I have changed the springs and weights in my HEI distributor using a Mr. Gasket set. After installing these and resetting the timing for 10 degrees initial at 700 rpm, I seem to have developed a slow/hard starting problem. For those familiar with the Mr. Gasket set, I am using the lightest (red) springs. The car runs much stronger but now the hard start is getting to me. Any ideas? What causes the hard start? The engine is a new 350/330 GM crate engine with 600 holley and headers.

Too much advance?

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Steve Strasemeier (70SS 396, Fathom Blue/White Stripes)

Off the top of my head, that would be my first thought.

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Try the medium springs. I had problems with the light springs in that it wouldn't always pull the advance mechanism back to unadvanced position. I would have timing set,shut down,start car, and timing would be way high. The medium springs (along with some weight grinding to get more mech advance) allows me to setup at 10 initial and have 36 total by 3000.

Ditto the last reply. The very lite springs could not be bringing the weights back in, or actually allowing them to move as the motor fires. I had the same problem 20 years ago when I first started playing with stuff. My recommendation is find someone with a distributor machine and have it set up witht eh proper advance for your combo. Usually all in by 3000-3200. It can't be that expensive. Or just keep playing with the springs and a timing light yourself.

Thanks for the replies. I do not understand how grinding the weights would alter mechanical advance. Doesn't this just change the speed that the mechanical advance comes in?

I have gone to the medium springs and yes it is easier to start but I feel a loss in oomph. I am going to start playing with the spring combinations and based on the answer above I will determine if I should grind. Oh, to grind or not to grind, that is the question.

Don, you're right, the grinding simply lightens the weights, hence allowing centripetal force to move them more quickly, therefore bringing in your advance quicker. I don't believe it will alter the total mechanical advance, but I donno. I've done this before with the timing light and change, retest, etc., and I still think the $20 or 30 that a shop would charge to curve it right is money well spent. But it may be more these days. Maybe it's BS but the fella who's building a brand new distributor for my L89 asked me a bunch of questions, vaccum, CR, gears, Auto/man, weight, etc., and said " we should bring it all in by 3200". What science is behind that, I donno.You can always use your timing light and the set of your pants as a guide.

In my case, I did my grinding on the stock HEI center weight. I could only get 15 degrees of mechanical advance.(with 12 initail got me only 27 total) With the distributor out, you can see the top plate has a pin/slot arrangement with lower plate. At rest, the weights wouldnt allow travel all the way to to the end of the slot-it started its travel about half way. I removed material from the center weight to allow things to retract all the way-thus allowing more total advance. Many late 70s HEIs had little mech advance. They used alot of initial advance-which was ok since compressions were low. On a high comp engine tho,too much inital makes turning over a warm engine real hard.

Did you check the total advance at 3000? I had some bad problems with after market spring kits in HEI distributors.

Don,
Both springs do not have to be the same. Try using one light spring and one stronger spring to split the difference between the two set-ups. The one strong spring may be enough to pull them back at idle.
Also you can grind the weight near the pivot end to eliminate any unneeded metal, this will make it so the mass of the weight is farther from the pivot to make it come in sooner. Between the ground weight and the stiffer springs you may be able to end up with about what you had with the light springs.
GaryR

Thanks guys. I know what I will be doing this weekend!