1.5 rockers whether roller tip or forged, are already the right height for the valves in a 940 head.
I've run Minispares forged 1.5s for years, no wear on valves, guides or rockers yet (they've now done 50,000 miles).
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| valve lengths and rocker angles https://ausmini.com/forums/viewtopic.php?f=5&t=36066 |
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| Author: | wisey [ Tue Sep 25, 2007 10:46 am ] |
| Post subject: | valve lengths and rocker angles |
I have a 940 head that has had unleaded seats fitted and bigger valves. I have a set of 1.5:1 roller tip rockers from minispares to go on, i know you can get different length valves for the a-series, just wondering how i can check the rocker angle to see whether i need spacers under the rocker posts or not. Or am I worried about nothing? |
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| Author: | drmini in aust [ Tue Sep 25, 2007 12:29 pm ] |
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1.5 rockers whether roller tip or forged, are already the right height for the valves in a 940 head. I've run Minispares forged 1.5s for years, no wear on valves, guides or rockers yet (they've now done 50,000 miles).
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| Author: | wisey [ Tue Sep 25, 2007 12:40 pm ] |
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cool, thanks doc. Just remember reading somewhere that there were two different valve lengths over the years for 1275 and when you buy roller tips they don't ask you the valve length. |
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| Author: | drmini in aust [ Tue Sep 25, 2007 1:06 pm ] |
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Every 1275 head since 1968 has had the longer valves, I've not run 1.5s on an early S head so can't comment. There's a few Mini racers on here, I'm sure they will pipe up. If you want a fairly good read on rocker angles etc get the book "How to Power Tune the BMC/BL/Rover 1275 A Series Engine" by Des Hammill. Available from www.pitstop.net.au or other motoring bookshops. <edit> Only US$25.16 + postage from http://www.amazon.com/Power-Tune-Rover- ... 795&sr=8-2 There are quite a few glaring errors in the engine assembly part, but his section on heads and rocker gear is pretty good. IMO. 
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| Author: | wisey [ Tue Sep 25, 2007 1:15 pm ] |
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thanks doc. I'll bung it all together and get it going. One other thing, the head has been faced but it hasn't cleaned up some of the corrosion around two of the water jacket holes, should I put a bit of blue silicone crap on there before i put the head gasket on, what do you think? |
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| Author: | drmini in aust [ Tue Sep 25, 2007 1:24 pm ] |
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I'd face it again, they are plenty thick on the deck.
a thin smear of silastic there if you can't, but don't put it all over the bloody gasket .....  
And I'd use the Payen BK450 black `turbo' gasket they seal better than the current `copper' ones. |
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| Author: | wisey [ Tue Sep 25, 2007 1:41 pm ] |
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mmm silicone all over the head gasket..haha  . I'll get one of those payen gaskets though ..cheers doco
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| Author: | leylandmini [ Wed Sep 26, 2007 1:16 am ] |
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O ritey lets kick it off with S heads and valves and 1.5 rockers. A few weeks ago we had a race engine built with early S valves which are shorter than A+. The 296 cam lift with the rockers caused the rockers to bottom out and broke a 1.5 roller tip in half. We replaced it and it also damaged immediatly the valve guide oil seals. After taking the head off and working out cam lift we realise the S valves where the problem and changed them to the longer ones. Its fine now. Hope this helps |
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| Author: | drmini in aust [ Wed Sep 26, 2007 7:23 am ] |
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Yep it's important that you DON'T use early S valves in a 940 type head. I found that out on a motor I rebuilt years ago- someone had put Mk1 S inlets in it. With a 544 cam fitted and stock rockers, the valve caps hit the valve stem seals. A new set of Mk2 S valves sorted it.
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| Author: | britishvita [ Wed Sep 26, 2007 11:11 am ] |
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drmini in aust wrote: There are quite a few glaring errors in the engine assembly part, but his section on heads and rocker gear is pretty good. IMO.
Any chance of a quick summary of the inaccuracies?? I know the distance he says to set the crank end float is a little too tight, is there much else. |
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| Author: | drmini in aust [ Wed Sep 26, 2007 4:35 pm ] |
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britishvita wrote: drmini in aust wrote: There are quite a few glaring errors in the engine assembly part, but his section on heads and rocker gear is pretty good. IMO. Any chance of a quick summary of the inaccuracies?? I know the distance he says to set the crank end float is a little too tight, is there much else. I'm not getting into a flame war here, I'll PM ya.
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