firefighterjed
SILVER Star
- Thread starter
- #21
No, my problem is a stumble when first accelerating, in each gear. If I’m slow with the throttle it goes smoothly. And once I’m up a few rpms I can mash the trottlw and accelerate nicely.
Tuning Weber 32/36 on a 2F (1 Viewer)
- Thread starter firefighterjed
- Start date
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It is interesting that you still have the Toyota linkage. I wonder if that is at its best? Usually they run cable linkage which requires an aftermarket accelerator pedal, or an earlier one.
Perhaps the accelerator pump needs servicing. But my ultimate priority would be checking that you are running the right jets. One of the best things about the Webers is that you can really dial them in. The worst thing about Webers is that people don't always dial them in.
Perhaps the accelerator pump needs servicing. But my ultimate priority would be checking that you are running the right jets. One of the best things about the Webers is that you can really dial them in. The worst thing about Webers is that people don't always dial them in.
firefighterjed
SILVER Star
- Thread starter
- #23
Is there a particular jet kit you would recomend?
Well, the big hurdle for most is getting an exhaust sniffer. Jets are basically ordered one at a time, or you buy too many that don't include all that you might need in a kit.
Those adapter plates must be absolutely dead flat - or you're wasting your time. Either have them surface ground at a machine shop on a belt grinder (made specifically to do this along with heads/manifolds) or use a piece of heavy glass and 220 grit. Use much thinner gaskets than what came with the kit, which is what leads to warping and leaks. I prefer 1/16" or less - most cases, 1/32" woven gray material. Any kit that uses bolts or studs - clean them with brake cleaner and use blue thread locker.
Off-idle stumble is either a clogged primary idle jet or that jet is sized too small. Most installs will use a 45 if the engine is in top condition, otherwise some can be as high as a 60. A full cold/hot compression test is necessary to know the baseline condition of the engine - otherwise, you chase your tail trying to tune it. Many times a Weber is installed due to a failed engine, not a failed stock carb. A Weber will not fix a worn out engine - this is why you must check the compression levels of all the cylinders. In some ways the aftermarket carb is a lot more sensitive than the OEM original - keep that in mind.
There are larger nozzles for the accelerator pump - but those are only used in extreme cases with low vacuum aftermarket cams. The only adjustment for the pump is the linkage itself, if that cam that moves the pump arm is worn, that can cause a slight problem. The stumble is more likely the primary idle jet being dirty or the wrong size. When it's right, the throttle should be very responsive and crisp, almost too sensitive in a way....
Sarge
Off-idle stumble is either a clogged primary idle jet or that jet is sized too small. Most installs will use a 45 if the engine is in top condition, otherwise some can be as high as a 60. A full cold/hot compression test is necessary to know the baseline condition of the engine - otherwise, you chase your tail trying to tune it. Many times a Weber is installed due to a failed engine, not a failed stock carb. A Weber will not fix a worn out engine - this is why you must check the compression levels of all the cylinders. In some ways the aftermarket carb is a lot more sensitive than the OEM original - keep that in mind.
There are larger nozzles for the accelerator pump - but those are only used in extreme cases with low vacuum aftermarket cams. The only adjustment for the pump is the linkage itself, if that cam that moves the pump arm is worn, that can cause a slight problem. The stumble is more likely the primary idle jet being dirty or the wrong size. When it's right, the throttle should be very responsive and crisp, almost too sensitive in a way....
Sarge
Because you identified running ported vacuum at idle, it suggests that your primary idle jet, Idle Speed Screw setting, and/or Idle Mix Screw setting are off. But first, get your adapter plate situated. That is the first order of business; I'm going to just assume that you don't need to add a quart of oil to the crankcase every time you fill your gas tank.
firefighterjed
SILVER Star
- Thread starter
- #27
Regasketted the adapter stack between the intake and the carb. 100% sure there’s no vacuum leak now. All bolts were of the appropriate length.
Pulled the carb apart and noted the size of each component. Sizes are as follows:
Primary/secondary
Air corrector 165/160
Main Jet 140/135
Idle Jet 55/50
Single pump jet -50-
Idle mix screw is 1 3/4 turns out from its seat
Idle speed is barely touching with RPM +\- 700
Timing is +10 with advance disconnected.
Vacuum Advance distributor verified as functional.
The motor has been painted and RTV is visible here & there so it’s likely that a PO did some motor work. No clue if his is the stock cam. I will test compression before my next reply. It usually doesn’t smoke or consume much oil, except about every 10th start it burps some blue smoke at startup.
I’ve been driving it a lot so I can really carefully describe the behavior I want to correct. It stumbles on throttle push, and time I try to accelerate unless I press slowly. So, no matter if I am starting from idle or cruising at 2000 rpms, if I press the throttle quickly, the engine falters before it races away. I believe I have a lean condition in that moment.
I have replaced the accelerator pump and it’s check valve and jet, and the power valve, just to be sure.
I believe I have ruled out all the basic parts as a problem and I’m ready to make some changes.
Since I’m idleing fine and have good power except for when it stumbles My first change will be to try a different accelerator pump jet. A double pump 55.
Here’s a pic of the jet kit I bought.
Pulled the carb apart and noted the size of each component. Sizes are as follows:
Primary/secondary
Air corrector 165/160
Main Jet 140/135
Idle Jet 55/50
Single pump jet -50-
Idle mix screw is 1 3/4 turns out from its seat
Idle speed is barely touching with RPM +\- 700
Timing is +10 with advance disconnected.
Vacuum Advance distributor verified as functional.
The motor has been painted and RTV is visible here & there so it’s likely that a PO did some motor work. No clue if his is the stock cam. I will test compression before my next reply. It usually doesn’t smoke or consume much oil, except about every 10th start it burps some blue smoke at startup.
I’ve been driving it a lot so I can really carefully describe the behavior I want to correct. It stumbles on throttle push, and time I try to accelerate unless I press slowly. So, no matter if I am starting from idle or cruising at 2000 rpms, if I press the throttle quickly, the engine falters before it races away. I believe I have a lean condition in that moment.
I have replaced the accelerator pump and it’s check valve and jet, and the power valve, just to be sure.
I believe I have ruled out all the basic parts as a problem and I’m ready to make some changes.
Since I’m idleing fine and have good power except for when it stumbles My first change will be to try a different accelerator pump jet. A double pump 55.
Here’s a pic of the jet kit I bought.
The question is why are you able to idle at 700 rpm with an essentially closed primary throttle plate?
Does the linkage that I'm pointing to below have a fair amount of freedom of movement when you back out the Idle Speed Screw?
With the Idle Speed Screw all the way out, confirm that both throttle plates are closed on the inside middle of the carb, and the outside drivers and passengers side of the throttle bores? Shine a flashlight and look at an angle, obviously, the choke butterfly must be open.
How did you accomplish this on the DGV?
Does the linkage that I'm pointing to below have a fair amount of freedom of movement when you back out the Idle Speed Screw?
With the Idle Speed Screw all the way out, confirm that both throttle plates are closed on the inside middle of the carb, and the outside drivers and passengers side of the throttle bores? Shine a flashlight and look at an angle, obviously, the choke butterfly must be open.
