The pretty blue ones, if they're made by Isky, sound pretty much like the
pretty green ones, also made by Isky, but I hate to pick on companies by
name. The issue here is that we had a rash of top cap failures that we
decided were caused by stress fractures in the aluminium top caps after they
were nicked by the valve spring ends in use. (isky valve springs also).
Other potential contributors might have been insufficient radius in the
machining of the valve seats, and incorrect heat treatment.
After I broke two, and bent two valves, and rebuilt two heads, I went to
Avonbar race quality steel topcaps, with their springs and valves. This was
about where several engine builders said "we used to use them and stopped -
didn't you know that" causing me to grind my teeth, and curse...
Brian
At 07:06 PM 3/17/98 -0500, you wrote:
>
><<If you go with new valve springs, get top caps to match, and only use
>steel
>top caps. The pretty green aluminium ones have a bad habit of getting
>nicked, and then shattering, causing dropped and bent valves, wiped out
>valve seats, and pistons with holes in them. I have such a valve (1.218"
>rimflow exhaust valve, to be precise) on my desk as a reminder.>>
>
>So how are the pretty blue isky ones?
>
>Suspect too?
>
>Need to know ...thats is what the PO put in mine!
>
>
>Ric Bergstrom, Richmond, VA
>1973 Midget 1275 '88 240 Volvo '92 F150 '74 Midget 1275
>(apart!)
>Central Virginia MG Classics, AMGBA, VMSC
>
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