Making a TDC finder

[chucketn]

I'm gathering tools to assist in replacing the distributor on my 1983 F-150 351W.

I watched a video linked from this forum of a guy making a TDC finder from a vacuum/pressure gauge and a compression testing kit.

I purchased both and am trying to put together the combination from the video. I took apart the compression tester and found the tire valve, but don't have fittings to adapt the vacuum gauge to the compression tester adapter. I need the thread size of the pressure gauge so I can buy a barbed adaptor for the vacuum gauge hose. Anybody know?

Chuck

[ArdWrknTrk]

Chuck, can you link the post or video you are working from?

A search of this forum for the term "TDC finder" yields no results at all.

Is there a reason you can't just use the timing marks on your harmonic damper?

I've always used a piston stop and degree wheel to find tdc when I have no marks to go by.

 

[chucketn]

Chuck, can you link the post or video you are working from?

A search of this forum for the term "TDC finder" yields no results at all.

Is there a reason you can't just use the timing marks on your harmonic damper?

I've always used a piston stop and degree wheel to find tdc when I have no marks to go by.

Might have gotten the link from another forum, but here it is:

https://www.youtube.com/watch?v=u2sA-q7_FtQ.

Actually, I haven't even looked at or for timing marks yet. PO had done some changes, carb, manifold, and thrown a bunch of parts at the problem. I decided to start with a new reman distributor and ignition module.

As I haven't done much major work on vehicles in 30 years, I read up on the methods and picked a starting point. I want to know everything is right as I go. I'll verify timing marks when I know it is mechanically in time and running. Short of tearing down the engine to expose the timing chain, I thought this method was better.

 

Chuck

[ArdWrknTrk]

Might have gotten the link from another forum, but here it is:

https://www.youtube.com/watch?v=u2sA-q7_FtQ.

Actually, I haven't even looked at or for timing marks yet. PO had done some changes, carb, manifold, and thrown a bunch of parts at the problem. I decided to start with a new reman distributor and ignition module.

As I haven't done much major work on vehicles in 30 years, I read up on the methods and picked a starting point. I want to know everything is right as I go. I'll verify timing marks when I know it is mechanically in time and running. Short of tearing down the engine to expose the timing chain, I thought this method was better.

 

Chuck

Man! How unnecessarily complicated. 🙄

He doesn't use any threaded adapter, just a piece of heater hose stuffed over the air chuck nipple of his compression tester whip.

You can do this with your finger in the #1 spark plug hole while you turn the crank with a 15/16 deep on a breaker bar.

Clean the pointer and damper timing marks, then use chalk, soap, a scrap of drywall, mud, whatever... to make the tdc mark more visible.

When you feel pressure building in #1 take your finger off and continue to rotate until the "0" is aligned with the pointer.

Remember that your rotor will turn as you engage the dizzy gear with the cam. (so you probably want to be pointing a little bit ahead of where you want #1 to end up)

 

[85lebaront2]

Man! How unnecessarily complicated. 🙄

He doesn't use any threaded adapter, just a piece of heater hose stuffed over the air chuck nipple of his compression tester whip.

You can do this with your finger in the #1 spark plug hole while you turn the crank with a 15/16 deep on a breaker bar.

Clean the pointer and damper timing marks, then use chalk, soap, a scrap of drywall, mud, whatever... to make the tdc mark more visible.

When you feel pressure building in #1 take your finger off and continue to rotate until the "0" is aligned with the pointer.

Remember that your rotor will turn as you engage the dizzy gear with the cam. (so you probably want to be pointing a little bit ahead of where you want #1 to end up)

To add to that, I made a piston stop from an old spark plug.

(1) knock the porcelain out of the shell and break off the side terminal

(2) find a suitable size bolt or screw (3/8-16 works well in 14mm plugs) and tap the plug shell

(3) install a nut on the bolt or screw and then screw it into the plug shell and snug the nut

(4) use a grinder to round off the end of the bolt or screw

(5) with the piston down a bit, insert and tighten the tool in #1 or #6 plug hole unless you are on an in-line 4 or V6

(6) carefully rotate the crank until the piston stops against the bolt or screw and mark the balancer, reverse the crank until it stops again and mark the balancer. 1/2 way between the marks is actual TDC, if it matches your 0 TDC mark then you have verified that the balancer hasn't slipped and can now be certain of your timing.

