This is an odd one to me. This is on my dad's engine.. Was working fine. 14* base timing, 36* total w/o vac advance at 3,000 rpm.

Then it started feeling slugish, rev wasnt smooth.. Cheched timing. 14* base, 18-20* total.

My 1st thought was the weights/springs sticking, so I took cap and rotor off.

Nope they are moving free, and in good cond.

What could cause lose of mech. advance like that???
Thanks

TTT

If you changed the rotor recently it's possible the weights are hanging up on one of the "ribs" on the under-side of the rotor. Had that happen once and it drove me bonkers.

Other than that I can't think of anything that would cause a limit on the advance unless your've got the weights/centerplate flipped over backwards or something odd like that. Of course, if they've never been off the distributor they can't just flip over on their own.

Is it possible that something is preventing them from returning all the way back home to base timing? You'll set the timing to the same initial but in reality you're already half way up the centrifugal advance curve which only leaves the last half of the advance curve to advance up, acting just like a limit on the advance.

Damon.. I never thought about the rotor. I'll take a look at that.

The rest is a no go.

That's the strange part. Dist. was recurved with right springs and weights about 5 years ago. Ran everyday since then. No changes to dist.

running good, then next day it started feeling mushy, soft, lose of power.

Checked timing. Initial was same as it was set about 8 mo. ago. when we put this dist. into this diff engine. Checked advance, it advances to about 2300 rpm, for a total of 18-20*, then don't advance no more past 2300 rpm.

It was set for total to be all in at 3,000, and was advancing to 36* at 3,000 rpm, just a few mo. ago when we last checked it.

Now it don't

I'd still remove the springs and weights and clean the bump were the weights ride on and clean the bottom of the weights. Then apply a small amount of dist grease on the bottom of the weights where if rides and apply a tad to the groove where the spring is locked into place.

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Mark D
1970 Z28
http://http://ca.geocities.com/mlvd@rogers.com/ (http://ca.geocities.com/mlvd@rogers.com/)
WTB: 70 SS396 Chevelle 4-spd, flapper hood car, no rag tops, 1-2 owner car.

Then I'm with COPO on this. Clean it out good and put it back together.

Also, while you have the stuff off make sure that the advance plate can rotate smoothly and completely from end-to-end of it's travel around the distributor shaft. Sometimes they get gummed up between the two after a few years. If so, pop off the bottom gear, yank the shaft up a few inches, push the advance plate down and then clean out/lubricate where the 2 rotate against eachother.

Sorry, I thought we were talking about a new distributor in the original post.


[This message has been edited by Damon (edited May 16, 2005).]

Thanks guys! I give that a try tommorw.