View Full Version : Tuning Help

Camaro Zach
08-15-2005, 04:43 PM
Ok guys this is for my daily driver i need to adjusting the motor, here are all the specs if it helps. 262ci (4.3L) v6, comp. 270 h .500 lift cam, MSD 6al, MSD pro billet, MSD wires, Edelbrock performer, edelbrock 500 cfm carb.

Ok so last year after the car was completed i had the stock jets/metering rods in it and it failed emissions ( i think it was NOx or CO2) so I went Stage 2 lean 8% which uses a .003 smaller jet and it passed.
So this year i take it to get inspected with the same jet and metering rod and fail HC which the year before i had passed with flying colors.

So what do i need to change or what do you think it is? I know how to adjust the carb and the advance springs on the dist. but i dont know what running good is supposed to be. Its hard to explain but i just dont know when i adjust anything if its better off than what it was. Right now the timing is advanced about 10* @ 700 rpms and if i bring it down to 0* it will bog and spit and sputter.

Well i dont know if that made sense to anyone but i just need to know when i should change things and how to tell if its doing any good.

Thanks for the help,

08-15-2005, 06:14 PM
Are you just trying to pass the smog test? When I lived in CA. I had my blazer smogged and the timing was set at 0* to pass, talk about running like a pig, I ran 4-6* all other times. This is with a stock 1987 5.7tbi motor. Possibly try retarding it and running a little lean for the test. SS

Camaro Zach
08-15-2005, 08:15 PM
Well temporary solution is to pass emissions right now but i would like to learn how/when to tune it later on to make it run better. If you drive behind me it smells like raw gas and really bad fumes but there is no black smoke.

For the emissions testing i already have it leaned out 8% should i go up to 12%?

And does backing off the timing that much actually help? even if its barely running.

Thanks zach

08-15-2005, 08:32 PM
Zach, I can't help you with your Edelbrock carburetor, but I can give you a quick fix to pass smog:

Buy yourself a gallon of alcohol (like some drag race cars and sprint cars use), and mix that with about 6-8 gallons of pump gas. Mix it good, get the car warmed up, and it'll lean out nicely.

Once you're done with smog, however, make sure you change your gas!

08-16-2005, 03:36 AM
maybe spark plugs playing up.

Camaro Zach
08-18-2005, 06:23 PM
ok thanks for the tips guys. I'm going to set the timing, lean it out 12% and experiment with different advance springs and metering rod springs later on. Hopefully i pass on saturday

Camaro Zach
08-20-2005, 12:25 PM
Alright well i leaned it out to 12% and the smell went away. Hooked up a vacume gauge to the PCV port on the carb and it was fluctuating alot so i adjusted the idle fuel mixture to get it steady then i adjusted the timing and adjusted the mixture again. It idles great and doesnt really smell of gas. When you lean on the throttle it accelerates OK... but could be better. Then once you get up to speed and keep the throttle at a constant position it stumbles but if you hit the gas it recovers well and once you leave it at a constant speed again it begins to stumble. Does it sound like its too lean?

I'm going to pull the plugs when it cools off BTW

thanks for the help guys

Camaro Zach
08-20-2005, 06:24 PM
plug after running 12% lean for an hour or so

08-21-2005, 04:34 AM
Have a look at this link for reading plugs