decided to replace the NGK BP5ES plugs in my 430 with some fresh NGK FR5 V power plugs before cruising season. I noticed all the old plugs were carbon fouled,which I would think indicates it is running rich. my holley 770 street avenger has a 6.5 power valve, 72 front jets, 75 rear jets. accelerator pump cam is brown. floats set correctly. ignition is MSD 6A, MSD Pro Billet dist, Blaster 2 coil I have been fighting with this problem since the day I put it on in 2003. electric choke appears to be working,with key on it opens like it should. WTF can I do to solve my problem???
Throw that holley in the can and get a real carb. p I tried one on a Ford I used to own and had nothing but problems with it. Holley's are sloppy carbs IMHO, but then I'm no carburetion expert either. The best running carb I ever had was my old Quardajet, after I was able to get it to stop leaking. ou:
I'm not going to switch to a q jet, or edelcrock carb . there's got to be someone out there who can tell me how to get it to work as intended
What's the manifold vacuum read at idle, in gear? Just wondering if a big camshaft might have the power valve(s) opening too early. Devon
the cam is a TA 310. if I remember right, the vacuum reading in gear at idle was 15-17" (can't remember exactly) no power brakes
That valve should stay closed, then. Hmmmm...another possibility is a torn power valve diaphragm, even though the new Holleys have a better design that resists backfire damage. Might be worth a look to see regardless. Devon
the 6.5 in it now is a fairly new one, hasn't had a backfire to blow it unless I ought to change the pump cam? maybe it's opening it too soon??
Accel pump cam shouldn't cause a constantly rich mix. Power valve was my only guess, since your primary jetting seems decent for your engine. o No: Does the carb respond to idle mix screw adjustment? You should be able to stall it by turning them in. Devon
last time I had a good friend look at it, he turned them in one at a time, and it did come close to stalling, he immeadiately turned them out 3 and a half turns won't be taking it out for a few weeks.
Jeff, If it's not the power valve, did you consider a warped main body? Did you buy your carb new? Also, if the check valve is not installed or dirty under the accelerator pump outlet then raw fuel can be drawn into the bores. Those are about the only three ways fuel can get into the manifold. Try buying or borrowing one of the Holley books, they can help temendously. Good Luck!
yes, I bought it new in 2003,wonder if those main bodies are the same? I have the main body off a 600 I could use. I doubt if holley would replace the main body if it was warped. I will check to see if the check valve is ok. I'll definately check into getting a holley book thanks!
Jeff,did you try running your mixture screws in a half to three quarters of a turn to see what that does? It also might make a difference once you get your new plugs in there and open the gaps up a little more to see what that does.
I'll try that when I take it out in a few weeks, am still putting trim pieces,and other things back on it after paint.new plugs gapped at .045. I'll have to look my carb up online, to see what the check valve looks like
warm up the engine. hook a vacuum gauge up to manifold vacuum and adjust the mixture screws for highest reading.
took an old 600 accel pump apart, found a check ball there above the diaphram. is this what I should inspect to see if it fell out,or is dirty??
what size & type of exhaust? are the throttle plates opened passed the idle circuit? how about coming down on the jets? 68/71 and dropping the pv to a 4.5
3.5" w/X pipe, 3" walker CVX mufflers I will look and see about the throttle plates I'll see about the jets/pv too.(I did try a 3.5 pv, no change) still pulls hard and strong though this carb has had problems since new, had same problem in another car, it had 3" pipe on it
Take out the shooter(s) and turn the carb upside down carefully the check valve should fall out. I dont know if it's a ball or a needle.
A number 37 is probably very close. Changing the shooter won't help a "rich all the time problem". you should only change the shooter to cure a stumbling problem. I would look for things that cause excess fuel to enter the manifold or things that prevent airflow.