Sweet!

I'd take a set of steel timing gears if they are OEM volvo B30 (big, heavy and unkillable). Just going to be about 10 years before I use them lol.

Cameron's 444 already has some on it, so it is all good I guess...for the day in the long distant future that I'd end up with that one potentially maybe kinda sorta who knows.

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Quick post here....I'll update more soon.
Does anybody know if the b20f had flat-top pistons? I'm trying to figure out how much to shave the head going on this car, and need to know if there's any dish in them to get the 8.7:1 compression. I can't find the info anywhere on this engine.

The Mahle catalog says all B20 engines used the same pistons and are flat tops. Later B20s had the larger wrist pins, of course. Compression is dictated by the head...

I'm going to put this post in here because that's where I think it belongs. I finally got Greg's port work done this weekend. It took me quite a bit longer to do the B20 than my previous B18 work as the casting is much harder (or my bits have gotten duller). I decided to try to capture a few things photographically and measured a few more things to get a sense of the numbers. I'll post the numbers later.

So here we are again at the start - we all know about the valve restriction in these heads - here's how I've captured it digitally. The red lines are my "idiot" lines for porting and keep me away from the seat area.

Face on - sure looks like the normal shot.


Lets light it a little differently.
Intake...


Exhaust...


Inside the intake - some attempt has been made to help flow around the valve.


About 6.5 hours of porting later we have this...


I've preserved the port bias and tried to improve things in the intake and exhaust tract. Here you can see how I've opened up the area behind the valve almost to the valve seat.



I've tried to direct the flow a little more forcefully around the intake valve and have done what I can with the exhaust (while preserving it's bias).



Finish on the intakes was left coarse - the exhausts were fine finished, but not polished.



Combustion chamber alteration - I've tried to unshroud the intake vertically here a little and clean up the ramps into the spark plug area.





I've not gone too far - but this is a little further than my B20 head. The good news is that nothing else on Greg's car will change - only the head. So we'll see how things get better as a result of improved compression and the port work.

Excellent. Thanks for the info Dale. I still have to crunch the numbers but I'm hoping to take the head from 8.7 to about 9.5:1 compression once it goes into the machine shop tomorrow.
Thanks for posting those photos Craig, and a big big thanks for the work. I'm excited to know how much better this car will drive once the new head is on.

A few numbers - while I'm only quoting areas and not volumes, I thought it would be interesting to take a few measurements of the ports. I used my T-gauges to find the maximum diameter of the smallest opening of the port. While the shape of the port restriction is not always circular - it is an approximation. The T-guage was then run through the other ports to ensure that no smaller port maxima could be found.

Stock B20:
Exhaust port max restriction size: 26.3 mm
Valve seat size: 34mm

Intake port max restriction size: 33.8 mm
Valve seat size: 43.11 mm

So we can see right off the bat that the ports have between 8 and 10 mm worth of narrowing right after the seat.

Ported Head - lets call this a Coburn Performance Stage 2 head:
Exhaust port max restriction size: 29.36 mm
Valve seat size: 34mm

Intake port max restriction size: 37.3 mm
Valve seat size: 43.11 mm

Running the numbers on the area difference, the port work that I did on this head resulted in a 23.77% gain in port area behind the exhaust valve and 21.78% gain in port area for the intake valve. The rest is all about the shapes that have been created. Either way you slice it, that's pretty crazy.

The tough part is explaining what is going on behind the scenes in the runner area as I'm trying to direct flow to certain parts of the cylinder. For example, I have enhanced the port flow around the valve and done so to increase flow to the outside in the hopes that this will create more tumble of the fuel charge on the intake side. On the exhaust side, I have left in what has been cast instead of trying to fix what is not possible (the short side radius is improved as much as it can be, but the port floor is left completely untouched) and I've biased the port towards the roof of the port. This is in an attempt to provide volume and velocity to the exit charge and to direct it up off the area where it will eventually get worse due to increasing cross sectional area. You do what you can with this area.

Right, so the head is back from the machine shop as of last week. I went into the shop to CC the head after they skimmed 20 thou off, and oddly the combustion chamber size had GROWN one CC from when Craig and I last measured, even after being skimmed. While this could have been differing weight of oil used, or differing measuring technique, the machinist boiled it down to the extra dish in my new exhaust valves (yep, the old ones were no good...off to Ebay, $20 for all four), and the extra cut in the valve seats which would have recessed the valve slightly more. Beats me. Sounds reasonable enough.

The machinist was pretty cool, and helped me do the measurements. We figured another 35 thou would be a good start. So onto the skimming machine-a-ma-doey to do the skim. We CC'ed the head right in the machine the next time, only to find it wasn't enough. So we took off another 15 thou, which put us right on the mark for the mid-9 point compression ratio I was looking for. So yes, the machinist took off 70 thou. Seems like a lot. I hope I did my measurements right.....

All in all it was pretty rad being at the back of the shop. The guy was a big help, and put the valves right back in for me, and packaged it up, pretty much in 15 minutes. And they only charged me for one skim. Really nice. The 3 angle valve job looks to blend really nicely in with the port work Craig did, so I'm anticipating big things.

Next up is putting the head on. I just need to paint it first, but then she's good to go.

Fingers crossed you didnt take off too much! 70 thou is alot, 3.5x what volvo says is the limit. It was that important to get to 9:1 cr? Why not save on some skimming costs and get a thinner head gasket and improve squish at the same time?

Thinner HG's cost a lot and we were compensating for the fact that Volvo left the pistons 20 thou down in the bores. If you've seen the R-Sport heads, they have over 100 thou knocked out of them. Yes, it is a lot, but it should work. Definately not the "right" way to do it. Can't be worse than it is. 48cc combustion chambers should liven things up a little.

Greg - deburr the combustion chambers and those valves before you paint the head. It just takes a second with a file.

How about a copper one? Kind of forgot about this one sitting under my desk...

How thick is it? I'm thinking about yanking the head on the Canuck sometime this summer and seeing why I still get some run-on.

Looks like it's .050"...

Thinner head gasket good!

Yeah, Athal, I was going to get the head skimmed no matter what, and had already purchased a gasket set. Since I only paid for one skim, it didn't end up costing me much. More squish would be good, but the way this one panned out, upping the compression was the easiest thing to do. Comparing the E and F heads, the height of the E is considerably less, and I believe that's where the compression bump with that head is. I'm basically just emulating that with this head, by shaving off the extra material.