northstar timing

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northstar timing

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Cadillac Forum >> General Technical Section >> Engine Specific >> Aluminum Block V8s >> northstar timing

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northstar timing - 8/19/2007 12:36:40 PM

stoveguyy

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i set #1 to TDC. crank and intermediate sprocket are at 6 and 12 o'clock. all cam sprockets are at 12 o'clock to deck surface. i pulled heads and timeserted block and put heads back on and reset tensioners. now when i turn the crank, it takes 10 revs to get back to the original starting point. i have read that it should be 7 turns, not 10. i am 99% sure nothing moved when the heads were off. yes, the sprocket dots/slots line up with the camshaft slot. everything looks good to me except for the 10 turn issue. any comments?

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RE: northstar timing - 8/20/2007 7:26:24 AM

stomper

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the ratio is determined by the number of teeth.

count the teeth on both, divide into each other , and
that will be the # of turns to return to its original point.

there is no magic to that.

(in reply to stoveguyy)

Post #: 2

RE: northstar timing - 8/20/2007 9:03:47 AM

stoveguyy

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well i don't have a "special" northstar motor. some websites say it will take 7 turns yet my motor takes 10 turns. timiing the motor is pretty critical and not open to interpretation. there is only 1 way to do it. so i expect someone to say yes or no, not it depends on how many teeth are on your sprockets. yes i can do the math but i was hoping someone who has worked on northstar motors would make a comment.

(in reply to stomper)

Post #: 3

RE: northstar timing - 8/20/2007 9:32:07 AM

stomper

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quote:

ORIGINAL: stoveguyy

well i don't have a "special" northstar motor. some websites say it will take 7 turns yet my motor takes 10 turns. timiing the motor is pretty critical and not open to interpretation. there is only 1 way to do it. so i expect someone to say yes or no, not it depends on how many teeth are on your sprockets. yes i can do the math but i was hoping someone who has worked on northstar motors would make a comment.

Last time I checked, every NortStar ever made, was a 4 cycle engine.
That means that for the CRANKSHAFT going fully around TWICE,
the CAM goes around ONCE! period ..

The CAM executes every valve movement for any given cylinder, each time around,
not 7 times, not 10 times.

I for one, have no clue what you talking about, regarding the 7 turns, 10 turns ..

I hope that helps.

4-cycle engine:

1. intake
2. compression
3. ignition & combustion
4. exhaust

Image complements of Wikipedia ..

< Message edited by stomper -- 8/20/2007 9:49:13 AM >

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(in reply to stoveguyy)

Post #: 4

RE: northstar timing - 8/24/2007 5:35:29 AM

devilleish

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SETTING THE CAMSHAFT TIMING

TOOLS REQUIRED

J 39946 Crankshaft rotation socket

J 39411 Flywheel Holder

[image]http://alldatapro.com/alldata/PRO~V18164707~C32315~R0~OB0~P3R0H~N/0/56775861/62803304/62803307/62803308/34853741/100411974/34853743/56492475/14452000/107602224/91147506/78361049" width=288 useMap=#NONE vspace=1 border=0>

Setting the camshaft timing is necessary whenever the camshaft drive system has been disturbed such that the relationship between any chain and sprocket has been lost. Even when only one sprocket is involved the following procedure should be observed since one crankshaft rotation will not provide conditions where correct timing can be confirmed.

The camshafts and crankshaft events are correctly timed when the relationships shown exist. The following procedure explains how to establish this condition. Correct timing exists when the crank sprocket and the intermediate shaft sprocket have their timing marks aligned and all 4 camshaft drive pins are perpendicular (90 °) to the cylinder head surface.

Remove the following components for access:

The left camshaft cover.
The right camshaft cover.
The engine front cover.
The 3 chain tensioners.
The oil pump.

The primary and secondary chain guides should be reinstalled if previously removed.

Rotate the crankshaft (2) until the sprocket drive key (1) is at approximately the 1 o'clock position. Use the J 39946 to rotate the crankshaft (2).

Install the crankshaft and the intermediate shaft sprockets to the primary drive chain with their timing marks adjacent to each other.

Install the crank and intermediate sprocket assembly (4) over their respective shafts.

Rotate the crankshaft (2) as necessary to engage the crankshaft key (1) in the sprocket without changing the relationship of the timing marks to each other. Use the J 39946 to rotate the crankshaft (2). NOTICE: Refer to Fastener Notice in Service Precautions.

Install the intermediate sprocket retainer bolt (3). Tighten the bolt to 60 Nm (44 ft. lbs.).

Install the primary chain tensioner or release the tensioner shoe. Tighten the tensioner mounting bolts to 25 Nm (18 ft. lbs.).

Ensure the timing marks (1) are aligned vertically.

Install the J 39411 to lock the crankshaft in this position. If the engine is on a stand, an alternate method should be devised.

Route the secondary drive chain for the LH cylinder head over the inner row of intermediate shaft teeth. IMPORTANT: The RE camshaft sprocket must contain the camshaft position sensor pick-up.

Route the secondary drive chain over the chain guide and install the exhaust camshaft sprocket to the chain such that the camshaft drive pin engages the sprocket notch marked LE (left head exhaust). There should be no slack in the lower section of the chain and the camshaft drive pin must be perpendicular to the cylinder head face.

Install the intake camshaft sprocket into the chain so that the sprocket notch marked LI (left head intake) engages the camshaft drive pin while the pin remains perpendicular to the cylinder head face. A hex is cast into the camshafts behind the lobes for cylinder -1 (or -2, LH) so that an open end wrench may be used to provide minor repositioning of the camshafts.

Loosely install the exhaust camshaft sprocket retainer bolt.

Loosely install the intake camshaft sprocket retainer bolt.

Install the chain tensioner or release the tension on the shoe.

Tighten the tensioner mounting bolts to 25 Nm (18 ft. lbs.).
Tighten the camshaft sprocket bolts to 120 Nm (90 ft. lbs.).

IMPORTANT: The RE camshaft sprocket must contain the camshaft position sensor pick-up.

Route the secondary drive chain for the right side cylinder head over the outer row of the intermediate shaft teeth and repeat steps 11 through 15 for right side camshafts. Right side camshaft sprockets are identified as RI (right intake) and RE (right exhaust). In addition the RE sprocket must contain the camshaft position sensor pickup.

Ensure all timing marks are properly aligned.

Install the following components:

19.1
The oil pump.

19.2
The 3 chain tensioners.

19.3
he engine front cover.

19.4
The right camshaft cover.

19.5
The left camshaft cover.

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(in reply to stomper)

Post #: 5

RE: northstar timing - 8/24/2007 5:36:57 AM

devilleish

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For some reason, the pics did not show, even though they did in my view. This should help, though.

(in reply to devilleish)

Post #: 6

RE: northstar timing - 8/24/2007 1:16:56 PM

_X_CaddyTech

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It is fine... when i was at the cadillac dealership my last 2 years there, I was the only one to work on any engines. and it is fine.. i never even rechecked it after setting it intially. Never had one engine come back on me AT ALL

(in reply to devilleish)

Post #: 7

RE: northstar timing - 8/25/2007 5:00:58 PM

FLCaddytech

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It's never a bad idea to rotate the engine around to take up the chain slack and verify alignment.
More cams mean more opportunities to make a mistake.
I have never counted the revolutions to bring all the markes back into alignment but it is quite a few.
It sure is a lot easier with the plugs out.

Anyhow i dont feel it is important to know how many times it takes as long as everthing does line back up again. if it took 10 revs and you are not sure it's right, do it another 10. If they all come back together again you are good to go.

(in reply to _X_CaddyTech)

Post #: 8