81' truck stock carb vs Weber 32/36

[RuralTowner]

The truck I got is an 81 model with manufacture date of May 1980...literally one of very first 22R's produced. Now onto my problem.

Back in Nov 11' my clutch took a dump and SOMEHOW took the excellent average 32-33mpgs with it after the old 4sp took a dump and I found a 5sp. For the last year I've tried just about everything...even had got it re-ringed. Oddly though...as irregular as mpgs were before the re-ringing, I did periodically see 30+...even 32 once...but the norm was 25-29ish.

Now its somewhere only in the high 20s since the carb that came with the truck started gurgling away as it dumped fuel. Found a used replacement on ebay...it proved a bit steadier as mpgs went but I still never got back that 4-6mpgs i lost...worse...the damn carb I had to crankcrankcrankcrank to get it to start but otherwise ran better, if only marginally. For the record the original carb did NOT have a starting problem.

THEN after a few months I decided that Third Time Must Be The Charm. Well again it was a mixed blessing. Found a carb whose tag number was placed only a few 10s higher (ie the 2nd to last number was bigger)...while being externally identical. Internally...the pressed in port for the 2nd jet was BIG. Now this carb is acting up...can go down the road all fine but then it will chug n cough n jerk at around 55-60...or a bit less or more.

The only other thing I've yet to try is to redo the valves...AGAIN! Otherwise I've had it up to my ears with this and am considering a fully new replacement. As stock replacements are pricey as all hell, have any of you with the old stock carbs had any luck with the Weber 32/36?

What kind of MPGs did you have before//after the change? I ask because I depend on my truck as my primary driver...
I also hear that the Weber can be...finicky...to say the least as tuning goes though. Feedback is needed badly!

 

[tbplus10]

I've used Weber's on some of the older engines (around the model year you have) they work ok but dont return the MPG you were getting, the Weber cars mostly increase performance, their a little finicky on cold mornings, and take a little tinkering every few weeks to keep running good.
Any chance of finding a rebuild kit for your original carb? Or maybe making your own rebuild kit to do the job?

 

[RuralTowner]

That's a bummer. The first 2 carbs (original to truck...and the 2nd one that I think might have come from a mid-80s) I put a kit in while making LIBERAL use of carb cleaner...to no effect it would seem. This 3rd one had a couple shot diaphragms (suck test kept sucking) so I swapped out those parts from the 2nd carb. I think what I'm going to have to do is once more...take each one apart and meticulously inspect. Hmm...since the 1st and 3rd carbs are identical (their tags first 3 #s are the same)...linkages and whatnot up top are, as well save for 2 vac ports on the engine valve cover side of the carb top.

Carb kits are easy enough to come by. As for Webers taking tinkering every few weeks? I DO THAT ENOUGH ALREADY!

A while back I thought I MIGHT have had the 1st carb figured out after one of the 2 vacuum holes in the baseplate (next to one another) I found it clogged (pin sized hole)...I'd put it back together but when I did the wire to the bowl vent solenoid got caught between the carb body and the top...thing ran like shit until..would die...while the carb would vomit gas fog out the barrels. I got it out of the way but it never seemed to run "right"...or at the least as well as it was before that. IDK...maybe it warped a portion of the seat INSIDE...away from the rim since no spray tests around the carb here while its runny betrays any vac leaks.

I'll see what comes of that, as well as a re-check of my valves. Timing might still be "iffy" since when I had the ring job done to it...it was just that...the front cover was never removed, so if SOMEHOW the chain is 1 tooth off down below it could be compensated for up top..at the cam sprocket and dizzy but prob not totally.

To make sure, it IS possible to remove the timing cover w/o pulling the head? (I hope so.) Presumably ofc its removing the pulley//balancer, valve cover, remove all the blots clearly holding the cover on...then remove the front seal and CAREFULLY pry it away, out and down at the bottom? IE taking it off at an angle since removing the seal gives about 1/4in of wiggle room.

Ugh...I really need to kick it into gear on the 78 Corolla (2TC) I have...get that ungodly beast of a sink done properly and it could become my daily driver for good. A past attempt to re-ring that thing saw a ruined set when the carb started dumping fuel during follow up...oil psi would drop from 60 to 5 in a few min...that thing was DUMP-ING! fuel. Found a replacement carb on ebay a while back for that one...just need to swap baseplates (its from a 72 w/ 2TC) so the throttle will work and bolt on.

EDIT: Re-adjusted the valves. Tried the top swap...no marked improvement. Hmm...
What kind of economy (at best) can be expected from the 32/36 Weber? ALSO...would be nice to figure just one thing out.

