them, they can provide a definitive answer.
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline Monkey Uncle

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Re: Carb recommendations
« Reply #41 on: March 02, 2018, 05:08:18 AM »
Thanks for that link, bd.  That does look like the right part.

FYI, I am still dead in the water due to the rocker arm issue, which also turned out to be a lifter issue.  Hopefully I will get the truck back soon and can resume my carb troubleshooting.  I'll post updates (and likely will have more questions) when I get into that.

Offline Jerr-conn

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Re: Carb recommendations
« Reply #42 on: March 03, 2018, 07:20:29 AM »
This Q J stuff will drive you nuts. just bite the bullet and buy a 600 cfm Holley with elec choke.
Problem solved.
Jerry

Offline Monkey Uncle

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Re: Carb recommendations
« Reply #43 on: March 19, 2018, 12:34:28 PM »
I finally have my truck back after a month-and-a-half detour to the shop, which resulted in all new rocker arms, lifters, and pushrods (all under warranty, thankfully).

The mechanic said he tweaked the timing a little, backing off the initial advance from 12* to 10*. 

He also rigged up a fix for the transmission vacuum tube.  I had bought a replacement T-fitting for it, but the mechanic said it wouldn't work because the original fitting supposedly is a "one way" fitting that only lets air move in one direction.  Not sure if I believe that.  At any rate, he epoxied over the broken off nipple on the top and attached the transmission vac line to the nipple on the side, disconnecting the 1/4" hose that had been attached to that nipple.  The fix looks like crap, but it seems to work.

The hose that he removed was supposed to go to the vacuum accumulator can (I think), but I had never traced it to its terminus to be sure.  Looking around now, I can't find anything that looks like a vacuum accumulator, so I'm wondering if that hose had just been hanging loose all this time, which would have created a huge vacuum leak. 

The idle has smoothed out quite a bit; not perfect, but a lot better than it was.  Not sure if it was the timing change, the vacuum hose fix, or something else.

When I got the truck back, I noticed that the choke wire was not connected.  Upon reconnecting it the right way, I realized that it had not been connected correctly before, so the heating element probably had not been operating properly.  With it connected the right way, the choke opened way too quickly and I was having a hard time with cold starts.  So I rotated the choke cover counter-clockwise to correct the previous adjustment that I had done to it.  It seems to be operating normally now, but I'm going to keep a watch on it to be sure.

Today I sprayed carb cleaner to check for vacuum leaks (throttle shafts, cracks between castings, and crack between throttle plate and intake).  It idled the same throughout the tests, so I am assuming at this point that I don't have any major leaks in those locations.

It still runs somewhat rich, and it is still seeping fuel around the accelerator pump shaft.  So my next step is to pull off the air horn and check the float and needle/seat.  Question: when I do this, do I need to replace the air horn gasket?  It is a new gasket, but it has gotten saturated with fuel because of the seepage.

Thanks, guys.


Offline Henry

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Re: Carb recommendations
« Reply #44 on: March 19, 2018, 12:58:15 PM »
Hi:
No, you can re-use a new air horn gasket if you let it dry out and it is still straight and not kinked or torn. When you have the air horn off and are inspecting/adjusting everything, you may discover you need to buy a replacement part so hold off on buying any carb parts until this inspection is done...the gasket may not be available as a stand alone part for sale anyway...may have to buy a whole gasket kit if you wanted it.
Regards,
Henry