Hey all, I am scratching my head for days here and have gone through Tomlinson's book cover to cover (several times). I recently got everything going again and was having some serious accel problems where I would really have to work the clutch to get moving and then had great response around 3500-4000 RPM. I pulled the carbs and found the pin through the throttle linkage that actuates the accel pump missing on one side.

So after a .20 cotter pin I thought I was good. While I had the carbs off I pulled every jet and documented everything (I had never done this when I got them) and put everything back together clean as a whistle. I re-used my old phenolic spacers/gaskets even though they werent in the best shape. Got it started and it idled better than it has in awhile. Got in for a test drive and sure enough, under throttle it bogged down almost to the point of stalling. Even gradual accel was not consistent.

First thought, vacuum leak, bad gaskets. Ordered/replaced/tightened/started up. Test drive provided same result. Going over everything again, jets clean, tight, quick sync, bench settings on mix screw followed by quick adjust to smooth idle, purred at idle. Same result on test drive. Found nuts a bit loose on base of carb to intake manifolds. Tightened and same thing.

Just a bit more description about how it drives. If I lightly increase throttle I get a bit of snapping from carbs as it comes up but then it still bogs. It did the same thing prior but mainly as it would load up when cold then the snapping/popping would smooth out and I would be good after things warmed up.

I really think I am starving for fuel but again I dont find vacuum leaks. Even sprayed carb cleaner around intake/carbs and the engine didnt change speed at all. I checked my float levels when I pulled them apart and they looked okay. Is it possible that when I fixed that accel pump I discovered another problem? Do I need to get bigger main jets? It was fine before when accel pump was not working but only at high RPM. Now it feels as though I am starving for fuel at all times off of idle.

Any help is appreciated

Am I correct in thinking these carbs have NEVER quite worked?

Actually they worked fine before pulling the motor for hell-hole repair. After putting them back on (I never really did anything to them while motor was out) they ran fine but only at 3000 or above. Below that they were sluggish but I attributed that to accel pump problem. They have never behaved like this before.

A bit more info:

2.0 liter
dual IDF 40's
Idle jets: 52
Main jets: 115
Air: 200
Emulsion tubes: F11
Venturi: 28
Bowl: 55
P jet: 50
Pump valve: 55

Pull the top covers and clean the bowl and needle valves.
Change all your fuel filters and clean any screens

I cleaned the bowls out and pulled the bowl inlet valves and they were all cleaned. If I pull the main jet stack I can see that the fuel level is near the threads for the main jet stack. Wouldnt that indicate that the bowls are working properly? Or could I be sucking down the bowls under load before they could refill?

Can someone explain what is the popping I would hear before when things were working better? When the car was just warming up the carbs would spit and pop until they smoothed out. I am not getting the same popping any longer even just revving in neutral. Could that be indicative of the problem?

Was the popping an issue before you replaced the cotter pin to accelerate pump?
And after replacing,mother popping is gone?

Verify that the accel pumps are squirting?
Verify they are squirting evenly?

Did you resync the carbs after replacing cotter pin?,
Resync carbs, adjust linkage, check timing, adjust valves. (Not necessarily in that order.)

The popping would only happen when first starting and warming up. I just have a blocking plate for the choke so I always assumed it was due to cold start and it would smooth out after a few minutes or idling and after driving. Now there is hardly any popping at first and only occasionally under load but only if I feather the gas. If I really lay on the throttle when driving in 2nd/3rd it will bog down completely. If I gradually bring it up I can get going somewhat but with some really loud pops intermittent.

Both accel pumps are squirting as they should and I resync'd carbs. Valves recently adjusted. Timing is dead on. Linkage is good for hex bar. Fuel pump is working fine.

I am lost at this point. Could the problem lie elsewhere?

.

Without hearing it running its hard to say cause you are in the driving range of the idle and main jets,my guess is to go to 55-57 idles and increase the mains to 120-125 and see.
Do the idle jets first and check if you get an improvement
Many say the 40's go well on 32mm venturies,there must be a trade off in lower end power ,I don't have experience with the Webers much but the Dellorto's go well with the bigger vents even in the smaller 36mm ones.
Good luck...report back.

Well tonight I pulled the carbs apart again. They are as clean as a whistle as far as I can tell. Accel pump jets are working fine and found no vacuum leaks. Checked timing and set it right at 34 degrees. Plugs all look fine. Fuel filter was a bit dirty so I changed that out as well. I got to drive it a bit more and am starting to think it may be the fuel pump.

Taking off in first is fine unless you really gun it hard. It will stumble and almost die if you do so. Easing it up slowly and then into 2nd it does the same thing. It will not go past about 4k even feathering the throttle. If you drive it slow and ease it up it will get into 3rd and rise to 4k there as well. However, if you throttle up too fast it stumbles then you have to let off then ease back up but again it tops out at 4k and will fall on its face after that.

If you have it just idling with no load and rev it up it will come up just fine for a few moments but if you keep going up in RPM it will eventually fall flat and stumble even at lower RPM. The accel pump jets still spit fuel even as it stumbles so I am starting to think fuel pump or main jets. The only thing about main jets is that it used to run just fine. I have a Facet fuel pump now but have been wanting to put a Carter rotary in there to eliminate any guess work about fuel pressure. Can anyone tell me if fuel pressure could cause these symptoms? It seems that the bowls must be remaining full if the accel jets still shoot right? And if thats the case wouldnt I be running from the bowls on the main circuit in mid to high RPM?