abody

Just put a had an HEI from jegs put in my 70 cutlass, it runs good, same as before, what would the timing be best set at? Feels a little less powerful, Had it put in while my trans was getting rebuilt.

shiftbyear

Your engine has it's own requirement for timing, HEI's can have excessive mechanical advance so check total at 3500-4000. I'd start of with 12 degrees initial and limit total to 36 with vacuum advance plugged. If your changed from points to HEI it may require a spark plug change or regap. Vacuum gauges are also good to have while tuning.

oldcutlass

Which HEI are you running, brand and model#?

Fun71

As said above, the mechanical advance on the electronic distributor may be less than the points distributor. If so, the initial advance may need to be increased from the points spec to achieve the same total. This will vary with different distributors, so knowing which one you have will help us give recommendations.

As for plug type and gap, no requirement to change anything. I open the gap slightly to .045” but that is not mandatory, it will work fine at .035”

abody

Here’s the one I had put in

Here’s the one I had put in from jegs

abody

Part Number: 555-40028 For the distributor

abody

The car is all stock except for 2.5 exhaust with an H pipe.

oldcutlass

On that HEI, it should have around 21* of mechanical advance. You can set your timing @16-18* and then limit your vacuum advance with a stop to 10.

Fun71

Your factory points distributor had 24* mechanical advance, so set to 10* initial per spec gave 34* total. You should be able to get the new distributor set close to that.

If your points distributor was working properly, don't expect to see any difference in operation/performance with the HEI distributor. The spark plugs will fire just the same as before, so the engine won't be able to tell any difference.

abody

Thanks, I appreciate the advice

coppercutlass

Fwiw on my 350 I run 14 initial total 36 around 2k. Of course my 350 is more of a race car I drive on the street and race as well at the track but that's what works for me. Guys always say to run a bunch of initial but I beg to differ.