Base Timing, total advance.

In the last few days I checked my timing on my Crusaders, vintage 1981 350 cid 270hp and found they were out of spec. After emailing Crusader this is the response I got,


If you set your base timing to 10^ BTDC then ?provided your advance is working properly on your distributor you should max out on the total advance and see a 26-29^ reading above 2600 RPMs, then all is working correctly.

Question, how many of you that have the Presolite distributor have the base timing set at 10 degrees and what performance have you seen? vs 8 degrees. I have read that there are some that have set their base timing at 8 due to ethanol related problems and lack of lead in the fuel and have been much happier with performance.
My Port engine was exactly 10 BTDC and 26 at 2600 RPMs. My starboard engine is sitting at 11 BTDC base and about 26 at 2600. Thoughts?

bshillam said:

I have read that there are some that have set their base timing at 8 due to ethanol related problems and lack of lead in the fuel and have been much happier with performance.

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Keep in mind that those problems are the result of falling octane due to moisture absorption and phase separation. If they started with a high octane fuel and/or only used fresh or non-ethanol blended fuel all the time, they would probably be happy with the manufacturer's prescribed 10 degree setting.

Install the vac gauge on the dash and make up a push pull cable to change the timing underway at will.

Just like was done 80 years ago .

Same problem , same cure.

The ethanol issue is a scary one although I beat the crap out of the assistance towing boat with a 454 and it seems to live reasonably happy.

A local marina sent 3 separate fuel samples out a couple years ago after so many alcohol related problems.

The labs reported never more than 5% alcohol...most of the pumps do say 10% but I'm not sure if they say up to 10% and what the real octane is most of the time...

Anyway.... as usual your real octane number is a crap shoot as I've heard that it was never strictly controlled anyway as per tours at refineries discussing how it's all shipped from ground to user tank.

psneeld said:

Anyway.... as usual your real octane number is a crap shoot as I've heard that it was never strictly controlled anyway ...

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And to top it off, it is calculated, not measured.

With single point pumps the mix is blended at the pumps, now there is no room for error with that set-up right?

I really don't like the single point pumps, in one of my bikes I run 93 octane and if the pump was used for regular the first gallon or so is regular fuel before the 93 mix gets to my tank. It makes a difference when only buying 4 gal. or so.

Ahh progress

Art,
If you've got an old fashioned distributor you have the option of putting it on a distributor machine (like a "Sun dist machine") and modify the vacuum advance or centrifugal advance (w springs(or both)) independently. So you may be able to enjoy your low speed low load running and starting performance w/o the full advance at the top end. Max power most certainly will be a little off though.

I'll check out the base timing and see how she runs up to WOT - as long as I get no pinging with fresh fuel I'll be happy. The Port side was running poorly before adjustments. I usually cruise at 5-7 knots I might plane at 12 but don't like pushing the motors - no need to. Yes they are made to run at 75-80% or 3300 RPMs but that seems like over kill for our needs. I like to relax and enjoy the ride along the way. Maybe there might be a few times we "get" to our destination but other than that I like to take it in along the way.

I usually cruise at 5-7 knots I

A quality 2 bbl carb might be a great improvement if you have an older 4bbl.