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Camshaft installation

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Advice please!

Hi all,

I'm rebuilding my head whilst the car is in the paintshop. Important to note that the head is off the engine block, which I'm yet to rebuild.

Ive fitted valves, new springs, seals, tappet buckets etc, and am trying to fit the camshaft. All valves are in their closed position, with the collects holding them in place.

Problem Ive got is that the camshaft doesn't not sit snugly in the head bearings - even when the timing mark on the sprocket is in the correct position. I've rotated the shaft through 360 degrees and at any given position there is at least 1 or 2 of the cams in contact with the tappets/shims preventing the camshaft 'seating' into the bearings.

Is this normal? Is it common practice to tighten the shaft down forcing a valve or two open? Doesn't seem right to me, but I could well be wrong. I'm told that this was common practice on some older Jaguar engines, but I've also read that any lateral pressure on the shaft creates risk of damage. Im also pretty confident (never 100% confident - first real rebuild!) that when I took the camshaft off there wasn't any pressure between the tappets/shims/cams - again, this could be my memory playing up.

Let me know if photos would help, if the above isn't clear.

Appreciate any advice!

Thanks








 

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...or should the camshaft not be re-installed until the head is fitted back onto the rebuilt block, so that the crank timing is set and subsequently some of the valves are open, allowing the camshaft to sit in the head bearings?

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When you are doing a head make sure that it isn't flat on a bench or table, use blocks of wood between the bench and the head to allow the valves to move to the proper location to the cam as the cam is at various angles that the valves need to be in whilst you are tightening the caps.

If you tighten the caps with the valves flat on a bench they can't move about as you are lowering the can and tightening it also don't work from one end to the other do it ziggy zag from the middle to the out side equally down a little at a time until they are all seated correctly.

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Where are my DIY Links?

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The short answer is - that's normal.
As Briano has said, put the head on the some blocks to allow the valves to open, and tighten in a similar pattern to how you do the head bolts - a bit at a time to try and keep even pressure. Get some assembly paste or engine oil on the bearing faces as well. Don't over-torque the nuts either, they don't have to be that tight.

My rebuild thread I will try and keep up to date: here

K-Jet fuel pressure test guage How-To

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Just checked, torque is 20Nm

My rebuild thread I will try and keep up to date: here

K-Jet fuel pressure test guage How-To

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Great thanks guys.

So presumably I should try and keep the camshaft as horizontal as possible throughout the whole process and start tightening at the 1 or 2 locations where the cams are in contact with the tappets. Then when the shaft is more or less fully seated (i.e. the relevant valves are open) I then tighten up following the zig-zag pattern?

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Now installed :thumbs:
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