[chucketn]

To add to that, I made a piston stop from an old spark plug.

(1) knock the porcelain out of the shell and break off the side terminal

(2) find a suitable size bolt or screw (3/8-16 works well in 14mm plugs) and tap the plug shell

(3) install a nut on the bolt or screw and then screw it into the plug shell and snug the nut

(4) use a grinder to round off the end of the bolt or screw

(5) with the piston down a bit, insert and tighten the tool in #1 or #6 plug hole unless you are on an in-line 4 or V6

(6) carefully rotate the crank until the piston stops against the bolt or screw and mark the balancer, reverse the crank until it stops again and mark the balancer. 1/2 way between the marks is actual TDC, if it matches your 0 TDC mark then you have verified that the balancer hasn't slipped and can now be certain of your timing.

I'll make a piston stop, just to verify the balancer hasn't slipped. Thanks... Now to find a spark plug...

Chuck

 

[ArdWrknTrk]

I'll make a piston stop, just to verify the balancer hasn't slipped. Thanks... Now to find a spark plug...

Chuck

I'm still trying to understand your first question.

If you want to use a gauge you've already got gutted of its check valve, why don't you find a foot or two of heater hose like in the video?

You don't need any kind of fitting, just a seal.

I would never trust this technique to precisely determine TDC.

You're better off with a plastic straw down the plug hole.

Why do you have any suspicion of the balancer marks if you haven't even bothered to look at it?

If your balancer is in such poor shape that you don't trust it, replace it as a matter of course. (anything rubber is a maintenance item)

Honestly I haven't seen that much (and I've been working on absolute junk since the '70's)

Piston stop and a degree wheel are for doing things like setting an adjustable cam gear, and is usually accomplished on an engine stand not in the truck.

[chucketn]

I'm still trying to understand your first question.

If you want to use a gauge you've already got gutted of its check valve, why don't you find a foot or two of heater hose like in the video?

You don't need any kind of fitting, just a seal.

I would never trust this technique to precisely determine TDC.

You're better off with a plastic straw down the plug hole.

Why do you have any suspicion of the balancer marks if you haven't even bothered to look at it?

If your balancer is in such poor shape that you don't trust it, replace it as a matter of course. (anything rubber is a maintenance item)

Honestly I haven't seen that much (and I've been working on absolute junk since the '70's)

Piston stop and a degree wheel are for doing things like setting an adjustable cam gear, and is usually accomplished on an engine stand not in the truck.

Ouch! I probably won't sit comfortable for a week at least.

As I mentioned,, I haven't done any vehicle maintenance like this in over 30 years. I don't know what the PO may or may not have done prior to my buying this project. He just threw money and parts at the truck. I am just trying to find a bullit proof starting point for the resurrection of this red mess.

I read of the balancer shifting and making the TDC tool here, I have the tools, so what harm would result from making it? The PO had issues with timing. Short of pulling the timing cover and aligning the timing marks, I thought the TDC tool was pretty bullit proof.

Pardon me for not having your experience or knowledge on these engines... I guess my best option is to just read the forum and not ask dumb questions.

 

[ArdWrknTrk]

I'm still trying to understand your first question.

If you want to use a gauge you've already got gutted of its check valve, why don't you find a foot or two of heater hose like in the video?

You don't need any kind of fitting, just a seal.

I would never trust this technique to precisely determine TDC.

You're better off with a plastic straw down the plug hole.

Why do you have any suspicion of the balancer marks if you haven't even bothered to look at it?

If your balancer is in such poor shape that you don't trust it, replace it as a matter of course. (anything rubber is a maintenance item)

Honestly I haven't seen that much (and I've been working on absolute junk since the '70's)

Piston stop and a degree wheel are for doing things like setting an adjustable cam gear, and is usually accomplished on an engine stand not in the truck.

