Carb Troubles - 76 2F

bashmatic · 06-30-09, 03:33 PM

I posted this in the 40 & 55 Tech, but no responses. Hopefully someone here can shed some light.

I have a 76 Fj55 that i have been chasing the bugs on. The PO didnt drive it much for 3 years and I want to drive it all of the time. It got to the point where I had chased everything down to the carb and I was dragging my feet on rebuilding it. So then I pulled it off and just rebuilt it.
When I put it back on it ran worse! Whenever I put it into gear it would die under a load, but ran really well at idle. A friend suggested that there may be a clogged jet or circuit. So I pulled it back off and cleaned them out.
So while it was apart, the buddy that was standing over my questioned whether I had put the jets back in the correct place. I swear I did, but he suggested switching them just to see what happened. So I did, and it seems to run great now.
So I am wondering if anyone knows which jet should go where? If I am looking at the front of the carb I have a #30 jet on the left and a #16 on the right. I think I am correct that the left is the primary and the right is the secondary.

I just cant put any closure on this until I know how it is supposed to be. I cant find anything in any of my books calling out what size the jets should be and it drives me crazy that simply switching them to "see what happens" fixed the problem.

Thanks in advance for any commentary!

Bash

inkpot · 06-30-09, 04:14 PM

Howdy! It's bee over 16 years since I played with an OEM carb, but I think it is safe to say that your friend is right. Buy him a beer, and then drive, drive, drive. If it works so much better, then it is probably right, now. Don't loose any sleep over it. Be Happy!!! John

romegadave · 06-30-09, 04:34 PM

Now that your pig has made it down to the 55 trough......lets see some pics of that verde swine!

cruiserbrett · 07-01-09, 01:30 AM

the larger short jets and the long thin jets are both setup so that the larger number(or orifice) go in the secondary venturi(the one without the choke)

bashmatic · 07-01-09, 08:38 AM

okay, thanks Brett.
They are back to where they belong. Still, it runs great but falls on its face when i let out the clutch. I have the mixture screw turned 3 turns out, and the book says it should be 2. Seems to run better the fatter I get it.
I remember reading that the air cleaner will richen it up too. Am I to believe that I have to put that air cleaner back on every time I make a 1/2 turn on the mixture screw? Seems like I should be able to get it close, then put the air cleaner back on.

Thanks for the help. Keep it coming! Til then I will keep messing with it!!

Bash

bashmatic · 07-01-09, 08:41 AM

Another thought.
since I have the Ranger putting extra strain on the drivetrain and I have regeared it to 3.73's, am I asking too much from that little carb?
I want it to run like my last 60, let out the clutch and it grabs and motors away.

inkpot · 07-01-09, 04:45 PM

Howdy! OK, you may have a fuel supply problem. Does the fuel show up in the little window on the front of the carb? Does it stay at about the same level when you open the throttle and let the engine run up to at least 3000 rpm? If not, then it could be a bad filter or a tired fuel pump. Could also be a problem with the power valve in the carb, or a timing issue. Go thru each area, one thing at a time and then retest.
The H42, Ranger, and 3.73 gears should not be a big problem, especially if the Ranger is in it's lower range. What size tires are you running now? Does the rig roll freely on the ground when it is out of gear and the brakes are off? My original 2F, H42, Ranger in direct drive, with 4.11s and 35's was a big doggy, but it ran OK like that for years. John

cruiserbrett · 07-01-09, 06:09 PM

does it stall if you unplug the idle cutoff solenoid?

how's the timing?

also check that the accelerator pump operates properly, so that with any increase in throttle it is discarging fuel out of the nozzle. a stuck bb on either the inlet or outlet of the accel pump will cause a nice little stumble off idle under load but be virtually transparent when your just bumping the RPM in neutral.

some 76 carbs had a powervalve controlled by the emissions. they have a small nipple in the front of the carb right under the air cleaner. if you have this, is it connected to anything?

bashmatic · 07-02-09, 11:44 AM

Brett, I will have to look for that nipple. doesnt ring a bell. i dont think i have that.
the timing was set at 7° BTC, I reset it at about 10° BTC to see what happens. not good though.

I will check the BB's. I can only remember one, so I may have a problem there.

John, the float level seems normal, but I havent checked it at higher than idle-speed RPM's.

I am running 31's. I shouldnt have any problems there.

