Overhead-camming a Type 1 engine

[Piledriver]

A 13" Monarch lathe like we have at work is <7 feet long, and smaller than a coke machine on its side.

A Bridgeport knee mill is frequently about the same size as a stand up refrigerator, but you need some room to travel the table and work...(they make HUGE ones too)
And a thick concrete slab to bolt it to.
Wood floor? Not happening.

Old is GOOD in this particular case, the raw iron castings the best were made from were usually "aged" in the back lot for a decade or three before becoming a finished product.

Note that most real machines use 3 phase power, the motors can be replaced, or an inverter can be used, but serious $$$ either way unless you live in an industrial area.

OTOH a real knee mill (well used but usable) even with relocation and power considerations is STILL likely to cost LESS than that toy setup, and you can then do ~anything. They can also be converted to CNC (even DIY)

Try to get as much tooling with it as possible, (bits/reamers/shell mills/collets/rotary table etc) that will eat your lunch if you have to buy bits and pieces retail.

[Jadewombat]

OK, that gives me a better idea of what to look for.

I avoid Chinese tools like the plague and try to stick with the American brands. I've been buying more metal working stuff the last couple of years as space, budget, and justification permit. Pexto, Whitney, and Roper have been around forever and their stuff still works great after using it a gazillion times. I got the wool pulled over my eyes somewhat by Baileigh. I bought a 3 in 1 machine and found out a little later this machine IS made in China and is also sold under at least a dozen other brand names (Harbor Freight, Bolton, Jet, etc.).

Anyhoo, the machine does work OK for what I need to do with it and it hasn't broken yet but the levers on the side have some really cheap plastic handles and lock nuts.

[Jadewombat]

I think I found the machine I would need and it's not Harbor Junk:

http://www.smithy.com/midasMachines

It's not a perfect machine and I don't expect it to be for the money. Space is at a premium in my garage and I could at least get something made that's close to what would be needed, measure it, and send it to a real machine shop for final adjustments. Again, I have other hobby projects that don't require better that 0.003" precision.

If Burt Munro (World's Fastest Indian) could set a world's record with an engine he fabricated cylinder sleeves from 3 inch sewer pipe he dug up

https://books.google.com/books?id=GReLW ... pe&f=false

This guy could fab. up a complete chassis from scratch in his garage:

http://engineeredtoslide.com/2016/02/et ... 00-photos/

And this guy could make a radial engine from VW parts:

https://www.youtube.com/watch?v=SyRJeZ6s8uM

Then that's pretty good inspiration...

[Piledriver]

That looks like a real machine, and a huge bargain compared to a Sherline.
Even their top of the line 220v "Granite" machine would be a better deal.

Still smallish, but certainly capable of this project and most other small-medium scale work, and takes std tooling and mounts.

[Marc]

Instead of the lifters , what about buckets and shims like a lot of OHC engines....

The bucket-and-shim type used in the Rabbit are susceptible to spitting out a puck at high RPM when the lobe contacts it near the perimeter, limiting the cam somewhat. Fiat uses the same design (they hold the patent IIRC) but with a larger diameter.
The type that have an internal wedge adjuster (924, Vega) are too heavy as a rule for high RPM use.
We used to use the Alfa Romeo cups in Rabbit heads, since they have the same diameter, light, and their one-piece construction eliminates the "tiddly-wink" effect. But valve adjustment is difficult - worst-case, it requires removing the head and grinding the valvestem (or renewing the valve); if set up to use lash caps, adjustment can be made by just removing the cup and selecting a different thickness...I've even done emergency adjustments using disks cut from feeler gauges and inserted under the lash cap.

We ran a Fiat 128 engine in one of our cars. One feature they have that would be worth considering if you were building an OHC head is a removable cam box. Downside to theirs is that the cam loads through the end so the bearing journals are larger in diameter than ideal, but we ran that motor continuously in the 8-9K range and it never became a problem.
The neat thing about being able to take the cam box off is that you can make spacers from shim stock to achieve gross lash adjustments. We had two complete cam/box assemblies made up which could be switched quickly; one cam had a larger base circle but a spacer under the box would compensate, so rarely did more than one or two valves need adjustment after the swap. The drive belt would need to be adjusted slightly also, of course, but that only took seconds.

