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Weber Conversion Jet Frustrations
https://www.slantsix.org/forum/viewtopic.php?t=45119		 Page 1 of 1
Author:  hexerror [ Thu May 26, 2011 1:51 pm ]
Post subject:  Weber Conversion Jet Frustrations
Greetings Gang,

Jeee whiz, it took me a week to figure out how to log back in after a year. Pardon as I cannot find the information at the moment but I did the Weber carb conversion on my 225CI Slant a year ago. I modified the manifold and linkage and it works fine operationally. However, it's a total dog performance wise.

It feels to me that the 350CFM is just a bit too much for the engine. I bog out badly when I kick the gas pedal and bog even at highway speeds when upshifting, etc.

I am at my wit's end trying to dial this carb in but I know it will work great if I only knew the tricks step-by-step. I am running a Weber 32/36 DGEV. My instinct tells me to go down a size or two in the jetting to optimize performance. Again, I think the engine is getting too much gas. Even too much to adjust out via fuel/air ratio etc.

I will be forever thankful if one of you great Slant Six mechanics could lead me to the right spot with regard to this set up. My '73 Dart is my daily driver to work and so I need to both improve fuel economy and performance within reason. And presently I feel I am wasting gas to no result or effect on the performance side of things.

Cheers!
Jason
Author:  olafla [ Thu May 26, 2011 2:18 pm ]
Post subject: 
The Weber is not flowing as much as 350 cfm, I have seen figures in the region of 255 cfm. Some users complain that it is a too small carb for the SL6.

Remember the Weber shall have only 2.5~3 lbs fuel pressure, so you may need a regulator in the fuel line if your pressure is high.
See this link to redlineweber.com.

Here is one Weber thread here in the forum, make a search for 'Weber', and you'll get more than 1200 hits, refine your search, and you'll probably find the answers you seek.

Olaf.
Author:  hexerror [ Thu May 26, 2011 2:22 pm ]
Post subject: 
Thanks Olaf. Maybe I can find the answer. Just exhausted over it all and hoped someone else had already found the right combination.

Thanks!
Jason
Author:  hexerror [ Thu May 26, 2011 2:35 pm ]
Post subject: 
P.S. Olaf, can you point in the direction of a regulator I should purchase and try out? I never even thought of this scenario. But also, I think my timing could be potentially off a tooth or so as well. It's driving me crazy!!!!!!!!

Other Symptoms:

To maintain idle in gear, I have to adjust the idle high. So in park, the engine is really revved. In gear, the idle drops dramatically and becomes rough like as if I am running a high performance cam big block. Haha. People in traffic occasionally pull alongside me and think I have some wicked sleeper drag car. If they only knew the truth.

And of course I mentioned the bogging. She's a dog at the moment. I am running a Super Six out of a 78 Monaco rebuilt and slammed into my '73 Dart Custom.

Hope for the Future:

The good news is that when I get the old girl on the interstate and break up over 65 MPH, she breathes beautifully and has what feels like unlimited acceleration. So I know that the Weber will be a fine addition to my drive train once I get it figured out and dialed in.

Cheers!
Jason
Author:  Joshie225 [ Thu May 26, 2011 2:46 pm ]
Post subject: 
If the idle cannot be adjusted and you don't have a vacuum leak it's likely the idle jet is too small. I tried a Holley/Weber 5200 on my 225 and I made a drill out of a pin to open up my idle jet so that the idle mixture screw was effective. I found my carb to be lean and the accelerator pump shot too small. Read the plugs before you conclude you're running rich. Lean is more likely.
Author:  olafla [ Thu May 26, 2011 5:23 pm ]
Post subject: 
I have a Mr. Gasket fuel pressure regulator that looks nice and has worked OK for many years, but I think any known brand would do. Simple is good.

BTW, I am not running a Weber, but I considered buying one. I currently run a worn BBD on my stock super six '77 Aspen, and I am working on a setup with a Motorcraft 2150 1.08 2-bbl for that engine, and an Autolite 4100 1.08 4-bbl on an Offy intake for a modified SL6 engine.

Have you performed a good basic engine tune-up, adjusting the valves and timing? You will find good links in the 'engine' FAQ.

Olaf.
Author:  Wesola78 [ Fri May 27, 2011 6:28 am ]
Post subject: 
I'm running a Weber carb on my slant six, but it's a Weber 38DGES. It's working okay now, but I had to jet down a couple of sizes. It was running way too rich. It sounds like you have a lean condition going on.
Author:  69a100 [ Fri May 27, 2011 9:04 am ]
Post subject: 
Dude, Your running lean! I have the same set up as you, only w/manual choke. When that happens and I pull the choke, it take off like crazy. The current numbered jets I'm running are this.
65/65 for the idle
150/190 for the mains
170/180 for the air, I need to do some more homework on these as when the motors cold and I take the choke out to soon I will get a bog if I floor it, but when it's op temp it's fine. Do searches here and Google for tech info and read all you can on jetting. Once dailed in you will be really happy with this. I can dail my idle down to 200 rpm in park, but won't handle that in gear so I know I'm pretty close.
Author:  hexerror [ Fri May 27, 2011 10:48 am ]
Post subject: 
Awesome information. Thanks fellows. You are all the reason why this is probably the most friendly and informative board on the web.
Author:  bmimken [ Sun May 29, 2011 8:55 am ]
Post subject: 
I also think you are running lean. I used to run the carb as yourself and had go up several jet sizes. I even went up in pump nozzle size if I remember correctly.

I also would recommend a fuel pressure regulator or switching to an electric fuel pump for a more consistent fuel pressure. Webers prefer a smoother fuel pressure that just a mechanical fuel pump by itself can provide.

Brian
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