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Was reading up on ignition timing in my authentic Pontiac shop manual. They make reference to the term, BUDC, regarding timing degrees. I know BTDC, but never saw BUDC. What does that " U " stand for? Also, I have the 12 volt inductive timing light. Can I hook the power and ground lead to a remote 12 volt battery and hook the spark signal lead as normal and have a properly functioning light to time my 6 volt straight eight? What gasselector setting do you guys find to work best with todays unleaded regular gas for the fifty 4 door chieftan with hyrdra matic? That gasselector concept doesn,t make sense to me, unless, their method of initial timing using power timing light KMO 318 involved rotating the engine by hand, not running with key on, while simultaneously moving distributor to line up the pointer with the desired mark and then fine tuning with the gasselector and test drives. The described timing technique proceeds my existance by a few years. Can any of you oldertimers enlighten me please?

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I can only answer one of your questions. The U according to my 1940 Pontiac Shop Manual means upper

Thanks Ragtop, Mystery solved BUDC = BTDC . I,m gonna try that 12 volt light trick. I,m thinkin it,ll work as long as I also ground the lights ground lead to the cars chassis ground. Old Fat n Flat,s rings must be freeing up in the grooves. She,s gettin torquey again. Cool when ya tromp on the gas and the front end picks up high on launch. Still wont break traction yet. LOL. I,ll keep at it till the silver streaks are but a blurr in the distance.

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Also, I have the 12 volt inductive timing light. Can I hook the power and ground lead to a remote 12 volt battery and hook the spark signal lead as normal and have a properly functioning light to time my 6 volt straight eight?

Fat n Flat, Have you tried to just hook it up on your 6 volt? It might work, I have a "modern" stroboscope timing light, and it works fine on 6 volt.

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Fat n Flat, Have you tried to just hook it up on your 6 volt? It might work, I have a "modern" stroboscope timing light, and it works fine on 6 volt.

Well thanks for your input C. Anderson. I haven,t tried that yet. Just kinda planning ahead in case the 6 volts dont make a bright enough light. I,ll try it .

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I have a Fox Valley 12V inductive Strobe light and use it on my 6V 53 Chieftain using a separate 12V supply for the light and it works well. When I checked the timing against the static setting it was bang on the money......

How did you go with the 6V supply for your light ? Was the strobe working / good intensity ??

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Well thanks for your input C. Anderson. I haven,t tried that yet. Just kinda planning ahead in case the 6 volts dont make a bright enough light. I,ll try it .

It worked, Thanks for the motivational shove.Soon as I read your post I went to the garage and hooked up, Timing was way off the scale advanced. Set at 6 BUTC and throttle response and power improved 100 %. However, while driving from standing stop, wide open throttle, she still has what feels like a bit of valve float. Next timing will be 3 deg. and see if that remedies it. Kinda almost like maybe the muffler might be restricting flow just enough to throw balance out of wack. It,s a pretty amazing engine to work on and get to drive. The torque it delivers seems like overkill. I,m nearing the dreaded task of val.ve adjustment Don,t have a lift, so am gonna have to jack it up ,take off the right steer, inner fender access panel and bear down

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Fat'N Flat,

if I could offer a suggestion you might like to try also as a secondary method.....

Over the years I have found that dynamic ignition timing is not always the best setting and can also be out of wack a fair amount given timing chain stretch , harmonic balancer outer pulley slippage on the inner hub, distributor wear etc

I used a vacuum gauge to set ignition timing on many older vehicles in my time and found its an accurate way to set the spark vs crank angle..... As long as you have a vacuum gauge ( good place to start :) ) and a suitable trapping point on the intake manifold to measure manifold vacuum at idle, then its straight forward.

Advance the dynamic timing to get maximum vacuum setting - usually ~ 21inches of Hg, then retard the timing to drop it back by 1 point eg 20 inches..... Button down the dizzy and see how you go..... If there is a passing intake exhaust valve inside this will play havoc with the gauge pointer but this method was used for years before timing marks were supplied on harmonic balancers, pulleys etc etc

Would be interested to hear the results.

rgds

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Yes, mine is a Sun Inductive born in 1987. Hooked it up as if the car was a 12 volt and pulled the trigger. To my surprise the light performed as if it was hooked to 12 volts. A pleasant surprise to say the least. Too bad Pontiac didn,t put more degree graduations on the balancer. Instead they put a fine tune "gasselector" in place that in my way of thinking left too much room for error and left the customer at the mercy of the mechanics ability to tune by the seat of his pants. Thanks!

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Very interesting. So what your telling me is , as long as my engine has no internal or external vacuum leaks, idles with high and steady vacuum showing on my gauge, that optimum ignition timing can be achieved solely with the gauge. Wow, now that you,ve explained why and how the timing light method could leave us with an ignition timing error, it makes perfect sense. And, it,s worth it to me to drill and tap a vacuum access port in the intake manifold. I,ve used the gauge to adjust carbs. but adjusting the timing with the guage never crossed my mind. After all, the measure of vacuum an engine can achieve is the measure of the condition of the engine. It makes perfect sense. Thank You Sir.

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The formula that you can use to calculate the distance on the crank pulley per 5 or 10 degrees rotation.

Its pulley diameter multiplied by 3.1417 divided by 36 or 72 for 10 or 5 degree increments.

Once you have the peripheral distance calculated you can mark it on the pulley O.D if you wish, I used that many times for phasing in cams etc etc

:)

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For memory, its possible to utilize the vacuum line up to the wiper motor to measure intake manifold vacuum, just put temporary tee into the line at the flexible line end at the wiper motor and tie in the Hg gauge there. No need to drill and tap really and fill the manifold with Swarf....

post-97131-143142627949_thumb.jpgor just tie in to the tapping / point line that goes to the vacuum pump / fuel pump combination, whatever suits ....:)

post-97131-143142627916_thumb.jpg

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Thanks for pointing that out to me. I too realized that using the wiper vac, supply tube would be best. My brain musta slipped outa gear, hafta check my synchros.

Thanks to all who have replied to my post with your words of wisdom. My engine now responds crisply to the accelerator and sounds strong and surprisingly smooth. Poor old Fat n Flat prolly hasn,t sounded this good for a very long time. Now to tweak some driveline issues and pack the trunk with essentials like tools and parts, pray to God to keep us safe and hit the road.

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Good result and enjoy the road trip :)

Thanks for pointing that out to me. I too realized that using the wiper vac, supply tube would be best. My brain musta slipped outa gear, hafta check my synchros.

Thanks to all who have replied to my post with your words of wisdom. My engine now responds crisply to the accelerator and sounds strong and surprisingly smooth. Poor old Fat n Flat prolly hasn,t sounded this good for a very long time. Now to tweak some driveline issues and pack the trunk with essentials like tools and parts, pray to God to keep us safe and hit the road.

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