1968 Skoda 1000MB air cooled V8 build up.

Forgot to mention the throttle box.
The carbs are all designed to be in the front operated by a cable so the mechanism is the wrong way round. Throttle box reverses the direction & also has a giant spring inside which helps the throttle pedal return to normal. Because the cable is 10 foot long don't forget.

Great project; My wife is from Czech (Moravia) and had exactly this car (also a '68) as her first car when she was 18. She recalls it as the best car in snow.
The backgrounds of the parked car look very Czech; We lived there for a year when I worked at Skoda in Mlada Boleslav.

Bookmarked!

Daan

22:
Pedalbox:

One of the few racing parts on this car is a balance bar & a triple reservoir made by Tilton. It runs DOT5.0 fluid.
Now I can BUY a pedal box for £600 from wherever. Do you think that is what I did?
It is better value for money and probably faster to make one yourself than try to get one of the standard issue things in there.
This one uses AP style cylinders.
The original Skoda pedal box has a common reservoir for brake & clutch. I didn't dig it much.

24:
Engine.

The first build of the engine was adequate. It got me to Prague & back & showed no signs of trouble but When I pulled it out last winter for a quick checkup I found horror due to my lack of experience & also the dimensional variations on the particular block. The trouble was with the mains delaminating & the big ends wearing unevenly. To cut a long tory hort the reason was misalignment of all the parts therein.
Luckily I had some spare blocks & one measured up lovely. That got new mains, new con rods, big & little end bearings. I also modified a cam & the followers to try to pep it up a bit.

So the photos show the basic architecture of it followed by how the trouble was detected & hopefully sorted out but first...

The Tatra engine has the following odd things going on.
It is air cooled.
Split skirt pistons
Individual cast iron bores in an aluminium block
Hemispherical combustion chambers in individual die cast aluminium heads
Single cam in the valley driven by a 3/8" TRIPLEX chain. No bearings, straight onto bores in the block
9mm diameter valve stems
8mm head bolts, 4 per cylinder.
No head gaskets!
Oil feed to the rockers via hollow pushrods
4 into 1 pressed steel exhaust headers like on a cement mixer
Five bearing crank runs in white metal bearings which have to be line bored by experts.
The lubrication filter system is plain inadequate
Old fashioned rope seals in the rear end of the crank.
There are two oil coolers to ensure the engine won't go above 40 degrees.
All together I counted 191 ways for oil to leak out of the engine & 16 ways to leak out of the gearbox
All made worse by what must be a misprint in the old service book which quotes some extremely low torque setting on the main bearing caps.
The book also goes on about what to do with a plate in the intake-exhaust heat exchanger when the seasons change in Slovakia & when to change the monograde oil.
The book also goes on about how to cast your own crank bearings at home & then hand scrape them over your knee. It has a recipe for the babbit metal right there! AND how to balance the rods & the crank for heaven's sake.
From experience there are no two Tatra 603 conrods alike.
Parallelism & perpendicularity are rare qualities in this lump.

And then it has my modifications;
Bad ones...
S shaped exhaust with 3 mufflers a side.
Intake manifold the volume of a cathedral
A full flow oil filter in a canister
Edelbrock carb is totally tunable, it can cope with anything but at the moment it is sitting on its hands.

That description makes it sound less like one large engine and more like several smaller engines working together.

OK, lets get rid of that rope seal.
Had to generate out the original diameter. there isn't enough meat there for a standard seal because there is a labyrinth behind it so you have to make do with that & reduce the thickness of the circlips & also reduce the thickness of the oil seal.
Then you have to machine the flinger off the crank & shring a new sleeve on & cylindruical grind it. No pictures of that sorry.

Use nitrile cord in the 2 vertical seals instead of asbestos rope.

What is wrong with the rods?
Here is a fixture which is the same diameter as the crank pin. It has been made in one operation so that diameter is perpendicular to its base which is bigger & therefore heavy enough to hold it down firmly onto the surface plate.
The technical term is "cylindrical square" but they are way obove anything I can make. I call it a near enough square.
The other square has a notch in it to admit the little end. Both diameters are equal.
The gudgeon pin should touch all the way round.

You can see the light pouring through from a mile away. The light source isn't needed.
This is amanufacturing issue not a damage issue. No two rods alike.

New rods needed.

I know the crank is right and I know the line boring of the mains in the block is right.
How do I know?
Well I had to make another fixture which is the exact diamter as the outside of the main shells, cylindrically ground to be parallel enough not to show up on any instruments in my posession. It has full contact all over the main bearing housing bores. Clock that fixture into the miller and now you can do polar coords off the crank axis. That is how I know everything is everywhere. It is also how I will fix it but in a different machine.

The main bearings were de laminating because the bearing caps had been walking about. I take responsibility but the cap faces didn't get like that in my lifetime.





When the caps were torqued down, the stress was going through the shells.

The idea is to skim the cap faces in the above fixture, make new caps undersize & send them for line boring. There will be a filler piece in the block which gets glued & pinned. Then they bore to a modern bearing size. Also, the new caps get bolted through a gusset plate to hold them down a bit better.

While it is in this fixture we can bore the cylinder holes in the block to take a an insert which will be of a tougher material. That allows us to raise the heads a little bit and get a bit more room for when we stroke the crank.

Oh yes and while it is there we will machine out the M8 head bolt threads & place an M10 or even M12 Helicoil there. Because I suppose we're going to need something to hold a blower down one day.