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Unread 11-16-2011, 07:49 PM   #1
swatson454
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Finding Top Dead Center or TDC

I needed to run through the TDC procedure recently and I thought I'd share the procedure in hopes that it may help someone else down the road.

Although the chopstick method is useful if your balancer is quite a ways off, this particular method is accurate enough to double-check brand new parts and is really easy to do, and pretty inexpensive.

The first thing you'll need is a piston stop for use with the cylinder head still on the engine. I use this one from Crane Cams because it is soft brass, has a rounded end so it doesn't ding a piston and it also has a through-hole so the cylinder doesn't compress on you as you bring the engine up to TDC. It's about 12 bucks from Summit.



Then you'll need a metric tape. I don't know exactly what it's called but it looks like this and if you have a woman in the house or you're a body-builder, you just may have one. The metric side is a whole lot easier to split a measurement in half than a tape based on inches. Well, at least for me.



Simply thread the piston stop into the #1 spark plug hole. A time-saving trick is to rotate the engine to roughly 20 degrees before top dead center (BTDC) and then thread the stop in until it makes contact with the piston. Removing all of the spark plugs will make life a little easier and you can come up to the stop in a more controlled manner. From contact and just to make sure that everything is good, spin the engine counter-clockwise a little bit, a quarter turn is plenty. Then rotate the engine clockwise until the #1 piston contacts the stop. With the piston making contact with the stop, make a mark on the balancer directly below "0" on the timing indicator. A short mark, a dash or even a dot may help eliminate confusion later.



Note the black mark next to "0" on the timing indicator. I used a magic marker this time because of the white timing tape but you can use machinist's chalk, a magic marker, the wife's nail polish... whatever you want, as long as it's visible. However, I like machinist's chalk as it can be easily removed, which will avoid confusion later.

After marking the balancer, rotate the engine counter-clockwise until the piston hits the stop again. Once more, make a mark on the balancer just below the "0" on the timing indicator. In this picture, the mark I made is on the edge of the timing tape so it's a little difficult to see. It'll be more visible in the next pic.



From there, with a mark on the balancer from each directional stop, you can spin the engine clockwise so that you have a clear shot of both marks from underneath the Jeep.



Measure the distance between the two marks you made (this is where a metric tape comes in really handy) and split the difference. If, for example, you have 20 millimeters between your two marks, make another mark or line preferrably, at 10 millimeters. If your measurement leads to a funky number that's hard to split, you can adjust the piston stop either in or out; which will either broaden or narrow your marks and possibly make your math easier.

Here's mine after splitting the difference. I had 9.2 cm between the two marks. The midway point was 4.6 cm, as indicated by a long line across the balancer.



From there, you simply have to remove the piston stop and rotate the engine around until your new line lines up with "0" on the timing indicator.



As you can see, my balancer has managed to slip 3 degrees over time.
If this sounds difficult or confusing, it's simply due to my lack of writing skills. It's easy like a Sunday morning and way more accurate than feeling for TDC with a chopstick. If done correctly, this will be dead-nuts, accurate to the degree TDC.

With our aging Jeeps and the need to find an accurate TDC for different issues, I hope you guys find this method helpful. It's actually extremely easy, quick and accurate.


Shawn

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Unread 11-16-2011, 10:03 PM   #2
CoryA
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Sorry if this is a dumb question but how do you tell if your on a compression stroke? Air won't leak from the #1 cylinder with the piston stop in it right?

I just bought a cj with a performance 383 and it has a solid cam so I have to adjust my valves and I'm trying to learn how to do it myself I save me money.

