MSD Ignition or Weber Carb Issue?
- Thread starter CESLAW
- Start date
You can also use water in a spray bottle (mist), will change the idle if you have some air sucking in where not supposed to. Not as fun sounding as propane 
Very interesting thread that confirms again that I do love the look of Webers but would never want them as it seems you need a lot of patience to get them going
By the way for Air filters they are pretty easy to make with some from Piper Cross and ITG. I have used the Piper Cross hot dog shape to make some for my friends odd v8 Dino with 4 weber 40 DCNF's. They may have them for a single carb and long ones that the base plate that can be cut for the 2 carbs on one side. They have most with blank base plates and some with correct cut outs for specific carbs if your lucky.
Competition Products | Pipercross Air Filters
General Product Information: Maxogen/Megaflow - Coast Fabrication (itg usa dist I think)
Sandy
Very interesting thread that confirms again that I do love the look of Webers but would never want them as it seems you need a lot of patience to get them going
By the way for Air filters they are pretty easy to make with some from Piper Cross and ITG. I have used the Piper Cross hot dog shape to make some for my friends odd v8 Dino with 4 weber 40 DCNF's. They may have them for a single carb and long ones that the base plate that can be cut for the 2 carbs on one side. They have most with blank base plates and some with correct cut outs for specific carbs if your lucky.
Competition Products | Pipercross Air Filters
General Product Information: Maxogen/Megaflow - Coast Fabrication (itg usa dist I think)
Sandy
Chuck, yup. Wasn't trying to be a know-it-all. Yes, the Tomlinson book is great. To be honest, the IDFs and IDAs are very similar to DCOEs, just rotated 90 degrees so the theory and operation is quite similar.
One thing to always check with DCOEs is to determine that you're working with the same spec DCOE, meaning, "DCOE - XXX" with matching DCOEs for any one application. The "-XXX" part is important because, among other things, it specs how the progression holes are drilled in the throat around the butterfly - this dramatically affects how the carb transitions from the idle circuit to the full circuit as the progression holes will flow a particular amount of fuel at particular butterfly angles. I'm not sure if this is the same for IDFs and IDAs. I mention this because I have been shipped supposed "matching sets" of DCOEs which are actually not matching and, frankly, won't work together even with exactly the same jetting and chokes, etc.
Cliff:
Good point. I was not aware that the size and location of the progression holes would add yet another variable to these carbs. I am confident that the IDFs on mine are the same, since as of Sunday it seems to be running well (but with 20 degree temps further carb adjusment is on hold). Nonetheless i will check for matching numbers.
Thanks for the tip
Chuck
Good point. I was not aware that the size and location of the progression holes would add yet another variable to these carbs. I am confident that the IDFs on mine are the same, since as of Sunday it seems to be running well (but with 20 degree temps further carb adjusment is on hold). Nonetheless i will check for matching numbers.
Thanks for the tip
Chuck
Jim Rosenthal
Supporter
Glad you got it running better. Question: was this set of Webers shipped to you with setting and parts that were supposedly correct for your engine? I'm asking because while I have always wanted Webers, this is not the only story I've heard about how hard it is to get the engine running with them on there. My engine was dynoed with a single Holley and we will start it up with that, but I think about Webers for later on......
Jimbo:
No, the carbs were not added to an engine I already had. That would excuse the tunning challenges. This was crate engine, dyno'd with the Webers, Webers 'tuned' by the engine builder. But the I suspect the builder was more interested in what they did between 3000 and 6000 RPM rather than what they did between idle and 2000 RPMs.
I am sure there will be more challenges fine tuning these Webers, but when done I suspect we will be glad we did it. Best advice, as has already been suggested on this thread, get your hands on several books, keep them on your night stand, and read every night before you doze off. Gotta get the theory down first . . . .
Chuck
No, the carbs were not added to an engine I already had. That would excuse the tunning challenges. This was crate engine, dyno'd with the Webers, Webers 'tuned' by the engine builder. But the I suspect the builder was more interested in what they did between 3000 and 6000 RPM rather than what they did between idle and 2000 RPMs.
I am sure there will be more challenges fine tuning these Webers, but when done I suspect we will be glad we did it. Best advice, as has already been suggested on this thread, get your hands on several books, keep them on your night stand, and read every night before you doze off. Gotta get the theory down first . . . .
Chuck
Jim Rosenthal
Supporter
Good advice. Anyway it's too cold to drive an unheated car here, so it will make good winter reading.
I Googled Weber setups and there is some difference in price. Does anyone have anything that they feel comfortable posting about where to buy the 44IDFx4 setup for a Ford small-block engine? Weber Direct seems to have it for about $2000.
