wheelz510 Posted July 14, 2009 Share Posted July 14, 2009 Just curious if anyone else has worked with a 470 cfm holley 4 bbl on an L28. I have searched and read about them on the v8 swaps, but not on an L-series. I am running an F54 block with an E88 head. I currently have the main jets set to 50 and the discharge nozzle set to 31. But it is still running extremely rich on the bottom end, and smooths right out on the top. I am ordering more jets today, but just checking to see if anyone else has gotten in the ball park with this carb. Dave from AZC is the only other car i have seen with the carb, and he has not had his running yet. So lets see who else has done this. Quote Link to comment Share on other sites More sharing options...
ozconnection Posted July 15, 2009 Share Posted July 15, 2009 There is quite a bit of info on these setups here on HybridZ. You gotta search harder The Holley 4 barrel does a fairly good job of supplying mixtures to the L28. I've been playing around with these 'things' for years. The thing to understand is that these carbs weren't generally meant for our engines. It means that the fuel curves are not ideal. That wouldn't be so much of a problem if you had a Weber as every fuel/air circuit is adjustable. The general 'run of the mill' Holley 4150/4160 square bore carbs are limited in which fuel circuits can be tuned. Having said that, you can still get these things to run fairly well. Primary fuel system running is balanced by main jets and power valve channel restrictions. Jets are changeable but the metering block PVCR isn't. Sure the Power valve can be changed, determining when the extra fuel is added, but not how much extra fuel is added. The first mod to correct your problem with overfueling is to reduce the size of the main jets and have your metering block drilled to accept replaceable jets like those used in the idle feed restrictions (found in those HP and specialty /more expensive carbs). After reducing the main jets to get the thing to run leaner than what you have, play with the PVCR until you have the correct A/F Ratio at wide open throttle. A carb shop or machinist can do this for you. Buy the jets for this from ebay or summit etc. Some are blank so you can drill them to your own size. Sub one mm drill bits can be bought from ebay etc if you want to do this yourself. The effect here is to realise that primary fuel is delivered through these two 'main' metering circuits and to get the fuel delivery close for our engines, this kind of work is often necessary. I could go on and on...but that's enough to answer your question I think. Quote Link to comment Share on other sites More sharing options...
Tony D Posted July 15, 2009 Share Posted July 15, 2009 Weber does make a jet block assembly that allows Weber Jetting and Emulsion Tube Componenets to be retrofitted to some Holleys... Quote Link to comment Share on other sites More sharing options...
ozconnection Posted July 15, 2009 Share Posted July 15, 2009 Weber does make a jet block assembly that allows Weber Jetting and Emulsion Tube Componenets to be retrofitted to some Holleys... Yes Tony I know, I've looked for them but never found one to buy. They're old now, do they still make them? Quote Link to comment Share on other sites More sharing options...
wheelz510 Posted July 15, 2009 Author Share Posted July 15, 2009 I have already changed the jets down to 50 from the 57's that came with the 470 carb, i need to go lower, this i know for sure. Just trying to figure out what everyone has them reduced down to with the 470 carb. Then what discharged nozzle is commonly used for the smaller jets to avoid the tip in sputter. I have a decent understanding of the holley 4 bbl. It is just the fine tuning i am missing, and curious what others have had better luck with. and checking to see how common the 470 cfm in particular is used. Quote Link to comment Share on other sites More sharing options...
Tony D Posted July 16, 2009 Share Posted July 16, 2009 Oh hell yes! Check out Summit Racing. I think they are in there. As far as I know they are still available directly from Redline-Weber in Compton or wherever they are now... Quote Link to comment Share on other sites More sharing options...
ozconnection Posted July 16, 2009 Share Posted July 16, 2009 I have already changed the jets down to 50 from the 57's that came with the 470 carb, i need to go lower, this i know for sure. Just trying to figure out what everyone has them reduced down to with the 470 carb. Then what discharged nozzle is commonly used for the smaller jets to avoid the tip in sputter. I have a decent understanding of the holley 4 bbl. It is just the fine tuning i am missing, and curious what others have had better luck with. and checking to see how common the 470 cfm in particular is used. To give you specific recommendations would require significantly more information on your engine/drivetrain combo than what you've provided us with. What cam, intake manifold, compression and exhaust are you running? Have you made any attempt to stove off heat soak? What size/type of air filter are you using?. What grade of fuel are you using? How hot is your ignition system? Manual or auto transmission? Get the idea? We would love to help you but you need to start the ball rolling by giving us this sort of detail. Without it, our recommendations are pretty much useless. Is your rich condition down low at cruise or WOT?......please be specific. Why has it been needed to drop primary jet sizes so low? Is there something else like bowl fuel levels that are too high requiring you to lean the jets so much? It 'sounds' like something isn't quite right there to begin with but without the extra info, I'm only guessing ATM. Cheers. Quote Link to comment Share on other sites More sharing options...
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