010 diameter wire so now my IFR hole size if. You can cause an extreme lean condition while cruising if not careful and understand how much you are reducing the overall size of the IFR hole. The wire you put in has to be super thin. Don't mess with that until you can get your idle mixture screws to be responsive. Pull out the wire you put in the Idle Feed Restriction. The transfer slot should only be exposed about. The transfer slot is not exposed to much on any of the throttle blades (I have checked by having the carb upside down) You shouldn't have more then about 100-200rpm drop going from idle to in gear. Also, you should adjust your idle mixture screws for the highest vacuum possible while in gear (parking brake set) for an automatic transmission. You should be able to close your idle mixture screws by lightly seating them (clockwise turn) and kill the motor. If your idle mixture screws are unresponsive this normally means your idling on the transition slot. I was able to correct some of it out with smaller idle air bleeds and higher power valve. Even with running an idle AFR of 14.5 ish it was way better but that high of an AFR caused me some lean cruise conditions.
Roller camshaft with 580 intake lift, 530 exhaust lift and 292 duration, I had a pretty stinky exhaust. Just one of the drawbacks of having a high performance camshaft. It shouldn't make your eyes water but it's going to be pretty prevalent. With a high lift, high duration cam, your going to have some "stinky" exhaust at idle. Running a high initial timing may require to adjust your distributor to only giving you 35-38 degrees of total timing. You will also need to recheck your total timing as well. This will allow you to readjust your primary throttle blades and get off the transition. It will stabilize your idle AFR by giving the fuel more time to burn and raise your idle rpms by 100 - 200 rpm. Try running about 21 or 22 degrees of initial timing. Last edited by chevycsb 08-20-2015 at 04:05 PM.įirst off if your cam has a high lift/duration, you need to be running as much initial timing as your starter can handle without dragging. Should I perhaps try to increase the fuel to the idle circuit instead of restrict it with the wire in the idle feed restrictor?ĭoes anyone have any ideas or tips how I should tune the carb to be used at the street with my monster camshaft? I think my problem is the carb isn’t using the idle circuit or the idle circuit isn’t setup according the low vacuum my engine produces. So yesterday I also tested this but it didn’t help at all. I did also the test with breathers instead of the PCV system but with no difference.Īfter all the above tests, I finally found some discussions about Holleys running to rich at idle when using cams with big overlap and the suggestions was to restrict the fuel into the idle circuit by putting a thin wire into the idle feed restrictor.
#Big cam 350 edelbrock problem drivers
I use a PCV valve in the drivers side valve cover and the passenger side valve cover is connected to the air cleaner.I have done all tests with the brake booster disconnected and the vacuum port plugged (if it was a vacuum leak there).
#Big cam 350 edelbrock problem manual
Finally the engine is equipped with a brand new Holley 750cfm vac carb (3310-SA) with manual choke. The engine also have a very aggressive camshaft (I don’t have any specs of it). My engine is a modified Chevy 350 with ported double hump heads, roller lifters and lots of more performance stuff. I have read almost every article and threads on the Internet about this problem, but haven’t found a working solution for my setup. Yes, this is another thread about idle problems together with camshaft with big overlap.
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