Printing the custom parts for the VW "cam doctor".
I have the 2rpm motor, encoder, dial indicator with data cable, and most of the extrusion and hardware already.
CB has shipped my parts and I got the heads back from the machine shop.
Re: Type 1 twin screw supercharger build / 9 yrs later I'm back at it
-
Alexander_Monday
- Posts: 415
- Joined: Sat Dec 13, 2008 1:30 pm
Re: Type 1 twin screw supercharger build / 9 yrs later I'm back at it
You do not have the required permissions to view the files attached to this post.
The older I get, the faster I was.
-
Alexander_Monday
- Posts: 415
- Joined: Sat Dec 13, 2008 1:30 pm
Re: Type 1 twin screw supercharger build / 9 yrs later I'm back at it
You do not have the required permissions to view the files attached to this post.
The older I get, the faster I was.
-
Chip Birks
- Posts: 4053
- Joined: Wed Mar 12, 2008 5:59 pm
Re: Re: Type 1 twin screw supercharger build / 9 yrs later I'm back at it
What's the goal here? Wanting to capture a profile of the cam?
-
Alexander_Monday
- Posts: 415
- Joined: Sat Dec 13, 2008 1:30 pm
Re: Type 1 twin screw supercharger build / 9 yrs later I'm back at it
Yes, specifically the custom ground cam from Jones Cams to see how aggressive it is and what it looks like "under the curve".
Also I have an FK87 and a FK87/FK10 I would like to profile for comparison.
There is not anyone local that can do it.
Most of the parts I already have.
Also I have an FK87 and a FK87/FK10 I would like to profile for comparison.
There is not anyone local that can do it.
Most of the parts I already have.
The older I get, the faster I was.
-
Chip Birks
- Posts: 4053
- Joined: Wed Mar 12, 2008 5:59 pm
Re: Type 1 twin screw supercharger build / 9 yrs later I'm back at it
Very coolAlexander_Monday wrote: ↑Sun Feb 16, 2025 11:34 am Yes, specifically the custom ground cam from Jones Cams to see how aggressive it is and what it looks like "under the curve".
Also I have an FK87 and a FK87/FK10 I would like to profile for comparison.
There is not anyone local that can do it.
Most of the parts I already have.
-
Alexander_Monday
- Posts: 415
- Joined: Sat Dec 13, 2008 1:30 pm
Re: Type 1 twin screw supercharger build / 9 yrs later I'm back at it
Still need to interface the encoder and indicator and write the code, but mechanically it came out nice.
The older I get, the faster I was.
-
Alexander_Monday
- Posts: 415
- Joined: Sat Dec 13, 2008 1:30 pm
Re: Type 1 twin screw supercharger build / 9 yrs later I'm back at it
Dug up a 4D Systems Gen3 micro/touchscreen unit I had used for the timing lights and tree for belt sander races and programed it for the cam profiler.
I feel really dumb, today I was going over the data and the cam timing just didn't make any sense to me.
Then it hit me that the cam rotates counterclockwise not clockwise.
And then some research to find that when the screw at the end of the oil pump shaft slot is at 45 degrees when at TDC #1.
Insert Homer Simpson Doh!
I will reprogram it and run the cam the opposite way.
I feel really dumb, today I was going over the data and the cam timing just didn't make any sense to me.
Then it hit me that the cam rotates counterclockwise not clockwise.
And then some research to find that when the screw at the end of the oil pump shaft slot is at 45 degrees when at TDC #1.
Insert Homer Simpson Doh!
I will reprogram it and run the cam the opposite way.
The older I get, the faster I was.
-
Piledriver
- Moderator
- Posts: 22858
- Joined: Sat Feb 16, 2002 12:01 am
Re: Re: Type 1 twin screw supercharger build / 9 yrs later I'm back at it
The only people that never make misteaks never do anything.
Addendum to Newtons first law:
zero vehicles on jackstands, square gets a fresh 090 and 1911, cabby gets a blower.
EZ3.6 Vanagon after that.(mounted, needs everything finished) then Creamsicle.
zero vehicles on jackstands, square gets a fresh 090 and 1911, cabby gets a blower.
EZ3.6 Vanagon after that.(mounted, needs everything finished) then Creamsicle.
