Compression Stroke after verifying TDC

I added FITECH efi to my car and about ready to fire it for the first time. I just verified my balancer TDC mark and it's dead on.

My question is, how do I know if I am on the compression stroke? I set the piston stop and moved cw first, marked the balancer, then went ccw and marked. Then measured in between those two marks and it's right on "0" on the balancer.

I am working on a 340 with the timing marks on the driverside. My goal is to set the motor at 15* advanced, so it will fire quickly. The pic shows the two marks and the one in the middle is TDC zero.

Thanks for the help!

back the crank up CCW ~20*, remove the #1 spark plug, disable the ignition system.
If you are by yourself;
and you have a bump starter;
then stick your finger over the hole and bump the starter.
If you are on compression stroke, it will blow your finger off.

If you do not have a bump-starter;
then find a minimum 2 ft length of hose that neatly fits in either the plug hole or the recess. Stick the other end in your mouth,loosely; then crank the piston back up with a bar in the CW direction. If you are on compression, the piston will send a shot of air into your mouth.

If you cannot find a hose;
then just plug the recess with whatever is handy, it doesn't have to seal all that well. Then crank the piston back up with a bar in the CW direction. If you are on compression, the piston will shotgun whatever you put in there, into next Tuesday.

If you cannot find a suitable projectile;
Pull the driver-side valve cover, and watch the valves as you crank the piston back up with a bar in the CW direction. If you are on compression, the valves will NOT move.

But if you have a helper;
Put him on the bar routine.

But if the helper is your wife, do not give her the keys to crank the engine. I never met a woman who could bump-start ...........no matter how many times you show her.
Instead, stick the hose in her mouth, while you crank the piston back up with a bar in the CW direction. You'll be able to tell right away if you are on the compression stroke..... Do yourself a favor; do not ask your wife for help with this particular project.

AJ/FormS said:

back the crank up CCW ~20*, remove the #1 spark plug.
If you are by yourself;
and you have a bump starter;
then stick your finger over the hole and bump the starter.
If you are on compression stroke, it will blow your finger off.

Click to expand...

Thanks! I don't have a bump starter, bit I can get a helper. So go ccw until the 20* on the balancer lines up with "0" on the timing cover?

Yup. No1 piston "coming up" will generate compression. Just like it says, "compression stroke." Stick your finger in. Other way --if you have the valve covers off, is bring it up on TDC and look at the valves. Whatever pair is closed, no1, or no6, is ready to fire

67Dart273 said:

Yup. No1 piston "coming up" will generate compression. Just like it says, "compression stroke." Stick your finger in. Other way --if you have the valve covers off, is bring it up on TDC and look at the valves. Whatever pair is closed, no1, or no6, is ready to fire

Click to expand...

That makes sense. Thank you!

If you can get a socket and breaker bar on the damper bolt from the drivers side, you can remove number one plug and only the number one plug and turn the motor clockwise by hand yourself once you are 50 or so degrees before TDC on number one (timing marks approaching numbers on the timing chain cover). As you turn the engine over you should be able to hear the air pushing out when you are on the compression stroke. If you are not on compression the rushing air sound will not be there.

After trying all the methods and getting use to the sounds the engine makes when manually rotating, I found this the simplest way and avoid taking the cover off.

And if it’s not on compression u wil have to turn the crank 1 full turn. Kim

AJ......you left off the instructions on how to bandage his finger up when he blows it off. You're slippin man!

JDMopar said:

AJ......you left off the instructions on how to bandage his finger up when he blows it off. You're slippin man!

Click to expand...

If he can find the finger in the rafters........

Ok, so I got my wife to put her finger over the 1 hole, with all the rest of the plugs in. She felt the air, but my balancer 0 mark is nowhere to be seen now.

I can spin both pushrods on the #1 cylinder, which means that both valves are closed right? I also checked #6 and one push rod spins and the other is tight and you can tell that one of them is open, based on the rocker.

So what do I do now?

plumkrazee70 said:

So what do I do now?

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First you back up and start over with a bar on the crank. When she feels the compression air coming , STOP. the piston is on the way up, and soon coming to TDC. You have to physically stick something in the hole to feel where the piston is. That something must not be made of anything that can break or lose material in the chamber I use a screwdriver with a really long shank on it. Do not use a bump-starter. On the compression stroke, you don't have valves in there to worry about. I put the tip of the screwdriver on top of the piston then lift up on the handle. As the piston rises, it will cause the handle to go down. Make small adjustments on the crank atta time, and pull the screwdriver out a lil, each time; because as the piston comes up, sooner or later it is gonna want to jam the screwdriver in there. When the piston gets to the top, there will be several degrees where nothing seems to be happening; just shoot for the mid point.
Now go look at your balancer.

You say you have a drivers side timing tab, and I can see that. The question is do you also have the matching balancer for it? By your piston stop work it would seem so, so the balancer mark should be there.
But if it's not, it may be on the passenger side, go look.
If it is then you will have to redo the piston-stop business and make a new TDC mark.
The thing is; once exact TDC is established, you can make match-marks anywhere you want to that is convenient. I have made them while laying on my back under the car cuz that was the only part of the balancer I could see. And I have on certain 70s vans, removed the doghouse, and drilled a hole in the bellhouse and made matchmarks there. You can put them anywhere. The factory chose one place up to 1969, and when the following year, they introduced a different aluminum waterpump, they had to move the timing tab to the other side.
I can see that you have the 70and up aluminum waterpump, and the 70 and up timing cover..... but from the installed pics, it is impossible to tell if you have the right 70and up balancer.
So if the mark doesn't show up, the simple answer is to make new marks. This will work just fine if the balancer is, or has been, matched to the reciprocating parts .
Since you have already done the piston-stop TDC finding method once, second time round is easy.

However, I agree something is odd; I does not matter whether you find TDC with the piston on compression or on exhaust; TDC is TDC. So that begs the question; if your mark doesn't come up on #1 DC compression then you have only three answers; #1, you were not on #1 cylinder, or #2 it was not at TDC, or #3, it moved after you marked it.

Happy hunting

BTW nice camera work

I may have been overthinking it. The piston was just starting the compression stroke. So I rotated the crank a little more and Bam there are my marks. I am shooting for 18* initial, so I set my 18* mark lines up with the 0 tab on the balancer.

I believe I have this correct.

Badaboom! nice detective work.

I just hook up a compression tester to #1 cyl. Then you can turn crank w bar and check guage when get to your mark. I noticed that you have adjustable rockers. If you can rotate push rods then you don't have any preload. Is that what you want?

if you have the valve cover off....crank engine over....watch Number one intake valve...open then close....once it is close the engine is coming up on TDC to fire.....KISS

3406pk said:

I just hook up a compression tester to #1 cyl. Then you can turn crank w bar and check guage when get to your mark. I noticed that you have adjustable rockers. If you can rotate push rods then you don't have any preload. Is that what you want?

Click to expand...

That's a good idea also. I'll have to get a set for the future. The valves were adjusted some time ago, but I am going to check them again.