Weber Tuniing Question (1 Viewer)

[Boaf 32]

Just the odd question: Will an exhaust leak (post header) cause a problem with lack of power (back pressure and all) in third gear going up a hill? I know it's there and it's on my to-do list.

Will get that picture shortly and compression readings (think good thoughts).

Boaf

 

[Boaf 32]

@Dizzy @Weber Sarge @Johnny C ,

I have a Mighty Vac hand vacuum that I hooked up to my intake manifold to check vacuum. The gauge is pretty beat up (Ordered a new Vacuum / Fuel pressure tester) so not really dependable. It did provide a reading between 16 and 25. I say that because of the wild fluctuation of the needle.

When the new gauge arrives, I'll repeat. If my memory serves, excessive fluctuation in vacuum (like a vibrating needle) may indicate bad valve guides. That makes sense as I did not have the guides done when the block was bored, and two(2) of the spark plugs were fouled ("carboned" up) when I removed and inspected.

What do you think?

Re-set my timing to BB, re-set the carb, and it definitely runs better. Just the power in 3rd gear is stuttering and will eventually backfire out the carb going up to highway speeds.

Boaf

 

[Boaf 32]

Duplicate

 

[Dizzy]

Is this correct for fitment?

Weber Idle Jet, 32/36 DGV / DGAV Carburetor, Small Size - Pegasus Auto Racing Supplies

 

[Boaf 32]

Attached is the picture of my idle jets.

• Passenger side (Primary) is the larger screw and is the 60.
  
• Driver side (Secondary, right side of picture, no rubber seal on) screw will not receive a 60. The screw is smaller, threads are smaller than the Primary screw, and the insert can only receive the 45. That is what I meant Dizzy.

Boaf

I think your link above will work.

 

[Weber Sarge]

Just a suggestion for anyone trying to work with these things-

Start with the stupid basics - such as a true compression test both hot and warm. Record those numbers and when you ask questions let us know the true engine condition as well. Most times a Weber is installed to try to solve a weak engine issue - changing carbs will actually make it worse as the Weber is truly more sensitive to tuning. The Weber is a carburetor kit - not a Band-aid.

If you own a Weber - you'd better have a vacuum gauge, period. Bouncing vacuum readings at idle, low vacuum with stock cams and such are symptoms of a bigger problem - number one issue is almost always a vacuum leak in those junk adapters, others are worn valves, shot rings/pistons and valve guides as well as cracked manifolds or gaskets. This is why I wouldn't do Cruiser conversions - the adapter kits are a joke, let alone trying to properly adapt the throttle system without destroying the carb in short order. For those that have been running a Weber on a Cruiser and have slowly developed a problem with idle position or off-idle response - I'll bet you've worn out the throttle bore on the primary side at minimum. The telltale sign is a lack of idle control and stumbling off-idle, due to leakage at the throttle shaft and primary bore wear. If you can't idle the engine down to around 300 revs smoothly - you have a problem.

The other real tool needed is a timing light with a dial back feature. You must be able to see if the vacuum advance is working, how far it moves (wear issues) and the static base timing. Plus, knowing if the distributor is honestly advancing the ignition timing as it should or not - many are gummed up and need rebuilt. These parts are old, keep that in mind and without everything working together you will waste your time trying to tune the engine for the expected performance. The carburetor itself is one very small part a much bigger system - it all must work together properly as a unit.

Some of the tuning stuff is really not for an amateur, no offense intended nor am I trying to lecture. Without a true mechanic's knowledge of how systems work, how to rebuild and repair all of these parts makes it almost impossible for a common person to work on this stuff. Mechanical distributors, carburetors and internal engine parts are nothing to laugh at - back in the day it was a long process of schooling and teaching mechanics on how to work on these things. Without years of experience, you have to start with the basics and learn from there. Yeah, there are those willing to share their knowledge, the internet can also help, but in the end you have to learn yourself how to diagnose things and find a solution. Most people that get on the internet are looking for the magic solution - it doesn't exist. Most problems with these things are many layers of sub-par system parts that have failed to work to specification. You end up lost and frustrated and blame one part - that is almost never the case - it is total of many issues that created the problem and without fixing all of them you are wasting your time.



