Polo motor build for junkyard coupe 58367

[merbesfield]

Agree, the Gauge Pilot looks amazing. Now just have to figure out how to hide all the data collectors on my 911.

[JTR70]

Hey Nigel,

Thanks, I will certainly keep the Gaugepilot unit in mind. I may go with the earlier linkage as Bill suggested as well but I'm just not there yet, but soon hopefully. Thanks again! Justin

7/17/16

Just took delivery of my new "Big Bore" kit for this engine. Sort of 356/1720 Big bore upgrade except for this "polo".
My air cooled engine Guru-buddy Tony G. recommended We go a little larger on the bore than the 102MM set I bought originally. With the 82mm stroke crank its running his thought was that slight "piston rock" as it cycled through might become an issue. He said a 103 or 104mm set might go along way in smoothing that out during operation. Who was I to argue? My next stop was LN Engineering's website to see what a set of 104MM P&C's would run. As I went through their offerings low and behold they offered a 106MM set. I wanted them; I thought what the hell if I'm buying a new set anyway lets go all the way!! A complete set of 6 106mm P&C's runs 5,650.00 but I only need 4 barrels minus the pistons as they will be made to the specs Tony determines later on. I spoke with Dean about them and he was shocked that they went that big. He chuckled a little and said "man you are really going for the gusto" LOL. He told me to hold off and let him investigate further with an inside contact there to see how durable a size that big would be. Everything checked out to his satisfaction and set of 4 106mm barrels were soon on their way.

Their Beautiful. Notice no groove for a head gasket or flame ring. The booklet that came with them states they go right onto the head with a coat of "Elring Curil T".

I thought I was going to have to have the block spigots bored for these but to my surprise their slip-ins. Razor thin sleeves though. They come "windowed" which was pretty cool.

The only machining that will have to be done is to this inner shoulder for piston clearance.

The windowed bases don't do me much good unless I have Bill machine in the reliefs for them.

My old 102MM piston in for a comparison. Very much reminds me of the difference between a stock 1600 piston and a 1720 bore for 356.

According to Dean this is about as far as you want to push it on bore size. Walls are getting pretty skinny at the center.


According to the displacement calculator an 82mm stroke X 106mm bore is going to bring this motor up to 2.9 liters or 2895CC to be exact. Each pocket will displace 724CC; up from 670CC.
Technically a Chevy 350 cut in half, should be plenty.
Still working on the tin modification and will post some of that next.
Thanks for looking!
Justin

[Edwin Ek]

A 2.9 liter 4-cylinder? I think you are going to need balance shafts to smooth the vibration ...

[Jack Staggs]

Edwin, you may want to read this:
https://en.wikipedia.org/wiki/Balance_shaft

[roy mawbey]

Wow Jack, that was interesting reading! I really enjoyed reading that article but it stretches my brain a bit, so kept just the bit advising the point about flat four engines not having the same problems regarding balance as the inline engines.

The internet can be wonderful sometimes. I would think Justin would have been pleased to read that too.
I noticed too it was Lanchester the English guy who developed all that but in 1904. Nothing to work from, just his mathematical knowledge and mechanical understanding. There are ( or were ) some really clever engineers around all those years ago.

Thanks

Roy

[JTR70]

Yes as Roy said, thanks for sharing that link Jack. Edwin had me spooked.

8/18/16

Cam towers getting ready to go under the knife.

Bill's getting ready to section them so we can preserve the end caps that Dean would normally just lop off. He will also be turning 3 large dowels that will insert into the rockers and cam journal to set and locate the end for TIG welding. A machined holding plate will also be fabricated. Its a ton more extra work and expense but worth it to me as want a more "finished" or stock looking tower in the end.

Dean's method of simply cutting and finishing the end is of course a lot more practical and trouble free but I decided to go the extra mile for my engine, what the hell.
Thanks for looking!
Justin

[JTR70]

10/8/16
Cam towers sectioned and shortened.

Bill was finally able to set some time aside to set up and knock out my towers.

Outer and center port halves Siamesed' together almost flawlessly.

