After replacing the point style distributor with a HEI and resetting the timing to original timing marks, engine is not as responsive. Is this due to a difference in vacuum or centrifugal advance? Do I need to try different timing mark settings? I should have tried this before posting but would like to hear what you guys think. Thanks

 

You need to determine how much total advance that distributor has. Do you have a dial back timing light? What HEI distributor are you running? I have the Summit HEI in my 71 98 and is ok (like most of Summit's name brand stuff).

 

Your stock timing settings are NA with the HEI as stated above. You do need to see how much mech. advance is built in but in the meantime a setting of 16*BTDC would be a good starting point. Also HEI needs a full 12v to run properly, the resistance wire needs to be removed or bypassed.

 

My advice :
Put the points distributor back in it . Change the points every two years . And drive on .
You aren't going to notice any performance increase with a HEI over a well maintained points system .

 

I 100% agree with this. Back in the '80s I had a very well set up ignition system with high quality components and stiffer spring in the points distributor and the engine would easily turn 5800 RPM with that setup. Some while later I swapped in a GM HEI distributor with quality parts and didn't notice any difference in engine performance.

 

I am going to differ with the majority here. When it comes to Pertronix I will stick with points. But a real HEI I recommend. When I bought the 72 Cutlass I sold last year (had it 23 years) one of the first things I did was put a junkyard HEI in it. I never touched it again. I widened the plug gap to 35-40, fiddled with the timing until it was happy and that was it. Of course I had to change the plug wire for the HEI. The HEI probably does give a better spark but not enough to measure. IMO Pertronix - No, HEI - Yes. That is just my experience.

 

The plugs neither know nor care if the spark is triggered mechanically or electronically. People forget that HEI was developed to meet emissions requirements, not for performance. The advance curve is far more important than how the spark is triggered.

 

Thanks to all, I will try the 16 *BTDC and go from there. If that doesn't help I will go back to points.