Flathead V8 Distributor Slot in Cam shaft

[Mart]

That's an interesting looking setup. I would be interested in seeing it working.

Have you seen or used a krw timing fixture?

I have a really nice quality Churchill unit here in the UK. I did show it in some of my earlier videos.

Mart.

[35fordtn]

I think a Sun Machine has a benefit due to spinning at speed to observe sticking weights, advance curve, point float etc etc. The only thing I could see a Software set up being able to do that a Sun Machine cannot is to stack graphs from all eight cylinders and overserve differences in dwell for each cam lobe.. ... Essentially what you have stated above. You will need a better way of holding a distributor accurately as the casting flaws will change the way it sits the way you have it clamped to a table. I would recommend bolting a timing cover to the fixture so that you could attach the distributor to the Timing cover. Essentially you are more closely replicating (in digital form) what a later KRW fixture does rather than a Sun Machine.

[Veeder]

Mart

First thank you for the videos I know they must me time consuming in fact I was looking at yours to attempt to get a sense of cam position and the angle of the slot relative to TDC of #1 compression stroke. I don't have an engine torn apart to look at this and wanted to mark a distributor body with that position.

have never used a Sun Machine or any one of the other units such as the Churchill or KW. They are a bit out of my price range. We have already changed a couple of things and are making a couple more modifications.

The attached document will be just a quick example of the data plotted. We have (my brother and I ) have plotted plots with zero mechanical advance and +/- advance curves which we found very interesting. For example we can see in the charts looking closely the interaction of the overlap of the set of points.

What is really nice is it allows you to step precisely to an area on the distributor lobe and set points.

We have more work to do on it but our initial objective was met.

Bob







bob

[Lawrie]

Great work,
I made my own distributor tester, brother in-law is an electrical guru who made his own electric motor bikes he is smart,
he made me the circuit board to drive the electric motor that drives the distributor, up to about 4ooo eng rpm,
I have a strobe and can map out the advance curves and set up the vac brake as per the service manuals,
It sure makes you realise there are good ignition points and BAD ones.
Let me know if you want some picks and info.
Lawrie

[Lawrie]

The only thing that I would like on my machine is some stuff ( software) that would map out the advance automatically ,rather than me physically do it ,
But as 35fordtn says ,it sure picks up advance units, sticking ,and not right.
Lawrie

[hubercats]

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Veeder's brother here: A quick note on the plot that Veeder posted. The blue ramps are from the Hall Effect angle sensor. Because of the way the sensor mounts to the stepper motor shaft, the angle reduces as the distributor moves forward (i.e., in the proper direction). We'll fix our software in the next revision to make the angles increase with time as that seems a bit more intuitive. The orange curves show the points opening/closing. The point opening/closing data are scaled to fit between 90 and 270 degrees (y axis) so they are visible on the same plot as the ramps which go between 0 and 360 degrees. In this particular test, we set the timing such that the number 1 cylinder points open at 0 degrees top-dead-center for cylinder 1 (compression stroke). We know this is not the proper setting. We did it to verify the calibration of the angle sensor and point open/close sensor.


The points are open for about 10 degrees out of every 45 degrees, implying that the dwell angle is about 35 degrees. The regularity of the point openings also shows that the the distributor cam lobes are uniform.


I've seen a few posts suggesting that a higher rpm capability would be nice. We have considered this and may make a variant of the system for that purpose. For now the stepper motor speed limits us to rather low rpm, but low rpm is perfect for assessing the main things we have been interested in thus far. A dc motor, perhaps geared, would allow for much higher rpm, but at the expense of angular control; at least using simple, inexpensive motors and motor control components. Veeder, who has the car with the flathead in it, does not intend to race it so floating points is not one of his primary concerns.

[AnthonyG]

As u ask I’ll answer! Hope u have a sense of humor! New world, new tech. Ur right, it is txt type! Im 71 & like it. fewer key strokes! Don’t have to think about it at all as I txt more than I talk on the phone! More efficient! Sorry it confused u, . I do understand, some old dogs & new tricks! Sounds like Veeder understood.
Again sorry & Best 2 all, especially 2 any who it bothered!
AG

[ford38v8]

Originally Posted by Ronnie

x 2 ^

r

So, Ronnie, as you agree with Lawson, I take it that you intend to stop abusing the King’s English at some future time?

