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scorchingeng · 02-10-2013, 08:45 AM

Hi,

If it's running well up to 3000 rpm I would not suspect fuel delivery at all.

It is either a timing issue ( but yours looks good to me...) or valve overlap. How about rechecking your valve lash, ensure your rockers are tightened evenly. I have no idea what heads you are running, hydraulic lifters, etc. But it's an idea.

By the way, you can check for floating valve, and narrow down a bank, by using a wideband O2 tailpipe sensor. If they are uneven, I think you can figure it out from there. Obviously if they are uneven, it's not your carb or intake.

Hope that helps you at all.

02-10-2013, 08:45 AM	#13
scorchingeng Registered User Join Date: May 2010 Location: Albuquerque, NM Posts: 21	Re: truck begins to backfire over 3000rpm? Hi, If it's running well up to 3000 rpm I would not suspect fuel delivery at all. It is either a timing issue ( but yours looks good to me...) or valve overlap. How about rechecking your valve lash, ensure your rockers are tightened evenly. I have no idea what heads you are running, hydraulic lifters, etc. But it's an idea. By the way, you can check for floating valve, and narrow down a bank, by using a wideband O2 tailpipe sensor. If they are uneven, I think you can figure it out from there. Obviously if they are uneven, it's not your carb or intake. Hope that helps you at all.