help with webers!

[wtenukl]

Hi gang,

I just installed some weber 48 IDA's on my 390FE. They have the 10 degree slant for hood clearance. Needless to say, I'm having trouble with them. The carbs are backfiring once in a while, but changing the jetting doesn't seem to help. I'm afraid my cam is not compatable. Here are the specs:
Comp cam 292H
Duration in 292 @ .50 Exhaust 292 @ .50
244
lift is .560
110 degree lobe seperation
Is this too much cam?

Also, when the engine is off, there seems to be some leaking of gas inside the carbs. I can look in the stacks and sometimes see a puddle of gas sitting on the butterflies. Then, the gas seeps onto the manifold by way of the carburator shaft. Is there any way to stop this?

What should my jetting be? Right now the engine runs best on jets sized at .130.

The enging is bored and stroked to 431cu. It has Edelbrock aluminum heads.

Is there an easy solution to these issues, or should I just go back to my dual quad's?

Thanks..

Todd

[ToyCollector]

Todd,

Did you buy the Webers new or used from a 3rd party? Webers can actually help take the lumpiness effect out of a cam and your cam doesn't seem overly radical IMO. Remove the screen on one of your carbs and take out both the idle holders and main jet holders.

Post your air corrector #s (usually a 190, 200 or 210, emulsion tube number (F7 usually), main jet of 150 or so, idle jet of 55-65.

The leaking fuel tells me they may need some gasket freshening. Is there any sloppiness in the throttle plate shaft on the leaky carb if you wiggle it? Do you know when these carbs were last fully rebuilt? They are a blast once you get the jetting right, so stick with it.

[ToyCollector]

Todd, I went out to the garage to get my sheet on where the consensus is with Webers. These numbers work big block or small for some strange reason.

Idle Jet holder 120
Idle Jet 60 most popular, then 55
Main Jet 150 and 160 most popular
Emulsion Tube F7
37 or 38 mm Venturis (aka Chokes in Weber speak)
Idle mixture screw, Inglese say no more than 3/4 out from full in stop, some run 7/8 turn out
For accelerator pump, some change the pump exhaust bleed (there is one per 48IDA at the bottom of the fuel bowl to a #50)

Some people have recommended a F5 emulsion tube to correct 2,000+ RPM stumble.

Float levels should be .165 inches below carb deck surface.

For those that in the future want a reference, my 289 HiPo with good flowing heads has the following:

Idle 60/120
Main 145/F7/210
Pump 50
Chokes 38mm (down from 42...the bulk of my problem)

[jamvan]

I agree with Toy Collector, good starting reference point is the specificationa he provided. May have to do a little fine tuning after, but it should get you running.

As to the "leakage issue", mine will do the same if I shut the car off when the engine is hot and the carbs full of fuel. You are just cooking off the remaining fuel. Usually it is the float levels as Toy Collector mentioned. Since I found out my car runs better with the floats a little higher, I have found another way to solve the issue. Before you shut the car off, turn off the fuel pump and let the car idle and cool down for 30 seconds. This will do two things; a. cool the engine down slightly, and b. empty some of the fuel out of the carbs which should solve this problem.

While it may take a little work to get them perfect, I feel it is worth it. Good luck.

Jim

[ack fia]

You may want to look at the needle and seats. I'm told that the latest Weber pieces have a tendency to leak. I'm waiting for Cal Metal to tell me he has more of the "better ones". I also was able to get rid of the leakage by keeping the fuel pressure under 3 lbs.
My setup is :
Idle 60 / 120
Mains 145 on F7
Air correctors 195
Pump and bypass 50 / 50
The engine is a very mild 302

[ToyCollector]

ack FIA, wow, we are nearly identical on the settings! I just dialed my synch in this weekend after re-mounting all the IDAs and used to have a 200 air corrector, just went to a 210. I will play with putting the 200 back in one of these days for giggles and let you know what, if any difference I feel as I see you are running a 195. Neat stuff.

I want to add my pump jet is a 50, and a 50 for bypass. Thank you again to Cal and all the others that have discussed this over the years.

[wtenukl]

Thanks you guys for your info. I'll try those solutions. In regards to the backfiring in the carbs, is that do to the possibility of the carbs running lean or is it a cam problem?

[ToyCollector]

I'd say it is a synchronizing issue if everything else is fine (valve adjustment, exhaust gaskets, no exhaust leaks). Do yo have a vaccuum tester to make sure the throats are all sucking similar vacuum ($60 item or so)?

[wtenukl]

Hey ToyCollector,

Yes, the carbs came with a synchrometer. They are all in synch, but I just got off the phone with Comp Cam and most of my problems are because of the cam that I am running. I need to go with a milder cam.

Doesn't look good for the Webers, but I really appreciate all your help.

Thanks,

Todd

[zimmy]

Todd:

If the carbs backfire up through the carb, then it may be that you have too much overlap in the cam. If they are backfiring out of the pipes, then you probably have some minor air leaks in the exhaust system (slip fit pipes, etc) or it is running a bit lean. Both will contribute to the backfiring. Mine has both and it sounds like World War Three when I get off it!

[wtenukl]

Hey Zimmy,

I had checked some of the old posts on this subject and you had a post about floats. I'm sure that had to be one of my many problems I was experiencing. I talked with a guy at Comp Cams and he basically told me that I had to have a cam ground for my application. I have had some other problems with the carbs, but the cam issue is definitely a big one. I'm pretty sure the webers are going up for sale within the next week or so. I'm not against webers, I'm just not ready to make more changes to the motor.
They are brand new. They only have 5-10 hours of use on them. So someone will be getting a deal. Your posts were helpful.


Thanks Zimmy,

Todd

[TerrysSPF]

Todd: Are you still thinking of selling the Webers? Where did you purchase them from, and have you ever called them for advice? I've heard Inglese is good about talking people through problems.
I may be interested if you end up selling them. Let me know.

[wtenukl]

Hi Terry,

I purchased them from a company in California named RPM Performance. They don't know a thing about them. All they know is how to sell them. I called Inglese and they weren't too much help due to the fact I didn't buy the webers from them (which I can understand).
Anyway, I finally found some people that had some experience with them and it turns out that the webers just won't work for me.
Yes, I am going to sell them. They will come with the intake, which I have to clean, fuel line, and a complete jetting kit.

Thanks,

Todd

[TerrysSPF]

Where in Illinois are you located? Perhaps we could get together and I could check them out.
I'm a little concerned as to why you feel Webers aren't for you. What did the "people with Weber experience" tell you as to why they wouldn't work? It didn't look to me (from the info you provided about your cam) that your cam was "too radical" for Webers. Heck, mine is worse than yours but I'm game to giving it a try! I know a guy with a Side Oiler that has a much more radical cam than mine and he has Webers and the engine runs like a charm. -Took him awhile to get there (which is common with Webers) but it was well worth the wait!
Send me a PM if you don't want to go public with any more info. Give me an idea on what you're looking to get for everything and I'll let you know if I'm interested. Are you in the Chicago area?

[wtenukl]

Terry,

You have a PM.