Making a TDC finder

classic Classic list List threaded Threaded
21 messages Options
12
Reply | Threaded
Open this post in threaded view
|

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
'83 F150 4x4 351W
Reply | Threaded
Open this post in threaded view
|

Re: Making a TDC finder

ArdWrknTrk
Administrator
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.

 Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.
Reply | Threaded
Open this post in threaded view
|

Re: Making a TDC finder

chucketn
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
'83 F150 4x4 351W
Reply | Threaded
Open this post in threaded view
|

Re: Making a TDC finder

ArdWrknTrk
Administrator
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)

 Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.
Reply | Threaded
Open this post in threaded view
|

Re: Making a TDC finder

85lebaront2
Administrator
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.
Bill AKA "LOBO" Profile

"Getting old is inevitable, growing up is optional" Darth Vader 1986 F350 460 converted to MAF/SEFI, E4OD 12X3 1/2 rear brakes, traction loc 3:55 gear, 160 amp 3G alternator Wife's 2011 Flex Limited Daily Driver 2009 Flex Limited with factory tow package Project car 1986 Chrysler LeBaron convertible 2.2L Turbo II, modified A413

Reply | Threaded
Open this post in threaded view
|

Re: Making a TDC finder

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

Chuck
'83 F150 4x4 351W
Reply | Threaded
Open this post in threaded view
|

Re: Making a TDC finder

ArdWrknTrk
Administrator
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.
 Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.
Reply | Threaded
Open this post in threaded view
|

Re: Making a TDC finder

chucketn
ArdWrknTrk wrote
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.
'83 F150 4x4 351W
Reply | Threaded
Open this post in threaded view
|

Re: Making a TDC finder

ArdWrknTrk
Administrator
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.
 Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.
Reply | Threaded
Open this post in threaded view
|

Re: Making a TDC finder

chucketn
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...

'83 F150 4x4 351W
Reply | Threaded
Open this post in threaded view
|

Re: Making a TDC finder

ArdWrknTrk
Administrator
15/16" deep (so the breaker bar or ratchet clears the crank pulley)

You still have a few years to catch up to Gary and Bill!  😃

Welcome to the forum.  
 Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.
Reply | Threaded
Open this post in threaded view
|

Re: Making a TDC finder

Gary Lewis
Administrator
Yep, you are 2 years behind me and 3 behind Bill. But I hope you don’t catch either of us for a long, long time. 😉
Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI

Reply | Threaded
Open this post in threaded view
|

Re: Making a TDC finder

mat in tn
is there a discussion here about what problem and symptoms you have that you are trying to solve? i looked briefly but did not see one. maybe someone here can help find a direction at least before digging too much deeper into the engine.
Reply | Threaded
Open this post in threaded view
|

Re: Making a TDC finder

ArdWrknTrk
Administrator
Mat, thank you.  
This is very much my point.  (assessment and diagnosis... first)

I didn't mean to come off as combative or even as an "expert" but I have timed a few engines and replaced more than a few distributors in my day.
This is why I asked Chuck if there is a reason he didn't feel confident with the marks on the damper, and only stated that a degree wheel is much more accurate than a weird method of finding TDC if there are no marks to go by

He replied that he hadn't even looked at the damper, and I came back with 'this is a basic and necessary step for changing and timing any new distributor '

While I do understand that someone who hasn't worked on a vehicle in 30 years may be unsure about its condition and want a baseline, to me that baseline is the damper's timing marks. (I don't see a reason to 'dig deeper' unless damage or decay is evident)
 Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.
Reply | Threaded
Open this post in threaded view
|

Re: Making a TDC finder

mat in tn
one of the biggest benefits of this forum is that a group of like-minded people, at least in our trucks, can join heads and help each other out. i know i have learned a lot from this and i have been dealing with these since 91 at least and exclusively for ten years or more. i am always learning and i do this every day. i certainly hope that i never come across as hostile or even impatient. however sometimes it does take someone asking about the a,b,c's in diagnosis. if we all assume that they have checked what we consider basic then we miss the opportunity to teach the basics to those following along.
Reply | Threaded
Open this post in threaded view
|

Re: Making a TDC finder

ArdWrknTrk
Administrator
Amen brother!

Often enough I find tips, tricks or information I otherwise would have looked right past, while reading this forum.
And Gary has amassed an incredible amount of factory documentation that few of us would ever have physical access to.

I do bicker with Gary.  It is all in good fun.  😇
Hopefully we contribute to the knowledge of others in the process.

 Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.
Reply | Threaded
Open this post in threaded view
|

Re: Making a TDC finder

Gary Lewis
Administrator
ArdWrknTrk wrote
I do bicker with Gary.  It is all in good fun.  😇
Hopefully we contribute to the knowledge of others in the process.
Someone once said “like an old married couple”.  But it is in good fun, and it has helped me immensely as it causes me to rethink things. 👍
Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI

Reply | Threaded
Open this post in threaded view
|

Re: Making a TDC finder

Les Kerf
In reply to this post by chucketn
The physical piston stop is the best method for accurately finding TDC and verifying timing marks.

That said, I will offer another REALLY weird method to get mighty close, and it's pretty easy.

This method does require some sort of screw-in adapter; I use appropriate end of my compression tester.

Just slip a toy balloon over it and rotate the engine by hand to TDC; the balloon will inflate, the start to deflate when it passes TDC. By rocking back-and-forth you can get it pretty close, within a degree or so. If your balancer has not slipped it will then agree with the balloon.

I have never seen a balancer slip by only a degree or two; when they do let go they move quite a bit.

My Brother-in-law taught me this method; he uses it to time his Onan generator in his motor home; there is no way to see timing marks on that engine when it is installed.
Reply | Threaded
Open this post in threaded view
|

Re: Making a TDC finder

Gary Lewis
Administrator
That’s a neat approach!  Thanks for sharing as I’d never have thought of that.

And yes, balancers don’t usually slip a degree or two. I’ve seen the slip every time the AC compressor comes on and I’ve seen them cock sideways. But they don’t seem to stay lined up and just slip frequently.
Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI

Reply | Threaded
Open this post in threaded view
|

Re: Making a TDC finder

chucketn
In reply to this post by Les Kerf
Thanks for that technique, Les. I'm a long while from installing the new distributor. Had to order the Painless DSII harness and it has an 8 week lead time. Lots of other stuff to do...
'83 F150 4x4 351W
12