timing chain options

Seight-V8 · Post by **Seight-V8** » Sat Apr 05, 2008 10:10 am

hiya all,

What are my timing chain options, with the 4.6 efi gems engine.

I know it has a camshaft sensor in the front cover, so presuming it takes its timing from the camshaft chain wheel.

So does this mean i cannot fit a cloyes true roller set?

and that a standard only set will work.

Notice that the camshaft wheel has 4 slots in it and one larger than the others.

cheers

scott

ChrisJC · Post by **ChrisJC** » Sat Apr 05, 2008 1:04 pm

The engine gets is main timing signal from a crankshaft sensor reading the flywheel. And given that it's a wasted spark ignition system, I don't know what the camshaft sensor is for.

Have you tried to run the engine with it disconnected?

Chris.

Wotland · Post by **Wotland** » Sat Apr 05, 2008 1:35 pm

Sensor on the front timing cover is not for the knock sensor ?

russell_ram · Post by **russell_ram** » Sat Apr 05, 2008 1:51 pm

It's definately a cam sensor, picks up from the cam sprocket as you describe. The cam sensor is required to know which cylinder is firing - a requirement if you're going to retard individual cylinder firing events due to detecting knock. The knock sensors are mounted one on each bank, half way along the block behind the exhaust manifold. Each bank is detected seperately. Should run perfectly ok without the sensor working but you'll lose knock protection and most likely put the MIL light on.

Not aware of any off the aftermarket sprokets that incorporate the cam sensor feature, so you're probably restricted to the OE sprocket and chain. To be fair, chain/sprocket wear is normally only an issue on very high mileage engines.

Russ

RoverP6B · Post by **RoverP6B** » Sun Apr 06, 2008 12:13 am

The knock sensor is fitted into the lower RHS of the block, facing the engine. If I recall correctly, it is close to a core plug.

Ron.

jrv8 · Post by **jrv8** » Sun Apr 06, 2008 9:27 am

RoverP6B wrote:The knock sensor is fitted into the lower RHS of the block, facing the engine. If I recall correctly, it is close to a core plug.

Ron.

Ron,
Have to argue with that one.
They are located close to the core plugs, but as stated on the previous post, there's one on each side of the engine.
Jim

RoverP6B · Post by **RoverP6B** » Mon Apr 07, 2008 9:38 am

Hello Jim,

Thanks for that. I only thought that there was one, having only seen one, but now I know there is two, excellent!

Kind regards Ron.

4.6 MGBegun · Post by **4.6 MGBegun** » Mon Apr 07, 2008 7:34 pm

Scott,
From my understanding the GEMS engine runs a true sequential fuel injection system which requires the cam sensor to time the injection pulses for each cylinder, unlike the older Hot Wire systems which use batch fired injectors. Unless you are going to switch to a carbureted intake or an older injection system I would think you need to retain the sensor.

Seight-V8 · Post by **Seight-V8** » Tue Apr 08, 2008 9:04 pm

thanks for all the replies.

Looks like a standard sprocket & chain....no problem as they are much cheaper than the double rollers anyway.

Just trying to get an idea of what i need to get my 4.6 block to half engine stage.

Still unsure wether it will be gems or aftermarket ecu at this stage....but would like to keep the sensor just in case i go either way.

At least its at the front of the engine and fairly easy to change if i need to.

scott