If I can do a weber so can you!!!!!!!

[race-it]

For those of you considering webers, I can say it is worth the learning curve. I admit it was hard at first. Then it got harder!!!!!!!! My answer!!!!!!!! Ask a lot of questions and read read read. I spent hours reading the weber manual over and over, Highlighting every thing that I wanted a quick reference for. I broke the weber up in my mind into three sections as the book describes and focused on one area at a time. I read and reread again everything in the book that dealt with each section. As the book says, the floats are the most important. If they are off, everything is off. Don't trust someones work but check yourself! Next was the timing. Check yourself. I had to pull distributor and rotate each direction until I found the exact spot that would work and have full turning range to set degree. Next I checked linkage for exact movement to each carb. Next was to follow instructions for carb sink. Everything is in the book and also discussed in several sections of the book. I followed the book to the letter. It still took a long time, but I was making headway and everything behind me was perfect for that point in the process. I checked and rechecked carb sink then moved on to jets. I already had placed the jets in the weber chosen from engine size using charts provided. I did not have all the jets I wanted, but with webers you can still arrive at the same point or close to, because of the varied other jets and adjustments. I changed my exhaust gaskets to the new aluminum ones. Checked plug wires, rechecked timing, hooked up the LM1 and checked the set up several times in the driveway. Several experimental tries with different jetting helped me further to understand this carb's workings. Each drive I would examine the data on the computer, make adjustments in idle mixture, jetting , air correctors and after the 7th run I hit payday!!!!!!!!!! ALL popping, sneezing, hesitation was gone! The car was a new vehicle and I really mean that. I hit the throttle the car went crazy. POWER POWER POWER!!!!!!!!!!
Like nothing I had ever had before in my car. The tires where screaming and the force of the acceleration pushed me back in the seat. The hole car seemed to rise up andthe back end began to go back and forth with each gear I hit. I finally knew what so many of you already know, these cars will kill you if you are not careful. I still have some fine tuning to do because I see a few more horses I can capture. The truth is, If I can do it You can do it. I am no motor guy but I can read and follow instructions. If any of you were thinking weber take the plunge. I am so happy I did!!!!!!!!!!
I will clean up the cobra and take pictures and post tomorrow if anyone wants to look. My three year reconstruct project is done. I hope you will like what you see. Thanks again for everyone who offered support during this project.
Jim

[lineslinger]

Good on you Jim, persistence reveals the payoff.
Will watch for your pictures.

[Dangerous Doug]

44 IDF's or 48 IDA's?

Hhmmmm... You've got me thinking....

DD

[Silverback51]

What a nice love story. A man, his Cobra, and her Webers find true happyness.

Congratulations Jim.

[priobe]

Just for giggles

What was your final jet setting?

Primarly the chokes

[Steve Bisson]

Way to go Jim! I'm happy to hear you two made up.

[race-it]

I have 44 IDF from Weber Direct.
Note, Between the drive that had popping and sneezing and the amazing transformation of my motor I found three of the eight idle jets were missing the small "O" ring that goes on them. I do not know but I now expect the missing "O" rings contributed to popping and sneezing. My tune up is not complete I want a professional to dyno it and make corrections. I do know I have a tremendous increase in power that I never had before. If you have have changed idle jets on you weber and still have unexplained popping check for missing "O" rings. They are easy to loose!!

I hope someone will have a print out of what the a 347 with Weber's in tune print out should look like so I can compare to my print outs.

My settings

Main Jet 140
Idle Jet 55
AC Jet 185

[franklin]

Still waiting for those pictures?

[Rick Parker]

Good job Jim, the journey is fun and informative; right?

[race-it]

Rick, I can now take my cobra out also and enjoy the sounds of weber's with no popping or sneezing, A real treat for me to hit the throtle and in any gear have the wheels break loose!
Jim

You can see pictures by clicking on my camera.

[Andrew Teal]

JIM,

My Webers are here, so this fall let put them on and get it right. not that I"m not pin in the seat now. Glad all is well, glad you got it right. I new you had more power when could get away from that rich bottom in.

Andy

[cobraviper_99]

I am so onboard with you race-it. I had Webers on my 428-powered ERA Cobra back in the 1980's and that made a true believer out of me. So many people told me I was crazy to go with the Webers and, yes, it wasn't simply a plug-and-play situation, but the benefits far outweigh the frustrations of dialing them in. Now I have them on my side-oiler and the payoffs are:

1. Stunning throttle response. A friend who drag races motorcycles went for a ride with me and after two gears said, "That's the closest thing I've ever felt to what it feels like launching on my Suzuki."
2. Developing a great "tactile relationship" with your engine. You listen to your engine much more closely, developing an ear for what each cylinder is doing, how the exhaust pipes "talk" to you, the cadence of each cylinder firing, even how black the pipes are getting (or not getting), the smell--too rich? Too lean? More timing? You will learn more about your engine and what it likes and doesn't like as you find the proper tuning for the Webers.
3. The sound of four 48IDA's at full throttle is decadent.
4. The "Oh Wow!" factor when you open the hood at a show or cruise night. A set of dual quads is pretty tasty looking to anybody, but when you open the hood and people see those 48's poking up, it's an instant crowd.

