I had the intake off my hemi last week and the valves were really gunked up from the 93 octane I'm running. What's a proven fuel system cleaner to run occasionally? Or should I just mix in some race gas every once and awhile? Thanks, Dave

Gumout, good reviews from multiple sources

See this:

http://www.hemmings.com/mus/stories/2008/01/01/hmn_feature19.html

"Numerous cold starts and warm-up cycles, excessive idling, short trips, and around-town motoring where the stop/start action is amplified are all ideal conditions for rapidly forming carbon deposits."

"The best defense against deposit formation is a fuel that incorporates the necessary additives, designed to keep the system clean and/or to remove existing deposits."

"Though carbon is going to form, you can limit its creation by using name-brand gasoline that contains a fuel system cleaner, limiting idling time and cold starts, employing high-quality oil and keeping the carburetor/fuel injection system tuned properly. Once these protocols are invoked, a semi-annual chemical cleaning will keep your engine carbon-free and in top running condition."

The author recommends Chevron gasoline with Techron as the best known engine deposit dissolver. I poured about 10 ounces of Techron in my gas tank each time over about four fill ups, and I did notice a difference: the engine quit dying 3-4 times on cold startups. This is my daily driver, a fuel injected V6, not a Mopar. Now I always buy Chevron for this car. When my 340 gets running, I'll be using Chevron, and I might be cleaning out the carbon deposits as per the link above if there is accumulation.

Conklin's 4-Power G, if you can find it.

Another vote for Techron.. A little spendy and a reason why, it works.

No chevrons in my area, so can I get techron in a bottle?

Answered myself by goggling it. I'll give it a try. Any others recommended?

I have read Techron is one of the better ones. Read a few times that Amsoil is supposed to be awesome. I don't have internal proof, but that's what I run through once in awhile. Might want to research it too but sounds like Techron is darn good too. We have Chevrons all over where I live so that's the only gas I run.

I think once you have valves with the amount of crud like the one in the pic, especially in our muscle cars that can run rich. No fuel system cleaner will do much.

Thanks for the replies! Back in the late 90's when I bought my 70 340 swinger the valves looked pretty much like those and I ran slick 50 fuel system cleaner through the 340 and it cleaned up nice. However being 15+ yrs ago I'm sure products have changed. I know it worked back then as I changed intakes a couple of times looking for that magic 1, lol

Techron is fine and have also used seafoam and BG 44K.Still not opposed to dumping a can of marvel mystery oil down the carb and cranking it up the next day and killing anything that flies.