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| 1100 Head, how much can I take out??? https://ausmini.com/forums/viewtopic.php?f=5&t=9519 |
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| Author: | -=MiniMafia=- [ Wed Jul 27, 2005 6:01 pm ] |
| Post subject: | 1100 Head, how much can I take out??? |
Gday all sometime soon Im going to put the head off my race motor onto the milling machine. how much can I take out from around the valves, i know to grind off the pointy bit, but what else? and inlet and exhaust ports, do i just get the manifold and put paint on the face of it, put it on the head and pull it off and grind where the paint is left? does anyone get what im saying or am I making no sense!!!! basically, how much metal can I grind out of my 1100 head before I brake it! cheers, josh |
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| Author: | drmini in aust [ Wed Jul 27, 2005 7:45 pm ] |
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I'd get thee a copy of Mr Vizard's weighty tome, `Tuning BL's A Series Engine' before you stuff it up... 
Be careful with the chambers, there's an oil feed to the rockers above the beak on #1 cylinder. See where it is then don't grind out that far. Here's one I prepared earlier..  
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| Author: | -=MiniMafia=- [ Wed Jul 27, 2005 7:53 pm ] |
| Post subject: | |
drmini in aust wrote: I'd get thee a copy of Mr Vizard's weighty tome, `Tuning BL's A Series Engine' before you stuff it up...
Be careful with the chambers, there's an oil feed to the rockers above the beak on #1 cylinder. See where it is then don't grind out that far. thanks doc! where could I find such a mighty book? tell u the truth I have been after it for a while..... I have a few stuffed 998 heads here, should I practice on them first??? |
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| Author: | drmini in aust [ Wed Jul 27, 2005 8:00 pm ] |
| Post subject: | |
www.pitstop.net.au search on vizard <edit> note- in pic in above post, I routed the chambers on my trusty bench drill, just pushed the bare head about on the table. Works a treat with the carbide burr pictured running full speed. 
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| Author: | 9YaTaH [ Wed Jul 27, 2005 8:08 pm ] |
| Post subject: | Club |
-=MiniMafia=- wrote: drmini in aust wrote: I'd get thee a copy of Mr Vizard's weighty tome, `Tuning BL's A Series Engine' before you stuff it up... Be careful with the chambers, there's an oil feed to the rockers above the beak on #1 cylinder. See where it is then don't grind out that far. thanks doc! where could I find such a mighty book? tell u the truth I have been after it for a while..... I have a few stuffed 998 heads here, should I practice on them first??? MiniMafia...if you are racing then you probably belong to a CAMS affiliated club...if its a Mini Club..... the library almost certainly has a copy of Vizard 
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| Author: | Zizzle [ Wed Jul 27, 2005 9:43 pm ] |
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Hijack, does anyone else gets lots of junk mail from pitstop once they ordered a book? Perhaps I missed a "no junk mail" checkbox? |
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| Author: | drmini in aust [ Wed Jul 27, 2005 9:56 pm ] |
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yeh I get it too. I should mark it as spam but I like to read the crap first.
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| Author: | fuzzy-hair-man [ Thu Jul 28, 2005 10:14 am ] |
| Post subject: | |
said yellow book says that those beaks are there for a reason, it may have had something to do with preventing the inlet charge being sucked out the exhaust during overlap,   
Can't remember but I definately reckon you should get the yellow book it is awesome and gives specifications on how much to grind out and where what to look out for etc well worth it. IMO
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| Author: | -=MiniMafia=- [ Thu Jul 28, 2005 12:22 pm ] |
| Post subject: | Re: Club |
9YaTaH wrote: -=MiniMafia=- wrote: drmini in aust wrote: I'd get thee a copy of Mr Vizard's weighty tome, `Tuning BL's A Series Engine' before you stuff it up... Be careful with the chambers, there's an oil feed to the rockers above the beak on #1 cylinder. See where it is then don't grind out that far. thanks doc! where could I find such a mighty book? tell u the truth I have been after it for a while..... I have a few stuffed 998 heads here, should I practice on them first??? MiniMafia...if you are racing then you probably belong to a CAMS affiliated club...if its a Mini Club..... the library almost certainly has a copy of Vizard yeah ill ring and ask tonight. they should have a copy kicking round, if not ill try the wilsons..... thanks doc for the link. 
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| Author: | drmini in aust [ Thu Jul 28, 2005 7:37 pm ] |
| Post subject: | |
fuzzy-hair-man wrote: said yellow book says that those beaks are there for a reason, it may have had something to do with preventing the inlet charge being sucked out the exhaust during overlap,
Can't remember but I definately reckon you should get the yellow book it is awesome and gives specifications on how much to grind out and where what to look out for etc well worth it. IMO If beak is there for a reason why doesn't the 12G295 (998 Cooper) head, or any of the 1275 heads have them? I suspect the reason is tractability and fuel economy. But the general shape of the 850/998 and 1098 heads around the valves, restricts breathing. My 940 head on the 1360 (and many race heads) has pretty much NO beaks at all, doesn't seem to detract from the performance.... kazjim's turbo 998 hasn't caught me at Wakefield Pk yet... 
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| Author: | Wombat [ Thu Jul 28, 2005 7:46 pm ] |
| Post subject: | |
Would you dare do that freehand or is it safer in a fixed drill? |
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| Author: | WhoDat [ Thu Jul 28, 2005 8:01 pm ] |
| Post subject: | |
How steady is your hand? 
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| Author: | drmini in aust [ Thu Jul 28, 2005 8:09 pm ] |
| Post subject: | |
I do the basic shape in the drill press, so I don't gouge anything that matters.... but I finish it off freehand.
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| Author: | fuzzy-hair-man [ Fri Jul 29, 2005 10:40 am ] |
| Post subject: | |
My memory is not so good so I may have been wrong, but I seem to remember that he advised not taking too much off the beak(I think this was for flow reasons but again I am not sure there is a lot to remember in that book ) and that you should maintain a minium radius as a sharp point will disturb flow.
Quote: If beak is there for a reason why doesn't the 12G295 (998 Cooper) head, or any of the 1275 heads have them? Vizard termed the 12G295 & 12G940 heads 'open' heads (12G295 is a scaled down version of a 12G940) the others(12G202 and other small bore heads) were 'closed' heads and he deals with them differently. Quote: I suspect the reason is tractability and fuel economy. But the general shape of the 850/998 and 1098 heads around the valves, restricts breathing.
I agree, especially as these 'closed' heads weren't designed for performance so much as economy. It may have been for fuel economy reasons he advised leaving it there, my 1100 at home will be a daily drive so i would have tended to remember 'leave beak', if that makes sense. I am certainly not saying you shouldn't deshroud the valves I am just repeating what I remember from the book as I am certainly not that knowledgable and haven't got around to do anything in this area yet. I hope to attack a 12G202 sometime soon though I think it made sense at the time
Guess I am saying that I would read up on the head modifications before I touched a head with a die grinder (even a 12G202 ) I may have remembered the wrong thing too 
<EDIT> ARGGH!!!! I was wrong I was thinking about the radius in the siamesed ports (I checked the book on the weekend) Sorry people 
If the head is being used on a 1100 then you are free to take out a fair bit of meat but for an 850 if you take out too much then there are problems getting the compression ratio high enough as there is a limit to how much you can skim the head due to that oil feed line/hole that Doc mentioned. On an 1100 this is not such a problem.
Sorry for being misleading and causing confusion
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