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Carb question, Update 10/13
https://www.slantsix.org/forum/viewtopic.php?t=49551
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Author:  73dust225 [ Sun Aug 12, 2012 8:20 pm ]
Post subject:  Carb question, Update 10/13

Actually a couple of questions. First I have a 73 225 that I put a Super Six set up on. The car idles bad but runs ok. I thought it was a vac. leak but can't find one. The carb is a Carter #2543 that was on the set up I got. Is this the right carb? I also had it rebuilt through a friend (now ex) who knew a "Great" carb rebuilder but I don't know if he told the guy if it was for a Super Six. Will this make a difference? Thanks for any info.

Author:  SlantSixDan [ Sun Aug 12, 2012 9:47 pm ]
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2543 is probably not the carburetor number. Carter carbs have all kinds of numbers cast into their various pieces, but none of them is the carburetor number which is found only on an aluminum tag secured to one of the bowl screws (and often missing). Carburetor specification is probably not to blame for the poor idle, but a faulty carb or one in poor adjustment could do it, as could numerous other factors. Is it one or more cylinders consistently misfiring, or random misfire?

Author:  73dust225 [ Mon Aug 13, 2012 9:05 am ]
Post subject: 

I would have to say it's more than 1 cly. It feels like it's stumbling at idle in gear but takes off and drives ok. When sitting in park and idling it has a random misfire.

Author:  Reed [ Mon Aug 13, 2012 9:49 am ]
Post subject: 

Pictures of the carburetor would really help at this point. Have you used a vacuum gauge to actually find out what your vacuum is? You should get the carb service manual HERE and go through and make everything is adjusted correctly on your carb.

Author:  73dust225 [ Mon Aug 13, 2012 12:21 pm ]
Post subject: 

I'll try to post pics tomorrow. I did browse through the carb manual thats why I asked if it would make a difference if the rebuild was for a V8 and not a six. I don' have a vac gauge it's just another tool I need.

Author:  Reed [ Mon Aug 13, 2012 12:37 pm ]
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Quote:
I don' have a vac gauge it's just another tool I need.

Yes, it is. A vacuum gauge is a VERY useful diagnostic tool. It wouldn't make a difference for rebuild purposes of the carb was intended for a 318 or a 225, so long as the correct gaskets were used. What will make the difference are the internals of the carb, whether or not there are holes in the throttle plate, and the choke linkage. These things are different between slant six and 318 carburetors.

Author:  73dust225 [ Tue Aug 14, 2012 10:05 am ]
Post subject: 

I'm not sure what you wanted but here's a couple of pics of the carb. I hope these are what you need.
Image
Image
Image

And here's a pic of the engine.
Image

Author:  Reed [ Tue Aug 14, 2012 10:28 am ]
Post subject: 

That does look like a super six BBD. Since the problems you are having occur only at idle, I would do the following:

(1) Get a vacuum reading at idle. If everything is in good shape, you should be pulling 17-20 inches at idle.
(2) Check your curb idle mixture settings. 2 1/2 turns out is the starting BALLPARK setting. Lean/richen the mix as needed to attain a smooth idle.
(3) Check your metering rod adjustment.
(4) Check your valve lash.


Nice clean engine by the way.

Author:  SlantSixDan [ Tue Aug 14, 2012 10:45 am ]
Post subject: 

I do believe I see (at least part of) your problem. It looks as if you have no PCV valve. From what I see in the pics, it looks like you installed a vented breather cap in the rear hole of the (poor quality Chinese unbaffled) valve cover, and connected it to the carb's PCV port. That'll make a large vacuum leak and you will not be able to attain a good idle.

Recommend you put the stock valve cover back on -- those Chinese chrome ones are junk. See Thread 1 Thread 2 Thread 3. If you are bound and determined to use the chrome valve cover on your engine, and if you can hack the bolt holes so they line up OK, then set up the breather and PCV this way.

Author:  Reed [ Tue Aug 14, 2012 11:01 am ]
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AH! Good catch Dan. I was assuming the hose that normally goes to the PCV valve was going to the rear chrome breather device and I was assuming that the rear chrome breather was the sort that had an internal PCV valve. If it doesn't have an internal PCV valve, then Dan is absolutely spot-on. I also second everything he said about the chinese valve cover. The chrome is nice and shiny, but there are many technical difficulties to overcome.

