Why so much initial timing? Is the distributor locked out?
Hope you can stand another "compression test results" thread
- Thread starter jcolman
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jcolman
Well-Known Member
I'm using a Hyperspark distributor so it's locked out
Ok. I gotchya. I guess with that setup, they are a little different? Normally, small blocks end up between like 34-36 total.
jcolman
Well-Known Member
Yeah I may have to advance the timing a bit. However my engine was tuned on a chassis dyno and I think the tuner but as much timing in as he felt was right.
Ok. Then it's probably optimized......I would think. Still it seems low......but I don't have a dyno either. lol
Phreakish
Well-Known Member
Sniper is running the timing? can you post a photo of your timing table or settings?
Like Rusty said, total is often 34-38 depending on heads and other parts of the combo. I run in the high 20's for idle, 34 by 3k, and 36 total.
Running an Fitech, I've found best results with the idle set lean, like 14.9-15.2 idle afr. "Power" afr (low MAP) is 12.9-13, and cruise AFR's are in the 13.5-15.5 range. With more overlap, the EFI tends to read leaner than reality due to the EGR going on at lower revs. This kept leading to sooty plugs for me until I cranked the idle AFR low and tooks a bunch of fuel out under 3k. My cam is advertised 295/305 (251/257@50) on 110 in at 106 in my 408.
If you get any backfiring on decel, you likely have an exhaust leak and that will 100% screw with your EFI tuneup.
jcolman
Well-Known Member
My idle is set to 14.7 AF/R but apparently it won't get there. For some reason I can't access what the tuner set the cruise and WOT timing and AF/R values. It's not showing up on the wizard. I don't get any decal backfiring but I use to get a backfire on acceleration which I thought was a lean backfire. So I had the tuner add a bit more fuel to the map.
See decarbonize you engine with water u tube videos
Phreakish
Well-Known Member
Idling at 11.8/12 will definitely cause issues. Sounds like that needs to be addressed. I don't have any experience with the sniper software, so can't offer much help there.
BTW, the difference in performance between my early EFI tuning attempts and when I finally got the timing dialed in were HUGE.
I never had to worry about this because even in my street days we raced every night so we kep our engine blowed out. Lol. But my uncle and old school mechanics kept n old 6.5 Oz coke bottles on their bench that they would fill with water and dump down the carb of a running engine before each tuneup. You wouldn’t believe the junk that cleaned out of those old lead loaded up engines. Carbon free in 30 seconds or less. Lol
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