Okay, here is the situation. I have a 78, f100 with a straight six and manual transmission. I had a gasket in my 1bbl carb go bad, so I tried to find a rebuild kit. But the tag that should have been on my carb to ID it isn't there. and I don't know any other way to figure out exactly which carb it is, other than a 1bbl carter. So I got some gasket material and cut my own gasket. After reassembling everything, it seems that my engine isn't running quite right. The gasket I replaced is the one between the throotle body flange assemby and the main carb body. The engine starts up fine, and runs, but it feels like it misses pretty bad at part throttle and sometimes at full throttle.

The one thing that I might have done wrong, is connect the vacuum hose that leads to the distributor in the wrong place, or perhaps my gasket cutting skills are not good enough to exactly replicate the gasket I replaced, although when I held what was left of the old one up to the new one they looked identical. So, if someone could tell me where exactly to hook up that one vacuum hose so that I can double check myself that would great? Also, if my gasket wasn't perfectly the same as the one I was trying to replace, could it cause the same problem? If anyone just happens to know another way to ID my carb than with that tag that is missing, please let me know so I can get a rebuild or something?

It didn't act up like this before I tried fixing that gasket, so that makes me think I did something wrong, but any other ideas as to what the problem is would be very much appreciated. I also just put a glaspack on it about two weeks ago if that might have somehow caused a problem.

 

Probably not the gasket if it matched the original. Sounds like you put the vacuum hose in the wrong place. A Haynes manual can set you straight for about $20, or you could try the old trial and error method..move the hose around and test drive it each time. The 300 I6 is very forgiving...you can't hurt it doing this.

 

I have a haynes manual, and if it tells me where the hoses hook up I haven't been able to find where. I have tried switching the hoses around, and no luck, other than it does run rougher when hooked up to certain ones. If my gasket wasn't perfect, could it cause this problem? My replacement gasket looked good, but it all I had to compare it to was a gasket that was in two pieces, so my holes could be off a little and me not know it. What about running too rich or lean? Or maybe my choke? Thanks for the help.

 

Many times, the ports will be labeled in small print. But the easy way to find is just note which one has little to no vacuum at idle, but increases when you add throttle. Thats the one that goes to the vacuum advance on the distributor. All the other ports will have vacuum at any speed , including idle. As far as I know, all the carter 1 bbl rebuild kits have the same gaskets. So it doesn't really matter about the date code for just that gasket. Just order for your year truck, and engine. Sounds like the carb to me...Beside rechecking that gasket, make sure the float isn't sticking, mounting gasket not leaking, etc...MK

 

Did you put a new fuel filter on when you put the carb back in? Removing and replacing the fuel line can dislodge the crap the fuel filter is meant to keep out of the carb and partially block it, giving you fuel starvation at high demand (acceleration). That's why replacing the fuel filter is recommended with any carb work. Same concept is true with any internal carb work. If you're going to work on it, clean it thouroughly and rebuild it fully. Kits are pretty inexpensive and fairly generic. A pretty small amount of gunk, sediment, mineral deposit, whatever can cause problems.

As far as the vacuum advance hose goes, it doesn't go on the tree, so that rules out most of them. There should be a place for it at the base of the carb itself that acts the way NM5K describes. Actually, I really don't see you messing this up. But it is possible that pulling and replacing it have damaged it to cause a vacuum leak. They get brittle and weak with age. Check the other end of the hose, too. Moving it around could have put stress on it where the other end connects.

Glasspack? Hmmm... If your old muffler was really restricted, this could increase airflow, which could demand more fuel. If your carb is due for a rebuild and can't keep up you would now "lean out" at higher rpm... possibly! The solution is still a carb rebuild.

Good luck in figuring it out.

