So when its going that lean is it falling flat on its face and not recovering at all......or does it seem to actually run. Any header vac system or anything that could be injecting undetected air in.......exhaust leak anything One issue with o2 sensors is if any air gets into the exhaust system before the sensor, but after the combustion process it can cause false readings.......so small exhaust leaks when you running an engine at rpm can cause air to get sucked in behind the exhaust pulse.....this air being not mixed with fuel or burnt will cause a false lean reading. What do you plugs look like..........if this was as lean as the sensor indicated it should be flat as a board and fall on its face dead when at wot......if its not a big dead hole that stays flat till you let off its not as lean as indicating
Probably gonna try a good known carb. Really annoying. I just swapped the squirters from 31/31 primary/secondary to 35/37 to see if that's where I need the enrichment. Quadrajets are now easier to me than holleys. What happened to the simple plug and play nature of the Holleys? BULL
Drove it again. Still dead lean at full throttle, sounds like it’s breaking up after about a half second of throttle
John , what is the "carb history" here? Is this a new carb right outta the box, or a used carb? Also, what happened to the carb the original owner had on it? Sorry if I missed this information....JIM
Right out of the box. I’m now wondering if my high speed air bleeds are clogged or something. It shouldn’t be so rich. But this engine does require a TON of air it seems
Just to give you some reference, we just put a 670 4150 vacuum secondary on that 496 boat motor......it will never go over 5000 rpm........but when it was on the dyno b4 the cam issue minus a pv swap from 2.5 to 6.5. Everything was seeming really good......ill know more tomorrow as the boat gets wet.......I'm thinking a little bigger pv. Maybe 8.5. But free rev seems fine and it worked on the dyno. Will your even rev up and take all 4 in park.......kinda look and see if gas is actually coming out of all 4 boosters........something isn't adding up here. Start simple.....us there even gas in the rear bowl???
Going to sell this carb instead, wish me luck. It’s effectively brand new, with only jetting changes and a lil bit of premium gas.
I was hoping he would get his hands on a good running carb and try that at least, just to verify the AFR guage is in the ballpark . Jim
Most new holleys come with that adapter. I have like 10 sitting around cause those lines always leak and swap everything to either fuel logs or an style fittings
So I decided to change things up: First drive, stock jetting and everything: 87/91, Idle air bleeds 70/70, high speed bleed 31/31, squirter 35s, 4.5 primary power valve Part throttle cruise is 13.2-14, idle is great. Heavier throttle cruise is around 11:1, but I have a feeling I can tune that out with bigger primary high speed bleeds. Full throttle is still 16:1 lean, even at tip in. Jumping to 90/98 jets and hoping to increase primary high speed bleeds to 38-40, depending on what I feel is best. And I put a 37 Squirter in the rear. Yeah multiple changes...including a new carb. We’ll find out how it goes
90/98 was crazy rich. So I dropped it to 82/98 and replaced the primary high speed bleeds, moving them from 31 to 45. I am actually very satisfied with the idle and cruise characteristics of this combination. However, it is still lean at WOT. So.....what I did is this. Installed a 4.5 power valve into the secondary metering block. With 98 jets and a power valve, I'm not sure if a Holley can get more rich. It might be time to buy smaller high speed bleed jets.
You shouldn't need that much, and its going to way imbalanced 82 up front and 98 and a pv in the rear....your talking 20 sizes difference with the pv. Thats not right.........something else is wrong. You went up 200 cfm and are still stupid lean by your gauge.........if you were 16 17 lean I would think it would fall flat and never try to pickup and run when at wot. Normally 8 -10 sizes difference front to rear with a pv I had a 1000 cfm pro system carb on my 464 it ran 84/92 and ran in the uppers 10 in the 1/4. What are the plugs telling you
John, I think your going the wrong way with the high speed air bleeds. The bigger the number the leaner it will run when you put your foot into it. Your making too many changes at once and can really make you run in circles.
