Hey everyone I have a 292 stroker with MSD distributor.  I am running higher compression and was wondering on opinions about timing advance.  I am at 12 degrees btdc @ idle and 39 degrees 2500 rpm with vacuum advance unhooked.  With vacuum advance 49 degrees btdc.  I am getting preignition at random but I think that is because my fuel injectin system is slightly lean at times.  I was just wondering what other people have run for timing and if 39 degrees is too much.

Robi

Every engine has different requirements. You said you're running 11.5: 1 in another post, right. 39 degrees is probably a bit much for that high a compression ratio. It's easy to check, take some timing out and see what happens.


Lawrenceville, GA

If your total mechanical advance is 39 degrees that is too much. Every Y block I have dynoed makes the most power at 32-34 degrees total. 12 degrees is kinda skinny on initial advance.. What really needs to be done is to restrict the total mecahincal advance in your distributor. A setting of about 16 degrees initial and a total of 34 should run better.. Also some vacuum advance cans add a ton at cruise. On a high compression engine I would limit vacuum advance to an additional 10 degrees

Thankyou, tomorow I am going to change my weights and get my timing backed off.  Would you suggest now hooking up vacuum advance.  I believe it is only advanced at cruising speeds when venturi vacuum is highest.  Can you also lose power with too much advance?

Robi

I installed heavier springs and biggest bushing.  The only problem I am having is I have to back my timing off to get my engine to stop pinging, but then my initial timing is low.  I think I may have to order some more bushings for my distributor.  That way I can have plenty of initial timing and not too much advance.

Robi

Have any particulars on your combination?  As you mention, your combination may be marginal for pump gas.

 

Your basic ignition timing adjustments should be made with the vacuum advance unhooked.  Using a dial back timing light can also be a problem as many of these vary in the timing readings they put out.  The older MSD instruction sheets use to be specific in what timing lights were recommended for ignition timing adjustments and there were no dial back timing lights on that list.

 

When you say you have 39° timing at 2500 rpms, does this mean that all the timing is in at 2500 rpms or that’s just where you’re setting the total?  If the timing is continuing to increase after 2500 rpms, then the total timing ideally needs to be set at an rpm point just above where the mechanical advance in the distributor is pegged out.  But that brings up another point.  Previous experience has shown that having the total timing in at 2500 rpms is likely too low.  For the EMC engine, I found that a lazy curve with the total timing coming in at 3400 rpms made more power in that particular instance.

 

I had a stroker Y on the dyno yesterday that had been simply timed with the initial settings and raced that way.  It has a stock distributor with an electronic conversion.  The total timing on that engine came in at 4700 rpms and was 26°.  Made 274 HP.  Kept bumping up the timing in increments and with each increase was rewarded with a HP increase.  The same engine was making 306 HP at 38° total and this is a pump gas engine.  The only problem is increasing the timing also leans the fuel mixture and in this particular case, the engine has a 3X2 setup with the Holley 94’s.  The jetting was already on the lean side before adding additional advance to the ignition.  There’s an easy 15-20 HP left on the table in this instance by not jetting the engine up fatter.  Because a single four intake and Holley carb will be on the engine when it leaves the shop Monday, there was no time wasted in tinkering with the jetting on the 3X2 setup.

Lorena, Texas (South of Waco)

With the vacuum advance unhooked all the timing is in at 2500 rpm.  I do still have one stronger spring for my weights.  Right now I have the middle -late springs in.  I may have to install the heaviest springs.  You think I should adjust my timing when it is totally advanced.  My timing light is a digital light.  Will it be a problem if I don't have enough initial advance?

Robi

Does your timing light have a knob on its backside for timing curve adjustments?  If so, then that will be a 'dial back' light.  With the MSD spring kit, the lightest springs typically has the timing all in at 2500 rpms.   Any other spring combination of springs should have the total timing coming in at a higher rpm.  Putting the original stiff heavy silver springs back in and working backwards from there would be a good starting point.  Runing the engine at less than optimum ignition timing will not be detrimental to the the engine other than making for some additional heat that must be carried away by the cooling system.

Lorena, Texas (South of Waco)

It is digital with up and down buttons to adjust advance.  I will install both heavy springs and try it.  I will also maybe try to richen up mixture a little bit.

Robi

Your timing light sounds like a modern equivalent of the ‘dial back’ lights to which I'm referring.  I’ll suggest borrowing a conventional timing light and comparing the timing reading against yours at both idle and with the engine sped up to where the total timing is in.

Lorena, Texas (South of Waco)