Riddle me this please: WHAT could have caused such radical MPG loss simply after several VERY hard stalls (3-4k RMP to nothing as fast as you can snap your fingers) when I was forced to rev the engine to simply get the clutch to initial disengage so I could get home? I power shifted the rest of the way to avoid using the clutch. NOTE: That mpgs were wildly erratic after the stalls but prior to re-ring though did rarely see the OLD good mpgs once or twice.

If I knew what had caused the loss, it would make my life far simpler.

- - - Updated - - -

Ok got the 3rd carb back in..the truck seems to run the best with that one for now probably because the jets are a bit larger and so admits more fuel to even things out. I think I found out why it would cough and sputter...the small retainer plate for the Power Piston..was turned around so the tab meant to keep the plate in place from turning when the screw is tightened, was in the piston tube...so it only had about 1/16in of travel and so couldn't act with the power valve properly (if at all). I guess I'll see in the morning on the way to work.

Okay to refine my question about "what" caused the mpgs loss. Timing chain? To the best of my knowledge the chain in the engine is the ORIGINAL, double row, and probably has a good quarter million miles on it. I very much doubt the single rows would have reached that. So.....would it be possible that having to over-rev the engine to try and get the clutch unstuck...and the repeated stalls could have caused excess stretch in the old chain? The engine does NOT idle as smooth as it used to...very little or no errant rumble at idle. I've been using a vacuum gauge to assist me in tuning the idle and even though I had a good 20in of vacuum, before the re-ring I had flutter in the needle (in total about 2 needles between the margins)...and now has more flutter with greater..random variation near the 20in zone. I DO know for sure that nylon-toothed gears can find themselves easily stripped if exposed to high speed then go to 0 in no time...while in my case they're all steel.

 

[toyotafan]

Could you have an additional problem maybe? I had a vehicle once (non-Toyota) where the rear brake calipers got rusty and they snapped into position so they were constantly just slightly applying pressure to the brakes all the time. I only noticed it after I saw a lot of brake dust on the rear-wheel rims and we noticed about a 15% drop in MPG overall over a 6 month period. I had the brakes re-done and all was fine after that.

 

[RuralTowner]

Had a 79 Chrysler Cordoba that did that once. Took me a few days to realized that the E brake pedal was partially depressed (easy to hit when getting in considering its placement)...so what should have taken 1/8 tank took more like 1/4.

Definitely not the brakes though on the truck though. I don't see those affecting engine timing//idle. At this point I'm convinced its the timing chain. Before the hard stalls...all was fine & MPGs were great...after them it was downhill. Before the ring job, mpgs were erratic but I still occasionally saw "normal" miles but only once in awhile. After the ring job...it was erratic but a bit more stable yet still only around old 4sp-equivalent economy despite having that 5th gear.

Aiming the timing light at the marks on the pulley...they won't stay constant as they should be...it tends to dance between the TDC mark (highlighted with white paint to make it visible) and 12deg before but usually between 0 and 8. That's with the dizzy securing bolt snugged tight to keep it from moving. Prior to the ring job a vacuum test betrayed flutter on the gauge (about 2 needles worth between its up/down margins)...while afterwards its more erratic. Another ?possible? indicator is that before the stalls...oil pressure was near 60psi running down the road...30-40 at idle depending on if engine was warm. Now its barely over 40 and can range up to 45. The last time it was like that was when my EGR blew. Since the tensioner is hydraulic and uses oil pressure I wouldn't be surprised if THAT incident a few years back somehow weakened it (took me 5qt of oil to get home...stopping every 15mi to add a qt...meanwhile blowing oil and coating my already caked undercarriage and tailgate)...and those repeated stalls simply finished it off by stretching it.

I'm in the process of tearing down the front-end of the engine to get to the timing chain...and taking the laborious method of pulling the cover w/o removal of the head while I wait on a Timing Set to arrive from Rock Auto. Autozone would have been more "convenient" but would have cost more and has shit for warranty. 3 months. The one from RA is 12mo/12k miles. I've exhausted all other possibilities...if it was a carb problem one of the carbs I have should have solved it despite being used. Each has its own temperament but still no 30+...I've torn the damn things down enough and used 2 kits that never seemed to do the trick.

OOOOOO I really should have opted to have the timing chain done at the same time as the rings....kinda like I REALLY shoulda down a full clutch replacement in May 11' when the ole 4sp took a digger...had I done that I'd still be sittin pretty at 32-33.

 

[TruckRider]

Hi RuralTowner Did you fix the issue so far?