Milwaukee Midget

[fordboy628]

Success!   Well, sort of . . . . . .

Well I got the new cam program up & running, no small feat in itself, especially without the documentation . . . . . . .

But after a fair amount of trial & error managed to load up some older Cam Dr. files.    Then after some more dinking around was able to generate some useful information.   (ie, net valve lift every 2 degrees, etc.)

And after that, later this afternoon, UPS arrived with: The Software Documentation.   Whoohoo!

BUT, and here's the BAD NEWS:   The files on the disc from C&S with the file extension   .prj    are not readable by the software . . . . . . .      We need to get the files with the  .cpp   extension.     That will be a total of 4 files.    I'll mail back the "Frankendiskette" & another to give to C&S.

BTW, I changed the file extensions to  .cpp  just to try the idea out, and the program was still unable to read the file.   I'm thinking the  .prj  file is the "setup" file, and the  .cpp  file is the data file.   Drat!
    
Snidely Whiplash

[edinlr]

As far as making the port molds, I just googled "making molds of engine ports" and came up with a ton of pictures and vendors.

[Andy Cooke]

Have you tried to open the .prj file with something like hexedit?  I'm sure you're right about the .cpp file, but you never know....

[fordboy628]

As far as making the port molds, I just googled "making molds of engine ports" and came up with a ton of pictures and vendors.

Only one of the hits on the Google search was for a BMC cylinder head, but I was glad to find that one.   That author also laments about the difficulty of removing the mold from a siamesed port using a solid silicone compound.    His solution was to mold the port in a "hollow" fashion with RTV and an additive, VERY labor intensive.   I've added the link below as the guy's build thread should be interesting to other BMC "floggers" following Chris's build.

https://aseriesmodifications.wordpress.com/tag/silicone-port-mold/

Will try the urethane foam again, and I'm going to limit the expansion of the foam from the ports with a plate.

The whole problem here is the volume of the siamesed section of the ports, making the removal of the port casting VERY difficult without damaging the port mold casting.   This is a problem you normally don't have with say a Lotus or a Crossflow Ford or a Non-Crossflow Ford, etc, UNLESS a molding compound with too much "hardness" is utilized.    Determining the right combination of "softness"/elasticity required for removal and "hardness"/rigidity required for maintaining useful shape is going to be a trial & error process.
 
Fordboy

[fordboy628]

Have you tried to open the .prj file with something like hexedit?  I'm sure you're right about the .cpp file, but you never know....

It appears to me that the size of the file would almost HAVE to include the data to be as large as they are.    But as I am not a programmer, AND, I don't want to spend time on something that probably won't be productive, the best course is likely to be to just get the correct files . . . . . . .

I'm doing enough "unproductive" work lately.

Chris: I've emailed you the files in case you want to take a crack at them.
 
Fordboy

[Elmo Rodge]

On the siamesed ports, any chance of doing 2 partial casts, trimming and bonding for a result? Wayno

[fordboy628]

On the siamesed ports, any chance of doing 2 partial casts, trimming and bonding for a result? Wayno

If the urethane foam casts don't work out, then a 2 piece urethane rubber mold will probably be the next effort.   I really don't like the idea of the hollow moldings because over time they deteriorate badly.
 
Fordboy

[gearheadeh]

On the siamesed ports, any chance of doing 2 partial casts, trimming and bonding for a result? Wayno

If the urethane foam casts don't work out, then a 2 piece urethane rubber mold will probably be the next effort.   I really don't like the idea of the hollow moldings because over time they deteriorate badly.
 
Fordboy

Love the info in this Thread,

What about doing the Hollow molding and then filling it with something hard after it is out?

[Milwaukee Midget]

Howdy, Hagen!  Where have you been?

Expansion - or contraction is the issue there.  A silicone mold that's hollow comes out about the consistency of an al dente pasta shell.  Even if you fill it, you really don't know if you've constructed an accurate representation of the port because the outside might stretch.

The port won't give, so if the mold medium is set while still in the port, you're not as likely to see shifting of the shape. 

