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Fitting and synchronizing VVC units



Assumptions are that you have the cam ladder (clean), both VVC Mechs with their respective cams, the synchronising shaft and hydraulic control unit to hand and that the cams are inserted correctly into the mechs and the mechs are correctly assembled.

All rotational directions will be described as viewed from the front end of the cam ladder/engine (the left end as outlined below).

Lay the VVC cam ladder upside down on a flat surface in front of you so that the inlet/VVC side is facing you, in this position the front of the ladder/engine will be on your left as will the machined hole and mounting platform for the HDU shaft.

Take the front VVC mech/cam (ensure it has the metal gasket attached) and place this in the ladder so that the cam fits properly into the bearing cups cast into the ladder and the mech fits flush to the front of the ladder. Take two of the attachment bolts (M6 x 20 flange bolts) and do these up nearly all the way into the front of the ladder so as to constrain the mech. from falling away from the ladder/cam while allowing the VVC mech to rock back and forth by 40 thou or so. The front mech. is the one that has no reluctor triggers on the cam. The mech. has a round receptacle area machined away into which the synch. shaft will fit when it is assembled, this should be facing you.

Turn the inner rotating part of the mech. so that the toothed rack on the outer rotor moves in a clockwise direction and the slot in the rotor lines up with the slot machined in the outer support ring of the mech casing at the top centre (as viewed). At this point the teeth on the rotor should start pretty much level with the cam ladder surface and extend down and below the surface of the rack radially, effectively from the 3 O’clock position to the 7 O’clock position as viewed from the front of the ladder. The start of the rotors toothed rack should be clearly visible through the break in the casing support ring where the synch. shaft will fit.

Support the VVC mech. with your hand and remove the two bolts holding the mech. to the ladder, do not let the mech fall away or disengage from the cam. Rotate the mech. slighty anti-clockwise so that the slot which accepts the synch shaft moves upwards a little away from the ladder. Take the synch shaft and enmesh the front end (this has two tooth pinions) into the teeth on the mechs rotor. Rotate the VVC mech back into its correct position and this should bring the synch shaft down into it’s correct position nestling in its bearings. Replace the bolts holding the VVC mech. to the ladder and do them up nearly tight.

Rotate the synch shaft in an anti clockwise direction until the pinion teeth meet the end of the toothed track on the VVC mech. rotor and the shaft will turn no more. At this point the slot on the rotor and the slot on the mech. casting at the top centre should be pretty much in line.

Take the rear VVC mech/cam and rotate the inner rotor in an anti-clockwise direction until the slot in the rotor and the slot in the mech housing at the top are in line, when this is done the teeth on the rotor should occupy the 3 O’clock to 7 O’clock positions as with the front mech and it should be a mirror image of the front mech with the end of the teetyh track clearly visible at the point where the synch shaft will fit.

Now fit the VVC rear mech/cam to the ladder while fitting the synch shaft rear end to the teeth track on the mech, There is a bit of a knack to making sure the synch shaft enmeshes in the correct tooth on the inner rotor. Make sure the cam is sitting correctly in its bearings and the VVC mech. is aligned with its bolt holes and then fix the rear VVC mech to the ladder with two bolts and ensure these are nearly tight as with the front mech. Rotate the synch shaft in an anti-clockwise direction until it will not turn any more and ensure that the teeth on each pinion at either end have reached the last tooth on the VVC mech rotor, if they are not exactly in synch then undo the bolts on the rear mech, rotate this anti clockwise a little until the synch shaft can be disengaged from the toothed track and re-synch the track and pinion, then re-seat the mech and do the bolts up. Continue until the two mechs are in synch. with one another and effectively mirror images and ensure the synch shaft is rotated fully anti-clockwise until it locks against the ends of the toothed tracks.

At this point the HDU base plate and shaft can be fitted, it is best to fit this without the top upper casing/cylinder so that the action of the mechs can be tested.

Take the shaft of the HDU and insert this in the machined hole on the top/side of the ladder and push until it engages with the teeth on the synch shaft, you will need to ensure that the teeth are facing the right way to engage, I.E. towards you as viewed, support the synch shaft so that it is not pushed away from its position and continue to push the HDU shaft until it is fully enmeshed and has started to turn the synch shaft.

The mechs and HDU are now synchronized. Test that the mechs deploy correctly by pushing the HDU shaft all the way into the VVC ladder while supporting the synch shaft to prevent disengagement from the mechs, this should rotate the rotors of the VVC mechs in a clockwise direction in synch. When the mechs are fully deployed ensure that both cams turn evenly by a rotation or two. Now push the HDU shaft back down out of the ladder unti the mech are nearly fully retracted and so that the end of the HDU shaft is level with inner part of the cam ladder boss at the end of the shaft hole. Again check rotation of the cams. At this point the HDU shaft should be enmeshed with the pinion on the synch shaft and the two mechs should be nearly fully retracted.

Turn both VVC cams so that their lobes are pointing away from where the followers will be when fitted (lobes pointing down as viewed), fit the exhaust cam into the ladder with new oil seals. Apply Loctite 574 or similar anaerobic sealant to the appropriate ladder surfaces and the ladder is then ready to fit. After fitting, don’t forget to do up all of the mech. securing bolts once the ladder is in place. The mechs can be leaned away from the ladder a little to allow them to slip down the side of the head as the ladder is fitted.

Job done..
 

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Hi everyone,

I am new to the forum and write from Spain. I have a Rover 200 BRM. The car is in the shop repairing the head gasket, rectifying valves and seats. Also you are putting rail oil.

The mechanic does not know how to mount the VVC mechanism. Do you have a picture of a synchronized?

And finally do not know if you can give me some advice

Thanks to all
 

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What is the relevance of the 'notch' in the sync shaft. I've read that this should be aligned with the mating surface of the carrier when the mechanisms are timed up. Is it not a uniform tooth pattern?
 

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mgf
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Interesting stuff. I am new to this forum so you may have already answered this before, I'm sorry.

I have a VVC MGF. It seams slower that one I have a few years ago. Does anyone know how I can test the VVC is actually functioning?

I have identified the following problems :-

The front radiator fan was not working. So far fuse in foot well, relay replaced. The car still does not turn on the fan. Disconnecting the temp sensor brings the fan on, due to sensor fault. putting a 100 ohm resistor across the plug (about 110C i think) brings the fan on. 1K ohm keeps fan off. with 1K resistor car is still not as quick as I think it should be. Temp gauge never reads above half, even when car is boiling up. Both sensors are currently removed for testing.

Does the coolant temp turn the VVC off if too hot or cold?

Thanks

Richard
 

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mgf
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Update:

I have fixed the fan problem. The header tank cap was faulty and was not pressurising the water system. As the fan comes on at 102C the car boiled up at 100C. Fixed the cap and the fan now comes on.

I would still like to know how the check if the VVC is functioning ?

Richard
 

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Update:

I have fixed the fan problem. The header tank cap was faulty and was not pressurising the water system. As the fan comes on at 102C the car boiled up at 100C. Fixed the cap and the fan now comes on.

I would still like to know how the check if the VVC is functioning ?

Richard
If its not working you should have lack of power and a trouble code sorted :)
 
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