holley jetting

4nford"Live wrong and Perspire"

Pulled my spark plugs for the first time since purchasing my car and its initial tune up. The plugs were white as new. With the use of unleaded gas, do the plugs turn darker as they did with leaded gas? (yup, its been some time since I tinkered with cars when I was younger) I am assuming that I'm running a bit on the leaner side. If this is so can anyone tell me what the stock jet size is on a 600cfm? I figured that I'd get a baseline here and buy a few sets of jets to try this weekend. Thanks

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Aloha from Hawaii

8/3/0412:18 AM

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Rover (Guest)

This link should help: http://www.eric-gorr.com/techarticles/sparkplugs.html

Sounds lean to me, but could also be effected by special additives for your locality of gas.

8/3/0410:33 AM

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Terry M (Guest)

I just had my 650dp rebuilt and setup by John at "John's Fuel Systems & Carburetion." He's in Hayward Calif and good source for carbs. (25 years) 510-786-2505

8/3/045:59 PM

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bosswrenchMember

AS I mentioned before, with many unleaded fuels, the plugs don't color up as the used to, or you get weird colors (try interpreting brick red!). A Holley 6619, a 4160 type 600 vacuum-secondary carb quite popular on Panteras in the '70s & '80s, runs a 64 main jet and a 73 secondary drilling with a 6.5 power valve. I passed CA smog with this carb for years on my 351C and it always ran lean at idle but richened nicely above 2000 rpms according to the air-fuel machine. Note that not all Holley jet numbers correspond to SAE drill sizes- a #66 is 0.066" but a #68 is 0.069".

8/3/048:56 PM

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