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Old 07-14-2011, 06:59 PM
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should I lock out timing ? BBC 454

I got a 66 elky with 454 .30 , stealth intake, 206 closed chamber heads with .020 gaskets, dished pistons, th 350 trans go kit, 2800 stall , 456 posi rear, MSD 6al box and pro billet distributor with vacum advance,cam is a comp cam 294s solid lift . I ask about locking out timing because at idle vacum is at 7 hg vacum ? i just got a bushing and spring kit so I can recurve distributor as need be please help

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Last edited by truckboy61; 07-14-2011 at 07:01 PM. Reason: left out cam info
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Old 07-14-2011, 07:26 PM
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Yes try it with the mechanical advanced locked out.
Set the fixed timing at 38deg BTDC.

Then connect the vacuum advance to ported vacuum.
Check that vacuum advance does not add more than 15deg additional timing at high vacuum.

Make sure you have the factory rear starter support bracket brace installed on your starter motor. It must be there on all GM starters.
If yours is missing get one.

You'll find it idles and runs much better with the increased idle timing.

With that cam, locked out timing works and modified timing curve also works

24 at idle ,,, 38 at max advance. (shorten the mechanical curve to 14deg)

The bushings in the kit are not the right one. They do not make the curve short enough to allow 24deg base at idle and 38deg at max advance.
You can make a thicker oblong bushing or weld up the end of the slot or stick a machine screw in the advance plate under the rotor to limit advance travel.


Try the locked timing first.
You want an additional 10-12deg of vacuum advance comming in at part throttle cruise. the rate has to be found by trial and error drive testing.

You could use a looser 10" converter.

If hard hot starting is an issue install a dash mounted SPST ignition power interupt toggle switch on the small red switching control wire on the MSD box. NOT the big power wire.

Last edited by F-BIRD'88; 07-14-2011 at 07:33 PM.
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Old 07-14-2011, 07:31 PM
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thanks i have a after market smaller high torque starter I was thinking about adding a kill switch from my msd box ? since Im using the magnetic pick up is it the red or white that would get switch

Last edited by truckboy61; 07-14-2011 at 07:33 PM. Reason: added
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Old 07-14-2011, 07:38 PM
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Use the small red wire that normally goes to the key.
To control the box on and off.

By rights those small aftermarket starters should have a rear brace also.

The two bolts alone are not enough. If you can fab up a brace for the end of the starter, do it. ( maybe using a old factory GM starter end brace with modification) There is a tapped threaded hole above the starter on the engine block for this purpose.
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Old 07-14-2011, 07:41 PM
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There is a MSD add on "starter saver" auto start retard box you can add also.
Its knocks the timing back 15 or so deg when cranking to start.
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