Oil Pump/Distributor Driveshaft Loose

[BenC]

I'm assembling an L28 using the timing cover and oil pump drive shaft from an L24.  The shaft fits looser than I'd like in the timing cover.  I measured the ID in the timing cover and the OD on the shaft and there is definitely over 0.005" clearance.  My inside snap gauge for this small a diameter is a POS but the clearance is certainly no less than five.  Specs are replace timing cover above 0.006" clearance.  A lot of money and time have gone into this build and I don't want to screw around with iffy timing having this shaft be loose.

 

What are folks doing when they encounter this problem?  This is not my first motor but it is my first L28.

 

Thanks!

[Lurcher]

Well if a lot of "time & money has gone into this build" IMHO you should replace both the distributor drive spindle with new one (most US based Z parts suppliers stock them)

and also replacing the timing case cover with a brand new one.

Edited February 28, 2016 by Lurcher

[NewZed]

Specs are replace timing cover above 0.006" clearance. 

Where is this specification?  Can't seem to find any reference in the FSM chapters.

[BenC]

Well if a lot of "time & money has gone into this build" IMHO you should replace both the distributor drive spindle with new one (most US based Z parts suppliers stock them)

and also replacing the timing case cover with a brand new one.

 

That is very helpful.

 

I was not aware that either was particularly available. 

 

Where would one find a new timing cover?  I have looked and not found any.  Of course with Z parts it is often about looking in the right place.

 

It seems like the kind of thing that could have a bushing installed if the center of the hole could be located.

 

 

[BenC]

Where is this specification?  Can't seem to find any reference in the FSM chapters.

 

It is in "How to Rebuild Your Nissan/Datsun OHC Engine: Covers L-Series Engines 4-Cylinder 1968-1978, 6-Cylinder 1970-1984"

 

http://www.amazon.com/Rebuild-Your-Nissan-Datsun-Engine/dp/1931128030/ref=sr_1_1?ie=UTF8&qid=1456679268&sr=8-1&keywords=how+to+rebuild+nissan+and+datsun+ohc+book

 

I'm at work right now but I think it is on page 130.

 

When the distributor, cover, and spindle are assembled the slop is not nearly so alarming but still present.  When it is just the spindle and cover it wiggles around.

[NewZed]

It is page 131, illustrated on 132, good memory. Thought you were talking about the hole at the top of the quill.  Seems like it could be machined and a bushing inserted.  Covers were probably cheaper and easier to find back when he wrote that book.  You might also find a Redi-Sleeve or Speedi-Sleeve that fits the shaft.  I'm not a machinist or engine builder though.

 

 http://www.timken.com/en-us/products/seals/industrial/products/Pages/redisleeves.aspx

 

http://www.skf.com/us/products/seals/industrial-seals/power-transmission-seals/wear-sleeves/skf-speedi-sleeve/index.html

[Chickenman]

Personally I wouldn't worry too much about it.... unless this is an all out race engine constantly turning high RPM's.  The distributor shaft is located by collars in both the oil pump and distributor drive end. This controls any primary oscillation of the shaft. The timing cover bushing is simple drip lubrication, not forced lubrication. It is not a high load area at all.

 

It may be a good idea to replace the spindle shaft, the tangs on the ends do tend to wear and that can cause spark scatter. One you replace the spindle,check the specs again. A new spindle may tighten up the specs a bit. If it is still out of specs, then you could consider a new timing cover... if available. If not I would take it to a machine shop and have a thin wall bronze bushing installed and honed to size. It may be more trouble than it's worth.

 

The fact that the factory service manual does not list a specification for this measurement should tell you that this dimension is not critical. In an L16 race engine turning close to 10,000 RPM... yes it may matter. On a stock or mildly modified engine running on the street, I don't think the the clearance is critical at all. Frankly this is the first time I've ever heard it mentioned....

 

Edit: It's interesting that only Tom Munroe's book lists this dimension. I've got the original version of: " How to Modify Datsun 510,610, 240Z engines & Chassis " by Bill Fisher & Bob Waar . And I also have " How to Modify Nissan and Datsun OHC Engine " by Frank Honsowetz " . Neither of these, nor any of the FSM's,  mention anything about the TC bushing to spindle clearance. I don't have Tom Monroes book, but it does seem to be something for a Race Only engine... and not that critical IMHO.

Edited February 28, 2016 by Chickenman

[BenC]

It is page 131, illustrated on 132, good memory. Thought you were talking about the hole at the top of the quill.  Seems like it could be machined and a bushing inserted.  Covers were probably cheaper and easier to find back when he wrote that book.  You might also find a Redi-Sleeve or Speedi-Sleeve that fits the shaft.  I'm not a machinist or engine builder though.

 

 http://www.timken.com/en-us/products/seals/industrial/products/Pages/redisleeves.aspx

 

 

I'll keep those sleeves in mind.  0.011" sleeves (adding 0.022" to the shaft diameter) would require machining the timing cover.  If it was more worn out it might work!

 

When I read "replace timing cover" I remember thing, "Yeah, how's that going to work?"

 

Thanks for the info!

[BenC]

Personally I wouldn't worry too much about it.... unless this is an all out race engine constantly turning high RPM's.  The distributor shaft is located by collars in both the oil pump and distributor drive end. This controls any primary oscillation of the shaft. The timing cover bushing is simple drip lubrication, not forced lubrication. It is not a high load area at all.

 

It may be a good idea to replace the spindle shaft, the tangs on the ends do tend to wear and that can cause spark scatter. One you replace the spindle,check the specs again. A new spindle may tighten up the specs a bit. If it is still out of specs, then you could consider a new timing cover... if available. If not I would take it to a machine shop and have a thin wall bronze bushing installed and honed to size. It may be more trouble than it's worth.

 

The fact that the factory service manual does not list a specification for this measurement should tell you that this dimension is not critical. In an L16 race engine turning close to 10,000 RPM... yes it may matter. On a stock or mildly modified engine running on the street, I don't think the the clearance is critical at all. Frankly this is the first time I've ever heard it mentioned....

 

Edit: It's interesting that only Tom Munroe's book lists this dimension. I've got the original version of: " How to Modify Datsun 510,610, 240Z engines & Chassis " by Bill Fisher & Bob Waar . And I also have " How to Modify Nissan and Datsun OHC Engine " by Frank Honsowetz " . Neither of these, nor any of the FSM's,  mention anything about the TC bushing to spindle clearance. I don't have Tom Monroes book, but it does seem to be something for a Race Only engine... and not that critical IMHO.

That makes sense.  I'll definitely get a new spindle.  I was struck by how much just installing the distributor tightened up everything.

 

I don't have "How to Modify Datsun 510,610, 240Z engines & Chassis" but I do have "How to Modify Nissan and Datsun OHC Engine" and was stuck with how much more technical information was in Monroe's book.

 

Thanks again for the info.  I'll buy a new spindle and see where that gets me.