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Too Rich????
Alright I know I was running a little rich at the end of last season; it was bogging a bit under heavy acceleration, and it just plain smelled rich...But now that I'm getting her ready for spring I'm changing the plugs and they're BLACK...I don't mean a little darker than they should be, I mean BLACK...it looks like I've been burning oil but I know I haven't...
Now since this is actually the first carbed car I've ever had, maybe I'm just not used to seeing rich plugs, so my question is just basically if this is normal or not???? And secondly, I guess I'm gonna have to put some smaller jets in the carb, but how the heck do you know what size jets to use?...I don't even know what size jets are in there now!!!! My basic setup is a 302, bored .030", Holley 600 dp, B303 cam (.480 lift, 284 duration), 1.7rr's, Edelbrock 60cc aluminum heads, and a Ford Racing dual plane manifold...I think those are all the relivant specs, if I'm missing something let me know; Thanks for the help! --Dave. |
First find out what size jets you have in your carb and what jets come standard on a 600 DP. I'm thinkin' around mid to high 60's. If jets are factory, you "may" have other circuits affecting your rich condition. Idle jet size, power valve defective or wrong size. Set up your idle enrichment properly, go to a chassis dyno shop that has a sniffer and work with the chassis dyno and sniffer to measure A/F ratio's at part throttle cruise (2500 rpm in 4th) on the dyno as well as WOT (wide open throttle) measurements up to redline. That will tell you a lot about how the motor is working with the carb. Bring some jets along in case you want to change jetting while on the dyno. Look for a part throttle cruise A/F ratio of 13.8 - 14.5:1 and a WOT A/F ratio of 12.8:1 - 13.5:1. Good luck.
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If you have access to a chassis dyno that is the way to go. If not then you can change the jets one or two sizes at a time, testing the car between. You also might want to get a good vacuum reading on your engine and check the power valve against it. Sometimes a very low vacuum reading at idle and low speeds can cause the power valve to open prematurely, resulting in a rich condition. You may also want to consider an MSD ignition. Won’t change a super rich condition, but it sure seems to burn more of what’s available.
Hope that helps, Steve |
thanks so far guys!
Steve I forgot to mention i'm running a full MSD ingition; 8582 Distributor, 6AL Box and a Blaster II coil... I had actually thought before that I might have a vacuum issue because I was having quite a problem getting the timing/idle set right a little while ago...For a time I couldn't get it to idle with anything less than 18degrees base timing; but after many hours of tinkering with the idle settings I got it down to a 14degree base; could this possibly be causing the problem? |
Go to a dyno with a wideband oxygen sensor. I learned more about my engine in three runs than I did in three month trying to figure it out at home. I gained 51hp by getting the timing correct. If your timing is not correct don't replace jets unitl you get the timing issue resolved. Every motor and elevation is different so don't listen to anyone about what you should run. Get a box of jets a timing light, advance springs and bushings and get to the dyno. Take a friend to run the car on the dyno and you man the timing light. You will learn a lot. Its the best bang for the buck. All the parts in the world don't mean jack if its not tuned. A/f of 12.5 to 13.5 as said above is what you shot for. Also dyno the car on the fuel your going to run on the street.
later Dennis |
I fought my engine for months in the alley thinking all the fouled plugs were the carbs fault turned out the ignition was the problem.
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Mike,
How was the ignition at fault? Everyone else thanks so much; I'll be taking her to a dyno as soon as the damn salt is clear from the roads! Thanks again! |
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