When's the last time you worked on ANY engine that required 20* of base timing to run. ;)Originally Posted by EagleMark
Even when I've worked on carbed engines, the most base timing I would use was around 12*, but would run fine all the way down to 4*, 0* on some.
The man who says something is impossible, is usually interrupted by the man doing it.
Some HEI without vacuum only add 12 degrees through centrifugal advance and depending on weights none at idle. So 20+ is not uncommon on carb with a big cam engine.
TBI base I always use 0 because it effects injector timing, but in the cal usually 23 for a good idle... it has to drop off idle...
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
I've worked with a lot of HEI and have NEVER needed more than 10* base.
What vehicles only add 12* of total timing?
The man who says something is impossible, is usually interrupted by the man doing it.
Aftermarket without vacuum...
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
Thanks for all the replies.
It is quite common to run more timing on a carbed SBC. Granted 20* initial is about maxed. I am honestly surprised that I don't get detination with no EGR. The engine is a low compression L08. The book says 8*, but the cam I installed said to add 4* which makes 12. When I ran 12 the engine did run, but ran very rich, and yes it would still run down to 0* and below, but very badly. At 12* I could not lean it out enough to run well. The plugs were covered in unburnt fuel. Thinking that my balancer had slipped I degreed the crank and verified that my marks are 100% on the money.
I added a spring kit and vacum kit to the dizzy. Experimentation led me to use 20* base. I could give it even more initial using the high vacuum method, but that gave too much at the top end. I am running about 52* total timing and the engine loves it. Like the old saying goes, give the engine what it wants, not what you think it needs.
Computer: 7747 with AFBZ 3557 prom
Injectors: GM5235206 RPD - 55 lbs/hr 350 injectors, yes?
I agree, 350 PROM and 350 Injectors. Send me a private message if you would like a quote for a custom chip.
dave w
You sure? Are you super rich? Something is wrong? 50* is nitro top fuel timing and their spark plugs melt before the end of 1/4 mile but magneto will spark to anything at that point...
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
I have no rich running trouble now. That's for sure. I even added around 2 turns out on the mixture screws. Note that my fuel economy is about the same. So I gained very noticable power for no loss in economy.
I did all the tuning after weeks of research and discussions on other forums, lots of trial and error, lots of testing and hard pulls, etc.
I am going to say his dampner has either slipped or he has the wrong one for his timing cover.
I always used 6-14* on my setups, especially with a CAM. Makes it easier to start and also brings the fuel delivery in earlier to match the longer duration cams. It also makes the engine run better if the EST should ever go into limp home mode, disabling the ECM controlled advance.
It personally makes sense to me being a carb guy. Yes, I'm old ;)
I have proven that my engine likes the spark advance to by high.
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