[Jadewombat]

We used to use the Alfa Romeo cups in Rabbit heads, since they have the same diameter, light, and their one-piece construction eliminates the "tiddly-wink" effect. But valve adjustment is difficult - worst-case, it requires removing the head and grinding the valvestem (or renewing the valve); if set up to use lash caps, adjustment can be made by just removing the cup and selecting a different thickness...I've even done emergency adjustments using disks cut from feeler gauges and inserted under the lash cap.

We ran a Fiat 128 engine in one of our cars. One feature they have that would be worth considering if you were building an OHC head is a removable cam box. Downside to theirs is that the cam loads through the end so the bearing journals are larger in diameter than ideal, but we ran that motor continuously in the 8-9K range and it never became a problem.
The neat thing about being able to take the cam box off is that you can make spacers from shim stock to achieve gross lash adjustments. We had two complete cam/box assemblies made up which could be switched quickly; one cam had a larger base circle but a spacer under the box would compensate, so rarely did more than one or two valves need adjustment after the swap. The drive belt would need to be adjusted slightly also, of course, but that only took seconds.

I'm confused again. Marc, are you referring to mechanical cups or hydraulic? The mechanical VW used up until ~'84 or so and '85 and later Golfs, Jettas, Sciroccos started getting hydraulic lifters. The cam and lifters are not interchangeable from mechanical to hydraulic heads.

The alignment of the bore for the cam and distance from the valve stem on this configuration would be semi-critical I know, but if they hydraulic lifter has some "wiggle room" of that distance of the lobe to the valve stem (i.e. the cam lobe just makes contact with the cam follower, then beds in a few thousands 0.000"? VW's procedure for T4 lifters of lash adjustment: "screw the rocker arm adjuster until it makes contact, plus 1/2 turn," is pretty inexact. Sorry if I'm not phrasing the question correctly.

The VW Type 1 valve angle is off-vertical (not perpendicular with the rest of the head) which makes it a little more difficult finding where in 2D space the cam will sit. I plan on using a VW type 1 valve cover modified for a Rabbit/Golf oil seal. I'll probably just mill a stock T1 valve cover and TIG a section of the Golf valve cover I need.

[Marc]

IMO it would be pointless to go to this much work and run hydraulic cam followers. If you were to modify them with larger bleed holes so as to delay the onset of "pumping up" you might be able to squeeze another 1000 RPM or so out of them, but as Piledriver pointed out the pushrod valvetrain can be reliable at the RPM limits 98% of ACVW engines will ever be asked to attain..and you can still amplify the valve lift through the use of higher-ratio rockers if needed.

http://www.jegs.com/p/Rhoads-Lifters/Rh ... 8/10002/-1

[Piledriver]

...Running rockers might also keep the cam pulleys off the exhaust better.

This is pretty much pointless unless the end goal is a motor that can run 9k+ all day long.
(other than simple proof of concept work)

[Jadewombat]

Thanks for the input. The point is not to simply raise the rev limit, OHC engines gain and maintain revs. much higher than OHV.

http://www.samarins.com/glossary/dohc.html

A pushrod engine is very likely not going to be able to gain revs. like this (even with an oversquare bore to stroke ratio, F1 engines are like 2:1 IIRC):

https://www.youtube.com/watch?v=XRXwWbo_mX0

or NRE. These guys chose to use the best of what they saw from Ford, Chevy, and Mopar V8s the last few years then went with their own design of a 4 cam DOHC plant:

https://www.youtube.com/watch?v=DRSugcmEaYo

I don't wish to argue the advantages and disadvantages and this may turn out to be a waste of time in actuality and I appreciate the concern for going down this road. Still though, I have this burning curiosity to at least try it and see how things go.

Two new stock heads, two cams, and some aluminum stock is all that I risk cost wise, plus a few hours of machine shop labor. ~$500 plus a lot of time and learning a lot about machining along the way? There's loads of reasons not to try this, but at the end of the day it's all for fun anyway.

[Piledriver]

Physics...

The "gaining revs" bit has absolutely nothing to do with valvetrain design and everything to do with inertia, in the form of incredibly low rotating mass.

