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Info to provide before asking a carburetor question

Updated: May 27, 2022

Why am I writing this? Because when a person messages me or posts to an online forum, frankly, I don’t feel like asking all of these questions. Simply put, you are wasting people’s time if you don’t have this info on hand.

Very common that a person approaches me with a minor issue. I spend weeks asking the questions below and awaiting responses.

This is very difficult for me as I often have 4-5 people asking different questions at the same time. Hard for me to keep track.

I find a good policy is to have a small file with all of your car details somewhere. This makes it easy to cut and paste or email a small text file with all of your info in one place.

Your situation:

You have a carb issue and are going to ask a carb expert or an online forum.

Here is a checklist of information needed before asking a question.

  1. What carburetor? List number, date etc

  2. Carb info. 4160/4150 etc. what jets? What bowls? What changes have you made? Carb condition? Float levels correct? Throttle plates set properly?

  3. Ignition info. Plug type, distributor type, ignition box, initial timing, total timing, what does the curve look like? Vacuum advance works? Are you 100% all of this is working correctly?

  4. Fuel system info. Manual or electric pump? What kind? Regulated? What fuel pressure? Fuel line size? Does fuel pressure change as rpm increases? Explain what it does.

  5. Engine info. Intake name or style, exhaust info, head info, cubic inch, compression? What accessories are attached to the carb? Can you test them for vacuum leaks? Can you isolate them and plug the vacuum nipple on the carb?

  6. Very important. Camshaft info. This determines so much about the engine and how the carb is pulled on. If you have a cam card, great!!! If not, no fear. A vacuum reading at idle and as throttle increases can often help a person understand how the engine acts.

  7. Car info. Manual or auto transmission? How loose is convertor? Rear gear? Vehicle weight?

  8. What is the purpose of this car? Driver? Street performance? Race? Etc.

  9. Fuel quality. This one is critical. Often with classic cars, fuel is old, or winter fuel is used. Often happens that I see folks with 9-10 month old fuel in the tank. Fuel needs to be filtered, clean, water free, fresh, etc.

  10. Can you explain the issue in detail? Simply saying “doesn’t run right” isn’t helpful, describe in detail every little thing it does and where/when. The most information given will greatly reduce the time needed to make an educated suggestion that can help you. A common issue with a Holley is a leak somewhere. Where is the leak? Gasoline can crawl pretty far, it can even crawl up a casting, so it is very important if something is wet, you need to wipe it off and watch where it creeps out of. Most of these issues are minor, but finding them is troublesome.

Typically when you ask a question on a forum, a poster will state they have an issue and give little to no info.

This results in 87 responses where people shout out parts: “it’s the power valve!” “It’s the wrong accelerator pump cam!” Etc.

Weed out the BS and have as much information on hand ahead of time.



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1 Comment

Great write up not fancy just basics needed to answer someones question.

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