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dinkel
Original Poster
21,015 posts
127 months
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And they all sound great on them! Spa6 2010:    Period Beemers seem to go quicker, but what do care . . . DSR12: maybe a Feb/March Run . . . No plans yet.
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Gene Vincent
4,002 posts
27 months
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The first car I bought, passed my driving test in her, I wish I still had her. 
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velocemitch
1,353 posts
89 months
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dinkel
Original Poster
21,015 posts
127 months
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TonyRPH
4,726 posts
37 months
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Can someone explain what's going on here? The engine is clearly a four cylinder, but yet there appears to be eight spark plugs here. Ok, two plugs per cylinder, fair enough, but the layout is bizarre! 
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Gene Vincent
4,002 posts
27 months
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TonyRPH said: Can someone explain what's going on here? The engine is clearly a four cylinder, but yet there appears to be eight spark plugs here. Ok, two plugs per cylinder, fair enough, but the layout is bizarre! Subject to an engineer getting this exactly right, this is how I recall the set-up. If you look at the 4 hexbolts that run down the centreline of the engine, that is the centre of each cylinder. The valves [just 2 per cylinder] are at 6 and 12 o'clock and the sparks are at 2 and 8 o'clock, the space is very confined so the spark plugs enter [from memory] the cylinder at 38 degrees to horizontal, this allows a lot of 'stuff' to encroach on the tiny bore of each cylinder. Not sure of the angle now I've written it and it may be 45 degrees, I think it's an early form of pent-roof design for cylinder heads. I will defer to anyone with proper knowledge and more recent familiarity.
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velocemitch
1,353 posts
89 months
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Sort of right I think, but the combustion chamber has hemispherical heads, as have the pistons. At this period of engine design I think that was a good thing, but as power outputs increased the hemispherical geometry limited the amount of power that the explosion could put onto the cylinder, some of the force was being directed almost horizontaly not verticaly. The twin plugs were arranged each side of the valves to ensure the fuel burnt quickly and evenly (fuel mixtures burnt slower in those days), also I think the gap in the centre between the huge valves wasn't large enough to fit a large enough plug in, so the space each side was used. The contemporary Lotus Twincam had flat topped pistons and although in period couldn't develop the power of the Alfa engine, with modern technology and fuel the Lotus engines can outclass the GTA engine in Historic classes. All this still doesn't detract from the Alfa Nord being a Masterpiece of 1960's engineering, both the 1750 and 2000 Engines in my cars were producing more power on the rolling road than Alfa claimed at the time, forty years after they were built. They are an absolute joy to use, willing you all the time to use that lovely seam of power 
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velocemitch
1,353 posts
89 months
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Here's a view of the head of a GTA from inside if it helps http://www.alfaholics.com/2010/07/gta-cylinder-hea...Just realised it's slightly different from the one in the car pictured earlier, might be because it's a repro one (Doubt it though), or perhaps the 1600's were different to the 1300's..... must look into that 
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TonyRPH
4,726 posts
37 months
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velocemitch said: Here's a view of the head of a GTA from inside if it helps http://www.alfaholics.com/2010/07/gta-cylinder-hea...Just realised it's slightly different from the one in the car pictured earlier, might be because it's a repro one (Doubt it though), or perhaps the 1600's were different to the 1300's..... must look into that Yes that helps! Now I can see the angles involved, it all makes sense. 
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joesnow
1,259 posts
96 months
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I've had a thing for the Bertone GTs since visiting Sorrento when I was 15. I was waiting for a bus and heard it before I saw it. Around the hairpin came a red bumperless GT rasping its way through the hills. I thought it was such a good looking well proportioned shape, and after a bit of research found that they were a great classic drive too. 15 years later and I've realised my ambition of owning one. Here's mine looking awesome:   
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jamieandthemagic
254 posts
61 months
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jamieandthemagic
254 posts
61 months
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velocemitch said: a Masterpiece of 1960's engineering, both the 1750 and 2000 Engines in my cars were producing more power on the rolling road than Alfa claimed at the time, forty years after they were built. I concur........my little 1300 books at 89bhp & put out 104bhp recently on the RR.
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L100NYY
26,783 posts
112 months
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A very dangerous thread.
Bugger.
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braddo
2,987 posts
57 months
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2000 GTV flavour rather than a Junior but close enough! Tremendous fun around Goodwood and still an excellent road car. 
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joesnow
1,259 posts
96 months
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Lovely GTV, looks like a lot of fun. I'd love to try mine out sometime. L100NYY said: A very dangerous thread.
Bugger. Be afraid Loon!
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jimmyjam
1,521 posts
88 months
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[quote=braddo]2000 GTV flavour rather than a Junior but close enough!
quote]
Yep, I guess the thread title should really be '105 GT appreciation thread'
I know they're not as popular and prone to leaks etc but I'd love a webasto like yours Braddo.
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braddo
2,987 posts
57 months
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You know, I've been quite impressed with the Webasto because it has needed no attention at all and has been perfectly watertight the whole time I've had the car. And around 2006/07 it seemed to constantly rain whenever I had a long trip so the roof got some pretty decent testing. It robs a bit of headroom when wearing a helmet though. 
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dibblecorse
2,203 posts
61 months
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What a great thread ..... cheers guys, been in a bad mood all day, but who says machines can't create emotion, thanks for cheering me up a little ....
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joesnow
1,259 posts
96 months
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L100NYY
26,783 posts
112 months
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joesnow said: I try to forget about that website!
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