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Refitting oil pump drive


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I want to refit the distributor, other than the radiator it's one of the last things I need to do, however whilst rebuilding the engine I have had to remove the oil pump drive, if I just put it back in it's unlikely it will be in it's original position and so will timing will be completely out. I have read the article in the Haynes manual but it's not entirely clear.

Do I just need to set cylinder 1 to top dead center and then drop it in? The article discusses measuring the space between the spacer and the block when the distributor is fitted and that this can take effect on the timing???!?


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The gear wheel has to be dropped in at the right point as you mentioned eg at tdc, but in such a place that the distributor will `look` in the right place
Some Distributors with rev drive ,for example, have to be in the position where by the drive offtake is pointing to the bulkhead
Also when you drop the gear in it will follow the curvature of the splines so when you think it will drop straight down , it doesnt, it will turn.
So when you drop the ditributor in ,which has offset/different thickness keys it may not be in the correct position
So its trial and error pulling out and turning the gear until it is in the correct position aloowing the distributor to be in correct
Another example , dropping the gear in any where, you may find that one of the cap retainer spring clips is slap bang up to the cylinder head
Double dutch, you bet      

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Some confusion here.
Chris refers to the endfloat question, and VR to just dropping the dizzie in.

I'm sure you know, having rebuilt the engine, that the camshaft drives both the oil pump and the dizzie.   There are three major parts:
The drive cog that takes drive off the camshaft.
The drive shaft to the oil pump
The drive shaft to the dizzie.

When you install the oil pump, you can't know what orientation the drive shaft should be in.   So when you come to install the drive cog, you must orientate the slot in the end of the oil pump shaft so that the cog goes in the correct place.

There is a dog gear, a slot and screwdriver like ends that engage, that links cog and oil pump.  Yiu can easily turn the slot in the end of the oil pump shaft with a long screwdriver,  Adjust it so that the cog shaft will engage when the cog is in the correct position, as shown (badly) on page 55, Fig 1.19 of my Haynes.  Remember that while the oil pump and drive dog is symmetrical, the slot in the top of the cog rthat engages with the dizzy shaft, is off-set.   Use the end of the dizzy shaft to know which way it should go.

More difficulty is due to the cog being a hypoid gear, that must turn while being inserted as it engages with the cam gear.  You need to insert it turned back from the correct position to allow for this.

To use the dizzie to check what position to set the gear cog, set the dizzie to No.1 and look at the ridge on the end of the dizzy shaft that is also off-set to see where the cog should be.  Don't forget that you will turn the dizzy right way up after you look at it!

This doesn't need to be done in a precision way.  You can 'swing' the dizzie, un-tightening the clamp and turning it to static set the timing, and have the vernier adjuster for fine adjustment while the engine is running!

Good luck

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And also, to add to the above, the position of the drive gear will not actually alter the ignition timing at all. Once the gear and dizzy are dropped in (with No1 at TDC on the firing stroke) and properly engaged, it can be anywhere really and the timing will be that same as when you took it out, as long as you have not undone the pinch bolt/clamp. The reason that the manual shows it to be in the position it is, is so that the vacuum pipe, cap clips, rev counter drive (on a Delco) etc are in a reasonable position. So you do not have to be super-accurate where you engage the drive onto the camshaft and into the oil pump slot, just somwhere where the connections and clips are convenient.

It's sometimes difficult to get your head round this fact, but a similar thread about a year ago proved (at length....) that this is correct. I can explain it all if you wish.

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michael_charlton wrote:

Also when you drop the gear in it will follow the curvature of the splines so when you think it will drop straight down , it doesnt, it will turn.

It will! So as Michael says drop it in in a position just about one tooth too far forward of where you actually want it, and as it meshes with the diagonal gears it will twist and finally come to rest pointing in the correct position. I worked this out the hard way after one of my GT6 went like a dream at 40 degrees BTDC, but died completely at the factory setting....

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