Ignition timing cali. emissions woes


I recently bought a short block,had my heads re done, and put the whole thing in my astro van. The base timing should be set at zero degrees to pass the california emissions test. It wants to run at twenty or thirty degrees btdc! I double checked the timing marks on the chain gears, with the timing mark on the harmonic balancer at 0 degrees. All was right. Two mechanics told me thet didn’t know what to think. I am now checking various sensors and everything I can think of. Any advice? Did I get the wrong short block even thoug everything matched up perfectly. If I cant fix this I can’t drive it in california. Should I just move(I really want to anyway.? Should I rent it out as a septic tank or a chicken coop? Please help me.


Are you setting the timing with the test connector grounded?
What year van/engine is it?


what is it Yr Make Model eng size ?


My van is a 1994 chevy astro. 4.3 v-6 I set the base timing like my book says i.e. disconnect the ignition advance system by disconnecting the wire near the distributor etc. Two pretty good mechanics as well as myself all end up with the same basic result. base timing way advanced= Likely mechanical problem= check valve timing etc, which checks out ok. Thanx for your response and I hope you stick with me on this,I am REALLY frustrated cause I usually figure this stuff out. Any other ideas?


what do you mean test connector. The timing bypass wire?


First thing to do is check to see if the TDC mark is really TDC. Remove all the spark plugs. Then when you think #1 is TDC, stick a pencil in the spark plug hole and rotate the crankshaft using a wrench on the front crank bolt. When you think that the pencil is at its highest point, check the other two cylinders on that bank. The pencil should go in each of those to the same depth. If they don’t, rotate the crank until they do, then #1 will be TDC. See if that corresponds with the indicator on the harmonic balance. If it doesn’t, then you have the wrong harmonic balancer on it, but you can just make a new mark on it and use it to set your timing.


If you can’t adjust it enough by repositioning the distributor, you have to take it out and reposition the rotor shaft. I hope I understand the problem.


If you are using an old harmonic balancer, the inner and outer parts might have “slipped” (the balancer has delaminated and failed.) This allows the timing marks to move out of the correct position. Keith explained how to locate actual TDC. After the engine is positioned at TDC using the pencil method, check and see if the TDC mark on the balancer lines up with the pointer. If not, the balancer has failed and the marks have moved…


I actually took off the timing chain cover, aligned the two marks to indicate tdc. Wouldnt this indicate tdc? With those marks aligned,the timing mark on the balancer was at zero degrees. This would seem to negate the need for the pencil test wouldnt it?