carb help

[Drives a 5]

New member with an 82 fairmont 200ci w/ 1946 & c5 auto. This is my first carbed car, was wondering if anyone could give me a little advice.

When I got the car a while ago, it needed a few things... it pinged under acceleration, 2 of the spark plugs were completely loose, dieseled most times when I turned it off, would die at stoplights, etc.
To make a long story short, I gave it a new cap, rotor, plugs, wires, air filter, set the timing, and adjusted the idle down. This fixed most things...
However it now has a kind of hesitation when starting off when I get on it. If I go gradually it accelerates fine and smooth. If I mash it it will die. If I hit it relatively hard, it will hesitate, then start to pick up speed and will be fine throughout the upper rpm ranges after that.

So anyone who could give me any info, ideas, whatever, it would be much appreciated!

 

[CZLN6]

Howdy SRB:

And welcome to the Forum.

From your description it sounds like your accelerator pump has given up the ghost. It's a little difficult with a 1946, but try looking down into the carb with the choke propped open. A flash light makes seeing alot easier down there. Now work the throttle to wide open. You should see a squirt of gas enter to carb venturi. If you don't, you have just identified your problem. You accelerator pump is not pumping. The solution? A carb rebuild and a good cleaning.

You might be able to cover the bog a little by using a little more than stock initial advance, and a slightly richer low speed air screw, it this Holley has one most don't. thanks to EPA.

Adios, David

 

[Drives a 5]

Thanks David, I'll definitely try that and see what happens when I get a chance.

-Scott

 

[HotRodLarry]

Let me know how that rebuild turns out. I've been putting it off for a week or two. My '83 Ltd has a 1946 carb on it and looks like it needs a rebuild.

 

[CZLN6]

Howdy All:

It might be a good idea to buy a rebuild kit well in advance of the rebuild so you can familairize your self with the process. A quality kit is usually very detailed and has good photos to study.

Unfortunately the 1946 is encumbered with many electronic and vacuum connections and switches. Most of the adjustments are bent rods, which should not need changing. Make sure the vacuum switches and temp sensors are working as designed.

I forgot to mention, a kit usually includes a new accelerator pump and gasket. Kits typically run about $20.00.

IMHO, there are five things that hold back performance in the '80 - '83 200s. They are advanced cam timing for low emissions and more low end grunt, reduced compression (emissions), a restrictive exhaust(emissions), too high rear gear(corporate mileage), and the Holley #1946 emissions carb.

That's my two cents, for what it's worth.

Adios, David

 

[JackFish]

They are advanced cam timing for low emissions and more low end grunt, reduced compression (emissions)

Advanced cam? You meant retarded?
I would also recommend buying a second carb ($15 and the junkyard or ebay) and rebuilding that if you have no experience with it and your car is a daily driver.

 

[CZLN6]

Howdy All:

Jackfish- There is an excellent article in the Jan. 06 issue of Car Craft entitled "Dyno-Proven Cam Tech".

I may have to apologize for previously stating the advance/retarded cam timing wrong. To quote the article, "advancing the camshaft improved bottom-end torque, while retarding the cam from the zero or 'straight up' position hurt bottom end power while slightly improving power at the higher engine speeds".

Also, "Since intake closing is the most important of these four points, advancing the cam closes the intake sooner to improve low-speed power while retarding the cam closes the intake valve later, which improves top-end power".

The article offers Dyno charts to illustrate their point.

FoMoCo used the technique to reduce emissions and to get a little more low end torque to complement the lowered CR and extremely high rear gear ratio they put in late model 200 vehicles.

Again, I apologize if my previous comments have added to this confusing concept.

Having a practice carb to rebuild is an excellent suggestion.

Adios, David

 

[JackFish]

Thanks for the clarification. My cam is in at 4* and yes, the low-end has more grunt and I've lost top-end. I think when I pull the front off again I will experiment with setting it back to tdc, or back -2* to get more top end.

 

[Drives a 5]

The update is I checked and it is spraying a jet of fuel in when I move the throttle, so any more ideas?

One more question, can a rebuild kit be found at any auto parts store, or is it more likely I'd have to order one (not that I definitely am rebuilding it anyway, just curious).

And while I'm at it... HotRodLarry - have any pics of your 83 LTD? I have an 85 LTD LX, I love LTDs! and about any fox body for that matter.

Thanks again for the replies.

-Scott

 

[CZLN6]

Howdey back:

Next check your initial advance setting. Not enough initial advance could cause your symptom.

Also check for and eliminate any vacuum leaks.

I get my rebuild kits through the local NAPA store. I'd guess Autozone or Checkers should have them or quickly get one for you. Even if you don't rebuild yet, the instructions and photos will help your understand and diagnose your carb.

Adios, David

 

[Drives a 5]

Thanks for another response David! It is possible there are vacuum leaks because the lower section of my air cleaner housing has cracked all the way around, and is even missing a small piece in the back - something I need to fix. Anyway, the reason I wrote that off is because the car was that way when I bought it and I don't think it acted this way then. I could recheck the timing, although even now at highway speeds I have heard a slight pinging a couple times, but usually it's minor and is not persistent. That lead me to believe it's probably about at the upper limits of it's timing threshold. Also, when setting my timing to the timing tab, there are marks on it but not really any indication of how many degrees they are. I think there is one larger tooth and 6 smaller ones - so I basically guessed and set it to the large tooth and it ran much better than before so I left it. So if all this gives you any more clues, let me know .

 

[80Stang]

If the timing marks are like in my '80 Stang there is just one line on the damper and a metal marker with teeth to show the timing. The first and slightly bigger "valley" between the first two teeth (when observed from the drivers side) is 0 degrees, and then it is about 4 degrees from tooth to tooth and some 14 degrees at the other end of the scale. Time it between 10 and 14 and I'd say timing is not the primary prob anymore. But your damper ring may be off zero, that should be checked first and new mark put on it if not correct. Mine was about 3 degrees of when I checked it. Punched a dot on correct place.

Acc pump works but it may squirt a little bit late; adjust it's rod by bending, try first to make it squirt a little earlier.

The 1946 has a power valve, and after seeing that apparatus I'd say the problem may be there. It has a vacuum operated valve that opens the PV needle when vacuum drops below certain amount. I could suspect the valve being stuck (or the needle) so it won't richen when it should - you go lean - and it dies while WOTted.

If you PM me your mail address and I'll send a set of pics of a 1946 disassembled.

I think you should find a Standard brand rebuild kit for your carb all over there.

 

[Drives a 5]

80stang - yep the timing marks are like you said. I can recheck the zero but I think I remember it being ok. So valley one would be zero (after the big one) then moving toward passenger side would be point=2, valley=4, point=6, valley=8 etc. correct?

About the acc. pump, will I be able to tell if it squirts late by moving the throttle and watching it? Should it squirt right away when I first start moving it? Also, the rod for it is internal and below the air horn, right?

The power valve is a good idea as well - like I said I don't know about all the workings of carbs yet, but it definitely would make sense since there is no vacuum (or is it just very little?) at full throttle. This would mean that the power valve only does anything when starting from a stop or low rpm correct? Because in this case I can do full throttle when moving, just not from low rpm or a stop or it would stall.

One last thing, would a rebuild fix any and all of these problems? Am I wasting my time wondering what it is when I could just rebuild it? Thanks again!

Oh yeah, I'll PM you my email, pics are always helpful.