I Googled Weber setups and there is some difference in price. Does anyone have anything that they feel comfortable posting about where to buy the 44IDFx4 setup for a Ford small-block engine? Weber Direct seems to have it for about $2000.
Jimbo:
In addition to checking with the regular Weber suppliers (which sounds like you have already done) you might consider contacting some larger engine builders, like Keith Craft or T and L, to see if they will sell you a manifold and carb set up. I suspect they have gottern some special deals, since several builders are advertsing engines with Weber IDF packages. They may be able to pass along some savings. Just an idea.
chuck
In addition to checking with the regular Weber suppliers (which sounds like you have already done) you might consider contacting some larger engine builders, like Keith Craft or T and L, to see if they will sell you a manifold and carb set up. I suspect they have gottern some special deals, since several builders are advertsing engines with Weber IDF packages. They may be able to pass along some savings. Just an idea.
chuck
Jim Rosenthal
Supporter
I'll do that. Nothing looks as good as the Weber rig.My engine made 355hp on the dyno with a single DP Holley (307 ci). Webers might add a few horsepower, though.
Google Inglese inductions. These guys know what is best if you have questions. They can jet your carbs just buy filling out the information stats of your engine. Again, I have been running Webers on my 66 Shelby for 12 years. I rebuilt the carbs once and checked airflow by the unisan every couple years with no problems... except from the neck due too stomping on the gas pedal.
Jim Rosenthal
Supporter
Chuck, can you post the name of the Tomlinson book? I am going to try and order it, but I have had trouble finding it. Everyone has the Braden book, but I think I would rather read the one you found the most helpful. Thanks!
Jim Rosenthal
Supporter
Oh, I don't expect miracles. (especially after spending eight or ten years building this car) However, Webers are very cool and they look and sound great. And it wouldn't make any LESS power, I don't think.
Jimbo:
You can get it from Pelican Parts. Here is the link:
Pelican Parts - Automotive Parts and Accessories - Porsche & BMW
The focus of the book is Porsche and VW. But IDF is what they mostly use, so it is most helpful. And it is written in plain English. Good stuff.
And here is what it looks like:
You can get it from Pelican Parts. Here is the link:
Pelican Parts - Automotive Parts and Accessories - Porsche & BMW
The focus of the book is Porsche and VW. But IDF is what they mostly use, so it is most helpful. And it is written in plain English. Good stuff.
And here is what it looks like:
Attachments
Claude Tomlinson (related to Bob) started Claudes Buggies which is now CB Performance....www.cbperformance.com a big VW performance part supplier. They are a good source for weber stuff.
Understand that the book is somewhat dated in it's information. I found the book to be okay when I was learning webers....the internet has been more helpful for me. I particularly learned my basic approach by reading these two articles:
Basic Jetting Theory and Procedure - Aircooled.Net Tech Article
Carburetors 102: Synchronize Dual Carburetors - Aircooled.Net Tech Article
Just for example on the book, I was trying to reconcile the bypass screw position, the mixture screw setting and the jetting between the book and the internet sources only to realize that there are different profile mixture screws out there. I had some real blunt mixture screws that only worked 1/2 turn out or less. For the life of me I was trying to set it up per the book and spent considerable effort trying it.
Then I bought some new webers and wrestled with them only to find out that two of the new mixture screws were honkled up - one was bent and one had a different profile to it. I could not get the two barrels to act the same. I got new mixture screws and the carbs dialed right in.
So, I learned to double check the parts - they aren't always as the are labeled. I have had mismatched mixture screws and jets that were labeled the same but the holes were different sizes. I bought a set of jetting gauges to check those...
Mike
Understand that the book is somewhat dated in it's information. I found the book to be okay when I was learning webers....the internet has been more helpful for me. I particularly learned my basic approach by reading these two articles:
Basic Jetting Theory and Procedure - Aircooled.Net Tech Article
Carburetors 102: Synchronize Dual Carburetors - Aircooled.Net Tech Article
Just for example on the book, I was trying to reconcile the bypass screw position, the mixture screw setting and the jetting between the book and the internet sources only to realize that there are different profile mixture screws out there. I had some real blunt mixture screws that only worked 1/2 turn out or less. For the life of me I was trying to set it up per the book and spent considerable effort trying it.
Then I bought some new webers and wrestled with them only to find out that two of the new mixture screws were honkled up - one was bent and one had a different profile to it. I could not get the two barrels to act the same. I got new mixture screws and the carbs dialed right in.
