locking distributor down

[shiloh87]

Hello all, I`m having issues keeping the timing set, no matter how tight(20 ft/lbs) I crank down on the distributor clamp bolt, it moves.
Didn`t have this issue last season, just seems to be this yr.
The engine is a reconditioned 1985 470, 20 hrs on it so far. When it`s set correct the boat runs like a trooper.
Any suggestions, getting tired of spoiled outings.
Cheers, Rick

 

[itsathepete]

Has the distributor clamp been removed for any reason? They have a bend in them and won't work if upside down. Also make sure it is slid over the distributor base fully

 

[shiloh87]

No bend in this clamp, its a thick chunk of shaped steel or aluminum and really will go on one way with the milled recess that engages the distributor lip.
Maybe it needs a lock washer, can`t find a diagram to confirm or deny this.

 

[itsathepete]

No bend in this clamp, its a thick chunk of shaped steel or aluminum and really will go on one way with the milled recess that engages the distributor lip.
Maybe it needs a lock washer, can`t find a diagram to confirm or deny this.

Is the bolt loosening or just not provided adequate clamping force? Is the gasket under the distributor missing or damaged?

 

[Scott Danforth]

Check to see if your dizzy bushings are going bad. That would be the only way the torque on the shaft would transfer any torque to the housing

 

[dubs283]

No bend in this clamp, its a thick chunk of shaped steel or aluminum and really will go on one way with the milled recess that engages the distributor lip.

The milled recess on the clamp you refer to is a 90 degree shouldered inside edge that fits on the distributor flange to keep it in place.

Remove the clamp and inspect the shouldered area, it should have a sharp 90 degree inside edge without any burrs or deformities. If not square you may be able to file it back to 90 degrees.

There is no lock washer required on the bolt to hold it in place

 

[stang32]

mark the dizzy and the clamp area, see if it physically moves. if not , the issue may be in the gears (teeth) if the dizzy is moving ,then change out the clamp. if the dizzy is not physically moving but the timing is off, then look at the gears.

 

[achris]

So this is what it looks like...


If there's any wear on either the lip of the clamp or the shoulder of the distributor, then it may not be providing enough clamping force.

If that's the problem, I would 'machine' it to decrease the thickness and allow the bolt to pull it down a bit further (only about 0.5mm would need to come off). But you need to confirm WHY the dissy isn't staying put!

Chris.....

 

[shiloh87]

Yes, the pictured clamp is indeed the one on my distributor, and the gasket was replaced with the rebuild.
All good advise gents, thanx, I will investigate all your suggestions and report back......
Again thanx
Rick

 

[tank1949]

No bend in this clamp, its a thick chunk of shaped steel or aluminum and really will go on one way with the milled recess that engages the distributor lip.
Maybe it needs a lock washer, can`t find a diagram to confirm or deny this.

Bolt may have been replaced and too long and is bottomed out.

 

[shiloh87]

Took the assembly out this morning, inspected it, its all good, gasket was good.
Cleaned everything, no oil residue, installed another new gasket, reinstalled, set timing, and locked it down to 20ft/lbs, maybe a little more, then went to the bay for a shake down, ran great, but I`ll definitely be keeping an eye on it now that I know the symtons. And all this and, in the water before 9am this morning, thank god for Saturdays....