Phil etc? A+ valve length?

[RobThomas]

Do any of the engine builders know if 998 A+ valves are actually shorter than A-series 948 valves or is it just that they are shorter than 1275 ones?
Thanks.
Rob.

[philthehill]

Rob

As far as I am aware but happy to be corrected - all of the 'A' Series valves are the same length except those fitted to the 12A185 and AEG163 heads - they are shorter because they are set deeper into the head.

Phil

[RobThomas]

Thanks for that, Phil.

After a tip-off about using A+ bits on the Alta I started hunting for info and I read that the 998 ones were shorter but it didn't say what it was that they were shorter than. I'd hoped they might have suited the Alta. Ho hum...back to Google.

[philthehill]

Rob
After a bit of research I have found the following regarding valve length.

998cc 'A' Plus head......................... 3.42" (Pt No: TAM1770) triple groove collet.

References also to 3.44" & 3.56" length valves with triple collet.

AEA163 head...................................3.52"

940 head.........................................3.52" & 3.57"

The above may be of help.
I will add to the information as it comes to light.
Further information can be extracted from:-
http://www.minispares.com/search/classi ... valve.aspx
Phil

[RobThomas]

I grabbed some 1098 valves and they are 3.42 inches. Maybe they are saying that 998 valves are the shorter 3-groove valves. Hmmm.

Thanks, Phil. I'll keep looking.

[philthehill]

Rob
These may be of interest and they have measurements shown:
http://www.ebay.co.uk/itm/GENUNE-BMC-A- ... SwDmBY5mga

They are the large collet groove 1 1/16" dia and fit the 850cc & 998cc Mini plus 803cc/948cc Minor (1.094" head diameter) 'A' Series engines.

Phil

[RobThomas]

Ta. They'd be a good candidate for a 9/32 conversion to an Alta. The collets aren't so common, though. I've found quite a few of the single groove ones and I'm fairly sure the 3-groove ones are 14 degree taper against the 10 degrees of the earlier ones so the 3-groove caps will be far to weak if they are machined down to fit the Alta springs.