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timing gear crank shims

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RestoreThemAll

Jedi Warrior
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I'm replacing the timing gears and chain on my BJ7 for no other reason than I have the engine out and torn apart. I'm ready to install and noticed a shim washer behind the crank shaft gear. My Bentley manual says to use the same number of washers as found when dismantling unless new crank or cam components have been installed. I believe that my engine had only one washer but it's been torn down longer than I'm going to admit to. So I need to measure. Also, the one washer shim that is there is in really tough shape. I'll replace it.

The book says to determine the thickness of washers required place a straight edge across the sides of the cam shaft wheel teeth and measure with a feeler gauge the gap between the straight edge and the crankshaft gear. I'm not real clear on that instruction. I understand that the gears must line up so that the chain runs true. Is the correct procedure: First install the gears on the shafts with no shim and lay a straight edge across the two gears?

One other question: Does it help to put the gears in the freezer for a couple of hours before installing to slightly open up the hole size?
 
Correct: 1st install with no shims to determine the thickness required.

The freezer is going the wrong way for what you want; you could leave them in the sun for a couple of hours...


Heating = expansion
Chilling = contraction
;)
 
Easy enough. Thanks for the hot/cold reminder.

You could leave them in the sun in Florida. Here in NY waiting for the sun to come out could take a while. :cool:
 
Hey Randy, you still on line?

I heated the gears with a 250 watt heat lamp and they tapped on easily.

It looks like the crank shaft gear needs three washer shims. The gap falls between .018 and .024. I believe that shims are .06 each. Does that seem excessive?

The cam shaft floats back and forth probably 3/8th". It was a little bit of a pain installing the cam shaft gear. The cam shaft slides back as I tapped in on. Is the gear supposed to ride on the retaining collar and secure the cam shaft in place?

Dale
 
Sounds like you're missing the thrust plate on the cam__goes between the cam and sprocket, and bolts to the block. That much end-float is not correct.

Furthermore, you shouldn't try to put the cam gear on before the engine backplate is on; the backplate will prevent the cam from damaging the rearmost cam bearing (it's a smaller diameter than the lobe). I strongly suggest that you inspect the cam bearings again before final assembly.

Fit the backplate, find the thrust plate and then recheck for the shims required.
 
Randy,
The front and rear engine plates were, and are in place before I put the gears on.

The cam retaining plate is bolted to the front plate holding the cam shaft in. The cam shaft doesn't move out of the engine past that retaining plate which looks like the correct running position for it. The cam shaft does move back into the engine.

Using the parts catalogs and the Bentley manual I don't see any parts missing. However, it does seem like something isn't right. I'll pull the gear back off and take some pics later today.
Dale
 
RestoreThemAll said:
Randy,
The front and rear engine plates were, and are in place before I put the gears on.

The cam retaining plate is bolted to the front plate holding the cam shaft in. The cam shaft doesn't move out of the engine past that retaining plate which looks like the correct running position for it. The cam shaft does move back into the engine.

Using the parts catalogs and the Bentley manual I don't see any parts missing. However, it does seem like something isn't right. I'll pull the gear back off and take some pics later today.
Dale
Click to expand...
That just doesn't seem right to me, but it's been a few years since I put one back together...

Is there anybody else that can confirm (or disprove) the amount of endfloat on the camshaft, once the thrust plate and sprocket have been bolted up tight?

Is it even possible to orient the cam sprocket the wrong way?

Unfortunately, I'm lacking in detailed pictures__gasp!__of the cam's timing gear, although I did find this one showing some of the parts after having a dry-film lubricant polymer coating applied to them (healeyblue's Longbridge engine, of which MANY pictures of the completed engine have been posted on here before).

IMG_1001.jpg


From this link, you can zoom-in on the high resolution version, just click the opened picture: https://spcarsplus.com/gallery3/index.php/LS_BN4_engine_build/IMG_1001

Best I can find of the assembled components...

IMG_1084.jpg


Note that later timing chain tensioner bolts used a locktab, but this Longbridge engine has drilled and safety-wired boltheads.
 
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Attached you can see the inside of the back of the engine before I installed the rear plate. There's nothing to stop the rear of the cam shaft from moving all the way back to the rear plate.

The other pics show the cam shaft pushed in vs pulled out. It's about 3/8" of movement.
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Randy, from your last post...
"the amount of endfloat on the camshaft, once the thrust plate and sprocket have been bolted up tight?"
My pics above show the end float pre gear installation.

Am I overthinking this? Is the cam restricted from forward movement by the cam retainer plate, and then the cam gear is tight against the front of the retainer keeping the shaft from moving backward? So the retainer has the cam riding on one side of it and the gear riding on the other side?
 
RestoreThemAll said:
Randy, from your last post...
"the amount of endfloat on the camshaft, once the thrust plate and sprocket have been bolted up tight?"
My pics above show the end float pre gear installation.

Am I overthinking this? Is the cam restricted from forward movement by the cam retainer plate, and then the cam gear is tight against the front of the retainer keeping the shaft from moving backward? So the retainer has the cam riding on one side of it and the gear riding on the other side?
Click to expand...
DING! DING! DING!

Yes, how much endfloat is there once the cam sprocket is done up tight? I expect it will only be a few thousandths, though I do not have the exact specification in my head.

If t could go in/out 3/8" like I read in Post #4, then something isn't right, as the lifters would be walking halfway off the lobes!
 
Ok. Non-problem solved. I heated the gear longer. I had to wear gloves this time. Put a little light oil on the shaft and gear and it slipped right on with ease. I didn't even need to tap it. The shaft didn't move at all. With the gear all the way home and the nut tight there is no movement in and out.

Thank you Randy! Sorry to use your time on such a simple problem.

Dale
 
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