This all made sense to me and I was really happy when I saw this post! Thank you
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Unread 11-16-2011, 10:35 PM   #3
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Many put their finger over the spark plug hole to feel for the pressure starting to build. Then you know you are on compression and can put in the piston stop. I have a hard time feeling this and rotating the engine at the same time so what I do it thread in the whip of my compression tester and tape a ballon to it. As soon as compression starts the ballon begins to inflate.
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Unread 11-16-2011, 10:56 PM   #4
swatson454
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Quote:
Originally Posted by CoryA View Post
how do you tell if your on a compression stroke? Air won't leak from the #1 cylinder with the piston stop in it right?
Good question. This is why the piston stop with the through-hole is so handy. The crankshaft doesn't care where the camshaft or the distributor is. TDC is simply the center-most position of the piston's maximum upward travel. With a fully-assembled engine, however, you're right, both valves are closed on the compression stroke (the one we usually refer to as TDC for the purpose of ignition timing) and a solid piston stop will allow the air in the cylinder to compress.

Like I said, the crank doesn't care where anything else is. Once the camshaft is installed, you now have TDC "on the compression stroke". With the engine fully assembled, you can tell when the compression stroke begins by placing a finger over the #1 spark plug hole. When cranking the engine by starter or by hand, when it tries to blow your finger off of the spark plug hole, you're on the compression stroke. Stop the engine rotation at that point and, if you've accurately located TDC, simply finish rotating the engine by hand to the point where either your new, accurate mark on the balancer or the factory hash mark (assuming your balancer turned out to be correct and this method will verify that) to "0" on the timing indicator and you'll know that you're on TDC of the compression stroke. Now you'll know that the 10*BTDC (as an example) that you might see when setting your timing, isn't really 15*.

Shawn
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Unread 11-17-2011, 04:46 AM   #5
Matt1981CJ7
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Shawn,

So the piston stop actually stops the piston from reaching TDC on both strokes?

Also, you mentioned "threading" the piston stop into the #1 spark-plug hole, but I don't see any threads on the piston stop. What am I missing, here?

Matt
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Unread 11-17-2011, 05:47 AM   #6
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Bad picture, it has threads, and it has a vent for the compression.

The good news is, you can be VERY accurate with a piston stop like this.
The bad news is, you very rarely, if ever, need to located TDC this accurately on a stock engine.

Even worse news, all the timing covers/balancer will be a little bit off, mass produced stuff always is.

With racing engines you have to know EXACTLY where TDC is, we use a custom balancer with an ADJUSTABLE timing tab so we can correct timing tab to balancer and be dead on.
-------------------------------------

What most 'Professional' builders do is to use an across the cylinder bar with piston stop that hits the piston head on, instead of at the spark plug angle.
Since the balancer, timing scale, ect. are all part of the lower engine assembly, we usually do it when we degree in the camshaft, set the accurate balancer that can't slip like the factory versions do,
And we leave it alone.

If you are checking for TDC with the heads on, then it's usually for a camshaft change.
(to degree in a new camshaft is about the only reason to do it with the heads on the engine...)

The only other reason I can think of is a broken timing chain, to see if the valve lift is starting and peaking when it's supposed to after a camshaft change...

-----------------

For our ignition work in these old factory engines,
The 'Chop Stick' method is plenty good since you aren't trying to find PRECISELY TDC to make 1 degree changes in the camshaft rotation timing,
You are just trying to find when the piston is pretty much at the top of the bore.
(Within ONE TOOTH OF THE DISTRIBUTOR/CAMSHAFT gears, which is 27 degree jumps on the balancer)

If you can get within 27 crankshaft degrees of TDC, you can set a distributor accurately.

--------------------------------

Now, VERIFYING THE HARMONIC BALANCER is another matter!

Most of the time, you can get within one or two degrees ( +/- ) of zero on the balancer.
That is usually the inaccuracy built into the balancer, front timing scale, slight inaccuracy of finging EXACT TDC, ect.

Since you are within 2 or 3 degrees, you can VERIFY the 'Hash' mark on the balance is pretty much where the factory intended it to be.
This lets 99.9% of everyone out there verify the outer ring of the balance hasn't slipped 90 or 180 degrees out of time with the crank,
Which does happen at a frightening rate!

