The Road to Drag Week 2014 - June 22

[KMcCullah]

I can't imagine the badass noise that would come from such a group of timing gears for a SOHC. 

All this technobabble about Megasquirt,Cherry,Hamlin,digital,analog,magnetic datalogging gizmos has me lost. I'm like a penguin cruising thru the desert....really lost! But I do enjoy the posts of your weekend efforts Jay. 1000hp or bust! Go Jay go!

[jayb]

Yes, the noise from those gears would be positively frightening.  Think of the noise from a normal gear drive setup, with three gears only, and then add another 5 or 6 gears!

I don't know if anybody has noticed this, but looking at Sneaky Pete's gear drive, he is turning the right cam backwards!  What the heck is that all about?  Maybe he is trying to compensate for the side to side differences in the SOHC valvetrain.  As set up stock, the right cam pushes on the rocker arm roller wheel to start the intake valve opening, and the left cam pulls on the rocker arm roller wheel to start the intake valve opening.  This leads to differences in how the valve acts from side to side, even if the cam lobes are identical.  Comp addressed this with their most recent cam grinds for the SOHC, by making slightly different grinds for the left and right cams.  Maybe Sneaky Pete was trying to address it with reverse cam rotation back in the '60s.  I wonder if you have to use two left cams with that setup, or a custom grind on the right, or what...

Edit:  Come to think of it, two left cams wouldn't work because of the bearing spacing.  Must have required a custom cam...

[dieselgeek]

Thanks Jay for having us up this weekend.   You always are tackling the odd projects and I always learn a thing or two.


I believe the sensors might wander as much as the 1.4* Jay calculated, but my money is on the megasquirt recording the falling edges accurately.   Another issue might be that we used a simple bolt head for the sensor targets.  But - the data we logged still screams "your cams are moving at least 9* from idle to 7000rpm" even if the absolute measurements might not be .01* accurate.

I submitted a question and our data to the Megasquirt gurus, told them what we're trying to do and asked what the best way is to turn Jay's MS3 into a highly accurate logger for the cams.  With the crankshaft trigger wheel and ignition coils we use, the ignition timing light makes the crankshaft look like it is not moving, so the basic timing functions of this ECU are definitely working.  But I told them "we highly doubt those cams are moving as much as the logs show" so let's see what they say!  they have always been helpful to me in the past.

This is a fun project for sure!

-Scott

[jayb]

Thanks for checking with the Megasquirt guys, Scott, I'm very interested in what they have to say.  Here's another odd thing about those logs.  If you look at the log for the cam that is mapped in red, it is changing fairly dramatically before the pull, without any change in engine RPM!  At a steady 1200 RPM, it looks like that cam retards 6-7 degrees!  I can't imagine that's right, but you never know...

[turbohunter]

but my money is on the megasquirt recording the falling edges accurately. 

-Scott

Would that be a trigger positioning thing, or a trigger type problem.

[dieselgeek]

but my money is on the megasquirt recording the falling edges accurately. 

-Scott

Would that be a trigger positioning thing, or a trigger type problem.

I'd believe a possible triggering issue (sensors, targets, or circuit conditioning on the Megasquirt inputs we are using) causing error...  but I am confident in the processor and code accurately recording the position of the falling edge signals it's seeing.  Otherwise we'd have to question the ignition timing, and anything else referencing crankshaft position.

[WConley]

Jay - I recognize that fist timing gear set picture.  I bought a 2x4 SOHC intake and a bunch of timing stuff from an older gentleman named Nat in Lake Havasu, AZ.  I want to say it was around 1999 or 2000.  That was his engine, and he had those gears custom machined.  It looked like the machinist knew what he was doing.

If you think timing a SOHC from scratch with the front cover on is hard, you should try it with the engine installed in a 427 Cobra!  No friggin' room, and it was a bear to even see the timing marks on the damper.

Your timing adventure makes sense.  Advance tends to give you more down low.  You must not be losing as much timing as those sensors indicate...

- Bill

[machoneman]

Yes, Pete's drive does spin that cam backwards yet.....

-I wonder if he did this solely to simplify the gear drive with one less gear, keep it compact and under a cover (his was a custom one of course) that was somewhat like the OEM unit?
Or......
-was the backward spinning cam also a part of improving the longevity and/or accuracy of valve timing events in addition to the gear drive idea? 

You seem Jay to be in touch with other cammer builders who may know. Earl Wade if he is still with us? Maybe Jon Kaase.

Yes, the noise from those gears would be positively frightening.  Think of the noise from a normal gear drive setup, with three gears only, and then add another 5 or 6 gears!

I don't know if anybody has noticed this, but looking at Sneaky Pete's gear drive, he is turning the right cam backwards!  What the heck is that all about?  Maybe he is trying to compensate for the side to side differences in the SOHC valvetrain.  As set up stock, the right cam pushes on the rocker arm roller wheel to start the intake valve opening, and the left cam pulls on the rocker arm roller wheel to start the intake valve opening.  This leads to differences in how the valve acts from side to side, even if the cam lobes are identical.  Comp addressed this with their most recent cam grinds for the SOHC, by making slightly different grinds for the left and right cams.  Maybe Sneaky Pete was trying to address it with reverse cam rotation back in the '60s.  I wonder if you have to use two left cams with that setup, or a custom grind on the right, or what...

Edit:  Come to think of it, two left cams wouldn't work because of the bearing spacing.  Must have required a custom cam...