-
Alexander_Monday
- Posts: 415
- Joined: Sat Dec 13, 2008 1:30 pm
Re: Type 1 twin screw supercharger build / 9 yrs later I'm back at it
Learned a lot coding and using the cam profiler.
First thing is that any spec of dust whatsoever will cause outlier readings.
Second thing is that I have to turn the cam really slow due to the dial indicator RS232 update rate.
So I added PWM motor control with a slider and off/forward/reverse to the main screen.
If I had to do it over, I would use a stepper motor instead of the geared down DC motor.
Mike said I needed way less cam and the profiles were all wrong for a supercharger and my valve sizes.
I haven't dove into the minutia yet, but obviously the Jones cam is a little more aggressive on raise than the FK's but about the same slope back down as the FK's have.
The horizontal scale is crank degrees, but I could not start over at 0 past 720 because of the way Excel plots so 720 is #1 TDC.
The vertical scale is raw cam lift in inches.
Here is a comparison of the Jones 112LC, FK8, and FK10/87 114LC cams I have available to plot.
Note that I had to eyeball where TDC was with a feeler gauge in front of the teat I designed on the camshaft holder so each could be a little off absolute degrees, although I ran the Jones cam 3 different times removing and reinstalling and came out with less than a degree variation.
But all lobes on each cam should be shifted the same because I only had to move the dial indicator between lobes.
However, it came out 2 degrees off on lobe centers vs the cam card each time so I assume it is ground 2 degrees off.
Unfortunately, there is some variation between the cam card and the camshaft and even some variation between 1/3 & 2/4 lobes.
Not sure if that is normal as I have not done the same for the engle cams.
It will be interesting to see if I get the same numbers when I put the cam in the case.
--------------------------------Measured vs Cam Card
#1 Intake Open @50--------13 BTDC---9.5 BTDC
#2 Intake Open @50 -----18 BTDC---9.5 BTDC
#1 Intake Close @50 -----39 ABDC---45 ABDC
#2 Intake Close @50 -----41 ABDC---45 ABDC
#1 Exhaust Open @ 50------63 BBDC---59 BBDC
#2 Exhaust Open @ 50-----65 BBDC---59 BBDC
#1 Exhaust Close @ 50-------6 ATDC---7 ATDC
#2 Exhaust Close @ 50------4 ATDC---7ATDC
#1 Intake Duration @50-------232------235
#1 Exhaust Duration@50------249-----246
#2 Intake Duration@50-------239-----235
#2 Exhaust Duration@50-----249-----246
#1 Intake CL-----------------------106----108
#1 Exhaust CL---------------------118-----116
#2 Intake CL ---------------------106----108
#2 Exhaust CL--------------------118-----116
#1 Intake Lobe Lift------------0.378---0.380
#1 Exhaust Lobe Lift----------0.350---0.350
#2 Intake Lobe Lift-----------0.378---0.380
#2 Exhaust Lobe Lift---------0.353---0.350
#1 Overlap@50-------------------19----16.5
#2 Overlap@50------------------22----16.5
First thing is that any spec of dust whatsoever will cause outlier readings.
Second thing is that I have to turn the cam really slow due to the dial indicator RS232 update rate.
So I added PWM motor control with a slider and off/forward/reverse to the main screen.
If I had to do it over, I would use a stepper motor instead of the geared down DC motor.
Mike said I needed way less cam and the profiles were all wrong for a supercharger and my valve sizes.
I haven't dove into the minutia yet, but obviously the Jones cam is a little more aggressive on raise than the FK's but about the same slope back down as the FK's have.
The horizontal scale is crank degrees, but I could not start over at 0 past 720 because of the way Excel plots so 720 is #1 TDC.
The vertical scale is raw cam lift in inches.
Here is a comparison of the Jones 112LC, FK8, and FK10/87 114LC cams I have available to plot.
Note that I had to eyeball where TDC was with a feeler gauge in front of the teat I designed on the camshaft holder so each could be a little off absolute degrees, although I ran the Jones cam 3 different times removing and reinstalling and came out with less than a degree variation.
But all lobes on each cam should be shifted the same because I only had to move the dial indicator between lobes.
