The V8 Owners Forum -

Hi guys,
I found top dead centre by inserting a depth dial gauge down cylinder no.1, and looking at the timing marks on the front pulley it was showing 2 degrees after TDC.
My questions are should i mark this as the new TDC and as its the first time I'm about to start the engine after its rebuild should this be where the engine needs to be or should it be 2 degrees BTDC?
Cheers
Paul

I just use a modified spark plug which has a small lenght of steel rod welded onto the end which protrudes about 20mm. I rotate the engine until no1 piston hits the TDC tool and then mark the crank pulley. I then rotate in the opposite direction until no1 piston hits the TDC tool and mark the pulley. The mid point between these two marks is the true TDC for this engine.

mgbv8 wrote:I just use a modified spark plug which has a small lenght of steel rod welded onto the end which protrudes about 20mm. I rotate the engine until no1 piston hits the TDC tool and then mark the crank pulley. I then rotate in the opposite direction until no1 piston hits the TDC tool and mark the pulley. The mid point between these two marks is the true TDC for this engine.

That's what I did



Break the old ceramics off, put a bolt through, then grind the nut down so it fits inside the thread, and round the bottom of the bolt off - don't want any nasty scratches on yer pistons.

Using a depth gauge is OK but it is hard to judge the amount of 'dwell' that the piston will have at TDC. Using the piston dead stop method gets around this issue. If the heads are not yet fitted you can use a steel bar bolted across the bore with the head bolts, the bar should have a bolt sticking out of the middle of it so that it hits the piston. Some people have pointed out that you could still get an error with the dead stop method due to the big end bearing clearance but personally I think that this error would be too small to measure.

Richard P6 wrote:

mgbv8 wrote:I just use a modified spark plug which has a small lenght of steel rod welded onto the end which protrudes about 20mm. I rotate the engine until no1 piston hits the TDC tool and then mark the crank pulley. I then rotate in the opposite direction until no1 piston hits the TDC tool and mark the pulley. The mid point between these two marks is the true TDC for this engine.

That's what I did



Break the old ceramics off, put a bolt through, then grind the nut down so it fits inside the thread, and round the bottom of the bolt off - don't want any nasty scratches on yer pistons.

That looks very like my TDC tool Rich I brazed the stub into the spark plug body to make sure it would not drop out. By far the BEST way to find TRUE TDC on any engine (new or worn) in my estimation

Perry

For sake of 2deg, I wouldnt worry too much. It's just a reference point.

When tuning etc you'll give the engine the timing it wants, not just a generic figure.

Thanks guy's really appreciate your help I've found an old spark plug will get it done Saturday. Awesome videos perry (mgbv8)

paulsv8manta wrote:Thanks guy's really appreciate your help I've found an old spark plug will get it done Saturday. Awesome videos perry (mgbv8)

Ha Ha!!
I've had some fun in the old MG for sure

Make sure that when you have fitted the stub into the old spark plug that you grind the end to a nice round dome / ball.

Spark plugs dont always sit the exact same way in each hole you you need to make sure that that the end / tip is fairly symmetrical.

Perry

paulsv8manta wrote:Thanks guy's really appreciate your help I've found an old spark plug will get it done Saturday. Awesome videos perry (mgbv8)

This thread of mine may be helpful
http://www.v8forum.co.uk/forum/viewtopi ... highlight=

Garry