TDC & Different Head Gasket
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From: CA
TDC & Different Head Gasket
I am pulling my heads soon and I bought one Felpro gasket. If I was only the passenger side head can I determine TDC by piston position on that side? Also, since one gasket is stock and the other will be a Felpro gasket with the slight different in engine compression effect the engine at all?
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From: Little Rock, AR
When #6 is all the way at the top, look at the lifters/cam lobes. Compare them to #1 and you should be able to tell if it is #6 or #1. You really don't need to worry about TDC unless you are pulling the opti or timing chain.
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I had problems with a misaligned harmonic balancer that a shop fixed. Since I was pulling the head I just wanted to make sure it was done correctly because I think it's off a few degrees.
So when piston #6 is all the way up it's at TDC? Does that mean piston 6 and 1 are at TDC at the same time?
So when piston #6 is all the way up it's at TDC? Does that mean piston 6 and 1 are at TDC at the same time?
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Joined: Dec 1969
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From: Little Rock, AR
Originally posted by DjArcadian
I had problems with a misaligned harmonic balancer that a shop fixed. Since I was pulling the head I just wanted to make sure it was done correctly because I think it's off a few degrees.
So when piston #6 is all the way up it's at TDC? Does that mean piston 6 and 1 are at TDC at the same time?
I had problems with a misaligned harmonic balancer that a shop fixed. Since I was pulling the head I just wanted to make sure it was done correctly because I think it's off a few degrees.
So when piston #6 is all the way up it's at TDC? Does that mean piston 6 and 1 are at TDC at the same time?
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Joined: Apr 2002
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From: AL
As shoebox said #1 and #6 are up at the same time. The cam determines which cyl. is at tdc, When the crank dot is at 12 o'clock and the cam dot is at 6 o'clock that is #6 TDC. You turn the crank 360* clockwise and the crank dot is back at 12 o'clock but the cam dot is at 12 o'clock also that is #1 TDC.
I just felt like typing that, dunno why.
I just felt like typing that, dunno why.
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From: CA
Are you saying that TDC is not actually determined by the position of the piston but the position of the CAM? So if I have the heads off my car and see the piston at the top that doesn't mean that it's actually at TDC?
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Joined: Jul 2003
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From: Indianola, MS
TDC means the pistion is on top it's compression stroke. Both valves closed. When #1 piston is at it's upmost travel, so will #6. TDC is determined by the cam. Lke shoebox said, look at the lifters/cam lobes.
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From: Hell was full so they sent me to NJ
Originally posted by DjArcadian
I had problems with a misaligned harmonic balancer that a shop fixed.
I had problems with a misaligned harmonic balancer that a shop fixed.
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From: CA
Originally posted by Injuneer
Its a "damper", not a balancer. Position on the crank isn't critical. If it was, they would have put a keyway in the damper hub to match the one in the crank, and installed a key.
Its a "damper", not a balancer. Position on the crank isn't critical. If it was, they would have put a keyway in the damper hub to match the one in the crank, and installed a key.
It is a bonehead design flaw with GM not equipping the crank with a keyway though.
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From: Hell was full so they sent me to NJ
I'm familiar with the holes, but the tolerance is on the order of 90degrees:
HUB AND BALANCER
The balancer is a two-piece assembly with a pulley that bolts onto the hub. Separating the two made it easier to install the Optispark distributor on the assembly line and out in the field. The holes in the hub are offset, so the balancer only fits on it one way, but there’s no keyway in the hub to index the hub on the crank. This shouldn’t be a problem unless the damper was drilled at the factory to "trim" the final engine assembly.
If it was drilled a lot to compensate for an engine that was out of balance, you could end up with a shaker, depending on how everything stacked up with the remanufactured engine compared to the original engine. If you encounter a balance problem on a remanufactured LT1, try rotating the balancer assembly on the crank 90° at a time to see if it eliminates the problem.
The balancer is a two-piece assembly with a pulley that bolts onto the hub. Separating the two made it easier to install the Optispark distributor on the assembly line and out in the field. The holes in the hub are offset, so the balancer only fits on it one way, but there’s no keyway in the hub to index the hub on the crank. This shouldn’t be a problem unless the damper was drilled at the factory to "trim" the final engine assembly.
If it was drilled a lot to compensate for an engine that was out of balance, you could end up with a shaker, depending on how everything stacked up with the remanufactured engine compared to the original engine. If you encounter a balance problem on a remanufactured LT1, try rotating the balancer assembly on the crank 90° at a time to see if it eliminates the problem.
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