Too lean

[drtlvr]

I've been having trouble this year with running too lean. The first race we melted the tip off 2 plugs. Since then, I've jetted up 5 sizes over what I always run. This is a 2300. Nothing has changed in this engine. From carb to oil pan, I've kept it the same for 3 years. 15 wins with this combo, temp usually stays at 200 after the race. Now it's 240 at the middle of the race. The only thing changed is buying gas from somebody different at the track. Can different brands of gas be this different? Track gas was 110 sunoco. Not sure what it is this year. Any opinions?

[return to dirt]

sounds like it could be detonation. i would get some of the sunoco 110 and try it. you may have already damaged the pistons. you also may want to recheck your timing.

olin

[Foghorn]

I think Olin is right. Sounds like a timing issue. Too much advance and a combination of lower octane fuel could be the cause. Also check your distributor and make sure there isn't something coming apart inside allowing it to advance way too far at high revs. You could also check for a vacuum leak. First guess though is a timing problem. Let us know what you find.

[RACEMAN]

Got an air leak somewhere?

[drtlvr]

Gonna take a fuel sample. Come to find out this is a common problem in my class. Will let you know. I'm pretty sure that's it, I just hate to blame anyone other than myself unless I've checked myself several times and others have went behind me checking too. Thanks

[drtlvr]

Sunoco 110 race fuel fixed my problem. Ran 180 all night. Didn't change anything else.

[return to dirt]

glad to hear that. hope you didn't damage anything else.

olin

you might want to have a talk with the guy selling fuel at the track. find out what he is actually selling.

[drtlvr]

We pulled the rod bearings and they were drawn up some from the heat. She runs like she's supposed to now. Thanks.