Any ideas why this happens with my distributor?

[67charger440]

My car misses and backfires when I tighten down the distributor adjustment bolt. When I loosen the bolt the engine runs perfect. It’s a 440 big block with stock ignition system. The distributor clamp seems to pull the distributor instead of evenly press down. What would cause this?

 

[Fran Blacker]

How are the distributor shaft bushings?

 

[Builderguy]

Yup yup, I agree with the above as the first thing to check. Second would be to check the end play.

 

[67charger440]

How are the distributor shaft bushings?

How do I check those?

 

[Builderguy]

From 2019 post by DaveLux over on "C" bodies
↑
I have a 67 newport with a 383. originally 2bbl converted to 4bbl. Im having issues with the distributor and might need a new one. Id like to stick with a points distributor, but will consider electronic. any recommendations? part numbers?

I think it may be worn..if I even think about loosening the bolt it runs funny. If I push on the cap at all it changes how it runs...I know the points are paper thin and im looking for new ones.
Can they be rebuilt or is it best to just replace it?

"It sounds like your distributor may have excessive end play, that would be the shaft having too much up and down motion. The fact that the car runs differently when pressing on the cap or loosening the retaining bolt points to this. Just for the heck of it, install new points and condenser, bend the rotor tab upward, check the cap to be sure the mounting clips are holding it tightly to the distributor and see if the car runs correctly. If you have excessive end play, the distributor shaft will probably re-bend the rotor tab fairly quickly to where the engine no longer runs properly. If you remove the distributor from the engine it should not have more that .002 free play, either up and down or side to side, use that as a guide. When removing the distributor, have the timing mark at TDC and note the positioning of the rotor before removal, this will simplify the re-installation. You can either have your existing unit rebuilt or buy yourself a reman or NOS unit. Philbin Electric does a really good job of correctly rebuilding the units. I do this because a lot of the new distributors are now made in China and most of them are crap. Same is true with many of the commercial rebuilds available at auto zone, car quest etc. Most are Cardone Remans and are also crap. www.philbingroup.com does quality rebuilds of you existing unit to OEM standards."

Dave

I probably have the exact instructions in the service manual, but I am at work right now. If no responds with the procedure I will send it to you.

 

[Fran Blacker]

Remove rotor and push front to back. If you see say.007" movement needs to be checked more closely. Watch the points, if you have them open you'll see whats going on better. Yes check end play another good point.

 

[Outsider]

Sounds like the dist shaft is too long and binding. I've had few that needed shims at the seat or some grinding at the drive tip. If the intake is off its pretty easy to check on a big block.

 

[Lefty71]

Sounds like the dist shaft is too long and binding.

I agree.....but I'd do little research, depending on the status (old, newly rebuilt, etc) of this engine, and make dang sure there isn't crud in the oil pump drive slot for the distributor, or maybe a freshly install bushing for same that is bad sizing or maybe didn't get fully driven in correctly.

HTH, Lefty71

 

[67charger440]

Yup yup, I agree with the above as the first thing to check. Second would be to check the end play.

On the distributor shaft or the gear in the block?

 

[Lefty71]

On the distributor shaft or the gear in the block?

He means on the distributor shaft..... but has the block bushing been replaced recently??

 

[67charger440]

He means on the distributor shaft..... but has the block bushing been replaced recently??

As far as I’m concerned it hasn’t been replaced. I recently bought the vehicle, engine came out of a motor home. How can I test the gear In the block?

 

[Tony Tee]

I've had this problem on two 440 engine blocks that had the hole for the distributor machined from the factory off center. So when the distributor is tightend down. You can see that the distributer was leaning slightly and when totally tightened down. It would put a side load on the distributor shaft and wear out the bushings in the distributor. So the distributor base was turned down on a lathe which eliminated the "0" ring. So a paper gasket was used to seal it. Worked great! But it also could be other problems. More investigation is needed.

 

[HALIFAXHOPS]

All good things to check also see if the o ring is holding it up (to large) and if it is it makes sense pushing it side to side changes the ground path which points should have through the base.

 

[67charger440]

All good things to check also see if the o ring is holding it up (to large) and if it is it makes sense pushing it side to side changes the ground path which points should have through the base.

Do you rebuild distributors?

 

[67charger440]

I've had this problem on two 440 engine blocks that had the hole for the distributor machined from the factory off center. So when the distributor is tightend down. You can see that the distributer was leaning slightly and when totally tightened down. It would put a side load on the distributor shaft and wear out the bushings in the distributor. So the distributor base was turned down on a lathe which eliminated the "0" ring. So a paper gasket was used to seal it. Worked great! But it also could be other problems. More investigation is needed.

This is interesting. I have no place to put a O ring on the distributor of my vehicle.

 

[HALIFAXHOPS]

Yes I do had a add up for a long time.
FOR SALE - rebuilt mopar only distributors. | For B Bodies Only Classic Mopar Forum

Since I was a teen.

 

[HALIFAXHOPS]

This is interesting. I have no place to put a O ring on the distributor of my vehicle.

If points it uses a metal gasket to ensure the ground or the spark "wanders" usually

 

[67charger440]

Yes I do had a add up for a long time.
FOR SALE - rebuilt mopar only distributors. | For B Bodies Only Classic Mopar Forum

Since I was a teen.

Should I send you my distributor for rebuild or buy one from you? What do you suggest?

 

[Outsider]

Check your clearance and make sure sure you've got a little vert dist shaft free play when tightened, and then have him rebuild your dist if it is old and worn. He is a good guy, and will treat you well. But if you have a block/dist clearance issue you must address that.

 

[gary h]

If points it uses a metal gasket to ensure the ground or the spark "wanders" usually

I have a couple rebuilt "points' Distrbs" with the O ring. I also see Cardboard gaskets too. Are metal gaskets even available anymore ?