Awesome thread, I've been reading a ton on here and learning quite a bit. I've also tried to teach myself some and read Passini's book on Webers and basic carb theory. Let me start with some background first so you know where I am coming from.
Bought an '84 CJ-7 back in '04 from a buddy of mine, with the intent to do a 3-month, $3,000 rebuild. Of course, the most I knew about cars was very basic, but I figured I could teach myself as I went. Well, got overly involved with it, had the frame-off and everything, and then I started deploying (military). 4 deployments, a wife and 2 children and 7 years later, and I finally get the dang thing back together and running (at least rolling, running may be an overstatement.) It's been a fun rebuild and I've learned a ton, but still learning for sure on the fuel delivery side of the house.
So, getting back to the carburetor, I rebuilt the 258, it's now a 261, but fresh with only 600 miles or so on it (you can run that engine pretty far even with the carb tuned like crud.) Stock intake, Weber (Solex) 34/34 DGEV from Quadratec (bought too long ago to return for a 32/36), DUI, etc. Well, the carb out of the box was a little finnicky, but had it running at least well enough to wheel when I was stationed at Ft. Lewis, but I never had it tuned properly and couldn't get any real power from it. Had the stock jets, etc. Moved up to CO, elevation 7K feet. Made the mistake of reading the Fjuerico post or whoever he was, and started messing with the jets. Now I've got myself a little dorked up and looking to get this thing tuned properly once and for all.
So, here's my basic setup:
I6 bolted to stock Luk clutch to SM465, Dana 300, AMC 20 and Dana 30 front, 4.56 gears (originally re-geared for the old T-5, but when it bit the dust I went to the 465...I know, super low gearset for this) and 33x12.50's. Oh and Holley FPR set at 3.5 psi (I know, psi at idle in the driveway ain't the same as in the dirt with the pedal on the floor, any input on this setting would be appreciated as well.)
DUI set at 10.8*, will move it back to 10* for the next round of tuning.
Tried a variety of jet sizes, 40/35 idle and 140/135 run left me with no power in 4th to climb over 40 mph unless flat or downhill.
Now set with 40/35 idle and 145/140 run jets, can't get it to idle too well, hops between 620 and 710 or so rpm with the mixture screw 4.5 turns out. Still not much power.
I read the entire thread and going to go back and start from scratch, complete with sanding the plates and loctite, finding lean best idle, etc. but wanted to ask you gentleman for your best guess as to what jets I should start with and what I should have on-hand to make the adjustments. I would like to order the jets in one whack so I don't get nailed on shipping.
I tried the math that McMud had, 34 mmx4 - 136 run jets x .42 = 57 idle jets, obviously I don't think I can get them exactly that size but if that seems (despite the altitude) like a good starting point I'll head that direction. The thing I've noticed recently, heading up into the mtns, is that as I climb the carb seems prett sensitive, and her characteristics really change with the altitude (climbing as high as 10-12K if you head over the passes is my goal, but have been up to about 9-10K recently.)
Gentlemen, your help is greatly appreciated. I will be printing this thread and putting it in my manual for future reference. Where did you guys learn all this stuff? Any books you could recommend? I'd like to get smarter on fuel delivery.
Also, somebody mentioned not to use the little air cleaner that comes with the weber (solex) carb...any recommendations on where to go with that?
Thanks, and have a great week fellas!
Last edited by mulliflier; 09-26-2011 at 10:06 PM.
Reason: forgot info