So, I learned to double check the parts - they aren't always as the are labeled. I have had mismatched mixture screws and jets that were labeled the same but the holes were different sizes. I bought a set of jetting gauges to check those...
Mike
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An update on the continuing Weber saga . . . .
Couple of weeks ago pulled the idle jets, mixture screws and cleaned the idle circuit thoroughly. It ran much better. No coughing or backfireing when cruising at 60 mph. Only a few spits at low speeds. Idled well. But this lasted for only a half hour or so. Then back to the backfiring and coughing at cruise speed and idle range.
Checked the exhaust manifolds and had two cylinder thats were not firing. By opening up the mixture screws another turn or so I could get those cylinders to fire, but clearly this was not a proper adjustment.
Let it cool down. Pulled the idle jets (again) and noticed a speck of dirt in one of the jets. Cleaned all the idle circuits (again).
Today had a chance to start it up after being gone for the last two weeks. Ran great initially. Stopped to get a bite. Started it up and it was back to its old tricks - coughing and backfiring. Checke and found one of the cylinders was not firing - but a different one than before.
I am wondering if there may not be dirt inside the carb in the float bowls (perhaps from dust generated while working on the body?) that keeps getting into the idle circuit. The fuel is clean and very well filtered. The IDFs have vent holes in the top of the body, so it would seem that tiny bits of dust could get inside.
We plan to pull the tops off the carbs and clean out the float bowls. But before jumping into that project, has any one had a similar experience????
Couple of weeks ago pulled the idle jets, mixture screws and cleaned the idle circuit thoroughly. It ran much better. No coughing or backfireing when cruising at 60 mph. Only a few spits at low speeds. Idled well. But this lasted for only a half hour or so. Then back to the backfiring and coughing at cruise speed and idle range.
Checked the exhaust manifolds and had two cylinder thats were not firing. By opening up the mixture screws another turn or so I could get those cylinders to fire, but clearly this was not a proper adjustment.
Let it cool down. Pulled the idle jets (again) and noticed a speck of dirt in one of the jets. Cleaned all the idle circuits (again).
Today had a chance to start it up after being gone for the last two weeks. Ran great initially. Stopped to get a bite. Started it up and it was back to its old tricks - coughing and backfiring. Checke and found one of the cylinders was not firing - but a different one than before.
I am wondering if there may not be dirt inside the carb in the float bowls (perhaps from dust generated while working on the body?) that keeps getting into the idle circuit. The fuel is clean and very well filtered. The IDFs have vent holes in the top of the body, so it would seem that tiny bits of dust could get inside.
We plan to pull the tops off the carbs and clean out the float bowls. But before jumping into that project, has any one had a similar experience????
yes - new fuel tank or new lines always seem to have junk in it....and takes a while to clean it out. What fuel filter setup do you have? You might want to put in a big fine fuel filter to collect the stuff that might be getting to your carbs. I would do this before opening the carbs up. You might check the inlet screens of the carbs to see if the stuff is coming from outside them first.
My last set had this same issue until I put a better filter on it and now it has been fine for a few years...no more clogged idle jets.
My last set had this same issue until I put a better filter on it and now it has been fine for a few years...no more clogged idle jets.
Mike:
I have two filters. One before the fuel pump and second, fine filtration filter after the fuel pump. The fuel is well filtered. Got 250 miles on it, so one would think that whatever crud was in the lines is gone by now.
But if there is debris sitting in the bottom of the bowl, I am guessing it could get stirred up.
I am ordering a replacement gasket set, just in case I need it, then will look inside for dirt. I am guessing that may the problem.
It is also noteworthy that the engine when cold ran good, but when thoroughly warmed up it started acting up. Wonder if that is a factor, or just a coincidental finding.
I have two filters. One before the fuel pump and second, fine filtration filter after the fuel pump. The fuel is well filtered. Got 250 miles on it, so one would think that whatever crud was in the lines is gone by now.
But if there is debris sitting in the bottom of the bowl, I am guessing it could get stirred up.
I am ordering a replacement gasket set, just in case I need it, then will look inside for dirt. I am guessing that may the problem.
It is also noteworthy that the engine when cold ran good, but when thoroughly warmed up it started acting up. Wonder if that is a factor, or just a coincidental finding.
Chuck,
Install these on your carbs along with some air filters like mine.
These two things will go along way to keeping the passages in your webers clean.
CB Performance - Online Catalog
S
Install these on your carbs along with some air filters like mine.
These two things will go along way to keeping the passages in your webers clean.
CB Performance - Online Catalog
S