I run MK1 size (31mm) Mk2 exhaust valves in my 940 head. But if you do with S inlets there's no room for unleaded seats... so I run Flashlube.
No seat recession yet in 50K miles.
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| Head Modifications https://ausmini.com/forums/viewtopic.php?f=2&t=97916 |
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| Author: | cooperess [ Fri Nov 02, 2018 3:41 pm ] |
| Post subject: | Head Modifications |
Attachment: 12G938 1100 'S' Mini Cylinder Head.jpg With the above inlet valve spring seat mods I can't see this being of any use. Don't all the valve spring seats need to be the same depth! |
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| Author: | awdmoke [ Fri Nov 02, 2018 3:45 pm ] |
| Post subject: | Re: Head Modifications |
Not at all. I had my previous head pocketed in the same spots to allow for extra lift. 1.5:1 roller rockers & a big cam caused coil bind on the springs before this mod. Just means you'll be using different springs inlet to exhaust (as you do). |
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| Author: | timmy201 [ Fri Nov 02, 2018 3:48 pm ] |
| Post subject: | Re: Head Modifications |
Does that head have unleaded exhaust seats added? You can get shims to even them out: https://swiftune.com/parts-shop/cylinde ... set-2.html |
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| Author: | GR [ Fri Nov 02, 2018 7:42 pm ] |
| Post subject: | Re: Head Modifications |
Hi Cooperess I can supply you shims .015/ .030/ .060, but just check that you don't have MK 1 inlet valves and MK 2 exhaust. Graham Russell |
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| Author: | cooperess [ Fri Nov 02, 2018 8:41 pm ] |
| Post subject: | Re: Head Modifications |
GR wrote: Hi Cooperess I can supply you shims .015/ .030/ .060, but just check that you don't have MK 1 inlet valves and MK 2 exhaust. Graham Russell Thanks Graham, I think this head will accept Mk1 inlet & exhaust valves, correct me if i am wrong. |
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| Author: | timmy201 [ Fri Nov 02, 2018 8:47 pm ] |
| Post subject: | Re: Head Modifications |
They both will fit, but the later valves are longer (nominally 3.52" & 3.57" according to minispares) |
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| Author: | cooperess [ Fri Nov 02, 2018 8:58 pm ] |
| Post subject: | Re: Head Modifications |
timmy201 wrote: They both will fit, but the later valves are longer (nominally 3.52" & 3.57" according to minispares) I also think the Mk1 exhaust valves are larger than the Mk2 exhaust valves. So the question arises, will this head accept the Mk1 exhaust valves? |
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| Author: | drmini in aust [ Fri Nov 02, 2018 9:17 pm ] |
| Post subject: | Re: Head Modifications |
I run MK1 size (31mm) Mk2 exhaust valves in my 940 head. But if you do with S inlets there's no room for unleaded seats... so I run Flashlube. No seat recession yet in 50K miles.
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| Author: | GR [ Sat Nov 03, 2018 6:53 am ] |
| Post subject: | Re: Head Modifications |
Hi Kev I can fit seats to the MK1 heads inlets and exhaust I have two here at the moment to fix. Graham Russell 
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| Author: | simonw [ Sat Nov 03, 2018 3:05 pm ] |
| Post subject: | Re: Head Modifications |
Just a quick question regarding shims for a 202 head : is there a dimension to work to ? I mean when installing the valves with the springs is it just a case of using enough shims to bring each valve spring to tension ? Thanks for any tips Sent from my iPhone using Tapatalk |
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| Author: | GR [ Sat Nov 03, 2018 6:22 pm ] |
| Post subject: | Re: Head Modifications |
Hi Simonw The small bore heads have a little problem with coil bind with the std springs if you install a cam with a bit more lift or high lift rockers, some times you can get away with it with the cooper springs (not "s"). That's why I had special valves made for the small bores they are longer than the std valve but not as tall s the 1275 valves, and the installed height for the springs is 1.38 to 1.4,so depending on what springs you use you can have seat tension from 75LB to 120LB. To answer your question yes you use the shims to get all your seat tensions the same. Graham Russell |
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| Author: | cooperess [ Sun Nov 04, 2018 3:31 pm ] |
| Post subject: | Re: Head Modifications |
How can you tell what size valve seats are installed in the above head. |
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| Author: | cooperess [ Sun Nov 04, 2018 5:19 pm ] |
| Post subject: | Re: Head Modifications |
Just measured the extra depth of the inlet valve seats and they are 0.12 inch deeper than the standard. |
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| Author: | GR [ Mon Nov 05, 2018 9:12 pm ] |
| Post subject: | Re: Head Modifications |
Hi Cooperess That's a long way down, to fit MK1 valves you only need to go about .060/ .080 depending on how low the valves are seated in the head, may be some one has tried to fit over size small bore valves which would be some where near that depth. You must be getting very close to water, there's not that much metal there to machine away I will have a look tomorrow on some of my cut up heads but you will need a 3mm spacer to shim them back up again with STD MK2 valves. Graham Russell |
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| Author: | cooperess [ Mon Nov 05, 2018 9:17 pm ] |
| Post subject: | Re: Head Modifications |
Hi GR, Looking forward to see how you think I can bring the head back to standard. |
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