Advancing Ignition??
10-27-2002, 10:12 AM
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Advancing Ignition??
1990 4.3l 190 hp, 2 bbl carb, under water exhaust....
How hard is it to advance ignition? Right now it is 8deg Before TDC, what about 10 or 12 deg? Would i gain any mph??
Thanks
Tommy
How hard is it to advance ignition? Right now it is 8deg Before TDC, what about 10 or 12 deg? Would i gain any mph??
Thanks
Tommy
10-27-2002, 02:26 PM
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Usually advancing the timing will hurt top end. It will help the bottom end though.
I wouldn't do it unless you know what you're doing. To much advance and you'll have detonation. Detonation can, and will, destroy an engine in short time.
The problem you run into when you start pushing the advance is that with all the noise a boat makes, exhaust, wind, people screaming, etc, you usually don't hear the detonation. But it is there and it is doing it's damage.
My $.02
I wouldn't do it unless you know what you're doing. To much advance and you'll have detonation. Detonation can, and will, destroy an engine in short time.
The problem you run into when you start pushing the advance is that with all the noise a boat makes, exhaust, wind, people screaming, etc, you usually don't hear the detonation. But it is there and it is doing it's damage.
My $.02
10-27-2002, 03:06 PM
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DOC. I agree with GEARHEAD however,if you use 93 octane and you see a speed increase you can most likely advance your timing to 10 degrees initial advance. I also would use a 140 degree thermostat. If you dont see a speed increase,put the timing back to stock! ....Might be easier to get a CHECKMATE?
10-27-2002, 04:21 PM
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HyperBaja, Bajas are very capable if you are willing to do some experimentation. My 1990 21 footer runs near 100 MPH with a less than 500" big block naturally aspirated. Rock solid and mid to high 90's all day long. I needed a short shaft drive and hydraulic steering to make it driveable. Your boat could probably use a different prop to start off. I would recommend trying a 3 blade Hydromotive, Mirage, Cleaver, Turbo, or something along those lines. Turnng up the timing a few degrees more than stock is OK, but you need to keep that in mind when holding the throttle WOT, and don't cheat more than 2 or 3 degrees and run 92 or 93 octane. A Stern Jack may be a good performance adder for your type of boat and at speeds in the mid to high 50's external steering wouldn't be required. Good luck and don't let those Checkmate guys give you a hard time. There are some guys with some very respectable Bajas on this board. Brad Perry's Hammer runs beyond 100 MPH with a blown 540. 
10-27-2002, 04:23 PM
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Have a 3blade stainless 16x19 turbo, looking at labbing and blueprinting it. Stern Jack? wont add many mph will it? and wont it REALLY stress the transom?
10-27-2002, 04:55 PM
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At your speeds a Stern Jack will not over stress your transom. Land and Sea claims a 9 MPH increase on a 20' Baja with a 205HP 4.3 LX. (45 MPH to 54 MPH). $1995.00 and if it don't work they will give you your money back. You need to try it within 30 days though. Also you need to try a lot of props. As many as you can get a hold of. Good luck!!!
