Dual carbs not working correct! Please try to help!

[wolffcub]

power brake booster under the floor.

[wolffcub]

One thing i have not tried is driving the truck with the booster line removed and the port on the intake plugged. I stick my vac gauge in the manifold there but always rehook the booster up after before driving it. I wonder if i have a vac leak somewhere in the booster or line that's messing with the vac after i remove the gauge and rehook the booster. I think PEV kicks in at a lower manifold vac does it not?

[Speedbumpauto]

I wouldn't even consider progressive linkage on that manifold. You should get a good idle and cruise transition from the primary side of each carb since only one of the two barrels is working. What are you using to synchronize the carbs? My best luck on a two carb setup has always been positive linkage with adjustment for syncing but only using one idle stop screw for adjusting curb idle. As for mileage, did you do those mods for gas mileage or to have fun?

[wolffcub]

Just got off the phone with tom. He is trying to help me out the best he can. After talking for about 30 min i brought up the fact that the tops of the carbs were punch with a hole for the bowl to vent, however the gaskets have no hole in them what so ever and are sealed all over so its not truly vented bowl. Tom said the gaskets must have a hole installed in them by something small like a paperclip or something similar. He thinks that step was missed when he punched the holes.

He said that without the gasket holes the carb will build pressure in the bowl due to temps and when i accelerate its actually pushing fuel out under pressure at a much larger rate. Also said that's probably why my oil is so contaminated is because when it sits after being run the pressure builds up in the bowl and it actually drains into the venturi and fills the intake.

So today my task is to punch 2 holes in the gasket to match the holes in the carb top and give it another try.

Still might be an issue with one of the carbs due the fact one still runs better than the other but i will try this fix first.

[1project2many]

Just got off the phone with tom. He is trying to help me out the best he can. After talking for about 30 min i brought up the fact that the tops of the carbs were punch with a hole for the bowl to vent, however the gaskets have no hole in them what so ever and are sealed all over so its not truly vented bowl. Tom said the gaskets must have a hole installed in them by something small like a paperclip or something similar. He thinks that step was missed when he punched the holes.

Missed / not communicated information is what makes internet "diagnosis by consensus" fail so often. Yes, bowl needs to be vented.

[wolffcub]

Im having such bad luck with this carb setup I'm ready to sell the truck for a dollar.

So I removed the carb tops to punch the holes in the gasket because the holes were already done in the top cab half already. Inspection it closely i noticed the gasket holes are probably unnecessary. The gasket is actually open around the float pivot pine any ways to allow for the pressure to be the same on both sides of the gasket. I also noticed there is also a stock pin hole vent port that goes from the top cap into the top of the venturi. Not sure why tom says the holes are mandatory possibly the stock one is just too small?

So i went out with the truck for a test drive with both cabs reconnected. Drove like it did before. All groggy, smelling like gas again, no acceleration. All of a sudden she just went all boggy. Like no fuel was being pumped in or delivered. then all of a sudden it working again and then not working. Opened the hood to see that one of the accelerator pump arms is actually stuck in the open position.



Could not push it back in but had to take the cover off and reinstall it on the side of the road. Truck fired fine after that and i managed to turn the truck around and start driving back home. Then like sure as **** when i started to press the pedal the truck would just die 100% and stall.

Opened the hood. pump arm was ok...................disconnected the carbs so they were independent of each other to see if one was causing an issue and guess what! the other carb that was running the truck by fine by itself (carb "B") about a week ago would kill the engine every time you you try to open the throttle slightest bit. If you just push on the carb throttle 1/16" the motor would die. Re attached the other carb that was not working correct as diagnosed last week (carb A) and managed to just roll her home in 1st gear.

Yesterday i gave up and ordered 2 more carbs from tom. I have no idea what it can be or what i have done. I bought the carbs last year, i installed them via the 4 bolts on the bottom i hooked up a fuel line after flushing it and installing a filter and im having this issue. Thinking a V8 is in order as much as im not wanting to go that route.

