Hi all,

First of all, perfunctory information: 1986 F150 4.9L with feedback carburetor.

I was messing around my carburetor today, looking at vacuum hoses, when I pushed on the carburetor and it moved, significantly. So I checked the two carb hold-down nuts and they were so loose I could tighten them with my fingers!

Tightened them both down incrementally until the carb is now rock-solid on its mount. Now I think my truck runs even smoother that before. I can't believe I have never checked that before.

Anyways, I have some questions about my carb. It does not have a carb I.D. plate on it anywhere that I can find. I want to be able to identify it properly because eventually I may have to rebuild or replace it.

Here are my questions, and pics to follow (if carb looks wet its because I blasted it with WD40 and then Fluid Film on the external moving parts).

1) Is it possible this is the original carb the truck came with from the factory? 25+ years and 95K miles later, still running strong?

2) Why is there no I.D. tag?

3) Lacking an I.D. tag, do any of the casting numbers shown in the pics allow me to fully I.D. this carb?

Here is is, a Dreaded Feedback Carb in all its horrible glory:





These next three show all the numbers I could find on the carb. First is up front, next to the fuel intake: 8509 6



Low on the carb, driver side front. 8603


Low on the very bottom of the carb. 7654S

 

IIRC the tag is attached by one of the screws).

That carb doesn't look factory to me....

 

My guess is it is the 7654S info that you need. I found several sites with info on those carbs by just googling that # and the word "carter".

And, it may well be the original carb. It wasn't at all unusual for mechanics to lose the tags when they rebuilt a carb, and that one's been rebuilt.

 

Thanks! How do you know its been rebuilt? I believe you, I just want to learn how you can tell that.

 

Way too clean, even with just 95K on it. Even if you've been cleaning it, there should have been varnish in the throat, on the choke, etc. And, the vacuum pot at the rear is rusty when they usually got greasy and that prevented rust.

Note that this is my guess, and I've only had one bad guess so far today so am due another few before bed time.

 

Well, I don't doubt it has been rebuilt, it is clean. I just wish they had left the I.D. tag on it. I can't find any stamp on the carb that indicates part number, design change, assembly code, etc. other than the number shown above.

From my Haynes manual: "Often times a tag is attached to the top plate of your carburetor and will aid the parts man in determining the exact type of carburetor you have. When obtaining a rebuilt carburetor or a rebuild kit, take time to ascertain that the kit or carburetor matches your application exactly. Seemingly insignificant differences can make a considerable difference in the overall running condition of your engine."

 

While it would have been good to have the tag, I still believe the 7645S is the info you need based on the search I did. Here's an example: Carter Y, YF, YFA, YH, YS - The Carburetor Doctor

Or VINTAGE CARTER YFA 1-BARREL CARBURETOR 7654 S FORD | eBay

That having been said, the kits I've gotten have covered a very, very large range of carbs. And, while it is true that the wrong parts will affect performance, if you match the parts you are taking off with those in the kit you won't go wrong.

The biggest issue will be in settings, such as float level. To get that you will want to know the # of the carb but, again, I believe the 7645S is it. However, you might post on What Have You Done To Your Truck Today as it may have a larger following than this thread. Surely someone has the same carb as you and may have the tag as well. Or, someone may have the '86 Ford factory shop manual (mine's '81) which will have the # for your specific application, meaning engine, transmission, etc.

And, this evening I'll try going through the Master Parts Catalog and see if I can come up with a #.

Another approach is to go on one of the parts supply house web site and put your application in and see what you get for a rebuilt carb #.

 

If you'll take the number you've found and call Daytona Parts at 386-427-7108, they can hook you up with a quality kit and nearly every other part you need. If it's running well, though, I probably wouldn't touch it. The throttle shaft bores are the key to doing a good rebuild, and especially so on these carbs. If you're not able to fix them, a carb rebuild on a "dreaded feedback carburetor" is likely less effective.

Holley does a good job of remanufacturing these carbs, but their service after the sale is atrocious.

 

It's definately been swapped with a rebuilt unit.

If it was original from the factory (IE: Never been touched) it would have the choke linkage protective cover plates, the tamper proof cap for the fuel mixture and it would have a protective "golden" coating on the metal of the carb body.

7654S is the Carter number of the carb. This will give you the right rebuild kit for it. However if you want the correct settings for your 7654S you would need the original Ford numbers off the tag that is missing. This is because there were several different calibrations (adjustments) of the same carburetor for different applications.

 

Sorry, but I won't be able to look MPC tonight.y grandkids decided to be born today!!!

 

Thanks to you all for the great help, I really appreciate it. I have the 1986 Ford light truck shop manuals, and the "Engine" book does describe carb rebuild procedures. But I couldn't find specific carb part numbers. My truck was built in August of 1986, it must be one of the last carbureted F150 300-I6's produced.

Maybe that tag I.D. info isn't really needed to get right kit or find the right rebuilt carb, and my casting number is sufficient. Thank you again for the info, it's clear to me now that my carb is a rebuilt unit, I didn't know that before.

P.S. congratulations Gary on your new grandkids!

 

This figure from the '86 shop manual shows where the I.D. tag is supposed to be (but isn't). It also shows the tamper-resistant screw cap 81-F150 mentioned.



I do know one fellow on this site that has *almost* the same truck as me, except it's an '85 not '86. Same feedback, ignition, engine, and tranny. But his does not have A/C (mine does) or I think cruise control (mine does). Do carb applications change based on presence/absense of A/C and/or Cruise Control?

My Emission Decal has some carb-related info on it, do any of these numbers (in particular I'm thinking perhaps those in the lower left corner) pertain to specifics on the carb model number?

 

The specs for the carb changed from auto to standard, but I doubt they did re cruise. Not sure about the info on the bottom left, but the info on that sticker does give the calibration #, which can be looked up in the manual.

But, the computer is happy with your carb the way it is, so you just have to keep it that way. About the only thing that would change due to a rebuild would be the float level, and that should be listed in the kit you buy.

 

The Ford ID number is not nessecery to find the right rebuild kit. However to get the right adjustment proceedures in the kit instructions it is nessecery to know the number. It is also nessecery to know the Ford ID number if you buy a complete rebuilt unit, due to internal adjustments, and possible feedback solenoid differences.

Yes, well done there Gary.

 

Actually that is the stickers engineering number, and not the calibration number, although you can "reverse engineer" that number to find the actuall code, but it's a pain in the butt...

The actual calibration number is or was located on the valve cover.

An example Calibration number would be something like: CK265AA