14 replies to this topic

[CSP]

Hi,

 

 

I bought a brandnew vernier duplex timing gear/timing set for a 1275cc A+ engine

 

I have likely the same problem as the topic here beneath.

 

http://www.theminifo...shaft-sprocket/

 

Unfortunatly the topic stopped.

 

It looks like the crankshaft sprocket is too thick behind the gear for the chain or the camshaft sprocket is too thin.

Normally it's vice versa the crankshaft sprocket has to be adjust with shims on the crankshaft to get a proper alignment.

I already removed al the shims of the crank, so the sprocket won't get any closer towards the engine.

Unfortunately there aren't shims available to adjust the alignment of the camshaft sprocket.

 

I'm sure that the camshaft is fitted correctly and the triangle plate isn't worn.

 

Does anyone know if this problem occurs more frequently?

 

Is this problem caused by a wrong production? And which solution is most recommended?

 

Thanks in advance.

 

 

 

[CSP]

I wrote that the crank sprocket is to close at the engine, but I mean that the camshaft sprocket is to close to the engine.

[carbon]

Do you have a standard steel timing cover backplate, or an alloy one?

 

Some of the aftermarket backplates are a tad thinner, this moves the cam sprocket in slightly.

 

I guess a very thin gasket between backplate and block may have similar effect. Depending on how much you need to get the sprockets into line may be worth seeing if you can get a thicker gasket.

[Spider]

Gently lever the Cam towards the Sprocket and re-check.

 

The Cam Lobes ARE or should be ground on a taper, this along with the radius on the Cam Followers cause the Cam to thrust in one direction ONLY, that is towards the Cam Sprocket. This is how there were done in the factory and 99% of all 'flat tappet' engine in the world are originally manufactured.

 

There are a few re-grinds that are flat and with those, you need a lathe or some one to do some machining for you,,,,,,,,,

Edited by Moke Spider, 06 October 2016 - 07:45 PM.

[CSP]

Thanks for your reply.

 

I used the original steel backplate.

 

The camshaft sprocket has to go 0,65 mm outwards to get a perfect alignment.

 

If I want to use i thicker gasket I think I have to cut it out myself from thicker paper. I only can find the original/normal gaskets.

 

But if I use a thicker gasket, do I get no problems with the extra space between the camshaft and triangle plate?

The clearance on the camshaft will be greater.

[carbon]

Worth doing the checks as suggested by Moke Spider.

 

If these come back same then it sounds like something is not right with the new parts as supplied. If you have an original duplex sprocket set compare these back-to back with the new items. Should be possible to see where there is a 0.65mm difference.

 

If the new parts are not right then I would ask for replacements, as they are not fit for purpose without modification.

[CSP]

Gently lever the Cam towards the Sprocket and re-check.

 

The Cam Lobes ARE or should be ground on a taper, this along with the radius on the Cam Followers cause the Cam to thrust in one direction ONLY, that is towards the Cam Sprocket. This is how there were done in the factory and 99% of all 'flat tappet' engine in the world are originally manufactured.

 

There are a few re-grinds that are flat and with those, you need a lathe or some one to do some machining for you,,,,,,,,,

 

Thanks, but doesn't the triangle plate lock the camshaft?

The camshaft sprocket is sitting on the triangle plate. So can you explain how it will effect the sprocket alignmente when you move the cam towards the sprocket?

[CSP]

Worth doing the checks as suggested by Moke Spider.

 

If these come back same then it sounds like something is not right with the new parts as supplied. If you have an original duplex sprocket set compare these back-to back with the new items. Should be possible to see where there is a 0.65mm difference.

 

If the new parts are not right then I would ask for replacements, as they are not fit for purpose without modification.

 Hi,

 

I compared the original sprockets with the duplex sprockets and there is a difference between the offset.

So I think the part isn't good, but I can't find similar situations on the web, and I think they were selled a lot.

So that's weird.

 

I installed the original sprockets to see if there went something wrong with installing all the parts.

But with the shims I can make a perfect alignment with the original sprockets.

But with the duplex the camshaft sprocket has to go further outwards.

 

Aren't there thicker triangle camshaft  plates available?

This will be a possible solution I think.

Edited by CSP, 06 October 2016 - 08:22 PM.

[Spider]

 

Gently lever the Cam towards the Sprocket and re-check.

 

The Cam Lobes ARE or should be ground on a taper, this along with the radius on the Cam Followers cause the Cam to thrust in one direction ONLY, that is towards the Cam Sprocket. This is how there were done in the factory and 99% of all 'flat tappet' engine in the world are originally manufactured.

 

There are a few re-grinds that are flat and with those, you need a lathe or some one to do some machining for you,,,,,,,,,

 

Thanks, but doesn't the triangle plate lock the camshaft?

The camshaft sprocket is sitting on the triangle plate. So can you explain how it will effect the sprocket alignmente when you move the cam towards the sprocket?

 

 

No. The Triangle Plate is a Thrust Plate. Cam, with it's Tapered Lobes, as designed, will thrust in to the Thrust Plate when Running. It is not a lock plate.

[Spider]

As a do it at home option, you could cut a shim to fit between the Thrust Plate and the Front Engine Plate. Just be sure the centre is clear for the Cam to Thrust against the Thrust Plate directly.

 

I have found with many of the Vernier type Sprockets that they are closer fit than factory sets, meaning that less or in some fit ups, no shims are needed.

 

0.025" is a long way off. I gotta ask - is the Crank set up with the right thrusts?

 

<Edit" A 'worn' Cam Thrust Plate could also help. While I say 'worn' I'm yet to see one that's worn out, they usually just have witness running marks. Or as you are thinking, a thicker Front Engine Plate Gasket. >

Edited by Moke Spider, 06 October 2016 - 08:26 PM.

[CSP]

As a do it at home option, you could cut a shim to fit between the Thrust Plate and the Front Engine Plate. Just be sure the centre is clear for the Cam to Thrust against the Thrust Plate directly.

 

I have found with many of the Vernier type Sprockets that they are closer fit than factory sets, meaning that less or in some fit ups, no shims are needed.

 

0.025" is a long way off. I gotta ask - is the Crank set up with the right thrusts?

 

Yes, I installed new thrust washers and main bearings, I measured the clearence so that has to be perfect.

 

I have polished the front engine plate, but I can't imagine that I have polished 0,65 mm off, but maybe it has something to do with it in combination with a thicker duplex crankshaft than normal.

Edited by CSP, 06 October 2016 - 08:33 PM.

[CSP]

As I see it, there are 3 solutions.

 

Return the duplex timing kit and ask for another one. (with the risk it will be the same and cause the same problem)

 

Order a second triangle plate and machine it to fill up the clearence to get a good alignment on the camshaft sprocket.

 

Or machine the crankshaft sprocket and make it 0.65mm thinner at the back of the sprocket.

 

Are there better options?

[Spider]

When I've come across this, I just machine back the Sprocket, and just as an off hand remark, I've haven't found this to be unusual.

 

Just as a 'by the way' thing, on performance engines, I don't use the shims at all, they tend to 'ooozzz' out. I machine which ever sprocket is need to align them.

[CSP]

Ok thanks.

 

I think I'm going to modify the crankshaft sprocket and get 0.65mm off.

[gazza82]

I've fitted a vernier to mine and a new cam plate. With the right float on cam and crank, there are no shims on the crank pulley.