The Stovebolt Site Forums The Shop Area Engine Shop SBC timing trouble MSD ignition

I'm gona try to explain this the best I can without missing anything. The problem I'm having is when I try to set the timing with a timing light it is way advanced. When I adjust dist. to where the timing should be it quits before I get close. I tore back into it thinking I lined something up wrong. I have a 350 in my 1970 chevy CST/10 I'm running a comp cams magnum cam 270 deg., double roller timing chain, MSD pro-billet dist., blaster 2 coil, and 6AL muti-spark discharge brain box. On the timing chain set there is 3 notches on the crank gear, they are marked off to the left a little with a circle, triangle, and rectangle. I have it on the notch with circle (which I believe is for factory timing). The dots on the cam and crank sprockets are lined up both at 12 o'clock spot with the dist. pointed at no. 1, also no. 1 at TDC compression. I put the timing pointer and harmonic balancer in place and the the mark on the balancer is at about 2 deg. advanced. So what I'm thinking is I have it all put together correctly and the multispark box is messing with my timing light. I'm using a craftsman inductive timing light.

Hy OldIronChevy, when timing the crank and cam gear the mark on the crank should be at twelve o'clock and the mark on the cam gear should be at six o'clock. If I'm remembering correctly the engine is not at T.D.C. #1 compression when the cam and crank gear are in alignment, hope that helps.

Both marks on the gears at 12 o'clock is #1 firing position. Crank gear mark at 12 O'clock and the cam gear mark at 6 O'clock is the #6 firing position. Do you have the vacuum line to the distributor disconnected and plugged? Do you have the timing light hooked to the wrong wire buy mistake? Is the timing light a dial back model? Try a timing light with out the dial back feature.

no vacuum line on dist, timming light hooked to number one, and timing light is not a dial back.

MSD=Multi Spark Discharge. m The scope patterns I've seen from engines running that system show 5 different firing lines for each spark plug in rapid succession instead of the one spike a normal ignition system presents. It's some sort of capacitive-discharge setup that rapidly discharges a capacitor across the coil primary winding repeatedly, causing the plug to fire several times.

It might be necessary to install a conventional ignition trigger to set the timing, then connect the MSD box once the initial timing is set. Personally, I wouldn't waste my time doing that unless I was running a race engine that might need a very hot spark. MSD is utterly useless for street driving.
Jerry

One approach might be to run the engine up to normal operating temp and then advance the timing till it "grunts" back at the starter when starting. Retard till this just quits. Drive and accelerate hard in high gear. If pinging happens retard a fraction more. Check with timing light to see where mark is at as the timing will now be very close to where it should be. You may have a Fluid Dampener or other after market unit but if a factory type this will show if the outer ring has moved on the rubber and thrown off the timing mark.

I've re-read this again. 3B has already written that the crank should be TDC #1 cylinder. The dot is at 12 oclock. The cam is at 6 oclock. It reads to be that you have the camshaft 180* out.Or the distributor is out.

It's possible you've got a mismatch between the timing mark on the harmonic balancer and the one on the timing cover. Early small block timing marks were about the 2:00 position on the timing cover, while newer ones moved to around 12:00 with a corresponding re-position of the line on the balancer. If you've got an early (or aftermarket) timing cover combined with the late-model balancer, the marks will be WAY off. Ditto for a new timing cover and an old balancer, which would result in the badly-retarded timing you're describing.
Jerry