Lower stud half will blend together nicely once its all welded.

Bill was taking off the last few thousandths on the other tower end when I stopped by.

Initial cuts are done but a lot more prep yet to go. All the mating surface need to be tapered for a "V" in prep for good thorough weld.

Side by side comparison of the standard cut tower and my sectioned tower.

The huge "cam dowel" will be shorted below the end cap where it will be tapped for a large bolt and washer to clamp this assembly together. Rocker dowels will remain free. More jigging to come, Half inch plate will be milled as valve cover jigs which will also double later as holding jigs for the actual valve covers that will be also sectioned and shortened. This approach is a huge and impractical gamble as it requires so much extra work and machining and it could still end up warping which would throw off the end journal causing binding. This would then require a new race insert in the end cap then line boring...but it can be saved. I've already been completely warned about this risk by both Bill and Dean but I just needed to try. The mirrored ends just make it look like such a proper factory component again.
I NEED IT!

[tham]

[JTR70]

10/9/16

A couple of shots showing what was removed.



Cam dowel now doubles as the assembly clamp.

Dean was kind enough to send a test cam for an accurate reference mockup.

Bill machined everything perfectly; the cam slips right in an spins effortlessly. The trick of course is preserving that alignment after all the welding and heat. I at least now know its starting out correct.

Tower mock up with my heads. Everything lines up and ends beautifully.

With the cam Dean also included the spacer cap used to bring back the deck height after cutting.

With the route I've taken that spacer will not be needed.

Another shot of the standard (and far more practical) cut down cam tower.

My impractical but mirrored version I'm obsessed on making. Taking the assemblies over to my buddy's next who will be performing the welding to get a plan on how much he needs Bill to mill out of the joints to allow a thorough root weld.
Thanks for looking!
Justin

[JTR70]

10/16/16


Bill took delivery of the machine plate for the rest of the jigging. Valve covers ready for sectioning/shortening as well.

The covers will be sectioned almost exactly like the cam towers. Fortunately the embossed pattern and bolt holes repeat so the "new" ends are going to match up perfectly. These are the factory magnesium covers so I've got to get hold of some magnesium rod to TIG them together.

The bottoms are a used after market alloy HD set I bought. The pattern ends on this set however will need a bit more machine work to be an uninterrupted match up. Then after welding they will of course have to be machined for surface and gaskets as well.
A ton of prep work but its getting there.
Thanks for looking!
Justin

[Tony G]

Very impressive Justin, looks like you are coming along fairly well. I will be taking lots of time off toward the end of the year, we have to get together. Keep the momentum going.

[JTR70]

Thanks Tony, Sounds like a plan!

10/30/16
964 Valve covers

Changed my mind on those red lower billet aftermarket valve covers and purchased a pair of factory NOS lowers from Parts Heaven.

Part of my decision was a more seamless joint once its sectioned and welded back together.

Another reason was I like that the factory plug holes are angled for a direct shot at the plugs where the after market is milled in flat. I also prefer the ringlet on the end for plug wire support where the other does not.

Sometimes its hard to improve on factory parts and in this case it does not IMHO.

A quick mock up with a tower section to reconfirm with Bill where they need to be sectioned.

On the chopping block next.

Bill had just sectioned the upper covers the day before.

The lowers will be tricky but these on the other hand will be a seamless alteration once welded and dressed.

Again just the initial cut as a few mm's more will need to be removed for a perfect fit. A long way yet to go but one more step closer.
Thanks for looking!
Justin

[tham]

I have no words, all of your pictures are amazing

[Bill Sargent]

Hi Justin - I have been lurking and reading on your progress from here in Beijing. I do not know
If it might be feasible or if there is anyone in your area capable, but google "vibratory friction welding" and look at some of the U-Tube videos. In your case the process could yield complete penetration welds with less pre-work, less post weld machining and likely less distortion.

In any event I continue to be impressed with the motor. How is the swing axel 5 speed transmission coming along? Or do you have another transmission solution?

Bill

[merbesfield]

Those valve covers look "cute". I love anything miniature.