FrontEngineDragsters.Org Forum
Technical => Matt Shaff's Engine Shop => Topic started by: Chuck466 on May 04, 2022, 10:12:58 AM
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So my question is what starting point with timing do you start with on a SBC blown with mechanical injection?
2nd question what's a EGT target I'm shooting for on a SBC application?
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Hey Chuck466:
I read your previous post.
Is it Alcohol fuel?
If it was on my dyno I would start conservative at 24* and slowly work up.
Matt
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Yes alcohol mechanical injection, I actually set it up at 24 but when I stalled it up on the break it wanted bang and backfire so I raised it to 28 and that stopped the back fire on the break, so 28 will be my starting point, for now.
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With 23° heads I ran between 28 and 32° depending on the track I was running watch for detonation. One thing to watch for is bolts coming loose if you see this back your timing off add fuel or both
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Timing I would start at 30* and move up 2 at time till et or mph fell off on a good run. I would read plugs for fuel and of coarse the strap for timing.
As for egt's. A llot of things change that answer. Main is how far down the tube is the sensor. Normally I shoot for 1050 as max with a sensor about 4" much more and temp will drop some. As a rule, once plugs burning all the way around and dwon to first thread I check bearings if they are good then I check my temps at that point. It is safe, but maybe not max power. You can carefully lean a little watch temp, plugs and time slip from there. Some cars like 1100 and have seen cpl that liked 1150 and like I said some of that was sensor location, some timing and some even cam made a slight difference due to overlap I am guessing.
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On my blown alky SBC, I usually run around 32°-35° but each motor is different. I don't have egt sensors so I go by engine response and plugs, old school.