The outer ring is held on the balancer hub by a rubber vibration damping ring, and that rubber gets oiled pretty regularly by leaking front seals...
Petroleum and rubber in open atmosphere don't get along very well, so pretty soon the outer ring is no longer aligned with the hub/crank, and your timing 'Hash' mark LIES TO YOU!

By finding TDC, by whatever method, you can VERIFY your balancer is still 'True' with the crank/TDC.

-------------------------------

Since most of you will have very safe timing curves, a 3 degree misalignment won't effect you anyway.

The guys that need to know a 100% accurate reading are the ones running racing fuel, have the timing set 1 Degree from turning the engine into scrap metal, and CAN NOT afford to be wrong...

Since none of us are running a "Top Fuel Funny Car Jeep", none of us mix nitro methane into our fuel,
None of us are running 40 lbs of supercharger boost,
We REALLY don't need to know where EXACT TDC is on the balancer.

Besides, just in case you didn't notice, You can't adjust the scale anyway...
If you find 3 degrees of misalignment, the best you can hope for is to use a corrected balancer tape,
Or you can grind/file a new 'Hash' mark in the balancer,
But that usually just confuses things...

---------------------------------------------

IF YOU HAVE THE TOOLS TO FIND EXACTLY TDC, AND YOU HAVE A FACILITY TO CORRECT THE BALANCER,
Then I don't see anything wrong with knowing exactly where TDC is,
Especially if you can access it with a timing light!
Never hurts to have thing 'SPOT ON' when you are working on tuning a camshaft or distributor timing curve...

But as for 'Joe Average',
I wouldn't pay the extra money for that stuff if I weren't trying to sneak up on an ignition advance curve charting or trying to degree in a new camshaft.

It's just not cost or time effective if you set the timing once on a stock distributor and don't look at it again until the cap, rotor, wires & plugs are worn out and it's time for new ones...

If you use the 'Right' cap, plug wires, It will be 10 years before you need to replace them,
And once a year you pull the rotor & plugs and throw them over your shoulder, plug in new ones, use an 'Ink Pen' eraser to clean the cap terminals, and you are good for another year...

-----------------------------

As for the OP,
I DO LIKE TO SEE PEOPLE EXPANDING THEIR HORIZONS!

Don't let us old, crusty guys bother you,
Do what you think is BEST, and do it anyway so you learn something!

When you get the chance,
Compare a piston stop across the cylinder with a locating pin that runs parallel to the cylinder,
And compare it with the angled pin (Spark Plug Hole Type you have now),
You might be surprised what you find!

If you get the opportunity,
Check the camshaft lift with the timing (Rotation of crank) and a LARGE degree wheel!
That will screw your mind up for days! (Just remember to BREATHE! There are 720 degrees in a camshaft circle!)

-------------------------

For the other 99.9% of you...
The 'Chop Stick' method is pretty good for verifying you have TDC of the cylinder you are working on...
Just take your time, move the crank back and forth at the top and you will be able to fairly accurately locate TDC enough to drop a distributor in correctly, and you will be able to verify the outer ring of your balancer hasn't slipped around the hub...

This crap is FUN! Don't you think!
I have to wonder if the guys before us that invented all this stuff were smarter than we are today...
Remember, when they came up with all this stuff, it was usually ONE GUY that thought of it,
Not a team of engineers like there are today plugged into a project....

Usually ONE GUY, in his workshop/garage/kitchen trying to figure out a better way to do things!
The first guy to invent 'Overlap' of the camshaft lobes to scavenge the cylinders of exhaust gasses,
The first guy to invent Anti-Reversion headers,
The first guy to invent centrifugal governors and later centrifugal advance for distributors,
Or the first guy to invent vacuum advance...

They MUST have called him 'Crazy' a million times for even working on something that 'Wasn't Broken' at the time,
But that's how AMERICA was built! One 'Crazy' guy at a time!

