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Thread: what carb on a chevy 250 inline 6

  1. #1
    Road Devil's Member Brian_RDeurope's Avatar
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    what carb on a chevy 250 inline 6

    does anybody has experience with the right carb for an inline 6. the internetz is full with info but also very confusing.
    from what i understand the bigger is not the better. the carb also should corresponding with a 200R4 tranny.

    any support can help. thanks

  2. #2
    President Patrick's Avatar
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    I always ran 2gc rochesters

  3. #3
    Road Devil's Member
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    Do you want one or more carbs? Best solution is 2 Carter W1.
    Or Check http://www.langdonsstovebolt.com
    They got good advices For inline sixers!

  4. #4
    Road Devil's Member
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    I've ran several set ups on my IL6. First I ran 1 Rochester, basically a stock set up with a home made split exhaust. It ran great, but the motor just didn't make any power. After I blew the motor up I went with a bigger bore and a hotter cam, 848 head and a Fenton split manifold.. I also upgraded to 2 Rochester's. This set up looked the best, but the additional carb really only made some difference on the big end. They were easy to tune, but you had to adjust for the cold/hot weather. They also always had a slight stumble off the line that I was never able to tune out. As for around town cruising they really just used more gas. I decided to I pull those off and went to 2 of Tom Langdons Webber set ups. They ran like crap. They fell on their face in the top of the RPM, they were a bitch to tune, and they ran super lean. Langdon argued with me about the jet size, and wouldn't even sell me different jets. I eventually found them on my own and after a little more tuning they ran ok. Fuel millage was lousy though and in general Id say they weren't worth the hassle and expense. Sold the whole set up off and turned my interest to Clifford Performance. HANDS DOWN the best IL6 guy on the market. I bought his single carb intake, and the single Webber carb, I think its a 48/48. This sucker right out of the box ran perfect, just like he said it would. The single made way more torque and HP than any other set up I ran. My car gets really great millage and the set up has not had even a hiccup yet. It bolted right on, no trimming or weird shit to fit, the only thing I did was set the fuel pressure regulator, and adjusted the idle 1 turn, that's it. The car idles mint, it'll start up cold without having to even pump the gas. Out of all the set ups its the way I suggest. Also, Larry is a real good source of information on these motors, and they still hold the IL6 record at Pikes Peak. This winter I'm switching out my cam to his grind, and going to do all the head work he has suggested as well as loosing my Fenton header and running a Clifford. Hes telling me that on a dyno I should see crazy numbers for a 6. I have called this guy a bunch these last few months and everything he has suggested has worked and every part I've bought has been the best.

  5. #5
    Quote Originally Posted by Brian_RDeurope View Post
    does anybody has experience with the right carb for an inline 6. the internetz is full with info but also very confusing.
    from what i understand the bigger is not the better. the carb also should corresponding with a 200R4 tranny.

    any support can help. thanks

    What do you mean by "the right" carb? Do you mean the correct factory carb or are you looking for performance? If you are looking for the factory correct carb, it would have been a 1bbl Rochester Model BC up till the early 1970's I think, then they switched to the 1bbl Rochester mono-jet. If you are running a 2o0R4 you will have to run a lock-up kit of some sort. TCI sells them and many others sell them too. You can buy kits for manual or automatic lock-up. The automatic ones typically operate off a vacuum switch. Then you just run a line from your intake vacuum source to the pressure switch. The manual versions operate off of a momentary switch under the throttle, or a toggle switch you place on your dash. The under the throttle style just locks up when you go to WOT.

    If you are looking for performance carbs, PT has pretty well outlined it. You could also consider a 4bbl offenhauser intake and a small 390cfm Holley 4bbl. You will need to determine what cam, exhaust, compression, etc you are going to be running to determine the best carb size and configuration, unless you go with the stock option.

  6. #6
    Road Devil's Member Brian_RDeurope's Avatar
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    after some research I decided to the following setup
    4bbl intake, splitt headers, holley 2bbl 390 carb. trans becomes the TCI lock up kit.
    will see how it works out after putting it together

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