Vintage Mustang Forums banner
  • Hey everyone! Enter your ride HERE to be a part September's Ride of the Month Challenge!
1 - 20 of 56 Posts

·
Premium Member
1966 mustang convertible sprint 200, manual steering and brakes
Joined
·
257 Posts
Discussion Starter · #1 ·
I’ve done some searching in the archives which has made me slightly smarter. But, I’d appreciate some feedback on the following “new to me” carb and engine (entire car actually). It’s a 66 with original (I think) 200 with 1 barrel.
1. Does this look like the right carb ?
2. Idling ok but stumbling on acceleration and erratic misses at speed. Blowing dark smoke when accelerating. How do I lean out the mix off idle ?
I‘ll be ordering a shop manual today but an impatient to get this car back on the road.
3. It had a broken aftermarket elect choke on it. What are your recommendations to replace it ?
4. where is the throttle return spring supposed to attach (pretty sure the last pic isn’t right ☺).

thanks much !
Wheel Tire Bicycle tire Automotive tire Motor vehicle
Motor vehicle Blue Automotive tire Rim Vehicle
Automotive tire Hood Motor vehicle Bumper Vehicle door
 

·
Premium Member
1966 Mustang Hardtop 289 4 Speed
Joined
·
7,239 Posts

·
Registered
Joined
·
38,621 Posts
C5OF-R would NOT be the original carb. That one would be for a '65-67 TRUCK application, possibly a Bronco or Ranchero. It SHOULD work fine on a Mustang with a 200 and DOES have the Spark Control Valve compatible with a Load-O-Matic distributor. Changing the IDLE mixture will not solve your richness upon acceleration problem which is most likely an incorrect setting of the power piston or the fact that the choke is disconnected and could be sucking closed. I'd recommend getting the original hot air choke thermostat cap and retainer and the hot air pipe that attaches to the exhaust manifold in the hole at the center. Here is a picture of the accelerator linkage and return spring... (bottom image).
Font Motor vehicle Parallel Automotive exterior Auto part
 

·
Registered
1966 Mustang Coupe
Joined
·
207 Posts
Looks correct for the stock 200 using the load-o-matic distributor. Just needs the heat riser tube and choke replaced unless you go electric with it.
 

·
Premium Member
1966 mustang convertible sprint 200, manual steering and brakes
Joined
·
257 Posts
Discussion Starter · #5 ·
Thanks guys, very helpful. Appreciate the pics woodchuck. That would be great if my richness issue at speed was just the plate sucking shut. I’ll wire it open for a quick test ride to see. Thanks for the links casper - I’ll definitely spend some time browsing thru them today.
 

·
Registered
'66 Convertible 200/c4 Vintage Inline Headers with Arvinode Duals
Joined
·
186 Posts
Big thing I see in your pictures is the choke. No cover on the spring that helps the choke open and no heat tube from the exhaust to tell it when to open. First thing I'd do is wire the choke open and see if the running rich goes away. If it does, get the replacement choke parts or a hand choke conversion.
 

·
Registered
1966 289 3-speed
Joined
·
1,003 Posts
I assumed you took the choke spring housing off for the pictures...did it come like that? Is the plate closed like that when driving?
 

·
Premium Member
1966 mustang convertible sprint 200, manual steering and brakes
Joined
·
257 Posts
Discussion Starter · #8 ·
I pulled the electric choke cover off this morning. The little plastic part that attaches the choke coil to the choke plate lever was broken off so nothing holding the plate open. The plate was wide open when I pulled the air cover off but I didn’t think to check if it was floppy or hung up inside the broken housing. Running it wired openin the drive and it seems a bit better. Also had a vac leak where pvc hose connects to carb base. Will take it out for a short test shortly to see if it’s any better. Trying to get the tail lights working at the moment. Flame thrower leds acting all wonky.
 
  • Like
Reactions: AZ_Ryan

·
Premium Member
1966 mustang convertible sprint 200, manual steering and brakes
Joined
·
257 Posts
Discussion Starter · #9 ·
Just did a quick test drive with the choke plate wired open. Success !! Totally different car. Must have been sucking down as you suggested. Thanks all, one issue down, a few more to go.

By the way, what is this treaded hole for in the side of the carb spacer, just to the left of the PVC hose pickup ? Looks suspicious being open like this. The idle speed doesnt change when I plug it.
Motor vehicle Automotive fuel system Automotive tire Automotive exterior Gas
 

·
Registered
'66 Convertible 200/c4 Vintage Inline Headers with Arvinode Duals
Joined
·
186 Posts
By the way, what is this treaded hole for in the side of the carb spacer, just to the left of the PVC hose pickup ? Looks suspicious being open like this. The idle speed doesnt change when I plug it.
I have no clue. Its also open on our car and its been running fille for the last 13 years.
Edit: running fine, can't spell today.
 

