Thread: *350 sbc With Demond 625*

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When I bought my 37 pickup I had it shipped back from Delaware. The fellow I bought it from said it ran good a strong and it does. I'm thinking maybe the altitude change from Delaware and indiana may have the carb off a little. My 350 has a Demond 625 (1902) carb and it idles fine but when I pop the throttle it's sounds a little loaded up and the second time I pop the throttle it sound fine like it cleared itself out and sounds fine but it smell a little rich at the exhaust. How Can I tweak the carb to make it a little more on the lean side? Is there one or two mixture screws and where? Thanks for the help.

See if you can find this closer to home - How to Tune and Win with Demon Carburetion~Barry Grant~Street & Strip~NEW! 1613250002 | eBay

It's an easy carb to work on, as long as you know some of the basics. And there may be some videos on youtube that can help. Also, get a vacuum gauge, it'll help out a bunch.

See if you can find this book closer to home ( and cheaper?)

How to Tune and Win with Demon Carburetion~Barry Grant~Street & Strip~NEW!

Also get a vacuum gauge, it'll help you make adjustments so much easier.

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And now there are 2? Hmmmm.. LOL.

I concur that these are good cards, but can be a bit tricky to work on. Holley now has what you need for the 265 Street Demon. Go here:

http://documents.holley.com/lit701rev10.pdf and download the pdf.

It will guide you through the tuning process. You may find it necessary to go one size leaner on jets and step down one size on the metering rods. If so, you'll need this kit:

https://www.holley.com/products/fuel...its/parts/1921

Have fun!
Glenn

Originally Posted by zippi

How Can I tweak the carb to make it a little more on the lean side? Is there one or two mixture screws and where? Thanks for the help.

Zippi, the mixture screws you mention are Idle Mixture Adjustment, only to affect the air/fuel mix at idle. Also, if you're talking "...popping the throttle" from idle, that is the job of your idle mixture plus the accelerator pump, which gives a shot of raw fuel into the carb throat to help the transition from idle to mid-range and/or wide open throttle. Adjustment of your mixture for cruise or WOT is a jet change, as Glenn mentioned.

Thanks for the help guys.

I bought a 625 Street Demon (The new style that looks similar to an AFB) and have never been able to get that thing to run right. It was incredibly hard to get the engine started with it; would constantly flood on start up. I finally took it off and put an old Holley 600 I had on. Thanks for posting the info; maybe I'll re-visit and see if I can figure out what's wrong with it.