Stumble off idle -

[decooney]

Originally Posted by patrickt

Alright. Grubby, order an 850 of your choosing and put it on there, run it, and if the problem is still there quickly clean it up and send it back for a refund. I hadn't thought of the sidepipe thing... I'm not sure about it, but maybe.

If he can get it to someone with a meter who can check the AF ratio (before buying another carb), might be money well spent. Would be interesting to know if the problem is better or worse in the summer heat vs. cold winter. Just recently came across a brand new Holley HP 750 that had casting flash on the base plate partially blocking one of the circuits; i.e. if everything is not perfect, little issues like this can pop up. A good carb blueprinter can find and fix his 750 and make it work better than it does now but its all time any money.

Note: Phil at Quickfuel is a good resource. I've used Phil a few times to validate my own assumptions. If Grubby provides all the engine/car specs, Phil at QFT can get him pretty close. They have spec'd out QFT carbs from 780 to 850 for FE engines set up like Grubby's. I like my own Holley HP 830 but may move to a Quickfuel 850 next. Super adjustable and better quality.