However, it came out 2 degrees off on lobe centers vs the cam card each time so I assume it is ground 2 degrees off.
Unfortunately, there is some variation between the cam card and the camshaft and even some variation between 1/3 & 2/4 lobes.
Not sure if that is normal as I have not done the same for the engle cams.
It will be interesting to see if I get the same numbers when I put the cam in the case.
--------------------------------Measured vs Cam Card
#1 Intake Open @50--------13 BTDC---9.5 BTDC
#2 Intake Open @50 -----18 BTDC---9.5 BTDC
#1 Intake Close @50 -----39 ABDC---45 ABDC
#2 Intake Close @50 -----41 ABDC---45 ABDC
#1 Exhaust Open @ 50------63 BBDC---59 BBDC
#2 Exhaust Open @ 50-----65 BBDC---59 BBDC
#1 Exhaust Close @ 50-------6 ATDC---7 ATDC
#2 Exhaust Close @ 50------4 ATDC---7ATDC
#1 Intake Duration @50-------232------235
#1 Exhaust Duration@50------249-----246
#2 Intake Duration@50-------239-----235
#2 Exhaust Duration@50-----249-----246
#1 Intake CL-----------------------106----108
#1 Exhaust CL---------------------118-----116
#2 Intake CL ---------------------106----108
#2 Exhaust CL--------------------118-----116
#1 Intake Lobe Lift------------0.378---0.380
#1 Exhaust Lobe Lift----------0.350---0.350
#2 Intake Lobe Lift-----------0.378---0.380
#2 Exhaust Lobe Lift---------0.353---0.350
#1 Overlap@50-------------------19----16.5
#2 Overlap@50------------------22----16.5
The older I get, the faster I was.
-
Steve Arndt
- Posts: 7420
- Joined: Sat Mar 10, 2001 12:01 am
Re: Re: Type 1 twin screw supercharger build / 9 yrs later I'm back at it
Very cool. In school we used a program called "working model" to plot position, V, A, and jerk of cams.
Steve
My Baja Build
My Baja Build
-
Alexander_Monday
- Posts: 415
- Joined: Sat Dec 13, 2008 1:30 pm
Re: Type 1 twin screw supercharger build / 9 yrs later I'm back at it
That would not be hard to do in excel.
Of course, I would not know what was excessive acceleration or jerk.
BTW, I am going to try putting some extra spring pressure on the dial indicator since it has such light pressure to see if that tames some of the noise in the plot.
As a side note, I wish the 4D Systems micro had more than 32K of ram available for variables so I could save all 4 lobes in ram at less than 0.4 degrees of crank rotation.
1800 int16 variables X 5 plus the other variables and program stack etc. puts me below 32K but at 0.25 degrees (2880 int16 X 5) it is above 32K.
I tried to save them in a file on the uSD on the fly, but that increased loop time drastically so it would miss every other rs232 packet.
The built-in quadrature decoder for the encoder is run separately in the processor so it stays current.
With the timing belt ratio the encoder gives 14400 counts per cam revolution, so it counts every 0.0125 degrees of crank revolution.
Of course, I would not know what was excessive acceleration or jerk.
BTW, I am going to try putting some extra spring pressure on the dial indicator since it has such light pressure to see if that tames some of the noise in the plot.
As a side note, I wish the 4D Systems micro had more than 32K of ram available for variables so I could save all 4 lobes in ram at less than 0.4 degrees of crank rotation.
1800 int16 variables X 5 plus the other variables and program stack etc. puts me below 32K but at 0.25 degrees (2880 int16 X 5) it is above 32K.
I tried to save them in a file on the uSD on the fly, but that increased loop time drastically so it would miss every other rs232 packet.
The built-in quadrature decoder for the encoder is run separately in the processor so it stays current.
With the timing belt ratio the encoder gives 14400 counts per cam revolution, so it counts every 0.0125 degrees of crank revolution.
The older I get, the faster I was.
-
Alexander_Monday
- Posts: 415
- Joined: Sat Dec 13, 2008 1:30 pm
Re: Type 1 twin screw supercharger build / 9 yrs later I'm back at it
Ran the other cam numbers and made the excel sheet it where I could advance / retard the cams.