So as race-it says, if you're thinking about going with the Webers, and you don't mind spending some time dialing them in, go ahead and do it. They're not cheap, you won't find many people in the neighborhood who can help you get them tuned, and the various combinations of venturis, jets, holders, air correctors, linkages, and adjustments might make you crazy. I'm not a mechanical whiz but I took my time, read the Pat Braden book and a few more, and now I can understand what my engine is saying to me. I rarely have to touch the Webers now that they're in the sweet spot and I sometimes just diddle with them simply to learn more about them.

A few tips on getting them right which I learned from my own experiences--

1. Don't overthink your setup if there's something amiss. Many times, a simple adjustment of the idle mixture screws will make a huge difference. They are rather sensitive to adjustment and just a slight turn to lean the mixture or fatten it up can cure backfiring under acceleration (too rich) or backfiring when backed off the throttle (too lean). That notorious "lean stumble" around 2000-2800 RPM's can also be minimized or eliminated by an idle mixture adjustment. But remember, being happy with Webers often means choosing a compromise. If the stumble is very minor and the engine really gets it on across the rev range, decide just how fussy you should be.

2. Clean plugs are critical! Read them every time you make a change to your setup. They are your most valuable tattletails as to what's happening inside your combustion chambers. Have a couple of sets of plugs on hand. Pull the plugs out and look at them after every test drive, and put clean ones back in.

3. Not all Webers are created equal. An old racer friend of mine told me that he has dialed in many a set of Webers by using different size idle jets in one or two of the carburetors to get the correct setup. I have 60's in three of my 48's and 65's in one. That may fly in the face of what some experts will tell you but my engine was recently freshened up, dynoed, and all is well inside. The different size jets give each cylinder what it wants and the performance speaks for itself. I've learned that just like two identical engines built on the same day in the same shop by the same guys, there are small differences. Webers are the same. Sometimes, you need to think outside the box when everything you've tried doesn't seem to work.

4. Air cleaners effect the flow and therefore effect the mixture. I've run nylon "booties" on my Webers and run them without and there's a noticeable difference in how the engine behaves. Don't overlook the possibility that your air cleaners (or lack of them) impacts the tuning.

5. A rich mixture is a big no-no. Crap fuel mileage, black smoke out the pipes that makes even the hottest-looking Cobra look like a crapcan, and extra fuel washing the cylinder walls, not to mention fouled plugs and crumby low-end performance. I've always gone with the leanest setup I can which still gives me the best across-the-board performance. I always use a little octane boost to help prevent detonation and when I can get my hands on ultra-high octane gasoline, the engine loves it. I've heard knowledgable tuners say really big jets just pour fuel over the problems and they're right. A big-block will probably run without stumbles or big lean skips with 70 idles, but you're just hiding the symptoms of an improper setup.

Webers rock. They just need a little love. You won't be sorry.

[aks801]

I have long lusted after the Webers, and figured that would be my choice when I do my big-block build. Then I talked myself out of it, figuring a single 4-bbl Holley would suffice.

This thread is really making me re-think it. The Weber really set-up is honestly what I really want, but I'm basically letting myself get intimidated by the folklore (and some reality, I'm sure) that surrounds them (i.e. you'll spend all your time tuning instead of driving...).

Two questions then, if I may:
- which book(s) should I read up on to learn and decide?
- since I'll be using an FE engine (either a worked 390 or a 428), what considerations should be made for the engine buildup (cam profile, head tricks...).

Sorry for the moderate hijack, but thanks just the same.

[rokndad]

Good for you guys. I did the same thing, wanted, waited, studied and then did it!! I don't think I'll go back to the 4bbl any time soon. The performance of the 48 IDA's is stunning. Still a little tuning to do, but for now I'm sticking with them. A blast to play with.

[Michael4yah]

Jim, Youve got a great looking car. Just some tidbits I came across when doing my research on Webers.
Keith Kraft said that you need at least 11 or 12 degrees of cam lobe separation when running Webers. Without that separation it will want to stumble, spit or fire back through the carbs. Others have said that sealing the air stacks to the carbs is important because it prevents air leakage that would make a difference in idling or cause stumbling out of the gate. If an air cleaner is used then these leaks would affect it even more. Some have even said that after they got em running they ran great for a while but then became hard to tune etc. A lot of the time its these small leaks that are causing it. The use of an air cleaner may actually help cause the air stacks to leak at the base if they arent sealed good. Path of least resistance etc.

