I've used 526 springs for years on road cars, no problems with GR's cams.
But years ago I took 4 lobes off a Camtech VP 3 cam in 30,000 miles using Penrite HPR30 oil....
Same springs.
I would only use 527s on a race motor.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

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1968 Morris Mini Deluxe - members gallery
1970 Morris Cooper S - members gallery
Mini's I grew up with
Slot car couch

Rusty,
Were those valves small bore length, or from a 1275?
What springs? 526 or 527 are too long for small bore valves..

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Ouch!...Now that's what I call a dropped valve Commiserations to Rusty

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"Show me the Mini!"

Hmm, I better double check which double springs I put in my 1098, and what length valves they are!

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We used VSP580P double springs from Karcraft on Joe's 68mm bore (998 crank) motor.
Valves are 998 Cooper inlet, 27mm exhaust.
RE266SS camshaft.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

They were valve springs recommend to me at the time, I cannot remember exactly which model springs they were, maybe I have an invoice still which will list the part number, I will check.
Perhaps they were too long, could well explain it.

Sent from my moto g(6) using Tapatalk

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1968 Morris Mini Deluxe - members gallery
1970 Morris Cooper S - members gallery
Mini's I grew up with
Slot car couch

I did buy some VSP... springs from Karcraft but I’ll have to check which ones. The valves are 31.8/27.2 from GR, I assume they were small bore length but I’ll have to check that too

To be honest I didn’t even think about it when I ordered the springs

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Tim, if they were double springs for a smallbore from KC, they are VSP580P.
Good for 7,000.
Their other VSP springs are singles for 803, 850, 998 and 1098.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Oops. I’ve checked and I ordered VSP3964P# (7000rpm) - 1275 double valve springs. Will these be an issue with the 998/1098 valves? They are the GR Paul Ivy race valves, so they are a really nice valve, but will the fitted length of the 1275 springs be a problem?

If the valve stems are the 998 length I’ll have to order some new 998 specific springs and swap them over? Hopefully there has been no damage in the last 1000km. I have the RPM limit set at 5750rpm, so I don't need super high rpm capable springs

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I got the crank back from the shop today. The crack check showed no problems and it was good to go at 10/10 which was great news. The stroke measured up as 70.0mm

Here is a comparison of the short stroke 1100 and standard small bore 1100 cranks.

One of the appealing features of this crank is the overlap between the main journals (red lines) and the big ends (green lines). In combination with the large 1275 size journals, it makes a really strong crank

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"I would only use 527s on a race motor"

I would not.

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The bitterness of poor quality (or Crappy Workmanship) remains LONG AFTER the Sweet Taste of Low Price is forgotten.

HI Tim
Those valves are longer than the small bore valves they will take the 1275 springs.
The spring height will be around 1.380 to 1.4 in those small bore heads.
Graham Russell

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"It's better to be not informed than ill-informed"

Thanks Graham, I was going to give you a call sometime. I had a vague memory you said to use the 1275 springs - these include the bottom collar for the double springs so I’ll see if I can measure them

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where did you get the crank? I'd love to build one of these motors

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did I tell you that I won a trophy?