Thanks again for the help. I am going to take tomorrow off and play with it. I know it is something simple that I have overlooked. I am even wondering if I have the external linkages hooked up correctly. The book is so vague. Everything seems to be in the right spot.
Worse part is that I have a 350 in the shop and almost ready to go in. Just dont have the time and space to do it til winter.

inkpot · 07-02-09, 02:02 PM

Howdy! I'm off from now til Sunday night. Don't hesitate to toss more questions out. I'll be around. Can't help much with the linkage as mine has been gone for about 16+ years. You'll get that Pig running so good that you won't even want to swap in that nasty old 350 anyway. I mean, like who would do a thing like that?!?! John

cruiserbrett · 07-02-09, 07:32 PM

there is a bb held down by a clip at the bottom of the accel pump bore. there is also a bb held in its passage by a brass pin, which is acccesible in between the fuel bowl and the primary bore when the carb top is off.

bashmatic · 07-03-09, 01:44 PM

Brett,
I know about the one accessible when the cover is off, but not the one in the accel pump bore. I will look at that.
When I unplug the idle solenoid it dies completely.
When I run the RPMS up the float bowl seems to be refilling like it should. No fuel delivery problems before the carb.

I have the idle mixture screw turned out to about 5 turns. it is kindof getting better, but I can imagine that isnt the real problem.

Thanks, Bash

inkpot · 07-03-09, 02:18 PM

Quote:

Originally Posted by bashmatic

Brett,
I know about the one accessible when the cover is off, but not the one in the accel pump bore. I will look at that.
When I unplug the idle solenoid it dies completely.
When I run the RPMS up the float bowl seems to be refilling like it should. No fuel delivery problems before the carb.

I have the idle mixture screw turned out to about 5 turns. it is kindof getting better, but I can imagine that isnt the real problem.

Thanks, Bash

Did you have a chance to recheck teh timing? You need to check/set it with the vacuum supply line disconnected and blocked on the carb side. Come to think about it, wasn't 76 a vacuum retard dizzy? Sounds like the timing is way high to me, just like my hotrod days. We used to jack it way up for top end, but it was nearly impossible to get off the stop signs.

On another note, 5 turns out on the idle mix sounds a bit much. Typical is 2-3, but anything is possible. I count a turn as 360 degrees. I know some folks count 180 as "a turn". John

bashmatic · 07-03-09, 03:47 PM

Thanks John,
I am counting 2 half turns as 1 turn; 360 degrees.

I have a Mallory dizzy with mechanical advance, the vacuum port is blocked off on that vacuum box that mounts to the inner fender wall.

inkpot · 07-03-09, 04:08 PM

Quote:

Originally Posted by bashmatic

Thanks John,
I am counting 2 half turns as 1 turn; 360 degrees.

I have a Mallory dizzy with mechanical advance, the vacuum port is blocked off on that vacuum box that mounts to the inner fender wall.

OK. That eliminates the vacuum issue. Does the Mallory have a mechanical/centrifacal weight advance under the rotor cap like a conventional? I have not worked with one of those. Since you know the idle solenoid works, you may be able to turn that idle mix screw back in 1-2 turns and lean out the mix a bit. It could be already too rich when you go to accelerate. If you don't get this fixed pretty soon, your going to force me to drag out my shop manuals! There IS a solution here, somewhere....... John

bashmatic · 07-03-09, 08:49 PM

put it all back together. runs like shit when the choke is in, but pretty well when the choke is out 3/8". went looking for vaccuum leaks and found one at the vacuum fitting on the intake manifold and a smaller one at the back of the carb. both of which i cured a while back. I'm done. this is good enough to get me through the summer and then I will do the V8 conversion. if anyone wants this engine in October it will be at the bottom of Lake Washington waiting for you!! 2F be dammed!!

Thanks for all of the help guys. It runs a lot better than it did. I can deal with it now. I appreciate all of the help.

Bash

bashmatic · 07-06-09, 01:30 PM

Okay so I looked for more vacuum leaks and found one at the manifold where the fitting feeds the brake booster, but that didnt quite solve the problem. So then I decided to swap out the coil for another one that I had on the shelf and while I was at it I cleaned the corroded surfaces where the grounds bolt into the inner fender.
I cant say that all of my problems went away, but it is a lot better and certainly what I would expect from a 2F!

Thanks again for all of the help. I really appreciate it!

Bash