[iowaboynca]

is that $1 CAN or $1 US... Stick with it you're almost on the road...If it was easy, this forum wouldn't exist

[OrrieG]

I have never had good luck with Weber carbs, tried them many moons ago when I was in my VW phase and ended up using Holley 2bbl because I could not get them to tune right on a 1200 cc engine. Bolted on the Holley, one jet change and it ran fine for years.

[wolffcub]

As mentioned before the truck is a 52 but has a 55 block in it. It was a 3/4t unit from Canada called the 1424series. Im wondering if it it possible the 52 bell and flywheel might be different from what the 55 actually needs. I believe the 52 3/4t was a 235. The current flywheel has a ball bearing with a stamp close to it marked (5) and if i keep advancing it lots i can see a triangle outline.

My vin plate on the door jam has the number XC591264 but im having no luck finding any info online with the number to see what the truck originally had in it.

[OrrieG]

Go old school and run #1 up to top on compression stroke and make your own timing mark. I always check on "new" motors, once had a harmonic balancer that either has slipped or was mismarked from the factory. I thought you said the timing was good based on the vacuum gauge, which should be even better regardless of what the marks say???

[wolffcub]

It was originally timed using the ball bearing for first startup with the gun. The marking I believe is 5 deg on the flywheel due to the 5 stamp. The timing setting on the gun was at 0 and not 5 as well. That would have given me 10 deg. Once the engine was running i used a vac gauge to better time it. It took some advancing past the ball to get the most vacuum. after getting the most the most vacuum on the gauge i clamped down the distributor and then started to advance the gun setting to see up to what number it took to get the ball to realign with the pointer (It was just for my record) It took an additional 7deg of timing on the gun. So for max vacuum it took 13deg advance overall to get 19" of vacuum. I then slightly retarded the timing so it would not over advance when under load or a higher rpm.

Sound like the right way of doing things? Possibly Im doing this all wrong?

[OrrieG]

What you did with the vac gauge is exactly the way I do it. Same with timing it by ear, advance to where it runs the best and back off (retard) it a little. Timing should not be an issue, but you will need to recheck once you start fiddling with the new carbs. Is it electronic or point ignition? If points, advance also affects dwell and visa versa...

[wolffcub]

all of the driving to date has been on the Pertronix system. I'm making tom a rich guy and am also having a HEI dizzy, wires and plugs sent up with the carbs. I think i have my old point system but im not sure.

[T and S]

IMO - I would have rebuilt the carbs and tried leaner jetting, as recommended. Sounds like their may be dirt or some foreign object causing sticking problems. I am interested to know why leaner jetting wasn't tried before spending hundreds on new parts.

[wolffcub]

No i never did try leaner jetting. few reasons.....the threads in the body got damaged trying to take out the old jets, could not find any info on obtaining jets for this carb, and still being somewhat persuaded that a jetting change is not required due to other running the same setup and having no issue.

I got the new carbs yesterday and installed them last night. Relocated all fuel lines further away from the block to keep it cooler. My existing runs were just above the intake and exhaust ports. It is now about 5" above that at carb level and runs across the engine bay near the rear. Installed a 1-4psi fuel regulator as i have got lots of recommendations to do from other forums. Will try setting it at 2.5-3 psi for the first try.

Should have it running later today. I will post up what happens.

[Old Crow]

Webers again? Reason I ask, my customer wants the dual carb setup now, but he wants to go Rochesters instead of Webers. Seems he's heard some horror stories about Webers.

[wolffcub]

Yes the same ones again. Looking into other options already for next season. I have little faith in these but i need to try to get it driving again so i can get it to where im storing it for the winter.

[wolffcub]

Yesterday was a good day.

I installed the carbs as I noted t posts ago and got the truck back up and running. I forgot to mention that i also split the carbs for a clean out prior to installing them. I found a little debris in on of them and found that both of them had a metal build up around the idle mixture screw right at the tip. Looked like some sort of pigtail drilling debris around the tapered tip of the screw. The tips were fine and were not damaged. I also re-plumbed the lines and kept them further way from the block this time so they don't get so hot.

