Turbo Timing for DSII

Comments? .. DS-II mods for a simple low boost carb'd turbo setup ... :

Following some forum threads , I opened up a DS-II to modify for more effective timing of the turbocharged 250 Maverick . I was going to plot/weld the advance plate to limit maximum advance. I was surprised to find a " 13 R " slot on the Centrifugal Advance plate. The 'twice at crank ' maximum mechanical advance of 13X2 = 26 Degrees BTDC (about max rec'd for 93 pump gas and @ 10PSI boost ). ... With initial set at @ 2 Degrees BTDC, manifold vac to the distributor should add Vacuum Advance at non-boost cruise and as manifold vac turns to boost with no vac' advance for a maximum mechanical 28 degrees ... sounds simple enough ... .

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haev fun

My low compression draw-thru will not start without 20 degrees of advance .

Now with 93 octane pump gas and DS-II's centrifugal 26 degrees total advance slot there is no longer any detonation or backfiring. The distrib vac' line is moved to the manifold for vac/boost with one-way valve and gives @ 15 degrees advance at @800RPM idle. THe transition to boost from Vac eliminates vacuum advance and distrib should only reach centrifugal max of 26 degrees. I get just under @ 10 PSI boost when spooled with 12-14 on the AFR, next need to get a tach and see about one-way or turbo PCV valve for blowby under boost ? . Very driveable NA below boost with torque of the Maverick 250 and it doesn't spool up much until fairly loaded, then it pulls strong until I let off throttle/boost ...

have fun

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drag-200stang":22oislhf said:

My low compression draw-thru will not start without 20 degrees of advance .

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Yep. Same here. On by blow through, I ran with the distributor locked out at 24 degrees. Started right up hit or cold and idled like a sewing machine. I probably left power on the table for sure, but I was erring in the side if caution and it ran great.