Camshaft timing marks 180 deg out ?

[cookie monster]

Im replacing the front crank seal on the zook (G13A) and have a possible problem in that the camshaft timing sprocket is 180 degree's out of alignment when the engine is on TDC on #1 on the compression stroke. The distributor is pointing to #1, both inlet & exhaust valves have clearance (#1) and both valves on #4 are rocking.

Do you think the sprocket is off another engine ? maybe a G13B or similar ? I am thinking this, because the timing cover has G13B writen on it.
Will the ignition timing marks moulded into the cover be the same as G13A ?
What other vehicles use the G13A engine, so I can go to pick a part and have a look, maybe an early barina or swift ?



Hoping you guys can help, as im baffled !

cheers

cookie monster

[sheps]

spin the crank one more time and use the crank timing mark. should be sweet then.

[cookie monster]

At the position the photo shows, the crank timing mark is aligned and everything is in the correct position apart from the cam sprocket marks.

The engine had had a new head fitted before we got the car and it has never seamed to rev out, the cam timing was out approx 1 tooth when i checked before disassembly.

If i spin the crank 1 revolution, it will align the cam timing mark, but the engine will not be on TDC on #1 compression stroke.

Cookie Monster

[jdk81]

If i spin the crank 1 revolution, it will align the cam timing mark, but the engine will not be on TDC on #1 compression stroke.

Cookie Monster

I think you are trying to say, the valves are in the wrong order?

Currently in the picture shown the exhaust valve should be closed or almost closed. As you turn the crank the, intake valve will open (or already be slightly open), #1 piston will move down, then intake valve will close and #1 piston will move up on the compression stroke.

Piston #4 should be fully closed currently at ignition point etc.

From your original post

If i spin the crank 1 revolution, it will align the cam timing mark, but the engine will not be on TDC on #1 compression stroke.

at camshaft 180 out of sync, It definitely appears to be ready for ignition on cylinder #1. Piston 4 is finishing the exhaust stroke, and beginning the intake stroke.
180 degree camshaft rotation will align piston 4 with TDC ignition point.

This reminds me of the barina engine my friend and I are putting in his sierra. After putting in an unkown make/model sierra camshaft (he sold his engine before realising he needed the camshaft), trying to gap the tappets guided by the manual was wrong, because after a 180 degree rotation of the camshaft the gaps on cyl 1 was much bigger, than it should have been.

Barina engine is BA, pulley/sprocket is BA, the camshaft is unknown. I would suspect the BA, and A camshafts have the little notch for the sprocket 180 degrees different.

EDIT: will go and confirm this hypothesis, will get back to you tonight. But it certainly helps explain both of our issues.

[sheps]

i could be wrong but i recon that it is on the exhaust stroke, to get the
rotor pointing to #1 you need to be at the start of the combustion stroke.

[cookie monster]

The engine is set at TDC on #1 on the compression stroke (both valves are fully closed with correct valve clearance gap).
The ignition rotor is pointing to #1 and the valves on #4 are rocking (ie exhaust closing/inlet opening).
This is the position that the cam timing should be checked at.
#1 is at the start of the combustion stroke and would have already ignited the spark plug (10 deg BTDC)

cookie

[cookie monster]

From your original post

If i spin the crank 1 revolution, it will align the cam timing mark, but the engine will not be on TDC on #1 compression stroke.

at camshaft 180 out of sync, It definitely appears to be ready for ignition on cylinder #1. Piston 4 is finishing the exhaust stroke, and beginning the intake stroke.
180 degree camshaft rotation will align piston 4 with TDC ignition point.

This reminds me of the barina engine my friend and I are putting in his sierra. After putting in an unkown make/model sierra camshaft (he sold his engine before realising he needed the camshaft), trying to gap the tappets guided by the manual was wrong, because after a 180 degree rotation of the camshaft the gaps on cyl 1 was much bigger, than it should have been.

Barina engine is BA, pulley/sprocket is BA, the camshaft is unknown. I would suspect the BA, and A camshafts have the little notch for the sprocket 180 degrees different.

EDIT: will go and confirm this hypothesis, will get back to you tonight. But it certainly helps explain both of our issues.[/quote]

I also think that this is the reason as the sprocket looks new, not 21 years old.
My only concern is that the keyway in the 'new' sprocket may not be exactly 180 deg opposite. Counting the teeth indicates that it is and im sure its the same sprocket, just the pin in the camshaft is in a different place.

cookie

[sheps]

did you try rotating the motor?

[sheps]

i just pulled the timing cover of a g13 i have and while the pulley looks different
the timing mark is opposite the pulley locating thingo like yours so i recon
your pulley is fine and you just need to turn the crank over once.
the pulley has also done at least 320000 ks

[jdk81]

Having inspected the barina engine and two cam shafts, the key etc was the same orientation.

When the hole bisected with the lines is at the top, it was tdc on piston 1 and 4 as expected. However, piston 4 was at ignition point, and piston 1 was finishing exhaust stroke, and starting intake.

We set the dizzy to fire piston 4, and everything now lines up as it should.

The little key in the camshaft and pulley/sproket when positioned at the top is where piston one fires.

[cookie monster]

Thanks for your help guys, I now understand.

It seams as though I have confused myself into believing that there is a problem, when there really isnt

I assumed that when the cam sprocket mark was inline with the cover mark, that the engine should be at TDC on #1 on the compression stroke. This is clearly false thinking as the engine is actually ready to fire #4 cylinder.
The only thing I need to ensure is that both the crank and cam sprocket marks are aligned to ensure proper cam timing.
When I check the ignition timing and valve clearances, it doesnt matter where the cam sprocket mark is pointing as long as I start at TDC on #1 compression stroke.

Hope all that makes sense, as the penny has only just dropped for me !

cheers for the help

Cookie Monster

[sheps]

it has got me in the past as well crank spins twice for the cam to spin once.

[St Jimmy]

The easiest way to find out, is to pull no1 plug out. Put screwdriver carefully in plug hole, so you can see if the piston is on tdc.Check the dissy is on tdc and the tappets are rattling, check timing marks are lined up.Then everything is sweet it will go,put a timing light on it .And Bob's your uncle

[jdk81]

I assumed that when the cam sprocket mark was inline with the cover mark, that the engine should be at TDC on #1 on the compression stroke. This is clearly false thinking as the engine is actually ready to fire #4 cylinder.

Yeah that got me as well. Common sense to me would dictate that the marks etc all line when cyl #1 is on comp stroke ready for fire.

Oh well, better off looking silly on the forum, than getting it wrong in practice and breaking something.

[cookie monster]

Zook all back together now, front crank seal replaced, timing belt replaced, radiator hoses replaced, fuel filters replaced, tappets reset, timing adjusted and carbie cleaned out. Removed the choke plate and disconnected the spring from the choke shaft.

Starts ok in the morning and definatly runs a lot better than previous. Just need to give it a good run out to check all ok.

cheers for your help

cookie monster