Carb swap and tuning issue

[max]

Hi, I am a new member and was thrilled when I found this site.
I have a 1980 Fox body Mustang with a 200 cu. in. 6 automatic.
The motor is stock except for a KN air filter and Turbo muffler. Pollution pipes (exhaust to carb) are removed, but it still has the cat.

I am considering a carb conversion, and it looks like the Holley/Weber 5200 with a Clifford or Stovebolt adapter is the way to go.
Has anyone done this to an early 80's Fox body Mustang?
Any carb linkage issues, it seems like the Clifford adapter may make for an easier throttle linkage.
Does anyone have experience with both types of adapters and if so, which do you prefer?
There is a lot of info on proper jetting, and as the Fox bodies have an electronic ignition, does this make any difference to jetting?
Any under hood clearance issues?
Any and all advice appreciated.

Also, I have had the car timed and tuned but after 8 months there is a very slight pinging when going up a gentle grade at steady throttle. No problems under hard acceleration, or when accelerating on an upgrade, or any other type of driving. It only happens when gentle or no throttle is applied when going up a grade. The car is stock except for a KN air filter and low restriction Turbo muffler, added after the tuneup. Any thoughts?
Thanks.

 

[fordconvert]

Slight ping could be from a carbon build up, higher temps, or lower quality/ more additives and other crap in the fuel. If other performance is good maybe restricting the amount of vacuum advance would help. I also see you have removed the EGR. I have seen cases where that makes a lean cruise get even leaner so if other tuning has not changed that could be what is pushing things a little over the edge depending on the first factors I mentioned.

 

[max]

Now that you mention it the plugs have about 10,000 miles on them, they look fine, very clean but are on the white (versus tan) side. I also have the timing retarded a few degrees more then factory specs, so it may very well be a running on too lean a mixture.
I checked my Clifford manual that says the model 1946 single barrel should only be adjusted by a "technician", so there are no instructions on how to change the air fuel ratio. The Haynes manual refers to idle adjustment, but nothing at all about the air/fuel mixture adjustment.
Maybe there is no adjustment for air fuel ratio?
Thanks for the suggestion, I will see what, if anything, I can do about the mixture.

 

[fordconvert]

Slight tuning changes sometimes can be made by adjusting the float level otherwise the main jet(s) have to be changed or modified. I dont know the 1946 at all so I dont know how hard it would be or what parts are available.

 

[JackFish]

Have you got a timing light? If not, look for one with an advance dial.
I have a 1946 and get good performance out it. Well it's actually about three of them I've picked up at scrapyards and used for parts for rebuilding. I also have several 5200s that I've picked off 4cyl Fairmonts, Zephs and Mustangs too, so that's one way to go if you're looking for spare parts.
It would be good to know how your vacuum is routed now that the pollution control stuff is off. Like where is the distributor getting vacuum from?

 

[CZLN6]

Howdy Max:

You've gotten some good direction already. Let me add a few more thoughts and ideas.

When you added a freer breathing air cleaner ellement and muffler you, in effect, leaned out an already lean system. And, unfortunately, the 1946 carbs were the last carbs to be used on these engines, just before FoMoCo went to FI completely. The 300 six family and even the 2.3 four cylinders got TPI. the 200 sixes got deleted.

The 1946 became more encumbered and less user friendly with each years passing. More and more temperature, vacuum and load feedback systems were added to safely attain leaner A/F, cleaner emmissions and better MPG. And it worked, to a point, so long as it all keeps working. And it is all covered by federal EPA regulations, so check with your local enforcement laws before you get too far along with changes.

The low speed air screw is sealed on most of these carb. To have a meaningful effect on the various circuits you would need to have access to the low speed air screw, enrichment circuit and the main jet system. Raising the float will have a slight effect.

Given that, looking into a two stage two barrel is a good idea. IIWIYS I'd look for a Fox variant like the Fairmonts, that used the Holley/Weber on the 2.3 four cylinder equiped cars. It's likely that because of the same source all from air cleaner to throttle cable will ease adaptation.

In the mean time, you might want to check the vacuum advance function in your distributor. It sounds like it is being a little lazy/late in retarding the advance under light load. Anything from dirt/sticky to a ballooning vacuum line could cause it. Your Dura Spark II is an excellent ignition system, but it is now 28 years old. It deserves a good check over. You may need to use a higher octane rated gas during the hottest months of summer. I hate to suggest retarding the initial advance because of lost power and mileage. That would be my last thought.

Also cleaning out the chambers of carbon build up will help. Make sure your climatic control air cleaner system is working to get cold outside air to the carb.

Also be on the lookout for a '66 to '68 exhaust manifold to replace your stock OEM with Cat attached. It is a heat sink. Again, while it may have worked fairly well 28 years ago, as a quick light cat system it is likely degraded in its intent and its function.

I seem to recall others on this forum that have gone the H/W route with Fox vehicles. Have you done a search? My guess is that having to use an adapter will get you into clearance problems.

Keep us posted on your progress.

Adios, David

 

[max]

Thanks for all the help.
I have checked with another carb expert who confirmed that there is no way to adjust the air fuel mixture.
I will check the timing at some point. I checked the tuneup receipt of a year ago and they went a few degrees more BTDC then the factory recommends.
I am pretty sure I have a lean mixture issue. so in the short term I have gone to an 89 octane fuel which has pretty much cleared things up. It seems to run smoother too. It was fine before, but seems even better now.
So now the search begins for a H/W carb, I will check the forum classifieds and start hunting around the local wreckers.
Oh Yeah, the hood clearance issue, anyone with experience on a carb conversion on a 1980 Fox body?