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MG MGF Technical - VVC Cambolt Saga

Hi all.

So much has happen since my last report that I don't really know how to start.

As you know my '99 VVC front cambolt has become loose.
As a result the engine stopped working properly.

As a first approach to the problem I vowed not to take the engine head off. I was feeling confident that no valves had been bent.

Here goes at I've done so far:

I took off the engine top cover and camshaft carrier. After a throughout inspection all the camshafts and tappets were in excellent order.

The locating pin between VVC unit and front inlet pulley had sheared. I bought a new pulley (cheap). First part came with a defective finishing, had to return it and a new one was delivered. Well...
I removed the VVC and took it apart. The manual specifically tells you not to do so, but it was the only way to correct the damaged VVC face that mates the pulley. (sorry about the English...).
Well that part is attached to the VVC bearing. It was slightly machined and now is perfect.
The first real problem came assembling the VVC unit back together. As you know there isn't any written information about this! But if I understand it properly, there's only one way to do it right! Bear in mind that my engine didn't start yet, so I've got no proof that that was done properly. However, you've got 4 steel "cubes" and 2 round eccentric wheels. The camshaft connects to 2 of these cubes, while the VVC bearing connects to the other two. These cubes move on slots on the eccentrice wheels. I assumed that these 4 cubes are all of the same dimensions. I compared all 4 and I found no reason why I shouldn't. The tolerances are VERY tight. I've got pictures of everything. I don't think I can be wrong, but I'm open to comments.

After that you must synchronise the front VVC with the back. This last item I knew for sure that was in working condition. The key here is to engaged the front unit on the exact same tooth as the back one is engaged to the VVC shaft that runs through the camshaft carrier. Then you assemble the camshaft carrier back together. 32 bolts!
Then you should rotate the shaft clockwise as viewed from the front and engage the hydraulic control unit on the first tooth. I had serious problems fitting this unit. Meaning that I found out to be impossible to remove or install the hydraulic control unit with the camshaft carrier on. It fouls the bodywork! The workshop manual is written for this type of engine, not specifically for the MGF!!! However you can't assemble it outside together with the camshaft carrier, as this unit conceals one of the 32 bolts that you need to tighten to install the carrier...
I had to first fit it unbolted. Then rotate it to allow fitting of camshaft carrier and then align it properly and tighten it down.
Rest is pretty much done following the Engine workshop manual. However I didn't change all the seals the manual tells you to. Some of them were exactly as new so I just dry install the old ones. Not wise some will say... But in my opinion it is way exagerated to use all these consummables.

You should pay attention to 2 slots on the camshaft carrier that tell you that both VVC units are synchronised. Then use compressed air through the oil transmitter hole to press the hydraulic control unit to it's full extended position.

Setting the timing is no problem. The main problem is really the AWFUL access that this car offers to the engine. Tensioner Allen bolt and so on... :(

I had also problems fitting the timing belt. If you go exactly per manual I found it impossible. I had to remove the tensioner back plate spring and then it was easy.

In the end after all this I made a compression test and... surprise!! No compression on 1st and 2nd combustion chambers. Valves are bent, meaning head will come off. :(

In the process I will change the head gasket and dowels for the new items. Does these items come in a kit together with all the necessary top end gaskets??
The job was done in my garage so far, but from now on will be done by me and a friend mechanic that is an expert in BDA/G/X racing engines. He is a top guy. No way in hell my car is going to MG/Rover they are so incompetent that I don't have words to describe it!

I'm also thinking in upgrading my inlet valves for the 1mm wider Paul Ivey ones. Any experiences anybody?

Any doubts please feel free to "annoy" me. :)

I'll keep you posted.

Valter.
Valter

The 'head set' includes seals for the cams, valves, exhaust and inlent maifold and the head, only thing it doesn't is the bolts
Will Munns

Nice work Valter ! A pity that despite all effort you still have to take off the head...
The re-inforced headgasket from Mike comes with the steel dowels,and I think that the standard Rover item does as well.
When the head is off there is some minor work that can be done to the waterways for better smoother flow as well as the usual light porting and change for new valves. Let us know how you get on, pictures will of course be wellcome.
Nice to see that I am not the only one that had a fight with the 8mm Allen tensioner bolt ;O)

BR, Carl.
Carl

Carl,

My Facon 8mm allen tool fouls the bodywork by just 1mm... It was a nightmare. In the end I had to cut one old allen tool and insert it on a 8mm dinamometer spanner...