LET'S KEEP THAT GOING! I'm all for hanging out with the 'CRAZY IDEA' guy!

I'm also all for hanging out with the guy that learns about this crap, he's the next 'Crazy Guy' inventor,
And he might come up with something I can use!
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Unread 11-17-2011, 05:50 AM   #7
CoryA
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Quote:
Originally Posted by swatson454

Good question. This is why the piston stop with the through-hole is so handy. The crankshaft doesn't care where the camshaft or the distributor is. TDC is simply the center-most position of the piston's maximum upward travel. With a fully-assembled engine, however, you're right, both valves are closed on the compression stroke (the one we usually refer to as TDC for the purpose of ignition timing) and a solid piston stop will allow the air in the cylinder to compress.

Like I said, the crank doesn't care where anything else is. Once the camshaft is installed, you now have TDC "on the compression stroke". With the engine fully assembled, you can tell when the compression stroke begins by placing a finger over the #1 spark plug hole. When cranking the engine by starter or by hand, when it tries to blow your finger off of the spark plug hole, you're on the compression stroke. Stop the engine rotation at that point and, if you've accurately located TDC, simply finish rotating the engine to the point where either your new, accurate mark on the balancer or the factory hash mark (assuming your balancer turned out to be correct and this method will verify that) to "0" on the timing indicator and you'll know that you're on TDC of the compression stroke. Now you'll know that the 10*BTDC (as an example) that you might see when setting your timing, isn't really 15*.

Shawn
Awesome ty
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Unread 11-17-2011, 07:55 AM   #8
swatson454
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Quote:
Originally Posted by Matt1881CJ7 View Post
Shawn,

So the piston stop actually stops the piston from reaching TDC on both strokes?

Also, you mentioned "threading" the piston stop into the #1 spark-plug hole, but I don't see any threads on the piston stop. What am I missing, here?

Matt
Yep. By physically stopping the piston before TDC on both strokes and splitting the difference between the two marks, you completely eliminate the 10 or so degrees where the rod is basically changing from one side of the wrist pin to the other and there's hardly any piston travel to try to feel for with a chopstick.

If you go this route and find your balancer a few degrees off, you can simply mark the timing indicator inline with your center mark on the balancer and use that instead of "0". I've degreed quite a few cams over the years and have verified the duration at .006, .050, .100, .200 and max lift along with aligning those cheap, chrome timing indicators to a new Fluidamper balancer and this is just how my poor brain works now

You didn't miss anything. Like hammer said, it's just a crappy pic. That's the only angle that the flash on my phone didn't turn it into a fuzzy, brass glow-stick and no flash at all was even worse.


Shawn
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Unread 11-17-2011, 08:15 AM   #9
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Warning:
This is all going to be WAY too esoteric and technical for most users here.
You might understand it, but you won't have much cause to use it with a stock engine vehicle.

The first thing that crosses my mind,
Why would you use a piston stop on anything that didn't have camshaft in it (Other than to find TDC of the crank when installing a new camshaft or replacing timing set, WHICH should already be located?)

If you are using a spark plug type stop, the heads are on the engine, and you more than likely have a camshaft/timing set in the engine already...

--------------

NEVER, EVER, UNDER ANY CIRCUMSTANCES USE A SPARK PLUG TYPE PISTON STOP AND TURN THE ENGINE WITH THE STARTER!

If you do, you stand a VERY good chance of knocking a hole in a piston, ruining the rod bearing/rod, screwing up the head/plug threads, and it's unlikely you will be able to get that bent piston stop out of the head anyway without cutting off the bent part so it will unscrew.

I have a couple of spark plug stops that have 'Whistles' built into them.
When you hit compression stroke, the whistle blows.
They work quite well when turning the engine by hand when you don't have help.
While you are turning the crank, the 'Whistle' alerts you to the start of the compression stroke, so you know you are getting close...

