Timing chain tensioner setup

[don58van]

All

This subject has been covered many times before, but I have a couple of specific questions:

1) As well as the tensioner itself, I will have to get a timing gear cover with the bulge to accommodate the tensioner. Will I also need a different timing case backplate to match the cover?

2) I want to take the opportunity to fit a harmonic balancer. Does the balancer engage with the later timing cover somehow?

Cheers
Don in Oz

[bmcecosse]

No - the original backplate is fine - but one small blind hole must be drilled to 'seat' the head of the tensioner pivot. Someone came up with an alternative idea for that - but I was not convinced! It's only seconds to drill the hole and can be done in car. Damper - if you can find one - just fits in place of the normal bottom pulley. It is an EXCELLENT idea! But sadly no-one seems to make them these days. The 'solid steel' pulley is NOT a crank damper - and has limited usefulness!

[alanworland]

Showing my ignorance here! What does a harmonic damper do? - I know my big car has a pulley like you describe, but I don't know why!

[linearaudio]

No - the original backplate is fine - but one small blind hole must be drilled to 'seat' the head of the tensioner pivot. ........ Someone came up with an alternative idea for that - but I was not convinced! It's only seconds to drill the hole and can be done in car.

That "someone" has covered 5000 miles so far and having stripped the engine for new shells, I see no evidence that it won't carry on!

It's not "a simple job" to drill that extra hole which is why I pursued a different method. My standard electric drill would not fit in the space between front plate and front panel of car. Yes it is a simple job with the engine out!

Get a secondhand damper from a scrap Mini/Metro, bolts straight on in place of the normal pulley! Supposed to prolong main bearing, or crank life, by damping out particular frequencies that set up along the crank at certain engine speeds, from what I recall, rather annoyingly corresponding to a fast cruising speed!!

[bmcecosse]

I was assuming the front panel would be off.......... can you detail again what you did LA - instead of drilling the hole ? I can tell you that way back when - I broke two cranks in fairly rapid succession on my warmed up 948 engine. What fun we had 'exchanging' them for service exchange cranks in far off BMC garages! With the third crank - I fitted a crank damper from an early 1098 EW engine (and an oil cooler) - and no more problems. It is an essential feature of any well modified A series.

[don58van]

Thanks all for your help.

Don in Oz

[linearaudio]

Here is what I did to obviate the need to remove/drill the engine front plate,hope it makes some sense!:[frame][/frame]

[bmcecosse]

Ah yes - the peening! Great drawing BTW - I can't draw a stick man!

[linearaudio]

I remember now a query about that word!! As I understand it in engineering circles that is the action of welting (another one!) the end of a pin into a recess, like in old fashioned rivetting. We used to do this as Apprentices, then had to draw-file the surface flat so no marks/ gaps were visible, to prove a good job had been done (no, I do not have photographic proof that I went that far with the tensioner....)
As it would not be advisable to heat the end of the tensioner pivot to facilitate this action, the idea was to turn it into a "semi-tubular" rivet by drilling a 3mm hole into the end to allow easy cold rivetting.

All clear?

[bmcecosse]

The trouble is - while your peened pin fixes the tensioner into the bracket - it doesn't anchor it into the backplate - as does the original design..........

[linearaudio]

We've been there as well! If you look at the"adjustment slot" in the base you will see that you actually cannot adjust the original design, due precisely to it having that peg located in a fixed position, disallowing movement of the baseplate! If however, you are doubting the capabilities of rivetting as a mechanical means of fastening, I suggest you get off that 75 year old footplate and leg it

[bmcecosse]

Oh the peening is fine - if done properly - no worries there. But I contest that I 'can't adjust the tensioner' - it pivots around the head of the peg in the plate. You have correctly shown in your drawing that the fixing holes are slotted.

[linearaudio]

Oh the peening is fine - if done properly - no worries there. But I contest that I 'can't adjust the tensioner' - it pivots around the head of the peg in the plate. You have correctly shown in your drawing that the fixing holes are slotted.

[frame][/frame]

As you can see there is only one slotted hole, and two fixed points, therefore it is physically impossible to adjust the base plate! (apologies to Minispares)
Computer graphics are wonderful things

[Simon P]

Is it possible there are different base plates?
I've just refitted mine and found that it can pivot approximately 10mm on the retaining pin,
I didn't notice if both holes were slotted though.

[bmcecosse]

Originals have two slotted holes..........

[M25VAN]

I think the front engine plate I saw had a larger clearance hole than the diameter of the pin head. This allowed enough clearance for the whole assembly to pivot on the bottom bolt hole.

[MarkyB]

/whisper Duplex is a piece of cake to fit, just countersink two existing holes /w

[linearaudio]

I think the front engine plate I saw had a larger clearance hole than the diameter of the pin head. This allowed enough clearance for the whole assembly to pivot on the bottom bolt hole.

HA!! Exit the "location on the pin head" theory in a puff of steam

[bmcecosse]

Nah - it should be a snug fit.......... Toot toot said Thomas.......

[linearaudio]

What a kerfuffle!!

5000 miles and it hasn't slipped/fallen to bits! "Lets stop arguing and have a cup of tea" says the Fat Controller...

/Whisper...duplex chain soon stretches enough to rattle................