As far as the performance goes , their response is only 2nd to a roots type blower. After using them Kenny Miles wanted them on every car he drove. He knew that coming out of a turn he could gain a fender on anyone.

Good luck with the car.

Michael

[cobraviper_99]

The book I use most frequently is the one written by Pat Braden. It's available everywhere--Amazon, eBay, etc. There are others which may contain more comprehensive info but the Braden book should be your first read.

Camshaft compatibility and cylinder head applications are a complex area and anytime I've had a question, the guys at Inglese down in Memphis seem to have a handle on such matters. www.inglese.com

[race-it]

I do like my weber set up. Again I want to mention the "o" rings on the idle jets. Absolutely 100% if you have a damaged, torn, worn out , missing "o" ring you will have popping and sneezing. twice now this has happened to me and it immediately went away when I replaced the damaged "o" ring. I never read about checking those in a book but found out by doing it myself so check yours out, it may well be the ghost you have been chasing as I did.

Jim

[cobraviper_99]

48IDA's don't have the O-rings but anyone running 44's should be aware of them.

[race-it]

Lets talk about the sputter zone 2000-2800 or what ever your weber RPM starts acting up. Of course that is the perfect cruse speed zone

I was told to increase fuel pump jet size, does that work or is it more fine tuning?

Jim

[cobraviper_99]

In my experience, it's just getting several contributing elements to work simultaneously. Obviously, it's an idle circuit issue. That means idle jet size, jet holders, idle mixture adjustment, spark plug condition, even fuel pressure can come into play. As I mentioned earlier, it's real easy to over-fuel the engine with Webers and run a too-rich mixture while chasing that stumble. An overly rich setup can camouflage a host of sins.

I start with a baseline setup I know is lean: 55 idle jets, mixture screws turned out half to three-quarters of a turn. I make sure the plugs are clean and fuel pressure is no more than 3.5 pounds. Some guys run as much as 4 pounds but again, I'm trying the leanest setup I can so I run the lower fuel pressure.
I also check the synchrometer reading to be absolutely sure the carbs are synched. Also, linkage geometry is key. Carbs which are synched at idle can be way off as the linkage opens due to a bogus hex-link configuration. All eight throats should be pulling equally at all RPM readings.

Now, I take a test drive, expecting to find that stumble. Yup, it's there. It's gone by 3000 RPM's because the main jets are now taking over. Before switching any components, I gradually turn out the idle mixture screws no more than an eighth of a turn and drive the car again. If there's still a stumble, I'll stop and turn the mixture screws out a little more, but no more than another eighth turn. Now, if the engine starts backfiring under acceleration, I notice what side it's happening on and that tells me I've got too rich a mixture in a cylinder on that bank. I may also hear a backfire when lifting and that tells me I'm too lean in a cylinder. It could be on the same side as the backfire when accelerating in another cylinder or on the other side of the engine. Here's where reading the plugs is so important.

I've seen sooty plugs and whitish plugs on the same side of the engine during this dialing in process. You've now got a reliable roadmap for what each cylinder needs. Make the cylinders happy, so that your plugs are reddish brown after a test drive and there's a good chance the stumble will be corrected, or at the very least, much better. One cylinder may want a bit more fuel, another may want less. The backfiring evidence (and/or the carbs "sneezing" under acceleration or at idle) is how your engine tells you that a cylinder isn't happy. Remember, unlike a plenum-type intake which delivers fuel to every cylinder from a common vapor bank, each throat of the Webers has to supply its assigned cylinder with the proper air-fuel mix. Now, there is a chance that your cylinder head choice, cam profile, or type of ignition can complicate the tuning, but Webers are so infinitely adjustable, I'm of the opinion that you can get them dialed in regardless of what other goodies you're running.

Don't rush the process. My Cobra spent most of the summer in my garage last year as I methodically used the Braden book and some other materials to understand what was happening in my engine, rather than just changing this and that, hoping to hit the setup. And don't be afraid to treat each cylinder as a separate patient. As I've suggested, you may think using the very same jets, holders, idle mixture settings, etc. in all four Webers is an unbreakable rule, but if you had eight kids, each one would probably have different personalities, wants, dislikes, etc. Your Webers are no different. The differences may be slight or they may be significant. But you would be amazed how your engine will respond if you step outside conventional wisdom when tuning these carburetors until each cylinder is getting what it wants.

One other thing: it's not a lock that a 2000-2800 RPM stumble is a lean stumble. If you're running too rich a mixture in a cylinder or two, you'll get a spark plug misfire and it feels just like a lean stumble. Again, I ask my spark plugs to give me the inside scoop.