While I could be off by a little, the amount I could be off would not compensate for the discrepancies.
So it appears that all 3 cams have grind discrepancies in and between lobes.
The Engle cams appear to have symmetrical lobes.
The Jones cam has asymmetrical lobes,
While I could be off by a little, the amount I could be off would not compensate for the discrepancies.
So it appears that all 3 cams have grind discrepancies in and between lobes.
The Engle cams appear to have symmetrical lobes.
The Jones cam has asymmetrical lobes,
The older I get, the faster I was.
-
Alexander_Monday
- Posts: 415
- Joined: Sat Dec 13, 2008 1:30 pm
Re: Type 1 twin screw supercharger build / 9 yrs later I'm back at it
Kevin sent me these pics and said he should finish Monday.
The older I get, the faster I was.
-
Alexander_Monday
- Posts: 415
- Joined: Sat Dec 13, 2008 1:30 pm
Re: Type 1 twin screw supercharger build / 9 yrs later I'm back at it
I drilled the oil hole in main #4 larger to increase oil flow because of the supercharger drive.
I tapped the case to plug the hole from the oil pump.
I cleaned up a few little casting nodules that might come loose
I measured minimum and maximum case and rod bores, main and rod bearings installed, crank mains and rod journals.
The CB White Rino case measures 2.5591"-2.5592" for #1-#3 and 1.9697" for #4 measured 90 degrees to the parting lines.
Main bearings installed for #1-#3 are 2.3641"-2.3642" and 1.5756" for #4 measured 90 degrees to the parting lines.
The crank main journals for #1-#3 are 2.3612"-2.3613" and 1.5742" for #4.
Main clearance calculates for #1-#3 at 0.0028"-0.0029" and 0.0014" for #4 measured 90 degrees to the parting line.
Eccentricity calculates for #1-#3 at 0.0011"-0.0014" and 0.0001" for #4
Approximate clearance value for diameter times for #1-#3 is 0.00119-0.00123.
Nicely within the scale for high performance bearing clearances C=D*0.00075 to C=D*0.0015.
#1-#3 main bearings are King MB3882XP and #4 is a round factory bearing.
(FYI, I got the King number off the box and looked it up and the description on King's website is "FOR VW FOR CB PERFORMANCE".)
(I paid $199.95 at CB and on King's website they are listed at $80.60, but not sure if they would sell direct but they can be added to cart.)
Not sure what the OEM application of these bearings is, but obviously the original oil holes were offset from centerline and the modified hole is not enough to line up with the case holes.
So I got a round file out and went to work on them.
I also did the bearing parting line modification to increase oil to the thrust surfaces.
Rod big ends measure 2.1250"-2.12495" any direction.
Side clearance measured at 0.018".
With the Mahle CB-610A bearings installed the measurements were 2.0019"-2.00235" 90 degrees to the parting line.
And 2.00415"-2.0045" measured close to the parting line.
The crank rod journals measured at 1.9991"-1.9993".
Rod clearance calculates at 0.0026"-0.00325" at 90 degrees to the parting line.
Eccentricity calculates at 0.00185"-0.0022".
Approximate clearance value for diameter times is 0.0013-0.00163.
This is on the higher end and just beyond, so I measured the bearing shells at the center.
They measured 0.0616" to 0.062" thick and for a SBC small journal bearing they should be 0.0622".
The Mahle bearings are too thin and inconsistent.
It would run ok, but most likely have loss of oil pressure and get unacceptable with wear far quicker than with better rod bearing clearances.
I ordered King CR 803XPN rod bearings and that will give me 2 sets since they are for a V8.
If they are true to 0.0622" as advertised, the clearances should be 0.00145"-.0015" which is a D times of 0.00070-0.00075.
I test fitted the cam, crank and rods to 1/2 of the case.
The case had plenty of clearance for the 86mm crank and H beam rods.
The CB 30mm lifters have plenty of clearance to the case with the cam at full lift.
There is one spot that I will have to shave a little off a crank counterweight for clearance to a cam lobe.
Makes me wish I would have asked for a reduced base circle.
And of course the cam needs clearanced for the rods, but not as much as I had expected.
If it was a +100 cam drop case I wouldn't have any clearancing to do.