There are bore differences in the Chinese knockoff carbs in relation to the jets - the common Italian made jets will not fit. Some of the older Holley generic jets may work, but they also may leak, which is a problem.

I highly suspect you have a knockoff carb, it is not easy to tell the two apart visually unless you really know them. Very few people own Genuine Italian Weber DGV series carbs - I've only ever had a few come through the shop over all the years I did them. Almost all are the later Redline units produced in Spain - so in all honesty, not the real-deal here. All of the screwing around by aftermarket vendors led to the Chinese knockoffs and now Redline substituting the junk Solex for real Webers - and charging the premium price to boot, what a joke.

And folks wonder why I got out of the business..

Sarge

 

[Boaf 32]

Just a suggestion for anyone trying to work with these things-

Start with the stupid basics - such as a true compression test both hot and warm. Record those numbers and when you ask questions let us know the true engine condition as well. Most times a Weber is installed to try to solve a weak engine issue - changing carbs will actually make it worse as the Weber is truly more sensitive to tuning. The Weber is a carburetor kit - not a Band-aid.

If you own a Weber - you'd better have a vacuum gauge, period. Bouncing vacuum readings at idle, low vacuum with stock cams and such are symptoms of a bigger problem - number one issue is almost always a vacuum leak in those junk adapters, others are worn valves, shot rings/pistons and valve guides as well as cracked manifolds or gaskets. This is why I wouldn't do Cruiser conversions - the adapter kits are a joke, let alone trying to properly adapt the throttle system without destroying the carb in short order. For those that have been running a Weber on a Cruiser and have slowly developed a problem with idle position or off-idle response - I'll bet you've worn out the throttle bore on the primary side at minimum. The telltale sign is a lack of idle control and stumbling off-idle, due to leakage at the throttle shaft and primary bore wear. If you can't idle the engine down to around 300 revs smoothly - you have a problem.

The other real tool needed is a timing light with a dial back feature. You must be able to see if the vacuum advance is working, how far it moves (wear issues) and the static base timing. Plus, knowing if the distributor is honestly advancing the ignition timing as it should or not - many are gummed up and need rebuilt. These parts are old, keep that in mind and without everything working together you will waste your time trying to tune the engine for the expected performance. The carburetor itself is one very small part a much bigger system - it all must work together properly as a unit.

Some of the tuning stuff is really not for an amateur, no offense intended nor am I trying to lecture. Without a true mechanic's knowledge of how systems work, how to rebuild and repair all of these parts makes it almost impossible for a common person to work on this stuff. Mechanical distributors, carburetors and internal engine parts are nothing to laugh at - back in the day it was a long process of schooling and teaching mechanics on how to work on these things. Without years of experience, you have to start with the basics and learn from there. Yeah, there are those willing to share their knowledge, the internet can also help, but in the end you have to learn yourself how to diagnose things and find a solution. Most people that get on the internet are looking for the magic solution - it doesn't exist. Most problems with these things are many layers of sub-par system parts that have failed to work to specification. You end up lost and frustrated and blame one part - that is almost never the case - it is total of many issues that created the problem and without fixing all of them you are wasting your time.



There are bore differences in the Chinese knockoff carbs in relation to the jets - the common Italian made jets will not fit. Some of the older Holley generic jets may work, but they also may leak, which is a problem.

I highly suspect you have a knockoff carb, it is not easy to tell the two apart visually unless you really know them. Very few people own Genuine Italian Weber DGV series carbs - I've only ever had a few come through the shop over all the years I did them. Almost all are the later Redline units produced in Spain - so in all honesty, not the real-deal here. All of the screwing around by aftermarket vendors led to the Chinese knockoffs and now Redline substituting the junk Solex for real Webers - and charging the premium price to boot, what a joke.

And folks wonder why I got out of the business..

Sarge

Sarge,

Really good summary. I agree with most everything you say. Tools are most important, and sometimes, you need to make do with what you have. Just looking for a fun ride good in the snow for a few years. Yeah, the business is tough, but what better challenge and what better fun than to try and find a way to make things work. Definitely not my primary car, but a fun one.

I appreciate all your contributions Sarge, thanks for helping me to get this on the road.