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Ok so I am New to this engine building. My 1974 westfalia is getting an engine... Finally.
The engine Bits Came i a box with the purchase of the car, so its a puzzle
I Went with the AA pistons 96x66 p and c set.
I had everything balanced so im hoping its gonna run Nice and steady.
I am using the 1700 heads that Came in the boxes. I had Them opened up to take the cylinders, but the shop took of material in the depth too, so i cc-ed the tops to 50cc.
From what i have been reading in here i should be aiming at a cr about 8.5 to 1..giving a deck height of approximately 2.0mm.
The Mock up gave from 1.65 to 1.95 mm so I am gonna have Block decked to have more uniform reading.
Any how....the engine Guy i am collaborating with says that i should aim for a deck height of 1.2..but that gives a cr of approximately 10 to 1.
I am a bit lost here... I am not looking to make it a race brick... But since I am doing the job I want to get the Best bang for the buck... And indurance and reliability.
Ohh I am also gonna be running the infamous progressive weber dfav32/36 for now as it Came with the boxes.
I am gonna try and add some pictures when i figure out this hosting Thing.
Kind regards Jesper

And also.. Should I try to remove and smooth out the material marked with red on the top end picture?

You should run a deck of around .040" - 1.02mm, 8.5 to 9.0 would be a reliable CR.

Your deck readings of 1.65 to 1.95 mm may not be from the case, but it wouldn't hurt to have the cases trued if you can get the studs out with out damage. I would look at the cyl's for a reason why the readings are off. Have those measured, find the shortest one and match the others, and have the tops trued to make sure their flat.

The only reason to remove any material from the chamber is to increase chamber cc's.

Another issue I would look at are the valve springs, if they are the stock springs & retainers they need to be thrown away. You'll need to get aftermarket springs & retainers that will work with a .523" lift cam, and setup them up to their recommended installed height, this is very important. Then you'll need to mock up the heads to check the valve & piston clearance, especially because of the valve lift & no valve reliefs in the pistons.

And get rid of that progressive weber.

I contacted CB and they ided the cam to be the econo cam..a bit of mid range torque if i use a set af 40 idf or similar. And better fuel economy.
The lift compaired to the stock cam i roughly measured to1,5mm more. It is not gonna rev above 5000rpm, so is it because of the lift I am needing the springs? I can imagine it has to do with the space between the windings of the spring.
I am gonna try and run it with the progressive, if it is the reason for poorer than expected performance, I Will up it to a set of 40s along the way.
Any experience with the econo cam? I can imagine tuning Guys skipping anything labeled econo ...
I am getting the Block decked one of these days to get the correct deck height.

Correction, I thought the 402 was lobe lift and had I looked closely would of seen it was valve lift. If the budget allows new springs & retainers it would still be a suggestion, you have to remember the original springs are going on 50 years old and you have no idea of home many cycles they have been ran. At the very least, I would get clearanced keepers, and check the grooves for mushrooming on the valve stems.

I aim for 1.2mm on most of my builds. Anything tighter than 1.5mm but less than 1mm is good. Results in better burn, better fuel economy and lower temps

HHmm… I'm not seeing the 2201 on their website.. https://www.cbperformance.com/Cams-and-Lifters-s/12.htm.

What they list as a stock cam - #2202 - shows 268 x 378.
Your cam being 264 x 402 makes me think it will be pretty close to stock, with a tad more lift,
Should work well in a bus.

-But-

For a bus, I'd be keeping your CR to 8:1 or close to it (or even less).
That cam doesn't have enough duration to run a high static compression ratio,
Because the dynamic compression ratio will be high, due to small cam duration.

New springs are always a good idea after 50 years of use.
Regular old CB or Scat heavy singles and their matching retainers/keepers fit right up.

You are going to have to reduce your compression if you want the motor to last.
Normally, bus motors are built with dished pistons.
Having your case decked is a very good thing after 50 years, but must be done perfectly.
Unfortunately, this will reduce your deck height even more.
Once you get that operation done, you'll want to be getting some shims for under the bottom of the cylinders.

I like your un-shrouding idea to get more CCs in the heads.
Not sure it will be enough to keep the deck tight, but can't hurt.

Depending upon how much you get from your un-shrouding, and how much they deck from your case will determine your barrel shim thickness.
Target 7.9 - 8:1 CR, and let the deck be a bit taller than many will say is ideal.
Too much deck isn't the end of the world.
If you really care, buy some bus (dished) pistons and sell off the ones you have.

Here's your calculator ---> http://cbperformance.com/v/enginecalc.html
Looks like with your 50cc chambers, and flat tops, you'll need almost .1 deck to get 8:1.
If you can find 5ccs by un-shrouding, you come down to .072 deck, which is way better.
5ccs is a lot of hogging in those chambers..
If you can find 5ccs and up the CR to 8.3 you get .057 deck, close to ideal.

So,
With the parts you have, you will end up with some compromise..
I'd be adding deck height myself.

Or, better yet, buying pistons..

Ok so what has happened is that i got the case decked. And the test on one cylinder gave the height of 1,2mm that we initially aimed for. And the barrels Are of equal height now so that is a good sign.
I took 3ccs out of each Chamber on the heads. I could be a little more aggressive on the sides I think, but this Will have to do.
Cannot wait to put it together.

The AA birals is some what wider at the base and therefor was standing on the imperfections from the casting. That gave the bogus readings in deck height and alignmemt of the barrels.

The original were not that wide

This is shaping up to be a nice motor..

How did your deck/CR numbers end up?

You could un-shroud to the cylinder ID - like you said.
And, you could tighten up the un-shrouding closer to the plug a bit more. There are pics of the 914 2.0 chamber in my build thread,
Maybe go for something like that?

Just know that too much compression is going to make for short motor life.
If you do end up near 8:1, or god forbid over,
You are going to have to be a ninja with tuning to keep it cool.
And, with a proggy on there.. Well.. Bueno, no. No bueno.
Seems that anything with birals at least deserves a pair of Webers or at least clones.

You have the 72-74 heaters and a header exhaust?
Hopefully not one of those VST log things..

Shaping up nicely.
Sweet pic of the birals sitting on a flat deck.
That’s the good stuff right there..

Type 4 Unleashed wrote: ↑Wed Apr 15, 2020 1:39 pm 8.5 to 9.0 would be a reliable CR.

^^^This guy knows these motors^^^

But he missed that you were building for a bus...

He’s a 914 guy,
And seeing those flat-top pistons,
It’s easy to see how he could make that mistake.

A 914 uses flat-tops,
And can get away with far more compression.

8:1 is for a bus with a bigger cam than you have.
If you are up near 8, you will need Webers (or FI) and a proper header exhaust tuned well.

A bit of deck isn’t the end of the world IMHO.
.040 is tight. Real tight. Especially for a bus.

I run 9:1 in my bus with T1 2110cc, engle 110 cam
keep the deck height tight and you shouldnt have issues.

Well, i ended up with a higher than recommended.. CR 8,7 :1 but I Hope it Will work out. The deck was right on the 1.2 mm that we aimed for initially.
I put standard valve adjustment screws in, and set the valve geometry... It was 1.7mm the pushrods had to be shorter... Doesn`t seem like much, but if that is what it tales.
I had and old bustet glass pack exhaust that i changed.. It is on backwards in the picture
Off course i forgot the plates above the pushrod tubes.
It is coming along slowly..