Author:  Rug_Trucker [ Tue Aug 14, 2012 3:00 pm ]
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You need to get off the Chinese VC Dan. I have one it sealed fine. I'll be damned if I'll pay for an Offy that has to be modded. They need to upgrade their design! Damn! The slant market is growing!!! Hotrodders know that "bolt on" is rather subjective, or hit and miss.

If you have a better alternative? Build it we will buy it.

You need to order a breather cap for a 81 Buick wagon. I want to say it is for 301? It is a push in breather. Use a rubber grommit for a regular PCV. Get a slant PCV. I found the way to make it work on this site.

Or just plug your PCV fitting on your carb and run 2 breathers.

Some Fords had breather PCV combos too. Maybe a 77 F150 with a 351M

Author:  SlantSixDan [ Tue Aug 14, 2012 7:24 pm ]
Post subject: 

Quote:
You need to get off the Chinese VC Dan
Nope. Don't like my opinions? Don't read 'em. You'll also want to stop reading (or start complaining about) the opinions of others on this board, including at least one who knows more than you and I put together, who consider the Chinese valve covers to be junk.
Quote:
I have one it sealed fine.
Very good.
Quote:
I'll be damned if I'll pay for an Offy
Is somebody trying to force you? If so, call the police!
Quote:
If you have a better alternative?
Stock valve covers are of excellent quality, have all the right baffles and ports, have the holes drilled in the right places, cost almost nothing, and can readily be plated or powder coated to suit whatever your whim may be (linked site belongs to CudaChick, a dyed-in-the-wool Mopar and A-body freak who does awesome powder coating work).
Quote:
I found the way to make it work on this site.
Yep, you did...in the how-to link I researched and wrote (and posted above).
Quote:
Or just plug your PCV fitting on your carb and run 2 breathers.
No, because the idea is to solve the existing problem, not create new ones. Two breathers do not provide adequate or effective crankcase ventilation. Result is the oil getting much dirtier much faster, the engine getting much dirtier much faster inside and out, reeky crankcase fumes entering the passenger compartment, and reduced fuel economy. And moreover, a carburetor designed for use with PCV will not idle properly if the PCV port is plugged. None of that sounds like a step in a productive direction to me, but that's just, y'know, my opinion. :roll:

Author:  73dust225 [ Wed Aug 15, 2012 9:10 am ]
Post subject: 

First, Reed thank you.

As for the valve cover the holes matched fine and I had no problem putting it on. The breather and pcv valve are billet aluminum parts I had on my 69 340 Dart. The breather is cleanable and the pcv valve can be replaced when needed its held in by a snap ring.

Well I can't get to work on the car until the weekend but I will pick up a vac. gauge. I have never tested vac. before and I have looked through the factory service manual and I can't find how to do this any info would be a great help. As for the idle mixtures thats about where I have them now. Metering rod adjustment is something to be checked if necessary by someone who knows what their doing (I've never been good with carbs). Valve lash is something I know I need to check because I've haven't done it since I've owned the car :oops: I printed out a how to on this and I know I should have done it before the swap but it's to late now so it will have to be done soon.

Thanks everybody for you help it is appreciated.

Author:  wjajr [ Wed Aug 15, 2012 9:58 am ]
Post subject: 

Quote:
I have never tested vac. before and I have looked through the factory service manual and I can't find how to do this any info would be a great help

There will be an instruction sheet with vacuum gage outlining various tests, and how to interpret the results.

Author:  SlantSixDan [ Wed Aug 15, 2012 11:27 am ]
Post subject: 

Quote:
The breather and pcv valve are billet aluminum parts I had on my 69 340 Dart
Great, but I'm still not done suspecting your PCV setup. PCV valves are not universal, they are application-specific, and the wrong one can and will cause idle problems.
Quote:
I have looked through the factory service manual and I can't find how to do this
Get the other two books in this thread as quickly as possible to learn how to work on your car.
Quote:
Valve lash is something I know I need to check
Yup. Follow the valve adjustment procedure. Also Tune-up parts and technique suggestions in this thread. And Carburetor operation and repair manuals and links to training movies and carb repair/modification threads are posted here for free download.

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