[Interested Observer]

Fordboy & Midget,
Assuming that the effort to measure the port shapes of the “good” head is to document and perhaps replicate them, another approach may merit looking into...
In this day and age there are a lot of electrically based contact and non-contact measuring techniques in use.  From coordinate measuring machines to laser ranging techniques.  While I have no knowledge of a particularly suitable set of hardware, it seems like somebody must need to be able to check the shape of similar internal contours.  Pipeline inspection, boiler tubes, etc.  What do Edelbrock, for instance, or other manufacturers do to check their manifolds or heads?  Or do they just assume the CNC work is perfect?  There must be some inspection iterations involved during development.  Such a setup is probably expensive to purchase, but there may be a job shop somewhere set up to do that kind of work.  The result would likely be a CAD file which is only one step away from a CAM file which, if replication is the goal, eliminates the whole mess of making molds and then trying to translate that into an electronic file.
Wish I could point to a solution, but something along these lines may be worth thinking about.  Perhaps somebody out there in landspeed land has some background or knowledge that would pertain.

[fordboy628]

IO,

Thanks for the thoughts.    Most of the big manufacturers of heads/manifolds and the like either use multi-axis laser scanning or multi-axis digital co-ordinate measuring machines for quality control/inspection using techniques as you describe.   The techniques they use replicate or measure to within VERY tight tolerances, but are EXPENSIVE.    AND large manufacturers just don't want to know about small projects.

There are some smaller CNC porting services, using these types of measurement techniques, just beginning to pop up.    Most of these guys are refugees from really big Pro Teams, or large manufacturers.    I talked to a couple about this project (and a couple of other projects) at the PRI show.   The problem is that, like every other startup, the investment is steep, so they have to charge the going rate to stay in business, let alone be profitable.    And because of the demand for these services is at the Pro Racing level, pricing is "Pro-appropriate".    These are big dollars better spent elsewhere on the Midget.   That's why I've been trying to do this on the cheap using this older, less expensive method.

It's the Lite Beer story over and over:  Less Filling AND More Taste?!?   It just doesn't happen . . . . . . . .      IMHO . . . . . . . .

It's more like Craft Beer:   You get what you pay for . . . . . . . .
 
Fordboy

[Seldom Seen Slim]

Chris (& Mark):  I got this from one of the NZ folks - and he asked me to pass it along to you.  Ready?



"Can you pass on to Milwaukee Midget that the best product I have used for port moulds is a product called Pinkysil might be worth a try.  Used for special effects work.
Regards
Grant"

[fordboy628]

Warning Will Robinson, Warning!!

Information Dump!!

midget,

Well this is all the info on valve dimensions and weights for every head I've touched in the last 12 months . . . . .     for your permanent record.

There are some interesting comparisons between valve types . . . . . .     not only weight-wise, but flow-wise.    The later designs are lighter and flow better, no big surprise . . . . .

Just a reminder:  On cylinder head/cam combinations where the engine becomes "valve spring pressure challenged" because of say, "packaging considerations",  lighter is always going to work out better.

I added a couple of Ford NCF race valves I had made, and a Cosworth valve, for comparison, at the bottom of the chart.

What is noteworthy here is that the valves manufactured by Race Engine Components are consistently lighter . . . . . .     even lighter than say, the Swiftune or Longman valves . . . . .   
 
physicsboy, er, flowmonkey, er, sudsmonkey!!!

[fordboy628]

Of possible interest to other BMC racers:

Check out this belt drive setup.   It is the first one I've seen with an adjustable tensioning device.    Readers may recall all the effort MM went through to try and install a tensioner on his adjustable chain drive for the cam.
The problem is that when a machine shop line bores or line hones your block and main caps, the distance between the crankshaft and camshaft centerlines usually gets reduced, providing slack in the chain or belt . . . . . . .

                   
I believe this item is from Dave Wells in the UK.    No idea on price, but if you have slack in your drive belt for the aforementioned reasons, this item might be: priceless!!

BTW, does anybody know why an image edited on Photobucket loses the editing when the image is imported into this website?   I rotated this photo 90 degrees so it would be a vertical image.   You see what happened . . . . .
                
apparentlynotphotoboy

[jacksoni]

Of possible interest to other BMC racers:

Check out this belt drive setup.   It is the first one I've seen with an adjustable tensioning device.    Readers may recall all the effort MM went through to try and install a tensioner on his adjustable chain drive for the cam.
The problem is that when a machine shop line bores or line hones your block and main caps, the distance between the crankshaft and camshaft centerlines usually gets reduced, providing slack in the chain or belt . . . . . . .

                   
I believe this item is from Dave Wells in the UK.    No idea on price, but if you have slack in your drive belt for the aforementioned reasons, this item might be: priceless!!

adjustable tension is good for the reasons you mention but I don't see ready adjustability of cam timing, ala Jesel belt drives for instance. Is that hidden on the back side of the cam pulley somehow that we can't see here?