hi all, I have a 350 in a 1950 Cadillac . its a 1978 eng mostly stock. here is what I've done to it. mild cam, performer non egr intake, street demon carb, moroso spring and weight kit for hei distributor . I have the total timing at 42 degrees @3500rpm and that left the initial timing at 20 degrees @700rpm. I have blocked the vacuum adv @10 degrees. I don't want to run too much advance but I can't find any real specs for this. the car weighs 3800lbs has a th400 tranny. it seems to run well as set but my hearing is to far gone to hear detonation. any help will be appreciated. thanks pat.

 

Have a friend who's a car guy who knows what he's doing ride with you. For a low compression engine you might not be too far off.

 

Too much base too much total IMO.
How's the idle? Smooth at 20°?
Is it an out-of-the-box non-smog era HEI? If it's the 78 distributor the stops aren't right even though you played with the springs and weights.

A general-purpose spring and weight kit isn't the magic universal trick. The centrifugal timing rate needs to be dialed in. Trial & error can get it close with patience and a set back timing light and tachometer. Its winter you may want to consider sending the distributor to a shop, You can mix different tension springs. The weights and stops need to be considered too. A good curve will produce a smooth steady timing increase to the total. You can feel it when its right.

Here is what I recommend...as much timing as the engine will handle without preignition.

Check the ignition system and fuel filter before you start tuning.

Try 12° base timing at 700 rpms
Add 10-12° with the vacuum advance at 700rpms. Use an adjustable travel, not rate vac canister.
Have the centrifugal start advancing around 1200 to a total of 36-38° all in under 3000rpms. The trick is the off idle to full advance needs to happen smoothly to get a nice curve,

Don't forget to tune with a vacuum gauge. Always use an intake port, not the carb ports.

Do the air/fuel tune at the same time you do the timing, working back n forth between the two until you achieve the highest vacuum signal at idle.
Road test and repeat avoiding spark knock under load, hot engine.

Once you get that tune dialed in consider adjusting the trans shift points and adding a shift improver kit with fresh fluid. Install a TM50 adjustable vacuum modulator, Make sure you have a good vacuum source for it directly off the intake. Trans fluid always needs to be fresh...same for the filter.

Close the loop here and let us know where the final tune went from my suggestions.

 

Your initial and total settings should run fine. Run your RPMs up in park with your vacuum advance connected to around 4-4500 rpm and listen for a miss. If you get missing limit your vac adv own until it disappears.

 

Yeah on a low compression, iron head Olds 350, leave it where it is. If you are worried, dial it back to 2 to 4 degrees, no more. Interesting swap.

 

FWIW, I set my stock 71 Cutlass at 12 BTDC and ran like crap. After lots of fiddling around I set at 20 and has run good for 4 yrs or so. I did have too much total timing but I corrected that later. If you have too much total timing engine rocks around so bad you can feel it. I felt it at about 1800 in 2nd gear, whole car sort of rocks. Well anyway, in my un scientific opinion, throw out the specs and set it where it runs best, starts good, etc. Todays gas is way different than even 1978 unleaded. Let us know how it goes, and welcome, bring on the pics!!!

 

hi again , thanks to all of you for your answers. I have tried settings from 14 degrees to 22 degrees initial and anything below 18 I have a bog when jumping on it. will play with it a little more, mostly I was worried about detonation I couldn't hear. thanks again, pat.

 

Yes could run less initial and mechanical but replace it with vacuum advance. The factory vacuum advance were like 30 degrees. Try running of manifold vacuum if you aren't already. Is the Street Demon tuned or just bolted on? Even the 204/214 cam will aggravate the idle a bit.