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+--- Thread: Timing gears (/showthread.php?tid=1109)
RE: Timing gears - Charles P - 22-04-2018
(22-04-2018, 06:35 PM)Colin Wilks Wrote: It is a sports engine with the original crankcase, crank and block. The gears have the Austin 00 and 0 timing marks so are probably original too. I'm fairly sure the damage has occurred since a PO had some engine work done about a couple of thousand miles and ten years ago (I've only taken it round the block so far). My priority is to preserve the crankcase.
Thanks Stuart and Dave, I'll give Tony a ring.
Jon, Chris Gould's guide says the front camshaft journal is larger than normal, hence the camshaft pinion has a larger centre hole. Apparently the timing gears were steel rather than iron. (A Guide to the Austin '65' and Nippy, CSW Gould, p36)
eta beaten to this by Alan and David - thanks.
With an original sports engine I'd be calling Dave Dye to get a new steel set. That fracture surface doesn't look like steel.
You really don't want them breaking
Charles
RE: Timing gears - Bob Culver - 22-04-2018
I acquired a pile of used gears. These came in a wide range of wear and meshing depths and short of trial assembling each it is tedious to assess. Apparently timing also varies markedly. Every time the gears are disturbed material is worn away to establish a new mesh.
Unless the gears are otherwise very noisy I would leave well alone. The mesh pattern seems to barely reach the chip.
If changing, beware tight gears lead to major failures.
It would be worth very close look to ensure that whatever action caused the chip has not caused cracking further in.
Perhaps smooth off the sharp edges.
RE: Timing gears - JonE - 24-04-2018
from Mr Williams (the other one)
RE: Timing gears - Austin in the Shed - 24-04-2018
(22-04-2018, 06:35 PM)Colin Wilks Wrote: It is a sports engine with the original crankcase, crank and block. The gears have the Austin 00 and 0 timing marks so are probably original too. I'm fairly sure the damage has occurred since a PO had some engine work done about a couple of thousand miles and ten years ago (I've only taken it round the block so far). My priority is to preserve the crankcase.
Thanks Stuart and Dave, I'll give Tony a ring.
Jon, Chris Gould's guide says the front camshaft journal is larger than normal, hence the camshaft pinion has a larger centre hole. Apparently the timing gears were steel rather than iron. (A Guide to the Austin '65' and Nippy, CSW Gould, p36)
eta beaten to this by Alan and David - thanks.
If you wish for the crankcase to survive and use the car regularly have the camshaft reprofiled with less lift.If there isn't much backlash in the gears I'd leave them alone.
If its pressure fed fit a modern seal on the front.
RE: Timing gears - dickie65 - 25-04-2018
I have dressed damage like yours with a file first then oilstone slips, remove all the jagged sharp corners and grain showing , usually the damage is either from something hitting the teeth during fitting / removal.
You can have a new front bearing made and change to a modified standard camshaft, The rear bearing is the same diameter as is the centre bearing which needs sports rollers as the outer race on the Nippy / 65 is larger.
Your other option is to have a standard timing gear re bored to suit the Nippy Cam.
It depends on whether you are after a quick fix or a major stripdown.
Can you do the work or does it cost you money !
I have just checked my Type 65 cam against a standard one.
Good Luck Richard
RE: Timing gears - Colin Wilks - 25-04-2018
Thanks Richard.
I'm just trying to get the car going for now and am looking at rebuilding the engine over next winter. The dynamo housing was only off so I could renew a core plug, but I'm glad I spotted the broken gear as the next tooth along also has a crack in it.
I've sourced a good second hand Nippy pinion from Ian Bancroft, who has leant me a selection of crankshaft gears to match up. He also modified the camshaft bush today to take up the endfloat - my set up measured .008" and a PO had installed a 40 thou shim (which I think probably counts as a washer) between the camshaft shoulder and the bush.
I can vouch for the truth of all the warnings about losing the rollers from the centre bearing. I thought I' d been quite clever putting a washing up bowl right under the sump, but three of the little buggers still escaped. I held the cam followers clear with small tie wraps and wish I'd popped one round the rollers when they first started to appear.
One interesting thing was that the crankcase had broken off a small lump at the bottom of the thread for the long bolt that holds the dynamo down. I thought that this had occurred due to the bolt having bottomed out, but Ian said this often happens due to oil and old gasket goo clogging the bottom of blind threads and so causing hydraulic lock when the bolt is run down. The broken lump was sitting behind the camshaft pinion and may have been the cause of the tooth breaking, or it may have been the excess camshaft end float. Backlash on the gears was .007".
RE: Timing gears - Zetomagneto - 25-04-2018
(25-04-2018, 10:10 PM)Colin Wilks Wrote: Thanks Richard.If you are that far in I would use a modified standard cam, pigsty, Paul Bonewell,
I'm just trying to get the car going for now and am looking at rebuilding the engine over next winter. The dynamo housing was only off so I could renew a core plug, but I'm glad I spotted the broken gear as the next tooth along also has a crack in it.
I've sourced a good second hand Nippy pinion from Ian Bancroft, who has leant me a selection of crankshaft gears to match up. He also modified the camshaft bush today to take up the endfloat - my set up measured .008" and a PO had installed a 40 thou shim (which I think probably counts as a washer) between the camshaft shoulder and the bush.
I can vouch for the truth of all the warnings about losing the rollers from the centre bearing. I thought I' d been quite clever putting a washing up bowl right under the sump, but three of the little buggers still escaped. I held the cam followers clear with small tie wraps and wish I'd popped one round the rollers when they first started to appear.
One interesting thing was that the crankcase had broken off a small lump at the bottom of the thread for the long bolt that holds the dynamo down. I thought that this had occurred due to the bolt having bottomed out, but Ian said this often happens due to oil and old gasket goo clogging the bottom of blind threads and so causing hydraulic lock when the bolt is run down. The broken lump was sitting behind the camshaft pinion and may have been the cause of the tooth breaking, or it may have been the excess camshaft end float. Backlash on the gears was .007".
the Nippy cam wrecks Crankcase, i.e. cracks and stud issues on the camshaft side of the case.
Looking at your picture this does not look like steel, someone has fitted a cast gear at some time
in the past
RE: Timing gears - Colin Wilks - 26-04-2018
Thanks for that zetomagneto.
I have discussed this with Paul Bonewell who has advised me where to look in the crankcase for signs of strain (at the back and beside the camshaft side block to crankcase studs). A modified cam from Paul is part of my rebuild shopping list for next winter.
For now he has advised me to reinstall the camshaft as is but with only single valve springs and to go steady.
RE: Timing gears - Zetomagneto - 26-04-2018
(26-04-2018, 10:43 AM)Colin Wilks Wrote: Thanks for that zetomagneto.Sounds like a good idea,well done
I have discussed this with Paul Bonewell who has advised me where to look in the crankcase for signs of strain (at the back and beside the camshaft side block to crankcase studs). A modified cam from Paul is part of my rebuild shopping list for next winter.
For now he has advised me to reinstall the camshaft as is but with only single valve springs and to go steady.
RE: Timing gears - Terrytuned - 29-04-2018
When fitting any different dynamo or timing gears the mesh of the dynamo gear to cam gear must be checked as too tight a mesh will damage cam gear.
See BA7C website technical section section look for dynamo housing and tin cover for how to check mesh.
Terry.