We are nearing the final stretch in our around Oz journey and I have come up against the do we or don't we problem. Driving in to Karratha from Broome 4 ( or 5) weeks ago I found no.4 ex valve was tight, no biggie due for an adjust anyway. Leaving Kalbarri after visiting Monkey Mia and Coral Bay roughly 1500km, I noticed power dropping and missing, checked valves again at Northhampton and found no. 4 ex tightened again. Worried now and checking every 500-750kms, bit tighter every time.
Before we left North Coast NSW I had the heads stripped, cleaned, crack tested and told they were good to use so fitted new ex valves cleaned the inlets and refitted. Also asked them to check the seats which were apparently serviceable. Asked for new guides to be fitted but unsure if this happened (learned a good lesson here Re replacement new head cost to recon cost!)
Checked again this Friday just gone in Denmark, not closed up but tight and running out of room on the adjusting screw. When adjusted correctly it runs like a dream.
So after that long winded story I was reading on the samba causes of valve seat recession and stretching of the valve( don't think this is the case as it runs well when adjusted) shouldn't be running lean, twin 40 IDFs 55idles 120 mains and only sitting on 3200max on the hi way.
However.......
Towing a 6x4 box trailer with shit in it, had it on the weigh bridge when we left combined mass was 2840kg so we dropped 90kg off it and stopped trying to get over hills maintaining speed.
In Darwin I fitted a 009 dizzy as I had one that had a pertronix electronic setup.(max advance 32')
Temperatures climbed after we left Emerald QLD to mid 30s for most of our travels till we got to Jurien Bay( bloody head winds too) but any pretence of speed was dropped accordingly.
I am going to fit the original svda dizzy tomorrow and keep our fingers crossed for the Nullarbor.
This wasn't meant to be a novel, the question is can you stop/slow down recession, for a period anyway if you back the CHTs off?

Are you running lead replacement stuff in the fuel? Eg flashlube valvemaster or the like? I know dubs should have hardened valve seats already but it can't hurt to give the valve some cushion. P.s in twenty years of working on hi revving bikes I have never seen valves "stretch" It is almost always seat/valve wear that causes recession. Or worst case cracked head and the seat is moving around and getting pounded in to the head.
Good luck though, try and keep revs down as much as possible.

if it makes you feel better have a read of Kombi Kim's adventures to Central Australia where he had some recession

http://forums.aussieveedubbers.com/viewtopic.php?tid=18708&page=1 

and when he got back

http://forums.aussieveedubbers.com/viewtopic.php?tid=8566&page=1#pid67361 

Yes - setting valves when hot can help

far out - that was over 10 years ago

and I remembered it

geeez - I'm getting old

Thanks guys, Plonked the original dizzy in and took it for a spin to Albany. Didn't go over 3000 and no trailer behind, ran sweet as. Bizarre, I cracked up reading that post by kombikim, same story as ours nearly word for word. We have gone a lot further but our troubles didn't start till a lot later in the trip too. Am going to risk the crossing, just going to take it real easy, am worried about the climb up the Blue Mountains from Lithgow for the same reasons. Fingers crossed

Come into Sydney via Goulburn. Much easier

Our destinationis in the Blue Mountains, Glenbrook. Would be easier climbing from the eastern side wouldn't it?

certainly would

that climb in to Mt Victoria is fairly short but REAL steep

Hey Dave - love reading about your adventures - certainly have life long memories for your family especially the kids.

Back to your original question: Can you slow down recession??

Yes you can - you can even stop it completely: Fit a Subie engine!! then you can go where you like, when you like and drive on your terms not on the engnes terms.

I love aircooled VW's but hate them in a touring camper.

I admire your resolve.

Thanks Karmann, the subie alternative has been thought about quite a few times, usually when going back to 2nd when climbing a hill! Don't think I can do it but, love the noise, the adjustments etc etc of being aircooled. After this trip any camping duties will be much closer to home