How far out can the Twinspark timing be? - Alfa Romeo Forum
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(Post Link) post #1 of 11 Old 19-05-09 Thread Starter
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How far out can the Twinspark timing be?

I have checked the timing on my GTV and found it to be 2 teeth out.

https://www.alfaowner.com/Forum/just-...ml#post2649917

The question is, is this enough to have caused valve damage? Thanks in advance, Mitch.
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Re: How far out can the Twinspark timing be?

I think you'll get away with that. The valves don't stay open for long.

In your close-up picture of the camlocks, the cams would have to be pretty much 180 degrees further round for them to be hit by the piston.
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Re: How far out can the Twinspark timing be?

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Originally Posted by iainfm View Post
I think you'll get away with that. The valves don't stay open for long.

In your close-up picture of the camlocks, the cams would have to be pretty much 180 degrees further round for them to be hit by the piston.
I think you may have got away with it, however there isn't much clearance between valves and pistons. There are cutouts on the pistons to make a bit more clearance.

The Valves and pistons may not be colliding in that position, but as the cams turn half as fast as the crank there may be other parts of the engines cycle where they are a lot closer together.
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(Post Link) post #4 of 11 Old 13-06-09 Thread Starter
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Just to update this thread in case anyone wants to know. Inlet valves are damaged. 2 teeth bad
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did oyu do a compression check or remove the heads?
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Removed the cam shaft ready to fit the new variator and several the followers stayed down.
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Quote:
Originally Posted by Mitch166 View Post
Removed the cam shaft ready to fit the new variator and several the followers stayed down.
This might sound daft, but they are hydraulic, won't they stay down if they are empty of oil?
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no, they still have springs in them. the hydraulics are only there to soak up the free play, which is measured in tenths of a mm...
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I'm really quite surprised it's done that much damage. Have you tried taking the followers out and seeing where the valves are...or even swapping a 'low' follower for a 'high' one?

The followers are only held in by gravity/suction once the camshafts are off...
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Quote:
Originally Posted by Cuore_Sportivo_155 View Post
no, they still have springs in them. the hydraulics are only there to soak up the free play, which is measured in tenths of a mm...
Ahhh I see,

Cheers for that.
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(Post Link) post #11 of 11 Old 16-06-09 Thread Starter
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You can see how far in they are here

https://www.alfaowner.com/Forum/just-...project-2.html

Made a start at removing the head today, just the head bolts to go now. Wil update the thread when it's off!
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