After getting it running and warmed up i rechecked the timing to see where i left off. Currently set at 12deg and vacuum is 17in. Everything seemed fine with the distributor and was advancing during revving. Checked all the new fuel line connections and set the regulator pressure to 3psi. Went back and forth setting the idle mixture and rpm and timing till everything was ok. Final readings were, 500 rpm, timing still 12 and vac 17.5 ish.

With my AMA card in hand and the tow truck number read on speed dial i got in a took her out for a boot. First thing i noticed doing neighborhood speeds is the engine was smoother than before. Got to the back paved country roads and tested out my new lead shoes. Its a completely different truck ! It pulls hard compared to before. Way more torque. When in third (final) and cruising at 1500rpm you mash it and she just gets up and goes. Still nothing to brag about but 100 times better than before.

The harsh smell of gas during acceleration is little to none compared to before, and when costing in gear it almost never spits and backfires now. At higher rpms the engine is smoother and does not want to jump out of the chassis and onto my lap. It still has a slightest feeling that it wants to go harder when you just let off the throttle when accelerating hard. I will play with the timing using the octane selector now for easy adjustments and see what else i can squeeze from it. Parking in the garage the only smell i got from it was from the header wrap burning from playing so hard and a bit from the top valve cover breather, the smell of gas to me was not present in my garage anymore.

I should probably install the HEI setup i got sooner than later before i go taking all the time to play with timing and then change out the system and have to do it again.

[iowaboynca]

Congratz. way to stay with it.

[OrrieG]

Good, hope you can get your $ back on the fubar pair....

[Gippetto]

Been following this thread in silance. I have the same carb setup from Langdon and am still a while from firing up the truck. I looked up the instruction sheet that Tom sent with the carbs and he does talk swapping jets to make things work. I wouldn't get too fancy building progressive linkage untill I explored the jets. just a suggestion.

[wolffcub]

Been about a week now on the new carbs. Put another 200 miles on it. Everything seems to be perfect now (knock on wood). I have no gas smell what so ever in my garage now after parking it. No gas smell when accelerating heavy. Cant comment very well on gas mileage due to the fact im so heavy foot now because of how it hauls ****. Think the idle screw is a bit lean because it take a few second of cranking to start. Might just give them a 1/4 turn out and see what happens. Still need to sync the carbs. The auto chokes on these ones are even set better. Never touched them yet but this time around they dont make the engine idle extremely high when cold. This time around its just perfect.

Need to think about what to do next year about gearing and a transmission. In a few seconds third and im not making use of the 2000 ish torque range very well.

Installed a HEI system and very happy with that also. Will post up a thread soon about that install.

[Gippetto]

Sorry I didn't catch up on your progress before I offered the jets suggestion. Great news that you've turned the corner. It showes that resolve is the only way to conquer.

Was there any one thing that you did the last time around that you feel made the difference. I have fixed things in the past making several changes at once then never knew what did the trick.

[solidaxel]

What was the stock application of these Weber carbs, what cars did they come on?

[wolffcub]

81 escort 1.6 or 1.9 liter. The first two carbs were just pulled out of the box and installed like i was told to do by tom. No adjustment were to be made till after i had major issues with them and that just made it worse. This second set i put on out of the box and they work perfect. Only minor idle adjustments required. I installed the new ones on the truck with the only addition of a pressure regulator. I still dont think that is why i had the issues with the first ones. Tom says no pressure regulator should be used and that the units are tested to hold to 10psi. My regulator is set to 3.5 lbs now and everything is cherry.

I found debris in the first batch, one would always puke fuel during idle. I would get fuel somehow leaki0ng down into the intake after the truck was not running diluting my oil. I think i just got 2 Friday carbs.

Just want to play with timing now to try to get more out of it.