It's always the exhaust valve stems that dish. No lash caps here, std rockers. Will they last? I don't know but in my case I think something else will cause a heads off problem before the ss ss valves do. I didn't expect it to do a lot more than 20,000 miles before the top end needs a good looking at anyway and valves are cheap enough. How much £ for the AA heads?
£375 for a pair of heads pre cut to 92 bore plus £65 to have them put to the required cc That’s off their own website I’d imagine there’s postage and import tax on top of that. I think it was mike d James that said he’d experienced mushrooming of stainless valve stems in relatively quick time.
These lash cappy types are running aggressive cams, high ratio rockers with stronger and sometimes double springs at high revs. Muchos spring pressure to push against. Stock cam/rockers/springs won't give the stems that kind of battering.
I’ve no need for anything other than stock springs. The AA heads come with single high rev springs. To me that’s sounding like they would have an increased spring rate compared to stock.
Stainless valve stems are probably harder than some of the valve adjuster screws going around. Mine dished noticeably, had to remember to file a little bit off to get the valve out without accidentally reaming out the valve guide if you took the valve out. But then pratting around with swivel foot adjusters was probably what started the exhaust valve off on the trail to destruction, rocker arm missed the valve stem as it chewed a swivel foot adjuster, because I was not using a solid rocker assembly with shims, but a stock washers and clips rocker assembly and the washer wore out and the clip snapped... Valve stem must have bent but sprung back with a slight chewing on the tip.. should have replaced it but... So now I am going to stay with stainless valves as fitted standard to the JK preservation parts engine, take a look at it at say 25k miles , if they look chewed just buy some more...
Cheers for the info mike What heads are fitted to those jk engines? I know we were chatting about them at eddies but I can’t remember now