Ouch! I probably won't sit comfortable for a week at least.

As I mentioned,, I haven't done any vehicle maintenance like this in over 30 years. I don't know what the PO may or may not have done prior to my buying this project. He just threw money and parts at the truck. I am just trying to find a bullit proof starting point for the resurrection of this red mess.

I read of the balancer shifting and making the TDC tool here, I have the tools, so what harm would result from making it? The PO had issues with timing. Short of pulling the timing cover and aligning the timing marks, I thought the TDC tool was pretty bullit proof.

Pardon me for not having your experience or knowledge on these engines... I guess my best option is to just read the forum and not ask dumb questions.

I certainly didn't mean to come off abrasively.

And I don't know anyone here who thinks there is a dumb question. (dumb answers and rabbit holes aplenty)

I am sincerely sorry if that was your impression.

As I said, I'm trying to understand what you first asked about coupling the compression tester fitting to the vacuum-pressure gauge.

What "fitting" do you think you need?

I don't see where ETCG has anything but a rubber hose jammed between the two.

Yes that will approximate TDCC #1, but i'm trying to explain that you can do as good -or better!- with your finger and a straw....

Harmonic dampers are pretty foolproof. They key directly to the crank who's stroke you are trying to read.

Yes. They can slip eventually. As I said all rubber has a lifetime.

But they won't budge just a little bit without being noticably out of whack and causing bad vibrations.

The rubber peeling out, the whole ring misaligned.or the seam open.

This is why I say clean it up and make sure you can see the marks clearly.

You need that at the very least when you put your timing light on to set the initial advance of the new distributor.

And..... it's the perfect opportunity to examine the damper for any sign of distress. 💡

If there's any doubt change it. (but this usually requires pulling the radiator, fan and shroud. Then you need the proper puller and a way to block the crank from turning while you take that nut off)

If it all looks good simply roll the engine to the '0' mark and stab the distributor in with the rotor ending up where you want #1 to be.

It is my opinion (and ONLY my opinion) that you don't need the kind of 1/4° precision you get with a piston stop and degree wheel to properly install a distributor.

[chucketn]

I certainly didn't mean to come off abrasively.

And I don't know anyone here who thinks there is a dumb question. (dumb answers and rabbit holes aplenty)

I am sincerely sorry if that was your impression.

As I said, I'm trying to understand what you first asked about coupling the compression tester fitting to the vacuum-pressure gauge.

What "fitting" do you think you need?

I don't see where ETCG has anything but a rubber hose jammed between the two.

Yes that will approximate TDCC #1, but i'm trying to explain that you can do as good -or better!- with your finger and a straw....

Harmonic dampers are pretty foolproof. They key directly to the crank who's stroke you are trying to read.

Yes. They can slip eventually. As I said all rubber has a lifetime.

But they won't budge just a little bit without being noticably out of whack and causing bad vibrations.

The rubber peeling out, the whole ring misaligned.or the seam open.

This is why I say clean it up and make sure you can see the marks clearly.

You need that at the very least when you put your timing light on to set the initial advance of the new distributor.

And..... it's the perfect opportunity to examine the damper for any sign of distress. 💡

If there's any doubt change it. (but this usually requires pulling the radiator, fan and shroud. Then you need the proper puller and a way to block the crank from turning while you take that nut off)

If it all looks good simply roll the engine to the '0' mark and stab the distributor in with the rotor ending up where you want #1 to be.

It is my opinion (and ONLY my opinion) that you don't need the kind of 1/4° precision you get with a piston stop and degree wheel to properly install a distributor.

Thanks for your reply. As I am 73, and my knees aren't what they used to be, I'm trying to find the least physically demanding method to check timing. I'll try the finger and straw method.

BTW, what size socket do I need for the crank nut? I also try to save steps back and forth to the tool box. If memory serves, it's 1 1/4".

My but feels better already...