Does my engine have to be at TDC to change the timing set?

[joesregalproject]

So after I put my new Buick 350 on the engine stand for teardown, I realized the back of the crankshaft is wedged tightly against the engine stand, so tight I can't turn the crank. Now that I have the crank and cam bolts loose, and the timing cover off, I'm ready to change the timing set, except I can't turn the engine to TDC. It was a nightmare getting the engine on the stand to begin with and I really don't want to take it off and have to put it back on with some spacers are something. But Does it really need to be at TDC though? Because the gears are keyed and only go on one way, and I know the crank and can are in time with each other. Can I just pull the old one off and slip the new one on? Or is there something I'm missing or forgetting?

 

[pontiacgp]

as long as you don't move the timing gears when you replace them you won't have a problem. If you have the heads on and the valves adjust I would slack off the valve lash until there is no tension so the cam won't turn when you are removing the timing hear set. I would make a mark on the block where the dimple on the cam gear is and on the block where the key is on the crank gear so you can make sure nothing moved

 

[lilbowtie]

Take the time and do it right !!

 

[87BlazeLS]

I would back off the mounting bolts to the engine stand on the lower first and install a large
washer or two between the block and stand finger. do the same to all on the bottom and
Retighten and then back off the upper ones the same way and install the washers until you
are clear. Washers are cheap. Even longer bolts that hold your block to the stand are cheap.
The cost of getting it wrong ! A do over or something ugly broken.

Consider this the engine was designed to have the timing gear set removed when at TDC on #1.
There are reasons for this.

 

[pontiacgp]

the timing mark on the cam gear and the key way on the crank gear are required to set them up when the engine is being assembled with number 1 at TDC. When changing the timing gears you just need to make sure nothing moves and they are set up like the old gears. .

 

[87BlazeLS]

sure I get that, But nothing will move if it's at TDC # 1. It's designed that way for replacement
without locking anything down from moving. You can also remove the plugs so no compression
is at work to keep things in place. ( Easier to turn over) Other methods too but the same outcome is fairly simple.

 

[pontiacgp]

sure I get that, But nothing will move if it's at TDC # 1. It's designed that way for replacement
without locking anything down from moving. You can also remove the plugs so no compression
is at work to keep things in place. ( Easier to turn over) Other methods too but the same outcome is fairly simple.

how does putting it at TDC prevent anything from turning?..It is not designed that way to replace the gears. How many engines have you put together?..in his case the crank will not turn due to the flex plate and it is easy to maintain the position of the cam.

 

[lilbowtie]

As I said earlier take the time and do it right. Not that you can't do it but God knows how much slop is in the old timing chain and you have no way to verify it is right (common sense)

 

[joesregalproject]

I already have the crank bolt removed, and I was able to get the cam bolt off easily without anything turning. I already have the spark plugs out so there is no compression to worry about. The old chain has some slack on the one side, but it's almost guaranteed that a new chain will be tighter and will only fit around the gears one way. These timing chains don't have any markings or colored links so I would assume that means it can only fit one way.

 

[87BlazeLS]

Stick to dogs with rockets attached...