Is it automatically TDC if I turn my crankcase pulley mark to the 0 on the timing marker, or do I need to do the "compression" check??
Thanks
d

On a small or big block chevy TDC could be #1 or#6 on firing on that cylinder. So if you are looking for TDC for installing a distributor yes you need to check for compression coming up on the stroke.


Dave

Thanks.
I did the compression check, and stopped where I felt the compression blow my finger off of the spark plug. This happened in the same postion as I checked it a few times.
My question is this; shouldn't the marker on the pulley be at 0?
Mine is at around 14* before tdc.
Thanks.
d

d,
Mechanically TDC should theoretically be at zero. When the pressure builds in the #1 cylinder as you rotate the crank clockwise, you should bring the timing mark to zero and that should be TDC.

OK, felt for compression and now the distributor wont drop, no matter what I try I can not get it to drop all the way. Any ideas??
d

You are probably engaged on the dist gear, but not the oil pump driveshaft.

If you have a large, wide blade and long, screwdriver drop it down the distributor hole and turn the oil pump shaft. Look at the bottom of the distributor, you'll see a pin across the bottom of the opening. Figure out which angle it is at when you drop in the distributor. Use the screwdriver to align the oil pump shaft. Once you get it close the distributor should drop in.

You can also crank the engine over by hand and the distributor will drop when it's aligned with the pump shaft. Then back the engine up to TDC again and make sure rotor is pointing to #1 wire.

EDIT: You did continue to TDC after feeling pressure in the spark plug hole, correct? Compression starts building as piston moves up in the compression stroke after both valves have closed. TDC is the very end of the compression stroke, not the beginning.

To seat the distributor, hold it down while someone hits the starter. If the gears are meshed it will stay meshed until it drops down on the oil pump shaft.

Thanks for all of the help. After I felt the compression I ended up turning the crank back to around 18* btdc. The distributor went right in. When I checked the timing after starting the car (at temp) it was 6* btdc. Took the car out for a ride - no backfire, no pinging, it never ran better, tons more power, idle is around 750, real smooth.
Because I did not take the timing mark to 0 after finding the compression on the #1 plug could I be damamging something?
d

No you won't damage anything. 6* BTDC is probably not enough though, don't recall what engine you have. If it's a small block take it up to 12* BTDC and see how it runs, if a big block go 16* to 18*. It will run cooler and give better performance and gas mileage with more advance. If it pings at all then that's too much advance, take it back down. You may be able to go even more than 12* on a small block but that's a good start. All depends on your engine, compression and cam. Like I said, any ping and go easy on the engine until you can bring the timing back down, pinging is not good, bad for the engine. You want as much advance as you can without pinging.

Thanks for all of your help.
I have a small block so I will move it to 12* btdc and see how it goes.
Anyway, the application went well, thanks to all of the guidance.
d