Difficulty seating the distributor

[drdano]

I was doing some checking yesterday with the distributor and with the intake manifold off the motor, it's proving very difficult to get the dizzy to seat all the way down.  Seems there maybe is an issue with the oil pump drive shaft, which is a brand new ARP unit.  I can get it to lightly "clunk" into place, but it takes at least a few minutes of pulling up out of the bore, then back down through the cam teeth and then it stops.  Wash, rinse, repeat over and over and with no real reason it will suddenly clunk into place engaging the drive shaft.  Is this maybe common with new pump drive shafts that they need to wear a little before you'll get them to slide into place easily?  I installed the retaining clip in the same location as it was on the old driveshaft prior to installing the oil pump, so I know that should be ballpark close.  Any thoughts?  Normal or is this a sign of something major being wrong?

[jayb]

After you get the distributor part way installed are you turning the crank a little to move the distributor gear?  Normally you have to do that in order to get the distributor to seat all the way, because the hex on the oil pump driveshaft has to line up with the hex hole in the distributor shaft.   It kind of sounds like you are really close, and repeated installations will move the components enough so that they line up and the distributor goes in the rest of the way. 

In any case, it doesn't sound like a major problem to me...

[drdano]

I didn't think of turning the crank slightly, that makes sense.  My worn out z-code 390 was super simple, just drop it and it would all clank into place.  I'll give that a shot.  Thanks!

[Kerry j]

Make sure you install the distributor before you bolt the intake down, the intake can move enough to make it impossible to fit the dizzy if it's off a bit. I usually set the intake on and install the bolts loosely, then install the distributor and make sure it's all lined up just right before I torque the intake bolts.

[drdano]

That is always good advice Kerry.  This exact proceedure is what lead me to finding the distributor hole offset from the factory by .125".  It would still slide into place, but the metal edge of the dizzy housing was pretty much in contact with the edge of the manifold hole.  Needless to say, it drooled oil a lot in past lives, and I don't want my "grandma gawld" paint all stained with this new motor.   

Right now I have the manifold hole cut oversized but am having trouble finding a local machinist who can make me a bushing for the hole that has an offset center.  The 4-5 shops I visited this morning had no problem making a bushing if the I.D. and O.D. shared the same common center point, but having the inner hole need to be .060" offset appears to be a bit of a special machining job.     Hell, maybe someone here has the capability and could do it and ship it to me?

[rcodecj]

Sometimes I turn the oil pump drive a bit, sometimes I turn the motor, either way works to get the shaft lined up.
Sometimes I get lucky and it all lines up! 

[jayb]

Right now I have the manifold hole cut oversized but am having trouble finding a local machinist who can make me a bushing for the hole that has an offset center.  The 4-5 shops I visited this morning had no problem making a bushing if the I.D. and O.D. shared the same common center point, but having the inner hole need to be .060" offset appears to be a bit of a special machining job.     Hell, maybe someone here has the capability and could do it and ship it to me?

I might be able to make that for you, but it will depend on the dimensions.   What are the dimensions of the part that you need?

[cammerfe]

That offer, right there, is an excellent example of why I think you are the epitome of 'class'. Good on you, Jay!

KS

[jayb]

Well, its probably only a 20 minute job on my CNC machine, if I can fixture the piece without too much trouble.  I've been in that boat myself, long before I had any of this machining equipment, and was always frustrated trying to get anyone to pay attention to these little jobs.  So I can empathize...

[ScotiaFE]

Sounds like an easy job for the 4 Jaw.
I'm surprised none of the 4-5 shops could not see this.
Has manual machining dipped that far?

[drdano]

Thanks for the offer Jay, I appreciate that.  I sent you a PM with the dimensions of the offset bushing.  Let me know if it's do-able. 

Sounds like an easy job for the 4 Jaw.
I'm surprised none of the 4-5 shops could not see this.
Has manual machining dipped that far?

I'm not sure what it is.  I dont have custom machining work done like this very often but it does always seem to be a major hassle to find a local shop that can do it a) correctly  b) timely  c) affordably.  The cheapest place I found was $60 at the local flat-track motorcycle engine shop...but I'd have to wait for him to finish a few motors before he could get to it, which could be months.  The most expensive was approaching $400 for the single unit, but "we could get you down to $250/each if you buy 100."  Seriously?!   

[66FAIRLANE]

Sounds like an easy job for the 4 Jaw.
I'm surprised none of the 4-5 shops could not see this.
Has manual machining dipped that far?

Yeh, amazing. I could do it at home. I would have made the same offer as Jay but I reckon Jay might be a wee bit closer.

[WConley]

It looks like Jay has got you covered. 

Otherwise, I could make the piece for you on my CNC.  It's pretty straightforward if you've got the intended diameters and offset figured out correctly.

Do you want to press the new bushing into the manifold, loctite it or ??  That will dictate the outside diameter.

[drdano]

It looks like Jay has got you covered. 

Otherwise, I could make the piece for you on my CNC.  It's pretty straightforward if you've got the intended diameters and offset figured out correctly.

Do you want to press the new bushing into the manifold, loctite it or ??  That will dictate the outside diameter.

The existing steel bushing I have that is non-offset is press interference tight.  It took a few good whacks with a seal driver to get it to come out.  I was a tad nervous even trying to remove it after the first hit, thinking it would be just my luck to have the manifold crack trying to remove it.  Not much meat between the hole and the edge of the manifold up front.  Brings up a good point, maybe better to locktite it or finally figure out how to weld aluminum with my tig and zap the thing in place.

I think there would be a market for various offset bushings that are oversized on the O.D. and say had varous assortments of offset on the I.D. you could buy such as .030", .060", etc to correct "special" manifolds.  All an average garage car guy would need to do is buy the correct ring they need, have their local machine shop oversize cut the distributor hole and install the new one in the offset direction needed. 

[Barry_R]

Too late now - but when we run into this stuff we'll indicate the hole in the intake and move the center of the "enlarged" hole so that we can use a thinwall "on center" bushing.  Your's could be easily made on a mill/lathe - don't even need a CNC for that.  Not sure why you'd be having troubles...

Our bushing has a small "top hat brim" on it that indexes into a similar spotface on the intake to ensure concentricity.  We use a light push fit on it and have a single tiny screw to located it and hold position.