[machoneman]

More here Jay:

http://www.network54.com/Forum/76346/thread/1292363027/Gotta+love+it-+Harvey+Crane's+take+on+the+SOHC.....

Both the link I posted above and the text below came from Harvey Crane's long dissertation on Pete, cammers, early Crane history etc. Funny, I had run across his text long ago and posted same in the old FE Forum.....which got me to thinking to go looking for it! You refreshed my memory Jay when you said Pete had stood in the dyno room...etc. Your own 2006 SOHC chain comments in the link are also a good refresher for our posters here.

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

After NASCAR banned this engine in 1964,Ford went drag racing with it.In Top Fuel and AFX,the fore-runner of Funny Car,the engines gave problems with consistent performance."Sneaky Pete"Robinson tested the engine and found the cam drive chain stretched so much,the cams went from 4 degrees advanced to 4 degrees retarded at 6,000 RPM and even more at 8,000+ RPM.The engine also had one bank of cylinders that ran hotter than the other,this was due to both cams turning in the same direction.Since the profile of the cam is different for lift and close,one cam had a different lift profile than the other,resulting in a different air / fuel charge in left and right cylinders.Pete's gear drive turns the cams in opposite directions so the intake profile on both banks is the same.Pete won his first major event after he installed his gear drive,but sadly was killed shortly after and no one picked-up where he left off.

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++


So, although you have seen all this before Jay, your current data methinks begs another serious look at whether the data is correct and then what fix, maybe even short of a 100% gear drive, could be designed. JMO!

[dieselgeek]

More here Jay:

http://www.network54.com/Forum/76346/thread/1292363027/Gotta+love+it-+Harvey+Crane's+take+on+the+SOHC.....

Both the link I posted above and the text below came from Harvey Crane's long dissertation on Pete, cammers, early Crane history etc. Funny, I had run across his text long ago and posted same in the old FE Forum.....which got me to thinking to go looking for it! You refreshed my memory Jay when you said Pete had stood in the dyno room...etc. Your own 2006 SOHC chain comments in the link are also a good refresher for our posters here.

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

After NASCAR banned this engine in 1964,Ford went drag racing with it.In Top Fuel and AFX,the fore-runner of Funny Car,the engines gave problems with consistent performance."Sneaky Pete"Robinson tested the engine and found the cam drive chain stretched so much,the cams went from 4 degrees advanced to 4 degrees retarded at 6,000 RPM and even more at 8,000+ RPM.The engine also had one bank of cylinders that ran hotter than the other,this was due to both cams turning in the same direction.Since the profile of the cam is different for lift and close,one cam had a different lift profile than the other,resulting in a different air / fuel charge in left and right cylinders.Pete's gear drive turns the cams in opposite directions so the intake profile on both banks is the same.Pete won his first major event after he installed his gear drive,but sadly was killed shortly after and no one picked-up where he left off.

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++


So, although you have seen all this before Jay, your current data methinks begs another serious look at whether the data is correct and then what fix, maybe even short of a 100% gear drive, could be designed. JMO!

Interesting!   so they found 8* of movement - similar to what we might have seen. 

[jayb]

Funny I didn't see that much timing variation in 2006 during my testing.  The original stock chains were not as good as the chains I was running in 2006, based on the chain pull-test data, so maybe they stretched more than the ones I was using.  I still think the data is suspicious, especially the data for the right cam, which is the red line in the graphs on the previous page.  With no change in engine speed, that right cam is retarding 3-4 degrees in that graph.  I don't believe that...

In any case, my precision sensors are on the way and I will be able to test with them installed this weekend.  Should be an interesting comparision...

[cjshaker]

Yes, Pete's drive does spin that cam backwards yet.....

-I wonder if he did this solely to simplify the gear drive with one less gear, keep it compact and under a cover (his was a custom one of course) that was somewhat like the OEM unit?
Or......

I have an old magazine article....somewhere that spoke about the Sneaky Pete drive system and he spoke about the reverse cam being needed because the gears had to be made to fit the space and engine design under the cover, and there was just no way to add another gear. I remember it talking about all the work and effort that went into the system.

[cdmbill2]

How will you test the new sensors?

[jayb]

The new Honeywell sensors respond at a higher frequency (100 KHz) than the Hamlin sensors (17 KHz), and also use simpler electronics.  The signal processing electronics used in the Hamlin sensors and the Cherry sensors is very sophisticated, but not designed as much for accuracy and repeatability as they are for detecting a wide variety of ferrous targets.  The Honeywell sensors require a magnetic field applied to the sensor, not just a ferrous target like a gear tooth.  So, instead of using a bolt head  as the target like I have in the tests so far, I've acquired some small Honeywell magnets that are delivered in aluminum holders with an 8-32 screw on the back of the holder.  So what I'm going to do (which is the same thing I did in 2006) is center drill the bolt head that I was using for a target, and install one of these magnets on each cam.  With the 100 KHz frequency response of the sensors and a repeatable magnetic field I should be able to discriminate down to 0.2 degrees of crank timing at the cam.

If I get the same results as last weekend then one more thing I'm going to try is a suggestion from the Megasquirt guys that Scott got for me, to remove some of the filtering from the inputs to the ECU to make sure that the filters are not skewing the data somehow.  And after that, I think I will have to accept that the data is the data LOL!

[machoneman]

Jay, I love it when you talk in Greek! Haha!

Sounds like your persistence (as usual) will result in good and accurate data from which a decision  can be made. Best of luck!