Tuning help
09-26-2013, 10:53 AM
#1
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Tuning help Here we go, after finally driving the car for a couple months this is my situation. I start it and idles fine cold. After a short drive and try to start it It seems to stay below idle almost like it has a lumpy cam. When I hit the gas it stumbles alittle then runs good. If I hit the gas hard and let off fast it will stall out. Also smells like I might be a tad rich. It's a 4.8 stock engine. Edelbrock setup using the eddy timing box seem to like #4 timing pill. Also a 625 cfm street demon carb. Th400 trans. I've been thinking about changing the carb to a holley 750 cfm. Any help would be great. Sorry for the run on of words.
09-26-2013, 11:59 AM
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Or just buy a quick fuel carb, do some research, tune it yourself and learn something while your at it? What are your plans with the engine op? Imo a 750 is goin to be harder to tune on a 4.8 unless your goin for all out hp and turning HIGH rpms. Judging by the stock engine I don't think that's the case here. Guys have good luck with 650's on 5.7's and 750's on 6.0's for the "normal" builds. I'd think smaller, not larger, would work in your application. that is if your dead set on switching carbs.
Last edited by 89gmcs15; 09-26-2013 at 12:08 PM.
09-26-2013, 02:26 PM
#4
Here we go, after finally driving the car for a couple months this is my situation. I start it and idles fine cold. After a short drive and try to start it It seems to stay below idle almost like it has a lumpy cam. When I hit the gas it stumbles alittle then runs good. If I hit the gas hard and let off fast it will stall out. Also smells like I might be a tad rich. It's a 4.8 stock engine. Edelbrock setup using the eddy timing box seem to like #4 timing pill. Also a 625 cfm street demon carb. Th400 trans. I've been thinking about changing the carb to a holley 750 cfm. Any help would be great. Sorry for the run on of words.
In order to achieve this efficiently, you will need a wideband a/f ratio gauge and/or data logging. The combination of the feedback from this tool and making fine timing adjustments
If you choose a Holley carburetor, you will be able to get help here as that is what most people use. In my opinion, Quick Fuel is the best value in Holley style carburetors.
As for the people who tell you to buy a pre-tuned carb from a "guru". I wouldn't waste your time or money. Those guys usually do a very good job at giving you a carburetor with the right wide open throttle mixture, but when it comes to fine tuning drivability and fuel economy, you will be on your own regardless of what the salesman says.
Last edited by speedtigger; 09-26-2013 at 04:06 PM.