Valter.
Valter

Valter, bad news about the valves on cylinders 1&2. Perhaps not all that surprising, but bad news nonetheless. But great stuff on the DIY VVC cam work! :o) Pulling the head off will be a piece of cake in comparison!

Paul Ivey valves are a good idea - but if you are going for over sized items, you're going to need to cut the valve seat to match. And if you are going to that trouble, then you might as well port the head as well...

What's your thoughts on upgrading?
Rob Bell

Valter, the bearing in the VVC is the mount for the cam wheel and there are about 75 different sizes of this bearing as each is matched to the housing which is not made to one size, weird I know but true and makes rebuilding these units a nightmare. The 'cubes' you refer to must be fitted back in exactly the same position and orientation in which they were assembled.You may have measured them and found them to 'appear' the same size bit they are critically checked down to a few microns and the slot they fit in is actually a taper and the fit is checked at a certain position in the taper. This information was given to me by the manufacturers and the checking equipment and specifications/tolerances of these parts haven't been revealed by them. The VVC units will probably work OK, providing you have reassembled them in the correct sequence but if you have jumbled up some of the components that 'appear' to be the same then you may find them a bit noiser than before. REC valves are very good quality and will flow better at higher RPM , standard valves can be reshaped easily asd as they sit less critically on the seat, i.e. position then potentially are 'easier' to get right. If you have a man who can cut the seats absolutely 'cock' on and get the valve height right then you may see an advantage in using them.
Good luck with the head.
Mike.
mike

Rob,

I'll give Paul Ivey a call. I can mild port the head including water passages with a high rpm tool. I've got a fellow here where at work that can easily machine the valve seats for me. For free! I know that I can still use the original seats, but will I have to take them out of the head or can they be reshapped "in situ"?

Mike,

Thanks a lot for the comments. I'm using the same bearing and same housing, so afaik I think I'll be ok in this matter. However, one of the cubes didn't fit the slot. Had to rearrange the order of 2 of them... I paid special attention to cleaning when rebuilding the unit. FODs is the worst you can have in these occasions. I manually tested their movement throughout the slots/tapers and they go smoothly. I hope it will work. Fingers crossed...

Cheers,

Valter.
Valter

Head is now off.

Access is a nightmare, but an electric elevator is the perfect tool! Car goes up and down as required and the job is a lot easier.

the damaged 4 inlet valves are removed. At a first glance on damaged was done to pistons, cylinder liners or head. Head gasket was in a perfect condition! Head bolts are also perfect in dimension.

Paul Ivey from REC is out of stock on the VVC big valves. Probably 3 more weeks delivery time... :(
I miss the F. So, the question is: will I wait one more month to upgrade the F, or will I assemble it back together asap with original items?

One thing that drives you crazy is the black plastic items that enclose and protect the timing belt. They are not easy to take out. Many hidden bolts... I'm almost tempted to remove this items for good. Competition cars don't use them... :)

Valter.
Valter

I would use standard valves and reshape them (also check the guides haven't cracked), they will flow sufficient for the standard set up. Seats have to be reshaped in-situ! The plastic cam cover should not have to come out, only the outer cover which IMO should always be replaced to keep the dirt and dust out. I have seen cam wheels/belts worn out by the dirt when these have been left off.Good luck.
mike.

Thanks once again Mike.

Yes, you're right that inner plastic item didn't came off. However I had to slacken the bolts holding together.

No cracks on the guides after a througout inspection.
I'm also being very, very careful with the liners, so they cannot move when the head is off.

I will at least improve water openings on the head as per Dave Andrews instructions.

Valter.
Valter

This thread was discussed between 17/03/2005 and 23/03/2005

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