TDC - BB or Line to install Distributor? (1 Viewer)

[eaj71]

Hello,

To Install a Distributor in 1980 FJ40 2f....

It has to be at TDC #1, but is the pointer at the flywheel to be a the BB 7 Deg. BTDC or on the line for TDC? for this operation

seems the FSM and other references flip flop a bit.

Also, any other cool tricks to finding TDC in a easy way is helpful

thanks
eric

 

[Living in the Past]

Believe it is at 7 deg. BTDC. Also be sure your on the compression stroke since the crank goes around twice for each time the cam makes one rotation.

 

[1911]

You want to use the 7 deg. BTDC timing mark.

The surest way to know you are on the compression stroke is to have the valve cover off and see that both valves on cylinder #1 are closed. If you don't want to take the valve cover off, then keep a thumb over the (open) #1 spark plug hole while someone else turns the engine over slowly, and you will feel the air pushing your thumb off the spark plug hole during the compression stroke.

 

[eaj71]

What do closed valves look like?

Sorry for the possible silly question

 

[eaj71]

use 7 deg btdc to install

worked great and had it on the compression stroke thanks to a balloon and valves 1&2 being loose on the head

thanks

 

[Mace]

In the end it really does not matter if you are on the compression stroke. There is plenty of adjustment by turning the Dizzy.

Glad you got it running

 

[Living in the Past]

In the end it really does not matter if you are on the compression stroke. There is plenty of adjustment by turning the Dizzy.

Not sure there is a easy 180 degrees of adjustment. Vacuum advance/retard hookup would be headed in the wrong direction. Not sure the diaphragm would have clearance from the pushrod cover. Plug wires might be a stretch too. If the rotor could go on two different ways, 180 degrees from each other it would a easy fit just pop it off and switch it.

 

[Mace]

Not sure there is a easy 180 degrees of adjustment. Vacuum advance/retard hookup would be headed in the wrong direction. Not sure the diaphragm would have clearance from the pushrod cover. Plug wires might be a stretch too. If the rotor could go on two different ways, 180 degrees from each other it would a easy fit just pop it off and switch it.

I should have explained better. It does not matter if you stab the dizzy on the bar or the BB if you are on the compression stroke. You cannot turn the Dizzy enough to deal with stabbing the Dizzy on the exhaust stroke (180 deg). However, you can move the wires around to make it work if you really need to. Also, the Vac advance or retard will always be going the right direction unless your motor spins backwards

 

[Living in the Past]

In the end it really does not matter if you are on the compression stroke. There is plenty of adjustment by turning the Dizzy.

Glad you got it running

I should have explained better. It does not matter if you stab the dizzy on the bar or the BB if you are on the compression stroke. You cannot turn the Dizzy enough to deal with stabbing the Dizzy on the exhaust stroke (180 deg). However, you can move the wires around to make it work if you really need to. Also, the Vac advance or retard will always be going the right direction unless your motor spins backwards

For the advance/retard I was talking about the physical hook up location being backwards not rotation. Stock it is toward the front. 180 degrees points toward the back. If you move the wires around on the cap it would fix that but that but that would not be fixing it by turning distributor. Not the way I would do it but will work.

You are confusing me when you say BB or bar. BB I know is the mark on the flywheel. Is the bar the pointer in the inspection hole in the bellhousing or the slot in the oil pump the end of the distributor hopefully seats all the way in? Like a lot of people I have a story about distributor and oil pump. In my case luckily didn't end badly. I think we both agree you need to know if you are on the compression stroke or exhaust when you install the distributor. Either will work just point the rotor to number 6 on the exhaust stroke.



Is this going to get me banned from Mud?

 

[Mace]

Bar is the line at actual top dead center on the flywheel. like this.

If you set the pointer on the bb or the line (bar) on the flywheel at TDC on the exhaust stroke, and install the dizzy you will be 180 deg off, but you can move the plug wires 180 deg off as well. Not that I recommend that, but it is possible.

Also, different dizzys have different means of advance, I have a stock Dizzy with no vac advance/retard. And the vac retard and advance dizzys without the external adjustment can be turned quite a bit. Again, not quite correct, but it's amazing what you can do when you don't know you can't
Heck, I just had a 70's 2F with a later big cap dizzy installed in it without replacing the side cover. It was a bit stuck

 

[Pin_Head]

As long as you get the nose of the distributor shaft engaged in the oil pump drive slot it doesn't really matter at all what the orientation is. Having oil pressure is the most important factor.

You can make it run and time properly with any dirstibutor orientation just by installing the plug wires in the proper position of the cap in the right sequence.

If you are OCD and you need to obsess about the tiny numbers on the distributor cap matching up with the actual spark plug wire, then you would need to know it is at TDC of the compression stroke for #1, in which case the rotor needs to be pointing to position #1 of the cap. This is also in the direction of spark plug #4.

Where many people screw up is forgetting that the distributor gears are helical and the rotor will turn CCW as the distributor drops down into engagement. Because of this, you need to start inserting it with the rotor pointing closer to #3 so it ends up pointing to #4 when it is in.

 

[Living in the Past]

Bar is the line at actual top dead center on the flywheel.


I just had a 70's 2F with a later big cap dizzy installed in it without replacing the side cover. It was a bit stuck

To be honest only flywheels I've worked with are the 67 and early made engines and never notice the bar for TC. I'll have to check the out.

Having the later big distributor on the early engines might help prevent it from slipping with the hand turn bolt setup that breaks easily if to try to tighten to much.

As long as you get the nose of the distributor shaft engaged in the oil pump drive slot it doesn't really matter at all what the orientation is. Having oil pressure is the most important factor.


