Hello All,
Is there a lower RPM limit for triple groove valves? I'd heard that there is (at around 5000RPM) but KAD and MED both supply triple groove valves. My 1293 engine goes to around 6800RPM and it currently has triple groove valves. The head is stripped so I'm wondering if I need to change to single groove valves.
Any help would be greatly appreciated.
Triple Groove Valves - Rpm Limit?
Started by
Mal Drummer
, Jul 25 2022 10:29 AM
6 replies to this topic
#1
Mal Drummer
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Posted 25 July 2022 - 10:29 AM
#2
bpirie1000
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Posted 25 July 2022 - 11:44 AM
Speak to your machine shop. Or KAD OR MED themselves. They are the ones who have done the leg work and ruined/tuned many a head so would be best placed for your info...
#3
Ethel
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Posted 25 July 2022 - 12:19 PM
There are other factors, spring rates & preload, valve train weight, cam profile...
I'd expect even the most basic original eqpt gear to cope with 5k rpm though.
#4
Lplus
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One Carb Or Two?
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Posted 25 July 2022 - 02:25 PM
Hello All,
Is there a lower RPM limit for triple groove valves? I'd heard that there is (at around 5000RPM) but KAD and MED both supply triple groove valves. My 1293 engine goes to around 6800RPM and it currently has triple groove valves. The head is stripped so I'm wondering if I need to change to single groove valves.
Any help would be greatly appreciated.
Seems unlikely, I understand the rev limit for standard 1275 engines is 6000 (possibly 6500 for later ones) evidenced by the rev limit marking on the 1275 rev counters. (5800 for 998 engines) All the later engines use the triple groove collets.
#5
mini13
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Posted 26 July 2022 - 07:34 AM
I suspect someone is thinking of the old keepers that had the clip on top,
spme good info here on tripple groove collets https://www.theminif...d-three-groove/
#6
DeadSquare
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Posted 26 July 2022 - 08:56 AM
In 60 years of playing with Mini engines, I have only once known the end pull off a valve stem.
It was a well thrashed 997, running a 544 cam, whose driver only used top gear as his overdrive.
#7
ACDodd
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Posted 26 July 2022 - 12:19 PM
I have seen the triple collect type fail. Its usually associated with high rpm and high lift rockers. I use the rule of thumb is the engine peak power is over 6krpm change to the single collet retention. Also if you at using 1.5 rockers on a road car with triple collet retention and drive hard be warned.
Ac
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