I've heard people say as long as your Eprom timing is correct you don't need to adjust the disturbutor much.. Let me tell you, I had my Distubutor timing at -4 and my ePROM timing at +6 and it run like a crap. I did not know this until I deside checked it this past weekend. The disturbutor it must have move on me over the past year or so.... Was wondering if anyone could help me understand the best method of adjusting timing. What i did was I have my disturbutor manually turned to +10 Degress and my EPROM base timing to +10 dregess. My question is what is the correct method to adjust timing. What are the cause and effect of setting up timing like this VS setting up the distubutor to +6 Degress ( stock) and my Eprom base timing +10 degress ( 4 degress past stock)? My goal is to advance timing before knock. how are you all setup??

I've finally replaced all the parts causing my poor preformance and now i'm ready to adjust my chip again. So i've got all my tools this time i'm able to datelog, so i'm ready to nail down the tune.

Another question, how many people have ported there base, pleuim, runners and air box to free up air and found that there bottom end is not as agressive anymore. I used to be able to smoke tires just stompping it at a dead stop. Well this past weekend it was not the case, it moves but it will not smoke tire unless i hit it side ways. I mean it could have been 90+ degree heat will and the tires gripping into the hot pavment. It does pull hard in the upper rpm range then it use too.

 

Your prom base timing must match your Distributor timing. The correct way to adjust your timing to just before knock is to do it in the prom, NOT with the distributor.
If your initial timing is set at 10 and your dizzy is set at 12 then in effect you've just given the whole timing table in your prom 2 degrees extra timing because the prom thinks your working off of 10. This can be helpful but if you're hitting knock in some spark advance cells you'll get retardation. There goes the usefulness. Change the individual SA cells for optimum tune. Datalogging will be your best friend in this area.
Make sure your fueling is right though before you start messing with the SA tables.

 

Ok thanks, So your saying I should set my Chip Base timing (6*) and my dissy (6*) the same and mod my spark tables. This makes sence to me is that correct? I will check my fueling too.


thanks

 

Yes.

 

The only reason to have the two match is accuracy of numbers in the tables (as accurate as any of that is by the time the spark occurs anyway) and having the timing where you want it. I have a separate timing control wired in that I use to adjust my base timing at the track so I dont have to mess with the distributor. Yes, it adjusts the entire range globally but sometimes thats exactly what you need. If you have emissions testing like we do here in Cali you'll want to set both those numbers at the stock timing number so you dont get $15 charged to set timing and have your timing off when they're done testing the car.

 

Cool man, thanks again everyone. I'm going to just stick with the stock timing. then I'm going to adjust my TCC time, Coolant times, Vats disable and thats it until i datalog...

 

Viprklr, you seem to know your stuff and I dont!!! I have an 89 vert that had a 305 and I replaced with a 350 bored 30 ,flat top 4 eyebrow pistons ,slight cam and 194 heads. I cant get rid of the spark knock. I unplugged the wire and set it at 6 degres ,then plugged it back in. It runs real smooth and starts good but really spark knocks when accellerating. I cant find anyone that knows these cars. What can I do, Ive read the threads but Im really not understanding the lingo. Can you offer any help.Thanks so much. dave

 

Please tell me you upgraded your injectors when you did the engine swap. That 355 is pumping a lot more air than the 305 especially if you've put on a larger cam and better flowing heads. You may be running lean.