The Stovebolt Site Forums The Shop Area Engine Shop Distributor hold down....

1956 Chevy 3100 235 straight six:

I bagged what I thought was the hold down for the distributor about a year ago. When setting up the distributor for correct timing today I discovered that the hold down was not correct, but the bolt, washer and lock washer that I had in the bag appear to be correct IF what holds the distributor in place is the advance/retard collar on the shaft of the distributor. I started to attach a large O-ring in the top groove of the shaft, but then decided not a good idea and stuck with just the gasket that seats nicely underneath the advance/retard collar.

So, the question is, is there actually a hold down for the distributor (and no place for it to hold down on the distributor) or am I correct in figuring the advance/retard collar serves as the hold down?

The "hold down" is the part of the vacuum advance unit with the slotted hole called the "octane selector". DO NOT install an O ring in that top groove- - - -it interferes with the free movement distributor housing by the vacuum advance. That groove is there to keep oil from migrating up the housing and it does its job by simply being there- - - - -no seal needed.
Jerry

Jerry, you are a fount of knowledge extraordinaire. Thanks, as always, for the info. Odd name for the vacuum advance, "octane selector" but thinking about it it makes sense.

Now, just got to figure out where that piece that looks like a hold down goes, lol.

Hawkman - Post a picture of it in a new thread in the Name that part... forum and folks will likely be able to help you figure it out.

Jerry was explaining the slotted hole. There is an image below...it doesn't show everything in clarity, though. You'll have two methods of adjusting timing, actually. One: your distributor will be held by a squeeze clamp which is part of the retaining piece. Unlike the distributor for say a 283 V8 there is no molded stop ring to make certain it only goes in so far. Before you adjust timing and tighten this, please pull up the distributor a wee bit (maybe 1/16") to get the tang just off of the oil pump piece. This clamp allows you to initially loosen and rotate the distributor to establish proper position relative to top dead center and flywheel, etc. And two: there is an engraved line in the center (which should reflect where proper timing for your engine is) and there are engraved lines above and below that line which correspond to advanced or retarded timing (a person could have chosen them to use with higher or lower octane gasoline). Once your timing is set properly using the squeeze clamp, you can adjust + or - your timing by loosening the hold-down bolt and rotating the distributor and that piece (which also incorporates the vacuum advance canister and linkage). Hope this helps.

Jon G - It looks like your pictures didn't attach correctly as the just come up as black screen. Can you try and remove those and reload them?

I've tried that a couple of times...also tried to attach in another post (about steering gear lube). For some reason it seems to happening this way...at least for me. I'll sign out and sign back in and see...

Dan, images attach correctly in the attachment manager but they don't make it to the forum when the post is made. Jon

Understood and thanks for the feedback Jon! I tested in the OOS Swap Meet forum and found the same issue. It's not us unfortunately.

A report has been sent to HQ as it appears to be affecting posts in all forums - Big BOOOOO!!!

Back to the distributor:

Does the Chevy engine use a spacer plate between the block and the "squeeze plate" (the book calls it Distributor Vacuum Control Arm Clamp)? My '52 GMC (uses the same distributor as the Chevy engine) has one. Maybe 1/8" thick with a hole for the distributor's shaft to pass through, another hole for the locking bolt to pass through and a tit to position it in a dimple in the engine block.

This part is not shown in any of my GMC Master Parts Books.

I'd post a picture, but pictures aren't posting right now.