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 Post subject: 1985 F1 cylinder head modification question
PostPosted: Thu Jan 05, 2012 5:16 pm 
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Joined: Thu Jan 05, 2012 5:11 pm
Posts: 2
Location: ABQ, NM
I'm in the process of fitting some 900i.e. cams (2x horizontal) into some 1985 F1 heads.

All 4 valve seats are fairly well beat-up so replacement is in order (likely guides too), so with that and the performance in mind...

How large can the valve diameters get w/o risking the castings? (These were originally the small-valve and 14mm spark plug heads BTW).

The remainder of the engine is being built to similar specs. Kind of a 'hot-street' set-up here @ 5000 ft elevation.

ANY help would be appreciated (especially some FHE in this area...)

Thanks much,
--Stuart


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 Post subject: Re: 1985 F1 cylinder head modification question
PostPosted: Thu Jan 05, 2012 8:41 pm 
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Joined: Sun Nov 07, 2010 10:54 pm
Posts: 425
Location: Brisbane
Hello Stuart,
I used a 650 Alazzurra rear head, similar to F1, and had the 14mm plug welded and re made as 10mm to get more room for bigger valves.
Also used 900ie cams.
The donor engine was a '95 SS 750, so the Ally head's combustion chamber was also welded up and shaped to match the SS bathtub shape of the front head.

Image

Image

Image

Hope this helps
graeme


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 Post subject: Re: 1985 F1 cylinder head modification question
PostPosted: Fri Jan 06, 2012 12:17 pm 
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Joined: Thu Jan 05, 2012 5:11 pm
Posts: 2
Location: ABQ, NM
Re: the above photos: :shock:

Damn... Amazing... What valve diameters are you running in those beautiful heads?


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 Post subject: Re: 1985 F1 cylinder head modification question
PostPosted: Sat Jan 07, 2012 1:47 pm 
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Joined: Thu Oct 14, 2010 11:23 am
Posts: 1074
And, this is what NCR did during the days of the TTs: 41 & 35mm conversions to the Pantah head for TT2s, and later as big as 44 and 38mm valves for TT1s and F1/Endurance racers. One set here has the 41/35mm version that was later converted to 42/37mm and dual plugs. Notice that on the biggest-valve versions the chamber is cut to 105mm wide, for BIG (92mm) pistons, on the one in the middle it is 100mm for the standard 88-90mm pistons. Ports were monsterous too, which is contrary to modern thinking (volumn vs. velocity). MikeV
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heads NCR IM007536.JPG [ 496.8 KiB | Viewed 830 times ]
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heads NCRe.jpg [ 88.34 KiB | Viewed 830 times ]


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 Post subject: Re: 1985 F1 cylinder head modification question
PostPosted: Wed Jan 11, 2012 2:49 pm 
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Joined: Sun Aug 08, 2010 4:37 pm
Posts: 360
Images: 6
Location: Ottawa, Ontario, The Great White North
I should point out that within the next 2 weeks, we'll be offering conversion services; taking Pantah and other 'big plug' heads and converting them to later F1 'small plug', 41/35 specification. We're just nailing down the pricing now, so stay tuned - or PM me to get on the list.

Regards,

_________________
Steve Munro
loudbike
http://www.loudbike.com
http://www.vintagemotorcyclesforsale.com


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