[AnthonyG]

Hi JSeery, I don’t think anyone asked so guessing I’m the only one in the dark . What’s the easy way to find & Mark pulley for TDC without removing the head?

[Mart]

Anthony. It's the cable tie method.

I illustrate in in this video:

https://youtu.be/dn446jjCVRg

Mart.

[AnthonyG]

Thx Mart!

[hubercats]

I've seen some comments on the internet where people are questioning the accuracy of finding top dead center using methods such as the cable tie approach on account of the fact that the crankshaft in flathead engines is offset from the center of the engine. While I can see how this introduces some error, my gut instinct is that the error is quite small, probably a degree or two at most. If anyone knows of the magnitude of this error, it would be interesting to know the number.

[JSeery]

Originally Posted by hubercats

I've seen some comments on the internet where people are questioning the accuracy of finding top dead center using methods such as the cable tie approach on account of the fact that the crankshaft in flathead engines is offset from the center of the engine. While I can see how this introduces some error, my gut instinct is that the error is quite small, probably a degree or two at most. If anyone knows of the magnitude of this error, it would be interesting to know the number.

Sounds like BS to me, TDC has nothing to do with crankshaft offset. TDC is TDC it is where the piston is at the top of it's travel. Using a dead stop with the heads on is as accurate as the person doing it. If it is repeated several times to eliminate/decrease any error, it is very accurate.

[hubercats]

I agree that TDC is TDC. That doesn't mean that the method for estimating TDC (with the heads on the engine) is necessarily perfect. So that people can judge for themselves, here is the web page where this subject is discussed: http://www.mapleleafup.net/forums/sh...ad.php?t=21652

[AnthonyG]

It seems pretty obvious you have to ascertain which method makes sense for the set of circumstances! If as I was in a project where head removal was required for something else anyway, the heads off method makes sense. If u simply have or acquired an engine w/o a timing arrow or marked crank pulley was the only issue with no need to remove heads then the tywrap method looks like a great way to go & as JSeery & Mart indicate as easy as it is do it several times to get a good feel & see where the marks end up & You’ll
get a TDC Mark that’s pretty damn accurate!

[Mart]

Hubercats. The people questioning it are right. The crank offset will have an effect. However, at the distance down the bore that we are talking about, approximately 1/4", the effect is so minimal as to be negligible. It is far less, for instance than your ability to accurately make the marks and locate the centre point of those marks by eye using hand tools.
It is far more accurate, for instance than using a test indicator to clock TDC and trying to work out exactly where TDC occurs in the dead band at TDC.
In other words the solid stop method is good enough.
Mart.

[glennpm]

I agree with Mart and Seery on the solid stop method being very accurate and suitable for most. An all out racer may want a "heads off" determination but for most, the solid stop method is very accurate.



For the zip tie, just keep the tie in the same location which doesn't have to be at the top of the piston; for the rotation up to the solid stop and then back in the other rotation, splitting the difference for TDC (Top Dead Center :-))

[Veeder]

Very helpful information guys thank you as always!!
Bob

[hubercats]

Thanks, Mart. I wasn’t questioning the utility of the tie wrap method. Rather I was just noting that it had been a topic of discussion in the Australian forum. I’m a big fan of “good enough for the job” approaches and the method you so nicely describe in your YouTube video (thanks for making and sharing it) is a method I would use myself - if only I had a flathead of my own. As it is, I’m enjoying these discussions as a side effect of working on the distributor test rig with my brother (Veeder) - vicarious fun. - Cheers!

[Veeder]

Another question
Since we are setting the mechanical advance to zero degrees and we know withing 1 degree or less TDC. Why can't I just set the points (Driver-side) to just be opening at o degrees and then set the second set of points to open at 11 degrees. Ideally I don't want to be isolating the two sets of points. My assumption is the correct overlap of the point activity is going to happen by default.

Also once that's done you can set the mechanical advance.

Correct?
bob