I tapped the case to plug the hole from the oil pump.
I cleaned up a few little casting nodules that might come loose
I measured minimum and maximum case and rod bores, main and rod bearings installed, crank mains and rod journals.
The CB White Rino case measures 2.5591"-2.5592" for #1-#3 and 1.9697" for #4 measured 90 degrees to the parting lines.
Main bearings installed for #1-#3 are 2.3641"-2.3642" and 1.5756" for #4 measured 90 degrees to the parting lines.
The crank main journals for #1-#3 are 2.3612"-2.3613" and 1.5742" for #4.
Main clearance calculates for #1-#3 at 0.0028"-0.0029" and 0.0014" for #4 measured 90 degrees to the parting line.
Eccentricity calculates for #1-#3 at 0.0011"-0.0014" and 0.0001" for #4
Approximate clearance value for diameter times for #1-#3 is 0.00119-0.00123.
Nicely within the scale for high performance bearing clearances C=D*0.00075 to C=D*0.0015.
#1-#3 main bearings are King MB3882XP and #4 is a round factory bearing.
(FYI, I got the King number off the box and looked it up and the description on King's website is "FOR VW FOR CB PERFORMANCE".)
(I paid $199.95 at CB and on King's website they are listed at $80.60, but not sure if they would sell direct but they can be added to cart.)
Not sure what the OEM application of these bearings is, but obviously the original oil holes were offset from centerline and the modified hole is not enough to line up with the case holes.
So I got a round file out and went to work on them.
I also did the bearing parting line modification to increase oil to the thrust surfaces.
Rod big ends measure 2.1250"-2.12495" any direction.
Side clearance measured at 0.018".
With the Mahle CB-610A bearings installed the measurements were 2.0019"-2.00235" 90 degrees to the parting line.
And 2.00415"-2.0045" measured close to the parting line.
The crank rod journals measured at 1.9991"-1.9993".
Rod clearance calculates at 0.0026"-0.00325" at 90 degrees to the parting line.
Eccentricity calculates at 0.00185"-0.0022".
Approximate clearance value for diameter times is 0.0013-0.00163.
This is on the higher end and just beyond, so I measured the bearing shells at the center.
They measured 0.0616" to 0.062" thick and for a SBC small journal bearing they should be 0.0622".
The Mahle bearings are too thin and inconsistent.
It would run ok, but most likely have loss of oil pressure and get unacceptable with wear far quicker than with better rod bearing clearances.
I ordered King CR 803XPN rod bearings and that will give me 2 sets since they are for a V8.
If they are true to 0.0622" as advertised, the clearances should be 0.00145"-.0015" which is a D times of 0.00070-0.00075.
I test fitted the cam, crank and rods to 1/2 of the case.
The case had plenty of clearance for the 86mm crank and H beam rods.
The CB 30mm lifters have plenty of clearance to the case with the cam at full lift.
There is one spot that I will have to shave a little off a crank counterweight for clearance to a cam lobe.
Makes me wish I would have asked for a reduced base circle.
And of course the cam needs clearanced for the rods, but not as much as I had expected.
If it was a +100 cam drop case I wouldn't have any clearancing to do.
Last edited by Alexander_Monday on Sun Apr 20, 2025 5:30 am, edited 1 time in total.
The older I get, the faster I was.
-
Chip Birks
- Posts: 4053
- Joined: Wed Mar 12, 2008 5:59 pm
Re: Re: Type 1 twin screw supercharger build / 9 yrs later I'm back at it
From what I've heard, it sounds like you got lucky on your main bearing clearances. I've heard of double those values within the last couple of months. Thanks for posting the King part numbers as well. Crazy to see the CB markup on those things.
I'm surprised to see that your cam isn't pre clearance. I must have been lucky, every cam I've bought over the last 15 years has been factory clearanced, I had to plunge a hair deeper into one on an 86 stroke build I'm currently doing. But just a little bit.
Keep up the good work!
I'm surprised to see that your cam isn't pre clearance. I must have been lucky, every cam I've bought over the last 15 years has been factory clearanced, I had to plunge a hair deeper into one on an 86 stroke build I'm currently doing. But just a little bit.
Keep up the good work!