F Engine timing/valve adjustments (1 Viewer)

[Nitro]

I am trying to remember/figure out the marks on my flywheel, there is a ball and a Line.

Is the ball TDC, and the Line 7dagrees advanced when timed?

I have a few manuals and can’t seem to make sense of it.

Then do I set the pointer on the ball or the line when setting my valves when cold? I am still going to check when running.

Cheers

 

[bhsdriller]

I believe the line is TDC and the ball is ~7 degrees before TDC

 

[Jonathan Hanson]

Bhsdriller is correct. You set the pointer on the line.

 

[Nitro]

Bhsdriller is correct. You set the pointer on the line.

Ok thanks

 

[Nitro]

I believe the line is TDC and the ball is ~7 degrees before TDC

Ok thanks

 

[Nitro]

Apologies for more questions, I’m finally able to get back to my F engine repairs. I’ll try to explain the best I can what I am doing/struggling with to understand.

I am doing valve backlash adjustments when engine isn’t running.

I set the timing marks in TDC, # 1 cylinder is off rocker, then I check/adjust Exhaust/Intake rockers following the manual instructions, then manual tells me to rotate engine 360 degrees so #6 cylinder is off rocker to make the check/adjuatments.

My question is when I turn the engine over once revolution so I can adjust #6, the #1 cylinder is off rocker still and # 6 is on rocker. I’m confused. Anyone able to make sense of this?

Apologies I am very green and trying to learn. Much appreciate any help.

Cheers

 

[charliemeyer007]

I take out all the spark plugs. When you are at TDC both valves will be loose. Adjust. Grab fan blade and pull up (or in high gear pull the rig forward until the next cylinder is at TDC adj, rinse/repeat. In the Haynes manual there is list of all the valves you can adj while #1 is at TDC, then you rotate the engine 1 revolution and do all the rest.

 

[Nitro]

I take out all the spark plugs. When you are at TDC both valves will be loose. Adjust. Grab fan blade and pull up (or in high gear pull the rig forward until the next cylinder is at TDC adj, rinse/repeat. In the Haynes manual there is list of all the valves you can adj while #1 is at TDC, then you rotate the engine 1 revolution and do all the rest.

 

[Nitro]

Yes I have the Haynes manual. I’ll have another crack at it tomorrow.

When I have pointer on TDC, then I rotate engine around to TDC again. That would be considered one revolution? Thank you for the response.

 

[charliemeyer007]

The piston comes to the top twice in a 4 cycle engine. Top Dead Center - one is at the compression stroke both valves will be loose at the adjustment ie the valves are closed/seated or there would be no compression.

I set mine on the loose end of the specs - better to hear the valves than to burn them.

 

[Pighead]

When I have pointer on TDC, then I rotate engine around to TDC again. That would be considered one revolution?

Yes,
there are two TDCs. One for #1 and one for #6 (and there associated cylinders). The camshaft rotates once for every two rotations of the crankshaft. You need to figure out which TDC you are at. There are at least half a dozen different ways to figure that out, we all have our favorite.

 

[Grayscale]

I've been there. I was off and set all kinds of valves being 360-out. I found my way out of the mess by confirming where I was with the cylinder number 4 settings on the exhaust and intake valves (only one of the two valves is open/pushed, which one, intake or exhaust?), with the flywheel's line at TDC on cylinder #1. The cam will be far one way, or it will be far the other, and it is pretty obvious on that cylinder.

The manual says that that is TDC the compression stroke. So, iiac, there is a puff of air out the spark plug hole when you rotate the crank clockwise (facing the engine fan), just before you make it to the line on the flywheel. You can hold an un-threaded spark plug in the face of the hole and it should whistle as air leaks on the compression stroke.

 

[Nitro]

The piston comes to the top twice in a 4 cycle engine. Top Dead Center - one is at the compression stroke both valves will be loose at the adjustment ie the valves are closed/seated or there would be no compression.

I set mine on the loose end of the specs - better to hear the valves than to burn them.

Cheers, Thank you for your response.

 

[Nitro]

I've been there. I was off and set all kinds of valves being 360-out. I found my way out of the mess by confirming where I was with the cylinder number 4 settings on the exhaust and intake valves (only one of the two valves is open/pushed, which one, intake or exhaust?), with the flywheel's line at TDC on cylinder #1. The cam will be far one way, or it will be far the other, and it is pretty obvious on that cylinder.

The manual says that that is TDC the compression stroke. So, iiac, there is a puff of air out the spark plug hole when you rotate the crank clockwise (facing the engine fan), just before you make it to the line on the flywheel. You can hold an un-threaded spark plug in the face of the hole and it should whistle as air leaks on the compression stroke.
View attachment 3809592

Cheers, Thank you for your response.

 

[Nitro]

Yes,
there are two TDCs. One for #1 and one for #6 (and there associated cylinders). The camshaft rotates once for every two rotations of the crankshaft. You need to figure out which TDC you are at. There are at least half a dozen different ways to figure that out, we all have our favorite.

Cheers, Thank you for your response.

 

[Nitro]

I've been there. I was off and set all kinds of valves being 360-out. I found my way out of the mess by confirming where I was with the cylinder number 4 settings on the exhaust and intake valves (only one of the two valves is open/pushed, which one, intake or exhaust?), with the flywheel's line at TDC on cylinder #1. The cam will be far one way, or it will be far the other, and it is pretty obvious on that cylinder.

Yes, I have lost where I am at on the TDC compression stroke do to having the rocker arm assembly dismantled trying to get it to stop leaking oil, I wasn’t getting oil to the top of the rocker arms on number 1 cylinder do to wear on the rocker arm shaft, rebuilt rocker arm assembly cost about 1k when/if u can find one, so I was moving around the rocker arms hoping I would get oil to the top rockers on #1, well now I’m not sure where I am at on TDC, I really don’t want to take the engine apart to look at the timing marks on the camshaft/timing gears but considering it.

Lots of learning going on. lol

Thanks again for all the support/ideas.

 

[pb4ugo]

You can put/drop the push rods in for the #1 cylinder and rotate the engine clockwise and watch them go up and down snd watch the line on the flywheel. When the intake valves' push rod goes down the next stroke will be compression, so you can rotate to the tdc mark.

 

[Nitro]

You can put/drop the push rods in for the #1 cylinder and rotate the engine clockwise and watch them go up and down snd watch the line on the flywheel. When the intake valves' push rod goes down the next stroke will be compression, so you can rotate to the tdc mark.

Sounds great, was thinking about that scooping 16in of snow. Thanks for the help.

 

[charliemeyer007]

The rotor bug will be pointing at #4 spark plug at the compression TDC of #1 unless you pulled the dizzy.

 

[pb4ugo]

The rotor bug will be pointing at #4 spark plug at the compression TDC of #1 unless you pulled the dizzy.

Or unless it was previously installed wrong.