If you are OCD and you need to obsess about the tiny numbers on the distributor cap matching up with the actual spark plug wire, then you would need to know it is at TDC of the compression stroke for #1, in which case the rotor needs to be pointing to position #1 of the cap. This is also in the direction of spark plug #4.

Where many people screw up is forgetting that the distributor gears are helical and the rotor will turn CCW as the distributor drops down into engagement. Because of this, you need to start inserting it with the rotor pointing closer to #3 so it ends up pointing to #4 when it is in.

In my case a replacement distributor I bought back in the nineties from one of the better know vendors was shorter then the one in my very early 68 model. I noticed that lack of oil pressure on the gauge right away and shut the engine off before I had any damage from a lack of oil. It did explain why I had no problem getting the distributor into the slot. Vendor took the distributor back without any problem. I have always heard that all the F engine had the same length distributor and why the replacement was different.

My wife accuses me of being OCD all the time which I don't understand. While I know this isn't rocket science just don't want to be the PO who the next owner is complaining about.

My only point here was it really matters if it's the compression or exhaust stroke when installing the distributor.

 

[Pin_Head]

My only point here was it really matters if it's the compression or exhaust stroke when installing the distributor.

It really doesn't matter much. If it won't start and run right away, you just swap plug wires that are on opposite sides of the cap 180 degrees apart. It might take a minute to do this.

The only deal is that if you have an OEM cap, the little number cast into the cap won't match up with the actual plug wire. If you get an aftermarket cap that lacks the numbers, nobody will know the difference and the only thing you will have to worry about when installing the distributor is that the engine has oil pressure.

 

[Living in the Past]

It really doesn't matter much. If it won't start and run right away, you just swap plug wires that are on opposite sides of the cap 180 degrees apart. It might take a minute to do this.

The only deal is that if you have an OEM cap, the little number cast into the cap won't match up with the actual plug wire. If you get an aftermarket cap that lacks the numbers, nobody will know the difference and the only thing you will have to worry about when installing the distributor is that the engine has oil pressure.

OCD = OEM

 

[koxfarm]

My eyes are getting worst so I used some liquid paper (ink corrector from stationery supply) and marked both the bar and BB on flywheel. The line is just the TDC on the flywheel and 7degrees before that there is the factory BB for setting the advance. I didn't actually set mine on the bull's eye but rather like an upside down letter P. It's because you can't bend down to the engine seeing it straight and also I like mine just above 7.. Sort ot 7 and half ish.
Hope this is not confusing.. The line of the P is the bar and the circle is the dot.

 

[koxfarm]

..on the dot

 

[honk]

Something to watch out for: I recently put a nice looking small cap with Pertronix into my '77 2F and it was a little puzzling for a while.

The FSM procedure for (I think) all F and 2F call for the oil pump slot to be perpendicular to the engine or 90* to the F/R line which is the same thing. But for this distributor it turned out that the oil pump drive slot needed to be parallel to the F/R line if I wanted to keep the secondary wiring in it's normal place and the rotor pointing at the bolt near #4 sparker as shown in FSM.

I don't know whether some long ago distributor rebuilder put the dist shaft together incorrectly, or if this is some off-shore version of distributor, or what.

Everything is fine, the truck runs great and I even get to have the little octane timing adjuster to pay with if I want. But I'll need to try to remember that with this distributor I need to set the pump shaft differently than the book wants or I'll never hit for oil pressure by repeatedly trying to outguess where it'll be engaged.

One thing I know is that trying to install distributors by guesswork is a frustrating business.

The thing is that if you buy one of these old girls there's the possibility of an unknown number of prior-to-you people working on it and applying a myriad of quirky methods, 'better' ideas, or just plain sloppy mechanicing to your truck before you ever had a chance to do it right.

(You WILL do it right, right?)

 

[honk]

I've posted this before, but one little easy-maker anyone can do is make a notch in their vibration dampener at 7* and a pointer from a piece of welding rod or coat hanger so that setting timing with a gun is easier to see. (painted notch is 7*. The TDC line is visible a little beyond. Sorry for the noisy image.

I put this over toward the passenger side when the engine was at TDC. That saves trying to aim the gun down from the top and somehow past the water pump, fan shroud, and what-all else.

 

[Pin_Head]

There is no contradiction between doing it efficiently and effectively and doing it right. You just need to understand what is going on to do both. Lots of novices install diestibutors without understanding fully what is going on and what is needed to do it right. Many novices don’t understand that the rotor turns CCW as it engages the gear and many people forget about the TDC at compression and exhaust.

My point is that for people that are novices, it is much more important to get the oil pump drive engaged than to have a spark plug wire off by one hole on the distributor cap. Any new owner won’t be fooled because they can follow the spark plug wires from the head to the distributor can just by looking at it.

 

[fj40cm1980]

As long as you get the nose of the distributor shaft engaged in the oil pump drive slot it doesn't really matter at all what the orientation is. Having oil pressure is the most important factor.

You can make it run and time properly with any dirstibutor orientation just by installing the plug wires in the proper position of the cap in the right sequence.

If you are OCD and you need to obsess about the tiny numbers on the distributor cap matching up with the actual spark plug wire, then you would need to know it is at TDC of the compression stroke for #1, in which case the rotor needs to be pointing to position #1 of the cap. This is also in the direction of spark plug #4.

Where many people screw up is forgetting that the distributor gears are helical and the rotor will turn CCW as the distributor drops down into engagement. Because of this, you need to start inserting it with the rotor pointing closer to #3 so it ends up pointing to #4 when it is in.

This is good info!