Timing chain replacement

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tom1985
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Timing chain replacement

Postby tom1985 » Sat Jul 28, 2018 7:46 pm

Hi everyone,

I'm having a go at replacing the timing chain on my 1000 with the duplex one. Partly to (in theory) reduce noise, but also just to give me experience working on the car. I'm using the kit that comes with the new sprockets, chain, gasket etc. As always with my posts, this all comes with the caveat that I'm a total amateur and am learning as I go along!

Although not strictly necessary, to make the job easier, I removed the radiator and front panel to do this work.

I've got as far as removing the timing chain cover, and what's underneath looks like this:
timingchain.jpg
timingchain.jpg (4.1 MiB) Viewed 427 times
And this is where I've hit a problem. The upper sprocket (camshaft I think?) is secured with a large nut. 3/4 W seems to be a 'tight fit', not sure what size it actually is. This doesn't seem to be mentioned in the instructions that came with the kit, or in the workshop manual. Before I go any further, my questions are:

- What's the best way to remove it? I removed the starter dog by putting the car in gear, with the handbrake on, and chocks under the wheels. Would this work with this nut too?

- Why is mine different? Is it a mod? Or is this a feature of later cars? (mine's a '68 1098 car)

- Removing the nut will presumably make it difficult to keep the timing marks on the 2 sprockets lined up. Should I remove it before attempting to line them up?

- Will my conversion kit still fit?

As always, thanks very much for your advice!

Tom
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philthehill
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Re: Timing chain replacement

Postby philthehill » Sat Jul 28, 2018 8:29 pm

What you have is the standard 1098cc timing chain arrangement.
The Duplex chain assy is the modification.
All nuts/bolts on the engine are UNF. The large nut is 1 & 5/16" AF.
Turn the engine until the dimple on the large gear is in line with the mark on the small gear.
Remove the starter and lock the flywheel with a tyre lever or large screw driver. A second pair of hands at this stage will help.
Undo the nut and pull off the large gear and small gear. You may need a puller or pair of tyre levers behind the large gear.. Take care in removing the large gear. Do not use a hammer in the removal or fitting process as you may damage the oil pump.
Note the shim washers behind the small gear.
Remove the two 1/4" UNF bolts (behind the small gear) held in place by a lock tab.
Countersink the two 1/4" holes (82 degrees). Use a vacuum cleaner to mop up the swarf.
Fit the two countersunk screws and Loctite in place.
I would replace the large triangular camshaft thrust washer whilst you have got the cam gear off. Make sure that the thrust washer is fitted the right way round.
Fit the large duplex gear and duplex small gear and check the alignment of the gear marks. Make sure that the woodruff keys are in place on the crankshaft and camshaft.
Check the running (for and aft) alignment of the two gears by holding a steel rule against the teeth and adjust by adding or subtracting the shim washers behind the small gear..
Fit the large gear nut lock washer and nut tighten to 60-70lbf ft. Secure the lock washer up against the nut.
You are now back where you started.
There should be no problem in fitting the duplex conversion kit.
When fitting the timing gear cover (with new seal preferably) fit the cover but do not tighten any of the bolts, fit the pulley which centralizes the seal and then tighten the timing cover bolts gradually.
Lightly grease both seal and gasket before fitting.
Any problems please ask on here.


tom1985
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Re: Timing chain replacement

Postby tom1985 » Sun Jul 29, 2018 9:05 am

Thanks for the excellent advice! I'll let you know how I get on.
Tom
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tom1985
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Re: Timing chain replacement

Postby tom1985 » Sun Aug 26, 2018 10:16 am

So it's taken me a while, but I finally got this job done yesterday, and put the front of the car back together. The good news is there is now a lot less noise from the timing chain.

The bad news is that, due to my usual 'two left hands' garage skills, I think I might have upset the timing whilst doing so. Never one to be afraid of admitting my mistakes, so here's what happened... Before putting the two new gears onto the two shafts, I put them both together with the chain and lined up the timing marks. Getting the gears onto the shafts was much more difficult than getting the old ones off, it was a very tight fit. Once they were eventually fitted, I noticed that the marks were not quite lined up any more - probably about 10mm apart. I assumed this must have happened once they were already on the shafts, and therefore would have both turned, and be alright. Probably the wrong move!

Once back together the engine started and ran easily. However, I did notice a few things that didn't seem right. Once warmed up, the engine ran at a higher-than-usual idle speed. It also, when revved at idle, to produce some blue exhaust (not loads, but more than I remember it doing unless the engine was cold). After a short test drive, I noticed that the engine was running hot as well - the needle sitting at around 100, whereas usually it would sit around 90 (however, I haven't driven the car much for ages, and did change the thermostat shortly before this work, so it may have something to do with that instead). Finally, after switching it off, the engine 'ran on' a bit.

My questions to you folk who actually know what you are doing with this stuff are:

Are these symptoms of the timing being out?
If so, can this be adjusted in any way except by re-fitting the timing chain?
If not, is there any way of getting the cam and crank shafts properly re-aligned?

Thanks as always for any guidance!
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philthehill
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Re: Timing chain replacement

Postby philthehill » Sun Aug 26, 2018 12:47 pm

To cut to the quick
There is no way you can alter the relationship between crank and camshaft other than taking it all apart again and checking the alignment of the timing marks and if necessary realigning the timing marks.
From what you describe the cam timing is one tooth out.
The 'A' series will run one tooth out but not very well.
Whilst I do not use a split link timing chains they do have their advantages in that you can fit the gears align the marks and fit the chain.
If you do use a split link chain fit the clip with its closed end in the direction of travel.

http://www.minispares.com/product/Class ... sic/timing chain.aspx|Back to search


tom1985
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Re: Timing chain replacement

Postby tom1985 » Sun Aug 26, 2018 4:16 pm

Great, thanks for the advice Phil, will give it another go
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paul 300358
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Re: Timing chain replacement

Postby paul 300358 » Sun Aug 26, 2018 5:49 pm

I have just rebuilt my engine and I have had the same problem with the engine on the bench, the timing marks could never quite be lined up perfectly. they always seemed 1/2 link out. I have now done 350 miles and it seems ok.

philthehill
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Re: Timing chain replacement

Postby philthehill » Sun Aug 26, 2018 6:03 pm

Unless you use two dial gauges and an angle disc in conjunction with a variable cam gear the timing is always going to be a compromise because of the fixed Woodruff keys/slots.
It has been reported elsewhere that using the standard set up the camshaft can be out as much as 15 degrees in relation to the crankshaft.
Timing the cam 1.jpg
Timing the cam 1.jpg (370.07 KiB) Viewed 191 times


ampwhu
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Re: Timing chain replacement

Postby ampwhu » Sat Sep 01, 2018 8:30 am

phil,

on this subject, when you fit a new timing cover rubber seal (1098), which way around does the seal go? (the meal rope seal)

cant find the info in any manual.

Alan

philthehill
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Re: Timing chain replacement

Postby philthehill » Sat Sep 01, 2018 9:10 am

Alan
The timing chain cover oil seal (whether it is fitted from the inside of the cover or from the outside of the cover) should be fitted with the lip and associated tension spring towards the engine/timing chain.
Make sure that the oil thrower plate is fitted the right way round. It has a 'F' stamped on it which indicates Front and should be fitted facing away from the timing chain.
Grease the lip of the seal well before fitting the cover so as to remove any chance of the seal picking up and tearing on the crankshaft pulley rubbing face.
Phil



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