Gary Lewis Posted October 26, 2019 Share Posted October 26, 2019 Gary, Holleys do not have a secondary air valve, Carter AVS and Thermoquads , Rochester Quadrajets, Motorcraft 4300 and 4300D use them. You can look down the secondaries and see if it looks like there is fuel from the idle circuits showing at the rear of the throttle plates. Take the shaft on the driver's side and try to rotate in clockwise, if it moves and the idle drops that is your problem. You can also slide a piece of thin hose in and listen for a load hiss with the engine running. I sit corrected. Obviously, Holleys are not my forte. So, Bill, are there idle circuits in the secondaries on his carb? Link to comment Share on other sites More sharing options...
85lebaront2 Posted October 26, 2019 Share Posted October 26, 2019 I sit corrected. Obviously, Holleys are not my forte. So, Bill, are there idle circuits in the secondaries on his carb? Maybe and maybe not, I would need the Holley list number and even then without my big Holley book I had at Preston it would be a crap shoot. If there are feed holes and a transition slot in the back side of the throttle body, then it has secondary idle circuits. Holley used them on almost all 4150 and many 4160 series carbs. Link to comment Share on other sites More sharing options...
Gary Lewis Posted October 26, 2019 Share Posted October 26, 2019 Maybe and maybe not, I would need the Holley list number and even then without my big Holley book I had at Preston it would be a crap shoot. If there are feed holes and a transition slot in the back side of the throttle body, then it has secondary idle circuits. Holley used them on almost all 4150 and many 4160 series carbs. If there are idle circuits would there not also be idle mix screws in the metering block? So, if he has the screws he has idle circuits, and if no screws no idle circuits? Link to comment Share on other sites More sharing options...
Rembrant Posted October 26, 2019 Author Share Posted October 26, 2019 If there are idle circuits would there not also be idle mix screws in the metering block? So, if he has the screws he has idle circuits, and if no screws no idle circuits? This carb does not have four corner idle adjustment...just the two mix screws in the front. The rear just has a metering plate instead of a metering block. It's this one below... https://www.holley.com/products/fuel_systems/carburetors/classic_holley/parts/0-80457SA I took a look down the barrels. Can't really see much. The rear barrels are pretty clean and appeared to be more closed than the primaries. Maybe there's something keeping the primary plates open a hair. I'll investigate a little more tomorrow. I'm done for today. I was tentatively planning to get rid of the Holley anyway and replace it with a Summit M2008 500CFM... https://www.summitracing.com/parts/sum-m08500vs/overview/ They seem to get rave reviews, but that fuel inlet means I'll have to relocate my coil. Anyway, that's a discussion for another day. Gotta get the one I have working properly first;). Thanks guys. Link to comment Share on other sites More sharing options...
85lebaront2 Posted October 27, 2019 Share Posted October 27, 2019 If there are idle circuits would there not also be idle mix screws in the metering block? So, if he has the screws he has idle circuits, and if no screws no idle circuits? No, the older Holleys have fixed secondary idle circuits, and if you look at the specs on the metering bodies (plate in the rear bowl) they have both main and idle jet sizes specified. Like I said, I miss not having the 3" thick Holley catalog I had at Preston. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted October 27, 2019 Share Posted October 27, 2019 Thanks for the comments guys. I'll do a little investigating. I assume the only way to check the secondary plates is to pull the carb and flip it over and have a look? I'll try the spray test tomorrow and check for vacuum leaks. Otherwise every single gasket and hose and tube and fitting is new. Brake booster is confirmed to be holding vacuum, and I plugged the PCV hose this morning for a test. Manifold to head leak....now I hadn't thought of that. The REALLY tricky manifold to head leak is when it's leaking into the lifter valley! Though that will eventually show as smutty plugs, and you may get knock because one of more cylinders are acting like a diesel. Link to comment Share on other sites More sharing options...
Rembrant Posted October 27, 2019 Author Share Posted October 27, 2019 Though that will eventually show as smutty plugs, and you may get knock because one of more cylinders are acting like a diesel. Well, the good news is that my plugs all look exactly the same and are all pretty clean. As Gary mentioned before, almost too clean. According to my Holley book, they look good. I have since changed them from Autolite 764 (Now obsolete I believe) to Autolite 104 (Same plug I believe, but with full length threads). Link to comment Share on other sites More sharing options...
Rembrant Posted October 27, 2019 Author Share Posted October 27, 2019 Though that will eventually show as smutty plugs, and you may get knock because one of more cylinders are acting like a diesel. Well, the good news is that my plugs all look exactly the same and are all pretty clean. As Gary mentioned before, almost too clean. According to my Holley book, they look good. I have since changed them from Autolite 764 (Now obsolete I believe) to Autolite 104 (Same plug I believe, but with full length threads). Oh...I should clarify...the truck is working OK, I just think it will work a little better than it does. Full disclosure...I have a bad habit of chasing ghost issues...that end up being nothing at all, other than me being too fussy about a noise or a vibration or whatever. Still...based on that idle, something isn't quite right, and I'd just like to dial it in a little better, and I think it can be. Link to comment Share on other sites More sharing options...
Gary Lewis Posted October 27, 2019 Share Posted October 27, 2019 Oh...I should clarify...the truck is working OK, I just think it will work a little better than it does. Full disclosure...I have a bad habit of chasing ghost issues...that end up being nothing at all, other than me being too fussy about a noise or a vibration or whatever. Still...based on that idle, something isn't quite right, and I'd just like to dial it in a little better, and I think it can be. Bill's the guru, but those plugs are awfully white. I would expect a light tan residue on most of them if properly jetted. Or, maybe I should say with the proper AFR. As for ghosts, the fact that it won't idle down below 750 RPM is not a ghost. You should be able to kill the engine by closing the throttle plates, even when the idle air/fuel mix is spot-on. That says to me that it is getting air somewhere other than the carb. And I think your new wide-band meter is telling you the same thing, although being new it is suspect. So I'd leave it out of the pic at this point and see if you can figure out if you are getting extra air and where from. Car cleaner! Link to comment Share on other sites More sharing options...
85lebaront2 Posted October 27, 2019 Share Posted October 27, 2019 Bill's the guru, but those plugs are awfully white. I would expect a light tan residue on most of them if properly jetted. Or, maybe I should say with the proper AFR. As for ghosts, the fact that it won't idle down below 750 RPM is not a ghost. You should be able to kill the engine by closing the throttle plates, even when the idle air/fuel mix is spot-on. That says to me that it is getting air somewhere other than the carb. And I think your new wide-band meter is telling you the same thing, although being new it is suspect. So I'd leave it out of the pic at this point and see if you can figure out if you are getting extra air and where from. Car cleaner! If you don't want to get things messy, use a propane torch valve on a low setting and not lit. Carefully aim it an any joint, manifold to head, carburetor mounting, vacuum trees. Unfortunately when everyone went to full numeric plug PNs for ease of computer use they do not mean as much as they used to, on the older numbers, Autolite would be higher numbers were hotter. My truck uses an ASF-42, colder would be ASF-32, resistor plug would be ARSF-42. The plugs do look lean to me, but depending on the actual heat range that could be misleading. Here is what I was referring to on the secondary metering bodies: https://www.holley.com/search/?q=Secondary%20metering%20bodies There used to be a real long list of these as both main and idle jets are in them. Link to comment Share on other sites More sharing options...
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