But again, NEVER, EVER TURN AN ENGINE WITH THE STARTER WHEN YOU HAVE A SPARK PLUG HOLE PISTON STOP SCREWED INTO THE HOLE!

------------------------------

Spark plug stops contact the piston at an angle, and no matter how 'Rigid' you *Think* the stop is,
It's going to deflect when the piston contacts it...

And, since there is never a locking bolt on this type of stop, the stop will deflect in the threads, they are NEVER 'Tight', so you will have some variation in your readings from 'Actual' TDC when you use a proper stop over the cylinder with the heads off.

That's why serious racers use a block over the top of the cylinder, with a stop that is in line with the piston travel... No deflection... Better, more accurate readings.

--------------------------

One thing not mentioned here is,
It depends on which way you turn the crank on what reading you will get.
There is slop in the rod bearing, there is slop in the piston wrist pin in all engines, and used engines it's much larger.

When the crank travels across Top Dead Center, every fraction of an inch in 'Slop' translates to degrees on the crank.
Crank shaft direction (Forwards and backwards to normal rotation) will throw in variables in fractions of an inch,
SO you wind up with degrees of inaccuracy at the balancer when doing things like this.

The ONLY COMPLETELY ACCURATE way to do a 'Dead On' crank timing check is to pressurize the block with oil,
Then use an across the bore, inline piston stop.
This takes an ADJUSTABLE timing tab on the front cover, or an adjustable timing mark on the balancer (you have to go with an EXPENSIVE aftermarket balancer for that),
To get a completely accurate TDC setting...

Then you have to consider that most blocks DO NOT have cylinders bored completely perpendicular and completely INLINE with the crank.
Most are angled one way or another to the crank and many are angled off on BOTH axis.

We spend a LOT of time and money correcting just that very problem with high performance engines.
And just because you have ONE cylinder that is accurate, doesn't mean they all are!


Then you have to consider the crankshaft,
Many cranks are ground with the rod journals not in time on the crank.
This presents as cylinders with pistons NOT coming up to TDC at the correct crankshaft degree marks they are supposed to.
So if you get ONE cylinder accurate, it doesn't mean they all are accurate...

--------------------------------------

Like I said, Swanson has shown you a VERY good way to 'Correct' your balancer.
I highly recommend you use the CORRECTED timing tape on the balancer, it's a VERY good way to see exactly what #1 cylinder is doing in relationship to the timing scale,
But there are so many variables in these older engines it doesn't GUARANTEE you are dead on with the timing scale on any, or any one of, the cylinders.

The GOOD NEWS IS...
Your engines had to be pretty close, or they wouldn't be running this long!
Engines with LOTS of problems, or just one severe problem wouldn't have stayed together this long!

Modern machining and quality testing has eliminated or seriously reduced the flaws you see in older engines,
But if an older engine has stayed together this long, it's got to be VERY close!
And since we aren't running at 9,000 RPM or 28 Lbs of boost, they should continue to stay together with what ever flaws they have...

------------------------------------------

Another way to locate your 'TDC' with the spark plug stop is to turn the engine one way, make a mark, turn it the other way to the stop, make a mark,
Then back the stop out a little, do it again.

You will see the marks getting closer together as you do this.
And like Shawn said, it will take some of the 'Windward' and 'Leeward' slop out of the wrist pin and rod bearing when you do it this way...

When the marks are VERY close together, it's much easier to figure out where 'Center' is, and that should be where your balancer mark lines up with the 'Zero' on the timing scale.

Once you put a tape on the balancer, you read your timing from the TAPE, not the scale on the front cover.
Once the tape is in place, you simply use the scale on the tape, and the 'Zero' mark on the scale, it's usually more accurate that way...

Most racing engines have a pointer on the cover (TDC/Zero Mark adjusted to the balancer), and a scale on the balancer, and that is normally the best way to do things accurately...

