points gap keeps closing

[rob63mess]

Has anyone ever had a problem with their points gap repeatedly closing. After every hundred or so miles on the roadster, I have to regap the points. The car starts to run poorly and sure enough, upon investigation the points are all but closed....no where near .020. I crank the set screw as tight as I can get it but still having problems. Any thoughts? I did replace the points block.....to no avail.

[johnbuckley]

A new cam might help - maybe the surface is rough and wearing the points block. (a small amount of lubricant on the cam might help if you don't want to buy a new cam!)

[Rex_A_Lott]

The rubbing block for the points cam wears. Usually pretty fast on a new set of points, after a time or two of resetting it stops wearing so fast. Good Luck

[rob63mess]

thanks guys

[J Franklin]

Check to see if the locking mechanism on the movable point works. Make sure the cam lobes are smoothly polished, and add a bit of cam lube on the rubbing surface. You should now have located and solved your problem.

[Brentwood Bob]

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Try an old points stationary block.

[BILL WILLIAMSON]

Rob,
Check for a WOBBLY point arm pivot post. It can cause the rubbing block NOT to fit squarely to the cam lobe & it will wear QUICKLY! It can be tightened under the upper plate, with a TAP-TAP-TAP, from a blunt center punch & don't use a BIG HAMMER !
Bill Tap

[Dave in MD]

Two other things you may want to check. Make sure the center hole in the upper plate is tight onto the distributor housing and also make sure the two bushings or shaft are not worn.
Dave

[marc hildebrant]

I use dielectric grease to lubricate the cam. Did you put some lube on the cam ?

Marc

[rob63mess]

Thanks for help. I ordered a new cam and some lube. Everything else checked out OK. Will keep everyone posted. The cam was probably original and I'm embarrassed to say that I never lubed it up.

[Mitch//pa]

Originally Posted by rob63mess

Thanks for help. I ordered a new cam and some lube. Everything else checked out OK. Will keep everyone posted. The cam was probably original and I'm embarrassed to say that I never lubed it up.

There you go.... The replacement cams I believe are B cams from most suppliers which will perform better..
Lube is your friend...but don't overlube it,, just a thin film on the cam... To much can get on the points contacts and create a problem like loss of spark

[chap52]

Lube the cam and a drop of non hardening loc-tite on the adjusting screw can't hurt.

[4port]

I just happened to read this interesting info yesterday on point alignment. I have also put a thin layer of epoxy on the rubbing block wear surface for better wear resistance for a pitted cam.

[tbirdtbird]

I find the best lube to be silicone grease used sparingly

[BILL WILLIAMSON]

To identify a "B" or an "A" cam: Look at the sides of the cam, a "B" cam has 4 distinct vertical "lines"---An "A" has 8 vertical sort of "lines". The "B" cam gives you INCREASED dwell angle, for a HOTTER spark.
Bill Dwell

[Tom Wesenberg]

Not such a big deal, but since the pivot point is also a moving part I put one drop of motor oil on it.

[Gerald1961]

I had almost the same problem and found that the point adjusting screw fixation (2nd screw going into the point mounting block did not really fix on my mepro parts. I slightly deformed the threads to increase friction. Works fine and no readjustment required.
Gerald

[RonC]

This is a NOS Model B distributor cam. Notice the surface has been polished after machining.

[Rex_A_Lott]

Originally Posted by 4port

I just happened to read this interesting info yesterday on point alignment. I have also put a thin layer of epoxy on the rubbing block wear surface for better wear resistance for a pitted cam.

Carbon Paper? I cant even remember the last time I saw carbon paper.

[james hitchcock]

I found the same thing happening on Ol Walter. Points were constantly closing. I found the little block that the point locking screw went through had a small crack. Each time I set the points and tightened the screw down it caused that crack to open up a bit more causing gap to drift closed. Took me forever to see the small crack. Gave me the excuse to replace with new modern upper plate.