 

I have checked the hoses, and it all seems to be hooked up right. I found out today that I am not firing on two cylinders, no spark from the distributor cap. Any guesses? How long are the cap and rotor supposed to last? I replaced them about a year ago, maybe a little more. If I have to fix the carb, I will probably just get a new one because I don't trust myself to rebuild it right (having never rebuilt one before), and I don't want to screw it up and have to do it twice. Or is it an easy enough thing to do? Any advice at all is helpful. My experience is limited, so I am a little afraid to jump in too deep.

 

The first time you rebuild a Carter 1brl, it's kinda nerve-wracking cause you don't want to screw it up. By the third time around, its a breeze. Not hard to do the first time either, as long as you work on a clean, white surface (ie. butcher paper or newspaper), go slowly and don't allow for any distractions. I remember doing it in about an hour the 1st time. Lay the parts out logically in order and you'll do fine. Don't know what they get for a Carter these days, but I bet its over $100 (maybe) so the kit will save you some green which you can throw at your no spark situation. Check the contacts inside the cap and on the rotor, then swap a no-spark wire with one that has spark to see if its the wire. If not, you may have a prob in the cap or maybe a dead plug or two. Always remember that every engine needs 3 things to run...air, spark and fuel...The big guy provides No. 1 and its up to us to provide the other two. Good luck.

 

Ford originally put a calibration label on the very front of the valve cover right behind where the coolant elbow is. If you still have the label, I can check the calibration number and cross reference the ford part number. The older vacuum diagrams have BOMs of the emissions equipment and the carb is part of that bill. It's a shot, if you have the label. In general the gasket you mentioned should be quite universal for the year vintage. Check out my loser site
http://www.tetraruby300.freewebsitehosting.com/

Follow the emissions stuff. I never seem to have time to scan and upload the remaining diagrams....the '77s are quite close to '78. The diagram will give you some ideas.
Cheers

 

I can get a new carter, or a remanufactured one actually, for about $70 including tax. I am not sure how much rebuild kits cost, couldn't find the right one so didn't even bother. I will look for that decal tomorrow morning, and hopefully it is still there. Thanks for all the help. I will keep you informed on any progress.

 

I still have that label on the engine. The number is JG251AC. It was a little hard to read, but I am pretty sure that is right. Can you please tell me what carb I have? If this works it will be amazing. Thanks guys

 

Custom trucker, the numbers of importance are the ones in the column on the far right hand side of the label. Meaning there should be a 3-4 digit code to the lright of the "C" and one digit code the right of "R".
If your unsure what I mean, look at my site again. Go to emissions->decipher calibration #-> 70's. There's a scan of one and it shows the sticker and the left hand column I'm referring to. It should be something along the lines of "52G R0" (as an example).

 

What's the word on the plugs/plug wires in relation to dead cylinders? While you are working to figure out and waiting to hear about the numbers, you can assess this. Having spark to all the cylinders may make a bigger difference than anything else you can do!

 

All clylinders are firing. and timing is good, but I still have a miss above idle. I couldn't read all the numbers on the side of the label, they were too faded and had rubbed off and stuff. I just went ahead and got a new carb, but I haven't installed it yet. Hopefully later this afternoon if it isn't too wet and cold outside. I am having to do all of this in the dorm parking lot at school. I will let you guys know if that works. If it doesn't, I will probably be back needing more help. Thanks.

 

I got the new carb on. It still runs horrible. I took it to a mechanic the other day to get it timed because I don't have a timing light, and he said it was right on. But to be honest, it runs worse after getting it back from him. What should I do? He is the one who told be two cylinders weren't firing, and I assume he fixed it. He said he did anyway. The guy is pretty reputable, but is there any chance he didn't time it right? Thanks for all the help guys, I don't know what is wrong with it now. I just don't know enough about it to have any clue were to go next.

 

I would have someone else check the timing, or invest in an inductive timing light and check myself. Does the miss occur only when you are accelerating, or all the time? If at acceleration, it could the carb but unlikely since it is brand new or it could be a worn vaccum advance down in the distributor. Are your points clean and set right? Have you checked coil?