One thing that is good about using the tape, you usually get WAY more degrees showing,
So you can see full advance as a direct read instead of just 12 degrees of advance or so on the typical front cover scale...
A VERY good thing when you are trying to map out your advance curve and make RPM specific or Vacuum specific changes since you can see FULL advance without having to mark up the balancer and try to remember what mark means what...

I'm with Shawn, I'm so used to actual racing dampers with the degree marks on the damper, and just an adjustable pointer on the front of the engine, My brain works that way, not with the scale on the front cover anymore...

Nothing like having 90 degrees of advance as a direct read off a good balancer instead of trying to mark the factory balancer for 'Compensation' and counting marks, then adding in the direct read for your advance total... (Made me tired just typing that!)

-------------------------------------

Shawn, I'm the all time king of crappy pictures!

I usually take 4 or 5 pictures of EVERYTHING, and often NONE of them are usable, then I have to try again...
And that takes a TON of time out of my projects to take the pictures, run in the house to see if ANY of them turned out fit to publish,
Then go back out and try to pick up where I left off...
Makes for DOUBLING the time of the project when I publish it on the forums,
And a TON of extra work trying to crop, resize, compress, transfer to the web site so I can link to them in the forums,
Then trying to write the project text in a reasonably coherent manner and in terms that a layman understands without his eyes glazing over...

One article on something that took two hours to do can take TWO DAYS to get corrected and published on the forums!
Then some Jack Wagon wants to argue about a .30 cost discrepancy in the parts listed on a $200 project, or what lube his uncle once told him to use 20 years ago, ect.!
(But I digress!)

Some people show pictures here I could NEVER do! I don't know how they do it...
Every picture I take is either over-exposed, under-exposed, out of focus, or just plain my Jittery hands screwing things up...

And that's not if I don't have a finger in front of the lens!

I have some EXTREME close ups of my fingers!
Some pretty good shots of my feet, the ground, the ceiling in the office, ect.
Seems the 'Accident' shots ALWAYS turn out better than the ones I'm TRYING to take!

I'm pretty good at getting every thing set up for a picture, then fiddling with the camera, when I FINALLY get ready to take the pic,
Crap has rolled off!
Not in frame anymore, and usually trying to hide in the cracks of the workbench, floor or office chair I use for picture backgrounds!

I'm FINE with gears and wires, but photography is an ART, and I'm no 'Artist'!!!!
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Unread 11-17-2011, 08:26 AM   #10
mopar408
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Quote:
The first thing that crosses my mind,
Why would you use a piston stop on anything that didn't have camshaft in it (Other than to find TDC of the crank when installing a new camshaft or replacing timing set?)
only reason we ever did was to check deck heights on pistons using closed chamber heads and for extra precision on cc'ing the combustion chambers ( we ran 13 to 1 so it had to be right) But then, with the heads off you use a dial indicator set up off on of the head bolts and went down .100" each way and then halved it (same procedure as 454 sez. )
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Unread 11-17-2011, 09:10 AM   #11
JeepHammer
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Yeah, I kind of got ahead of my train of thought...

What I intended to say was,
If you are changing camshafts or timing sets,
Shouldn't you already have a balancer set up that locates TDC from the ORIGINAL build?

My fingers sometimes don't keep up with my train of thought,
And my train of through has more derailments than AMTRACK...

--------------------

We would CC combustion chambers, get them equal after cutting the head,
Then grease the rings/cylinder walls so we didn't have leaks (Gapless rings, no matter what we were using when the engine ran, during set up, it was MUCH easier to keep fluid in the cylinders with gapless rings and some grease...)

Once the piston was FULLY up, we would CC the chamber with the HEADS ON the engine.
Then make corrections to the top/dome of the piston to get the cylinders equalized.

I HATED doing that, slow, time consuming, real pain in the arse, and I'm not too sure it was entirely called for...

