pistons and valves contact

[promotor]

I have followed Rohan's instructions and the problem is the ex. cam, it will not turn one full revolution,
Its no.3 valve, the lobe on the cam is trying to open it, thats where the jam is.
The inlet cam will revolve fine., So the head will have to come off again

John

Is the cam lobe catching the top of the follower bore? Sometimes if you swap inlet and exhaust cam positions the lobes that cleared before will catch in the follower bore tops where the other cam once cleared OK. Have you switched cam positions over (another issue in itself in terms of keeping cams and followers matched as worn together units)?

The cam lobes aren't always exactly in the same position from one camshaft to another.

[rgh0]

I have also seen the cam catch on the sleeve if the sleeve rotates a little in the bore so the cut out does not align with the cut out in the head. If thats the case then the next question is why did the sleeve rotate.

cheers
Rohan

[checkrail]

I have finally got the cam to rotate by swapping the followers around. If you remember I lost the original position of them when I had the head on the bench, the shims have now got to be tackled again

Would you fit a complete new set of followers?
Thanks again John

[rgh0]

If you have lost the relationship between the cams and the followers then I would personally install new followers expecially if they have done significant mileage.

I swap cams on my race engines frequently and I keep a dedicated set of followers with each cam

cheers
Rohan

[2cams70]

I have finally got the cam to rotate by swapping the followers around. If you remember I lost the original position of them when I had the head on the bench, the shims have now got to be tackled again

Would you fit a complete new set of followers?
Thanks again John

What kind of camshafts is this engine running and are the inlet and exhaust camshaft the same specification?

If it's just running standard or sprint lift camshafts and standard followers you should not be having to swap followers around to gain clearance. You need to investigate further to determine the cause as to why this has been necessary.

If this engine is running some kind of oddball or unknown specification camshaft or camshafts (they may not necessarily be both the same if someone has fiddled in the past) you may wish to consider replacing these (and of course the followers as well) with something that is a known quantity. If the camshaft is unknown then the correct valve timing and valve clearances are also unknown.

When things start reaching that point it's really worth considering a complete professional rebuild of the head. That way you can be sure it's done right because there certainly are a lot of things that can go wrong!

PS. I should have said "more sure" instead of "sure" it's done right because experts can get things wrong too!

[checkrail]

The engine has QED 420 cams and springs as fitted by the PO. As I have already explained all the followers/shims have all been mixed up, hence all the problems. Previously it was running fine.

John

[alanr]

John
Unless there is significant side play in the followers or the actual face of any of followers are really worn it shouldn't be necessary to replace them on your road car.
You seem quite consumed by the fact that the shims have got mixed up. I would not try and sort out the thickness permutations from your present shims. Just start from scratch and work out what shim you need for each valve.
Personally I have a box of assorted shims accumulated over a number of years but if you don't have the appropriate thickeness shims just order from QED what thickness's you need.They are only a couple of pounds each.
I assume you have feeler gauges and a micrometer?

However I would be concerned about this No3 valve that you have identified as the problem. With say an approximate shim fitted does the valve appear to open and close ok? Or does it just jam when the cam lobe presses on the follower and it tries to open the valve?

Alan

[checkrail]

I have decided to replace the cam followers because they are not consistant when or if they jam. It,s not always no,3 that is the problem.
The engine was perfectly alright before they dropped out of the head
I could do without the expense but I don't see any alternative

John

[rgh0]

I have decided to replace the cam followers because they are not consistant when or if they jam. It,s not always no,3 that is the problem.
The engine was perfectly alright before they dropped out of the head
I could do without the expense but I don't see any alternative

John

Hi John
What do you mean by "not consistent". Have you measured them and they are different dimensions ? or is it they are not consistent in freely mving in the bores ?.

If the cam is not jamming on No 3 exhaust by hitting the head how is it now jamming ?

cheers
Rohan

[alanr]

Sorry John I tried! But I think I will now bow out of trying to help you any more...The advice given is clearly not being taken on board.

Good Luck!

Alan.

[rgh0]

Hi John

Potentially you have a mix of followers and sleeves in the head that are either standard or overbore size and with the followers dropping out of the head and being mixed up it means some followers that are oversize are jamming in standard bores or standard followers are tilting and jamming in oversize bores. You need precision measuring equipment to determine if this is the case. Do you have an accurate micrometer or a digital calliper to measure the followers diameter with or can borrow them from someone? This is a starting point to determine how to set up the followers in the head

cheers
Rohan

[Hawksfield]

Hi
Something that gave concern on the first post is the statement "I stood the head on its end and the tappets came tumbling out" I am no expert and only worked on two twin cams but never found the cam followers fall out. even if upside down, maybe left for a couple of days.
The fit is quite close and any oil tends to stick causing stiction. they must be a really sloppy fit, I normally have to use a suction grinding tool to get then out.
This indicates what Rohan and others have intermated there is a mismatch of sleeves and followers with different sizes. Clearly checkrail must put it in the hands of someone who can fully measure all the parts and make report on a solution.

I have read all your posts and you are not trying to help yourself. Think again before you do serious damage!

[HCA]

Just did a surf and see there is a huge 'Lotus Drivers Club' in Lincoln where you live. They are on Fessbook. There is one keen member with a Europa and I am sure others. Why not send them a line and ask for assistance from someone. I bet you could have someone around the next day...

[checkrail]

Thanks very much for all your replies, I've had a good examine of the followers and they are lightly scratched all the way round. When they are in the head you can push them round with your fingers, I have smeared them with Graphogen and you need a rubber suction to remove them. I've managed to get the ex. cam to rotate round and round on its own, but fixed up with the inlet cam/timing chain after a turn on the crank spanner it jams.
I have ordered a new set of followers, I don't have a digital measurer

John

[HCA]

Where were the timing marks and piston position when you connected the chain..?