·
Registered
Joined
·
1,843 Posts
I’ve got my C4 auto trans vacuum modulator hooked up there. And my stock brake booster vacuum too, through a ”T” fitting.
 

·
Registered
Joined
·
1,771 Posts
Here is the Autolite 1100 on my '66 HT which I've owned since `84. My A/T vacuum port is off the intake manifold & shown circled below. The threaded hole on the plate below the carb on mine has never had anything threaded into it.


Vehicle Motor vehicle Automotive fuel system Gas Auto part
 
  • Like
Reactions: tb65m66

·
Registered
'66 Convertible 200/c4 Vintage Inline Headers with Arvinode Duals
Joined
·
186 Posts
I’ve got my C4 auto trans vacuum modulator hooked up there. And my stock brake booster vacuum too, through a ”T” fitting.
My trans modulator is connected to the manifold under the carb where the plug is in his picture.
 
  • Like
Reactions: Woodchuck

·
Premium Member
1966 mustang convertible sprint 200, manual steering and brakes
Joined
·
257 Posts
Discussion Starter · #14 ·
We’ll, looks like I can move onto other concerns. That threaded hole doesn’t seem to be causing any harm.
 

·
Registered
1967 i6
Joined
·
46 Posts
I would check for vac leaks at that threaded hole.

Also, you likely have a small vac leak with your choke thermostat missing. There is a small vac port that pulls hot air thru the thermostat from the heat riser. and given that vac port is very small it could be clogged which may cause the choke to work poorly. Definitely worth checking when installing the new choke thermostat.
 

·
Registered
Joined
·
207 Posts
That threaded hole in the side of the spacer is for a throttle linkage pivot in a different application. Shouldn’t be deep enough for a vacuum leak. I drilled a small hole through, and tapped the outer part 1/8 pipe thread. Screw in a hose barb and you’ve got an extra vacuum port for your distributor or a gauge.

Wood Household hardware Gas Machine Hardwood
 

·
Registered
Joined
·
2,343 Posts
What he said^

That threaded hole is used for different applications to hold the throttle linkage. I know my 67 has a stud attached there that everything pivots on. There's no vacuum there.

Also, that looks like you've got the 67 style spring. The reason it's so long is that with the totally different linkage they hooked it up on the front of the intake log. The 66 spring is much shorter so that it can attach to the exhaust flange like it shows in the illustration. If the gas pedal feels ok and it's working for you though there's probably no reason to rush to swap that out.

Here's an example of the 67 setup just to show what they did with that threaded hole and the spring:
Automotive fuel system Motor vehicle Vehicle Gas Auto part


Just before everyone comments on it that plastic fuel filter was temporary, the orange silicone on the vacuum port has been removed, and the SCV isn't necessary with the car's DSII dizzy.

Your car looks great though. Nice find!

EDIT: We'd need to see a pic of the driver's side to be sure, but I think that carb is for an automatic and it looks like you may have a stick. Not that it really matters, it'll work just fine it's just something else to know.
 

·
Premium Member
1966 mustang convertible sprint 200, manual steering and brakes
Joined
·
257 Posts
Discussion Starter · #18 ·
Thanks all and good catch on vac leak in chock housing, I’ll get that plugged. Here’s a pic of the other side of the carb.
Motor vehicle Bicycle part Rim Gas Auto part
 

·
Registered
Joined
·
264 Posts
According to my 66 service manual, C50F - Y is the carb you should have on that application. I think your tag showed that number, but I don't think that is the right tag. The manual trans carb doesn't have the diaphragm on the passenger side that looks like an accelerator pump. It is actually a throttle return dashpot.

On the throttle body there should be some stampings that may be all of the numbers on the tag, but are usually just the ones that distinguish some feature on the carb. A C5OF-Y TB casing might might just have the 5O and Y for example since the C and the F don't tell us something we don't already know.

The carb on the 200 also has a slightly larger Venturi than the 170 application.
 

·
Registered
Joined
·
207 Posts
Probably won't be an issue unless you remove and replace your carburetor a lot. But usually the carb is held down by nuts on studs threaded into the aluminum spacer. Looks like you have bolts from on top down into the spacer. Might eventually wear out the threads in the relatively soft aluminum. Plus the stud setup makes it easy to align the carb and the gasket and the manifold opening.
 
1 - 20 of 56 Posts
Top