Once you had the ACTUAL chamber volume,
It was pretty easy to figure cylinder area/stroke and divide one into the other...

I was SO HAPPY when Fel-Pro came along with a head gasket that would crush to the same thickness every time! Made my life so much easier!


We used to 'Cheat' with valve lash some (and timing).
Opening up the valve lash kept the cylinder pressure/compression down when running on the street or messing around with chassis tuning so we didn't use the engine up,
Then closing the lash, bump up the timing and getting full value when we were serious about making horse power...

I'm all about fuel injection & supercharging now,
None of that silly stuff *IF* you race in a class that allows it!

Since we run 'Auto Cross' there aren't any restrictions, it's about going around corners instead of a straight line... And my life is MUCH more simple than it used to be!
Now I get the crap kicked out of me about the SUSPENSIONS instead of some guy wanting 500 Horse Power out of mismatched parts that he doesn't want to put ANY money into...

A pretty well built STOCK engine will overrun most suspensions around the curves, so horsepower isn't the beginning and end of my day...
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Unread 11-17-2011, 09:54 AM   #12
swatson454
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This is what I do with brand new stuff. I completely disregard any marks that come on the timing indicator (they're usually wrong anyways), run through this procedure with a positive piston stop either through the head or across the cylinder (you can use a dial indicator if you want but I much prefer a positive piston stop) while making erasable marks on your degree wheel and cut a point into the timing indicator just above the hash mark on the balancer.

This pic shows what I mean here. Look at the timing indicator and notice the point that I cut into it.





Shawn
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Unread 09-22-2012, 02:20 PM   #13
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Question on finding top dead center using chopstick as I don't have bump stops.
I know the original mark no longer points to TDC, found the PO mark which is close to TDC.
I put short tape on balancer to mark, but I also know/see that there is that "moment" when the cylinder first hits at TDC, a pause as you move it, then the "moment" when it decends. So if I am careful in turning it and watch closely, i have two marks, about 4 degees apart, then know TDC is actually halfway between?
Just want to verify before marking the balancer I am thinking correctly.

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Unread 09-22-2012, 02:38 PM   #14
swatson454
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You've got the basic idea. It's always a little more accurate if you can get a couple of inches between your marks but sometimes you just have to use what you have.

I suppose you could always roll the crank roughly 20* counter-clockwise (ccw) from what you think is TDC and make a mark on your chopstick right at the spark plug threads or somewhere easy to see and accurate enough to repeat. Roll the crank ccw a few more degrees so your mark on the chopstick disappears and then go clockwise until you just barely see the mark. Stop and mark the balancer at "0". Continue clockwise until the mark on the chopstick just starts to duck back out of sight and mark the balancer again. Split the difference.

I've never tried it that way but I suppose you could make it work well enough.


Shawn
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Unread 09-22-2012, 02:50 PM   #15
fourbtgait
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Quote:
Originally Posted by swatson454
You've got the basic idea. It's always a little more accurate if you can get a couple of inches between your marks but sometimes you just have to use what you have.

I suppose you could always roll the crank roughly 20* counter-clockwise (ccw) from what you think is TDC and make a mark on your chopstick right at the spark plug threads or somewhere easy to see and accurate enough to repeat. Roll the crank ccw a few more degrees so your mark on the chopstick disappears and then go clockwise until you just barely see the mark. Stop and mark the balancer at "0". Continue clockwise until the mark on the chopstick just starts to duck back out of sight and mark the balancer again. Split the difference.

I've never tried it that way but I suppose you could make it work well enough.

Shawn
Only problem I "see" is to accuretly get the chopstick in the same "position" each time. That is where i can see the bump stops working exact as they take into consideration the slack in the system.
Now my problem is to figure/understand why when at TDC on compression stroke, the rotor is not at but halfway between #1 and #5 on the cap tet runs.
I do have another post going of this, do not want to clog the system up.

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