That F1 cars flywheel/clutch combo is very likely 4" across and is probably titanium with some carbon/carbon composite clutch bits and weighs about ...
...as much as a Cafe Mocha Venti with 2 extra shots of expresso...

The super short stroke, titanium connecting rods and ultraight bad ashtray pistons don't hurt either...

That (and programmable DBW ITBs) is how you can change RPM fast enough to play God Save The Queen on an engine.
Note those engines idle at about 10K. They are just fiddleing the programmed idle speed to play the song.

The 2 vs. 4 valve example the first article gives comparing a 4 valve pathfinder V6 to a base Durango 5.9L (old school 318) V8 is laughable, there were 2V head Durangos with 5.7s making >400HP NA (Hemi), its all about state of tune.

With a bigger cam and replacement pistons/headwork etc the same 5.7L can make 600HP++ all day long.

I agree with everything else.

[Jadewombat]

I got an old South Bend lathe today. Really excited about putting it to use. It's a 9C model made in 1963 and is quiet, smooth, and heavy as hell (my guess is over 500lb. with the table). The guy I bought it from took great care of it. He didn't want to part with it, but it was too small for him for most of the stuff he works on. There's tons of parts for these SBs still available on the ebays, etc. It's about four feet long and will handle stuff maybe 24" or 26" wide at most. I'm going to weld some castors to the underside and figure out where it's going to live in the garage, then practice turning some metal before machining some center caps for the bus.

[Steve Arndt]

Our Monarch CK10. Full DC direct current drive. Made in 1944. Off a battleship.

The DC has even smoother feed and cut rates than 3 phase machines. Single phase pffff.

[GoMopar440]

Congrats on the find! I'd love to get my hands on an old South Bend lathe, preferably a Heavy 10 or something a little bit bigger. I'll have to make due with my little 7'x14" mini lathe and a 1941 Atlas 10" lathe I'm still restoring until I can find something better.

BTW: Machining equipment like lathes and mills really need to be solidly mounted. Vibration and leveling the machine accurately are the two biggest reasons for that. Vibration makes reliably and repeatedly getting a smooth finish very hard to do. If the lathe isn't accurately leveled when you set it up, there is a very high possibility of your part being different dimentions from end to end. A SB 9C is small enough to mount on a heavy and very solid table top. When using a level, you'll want to sit it on the bed ways to level it from end to end and front to back. Shim stock of varying thicknesses is placed under the lathe feet around the mounting bolts at each corner to make the bed level.

After it's leveled you'll also want to cut a few long (at least 12") test pieces of scrap metal to check how true the lathe is cutting. After you make a full cut along the entire length of the test piece measure it at each end, and in the middle. The results will tell you if you need to adjust the tail stock, head stock or if the bed ways may have grooves worn into them from repeated use over a small area. That last bit (grooves in the ways, is more of a problem with machines that have been used for production use in the past. The saddle ends up just using a small section of the ways and wears it down in that area.

I've set up a number of different types of machining equipment as a machinist (MR) in the Navy and in my own shop. If you need any advice or assistance getting it set up just give me a shout via PM.

[Jadewombat]

Thanks Guys, I've been very busy with the lathe since the site here has been down. I've been cutting my teeth learning how it cuts and works and how accurate I can get things.

The lathe is mounted to that desk. The whole thing is probably in the neighborhood of 500lbs. and solid metal. I welded up the bottom with wheels and cross bars to stiffen it up more. It's level and very smooth and quite for an old machine. The PO took very good care of it and made a few changes here and there for the better (serpentine belt instead of the leather belt, kill switch in a better location to get to it in a pinch, etc.).

Not too bad for a first try??

Cut from 3" aluminum 6061 round rod.










I'm painting the inside of the bus cab. soon, then get it running again, put the front glass in, circle back to the other 3 spike center caps, and somewhere along the way start gathering specs. of the Golf lifters, etc. Maybe by late spring or summer I'll get the plate to pursue the OHC.

[Jadewombat]

Still getting to know my lathe a bit more. I finished another spike center cap and machined an adapter plate for use with my dremel on an old bench drill press I found recently at the neighbor's curbside. Slowly gathering tolerance specs. for the camshaft, lifters, etc.