Hi guys,
Looking for a early or late B20B cylinder head, prefer 42mm intake valves but 44 will also do fine,
If the intake manifold alignment rings are there thats great.
Also it cant be too thin, will need a pic and or a measurement of head thickness with some verniers if possible.
These heads came out as 86.7mm thick so thicker the better as i was having detonation probs with the old thin head.
Brissy is preferred but interstate is fine too :)
Kind regards,
Matt.
Probably better to sort out your fuel/air and spark/timing first of all to get rid of pre-detonation in the first place.
Copper head gaskets can be made to specification, and can even be reusable. I've had good success in the past trying to sort out vintage engines For example.
https://www.coppergaskets.com.au/I probably have a bare head in my stash, but I am far from local. Let me know if you can't get something.
It can also be worthwhile dulling the sharp edges in the chamber so that they are slightly rounded. A scraper or jewelers file followed by some emry works.
Have you had the distributor to bits? The little plastic lugs at the connection posts to the springs break, as does the washer under the weights . The weights and the advance is all wrong, and they tend to cause lots of pre ignition once they have got out of whack here. Also the old grease on the shaft gets hard.
What @1971_144GL says is correct. The B20 heads are known for detonation due to hot spots around the plug and along that ridge. Your high compression head provides you with an opportunity to unshroud your valves a bit and increase the bowl volume instead of finding a taller head. If you stuff it up there are replacements around. There's a series of reasonable vids (Youtube) on porting out a B20 head and bowl. Dealing with the bowl is less problematic than playing with ports.
Not sure why you'd want 42mm inlets over 44mm. That extra 2mm makes a big difference in performance. Also, the B20B went to 44mm valves in YM 1972, IIRC, while B20A stuck with 42s.
