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Discussion Starter #1
Hi guys!

I am installing a new camshaft 276º/112º/11 mm in my engine C30NE, that already had its head lowered in 2.0 mm. Will be that I will have problems of the valves to touch the original pistons?

Thanks!
 

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One quick way to tell is fully assemble the engine. Leave the spark plugs out and slowly rotate the engine by hand with a wrench on the front pully bolt through a few rotations. If it doesn't stop rotation from contacting internal parts then this is an inaccurate but easy method.
To do this the proper way you must go and take the head off. Put some clay on the piston tops and reassemble the engine. Then rotate the engine as stated before. Remove the head and see how much of an impression the valve made on the clay. See how much of the clay was left under the impression before you get to the piston. This will give you an accurate idea of the space that will be there during running of the engine.
This is a very simplistic answer and if you do a search in this site you might find more detailed description of this proceedure.
Read as much as you can on this proceedure and learn from it or let a pro do it but it is important to do it as you have cut the head down some.
Good luck, Mike
 

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Opel Rallier since 1977
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1,705 Posts
Hi,

This is a very general answer to your question:

11 mm is a significant amount of valve lift, and shaving the head by 2mm is serious too. It is not a good idea at all to assemble the engine and to fail to perform the test that is listed above with the clay on the pistons. Unless someone has done these exact same engine modifcations, and can tell you the results, you are taking a big chance of damage, in my opinion.

If you want someone to be able to give an accurate answer, you need to also list the camshaft timing (advanced or retarded) that you plan to use. But even if someone says they have done this with the same parts and modifications, I would not assemlbe the engine without performing the test with the clay. Turn the engine very slowly by hand to do this test, and be ready to stop if any strong resistance is felt. People ususally install very light temporary valve springs to do this test.

Clay and valves on one cylinder should be sufficient for this check. It is often recommended that you want 0.100" (2.5mm) of minimum clearance between the valves and piston tops. Something less may be OK if you are not revving the engine, but clearance < 2 mm is not considered wise, and a clearance of 1.5 mm is only for experienced engine builders.

Regards,
Mark B.
 

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Old Opeler
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5,564 Posts
First ....

Before you bolt the head on and turn the motor over you have to be very certain that the valves will NOT touch the pistons.

FIRST set piston #1 at top dead centre then place some bits of modeling clay, about 4m thick, on top of the piston. Now with a used cylinder head gasket place the head gently onto the motor with the valves on that cylinder at split overlap (ie: both intake and exhaust slightly open just as they would be at top dead centre at the end of the exhaust stoke).

Do not bolt the head down - for if the valves do touch the piston they WILL be bent if the head bolts are tightened. DO NOT rotate the crankshaft or cam!

Now lift the head off and check the thicknes of the clay between the piston and the lower edge of the valves. You should have no less than 2mm clearance for the intake and 2.5mm for the exhaust valve. If the place the valves touch the clay is thinner than that or the valves touch the pistons then you need to make the valve notches in the pistons deeper.

This is not exact as the valves may be slightly closer to the pistons a little each side of top dead centre. So, leave the clay on top of ALL the pistons if there is enough clearance, replace the head and connect up the cam chain. Once again DO NOT use the head bolts so that if a valve does touch a piston the head will be lifted - hopefully the weight of the head will not bend a valve. Now rotate the crankshaft two full turns while carefully watching and feeling to see if a valve contacts a piston. If the head lifts or you feel contact STOP! Lift the head off and examine the thickness of the clay to find the close valve.

A couple of head bolts loosely threaded into the block will locate the cylinder head - though there is usually a couple of dowels in the block face to do that.

NOTE: The clay must only be placed in the area of the valve notches in the piston so that it fits up into the combustion chamber NOT under the quench area where the piston gets close to the flat surface of the head. The picture below shows a bit much clay (actually orange PlayDough on "Thumper's" pop-up pistons!) except on cylunder #2.
 

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Hi guys!

I am installing a new camshaft 276º/112º/11 mm in my engine C30NE, that already had its head lowered in 2.0 mm. Will be that I will have problems of the valves to touch the original pistons?

Thanks!
Hi guys!

I am installing a new camshaft 276º/112º/11 mm in my engine C30NE, that already had its head lowered in 2.0 mm. Will be that I will have problems of the valves to touch the original pistons?

Thanks!
Hi how do I remove the camshaft on my c30ne head?
 

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It depends.
1) If the head is loose on a bench, just unbolt the rockers, take out the lifters and take off the small cover in front of the head. Now the cam can be pulled out. Be careful so you don't nick the cam journals or bearings.
2) If the head is bolted on a loose engine, cut the timing chain and unbolt the cam gear(be careful not to drop the chain in the cover) and repeat the above, after that unbolt head bolts number 1 2 and 3 on the plug side seen from the front and pull out the cam.
3) If the engine is still in a car, depending on model, unbolt the engine mounts and rise the engine with a jack or by some other means until the head is high up enough to let the cam slide out without hitting the radiator or other parts. The rest like above in version 2).
opel, senator, monza, omega
 

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It depends.
1) If the head is loose on a bench, just unbolt the rockers, take out the lifters and take off the small cover in front of the head. Now the cam can be pulled out. Be careful so you don't nick the cam journals or bearings.
2) If the head is bolted on a loose engine, cut the timing chain and unbolt the cam gear(be careful not to drop the chain in the cover) and repeat the above, after that unbolt head bolts number 1 2 and 3 on the plug side seen from the front and pull out the cam.
3) If the engine is still in a car, depending on model, unbolt the engine mounts and rise the engine with a jack or by some other means until the head is high up enough to let the cam slide out without hitting the radiator or other parts. The rest like above in version 2).
opel, senator, monza, omega
Thanks alot it really helped and it out
 
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