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Spyderman
Alfasud
Joined: 04 Sep 2003
Posts: 48
Location: Hampshire
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 Posted: Sat Dec 04, 2004 5:00 pm Post subject: 1.7 8v and 1.7 16v |
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Hi guys any idea where I can find some pics of both a 1.7 8v combustion chamber and the same for a 16v
I.E pics of the cyl heads with views of the valves and pistons within the block |
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Sprintervention
Alfasud
Joined: 30 Jul 2004
Posts: 60
Location: York
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| Posted: Wed Dec 29, 2004 5:50 pm Post subject: Combustion chambers |
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Hi,
I have 16v heads on my bench and 8v heads on my mate's bench, both 1700. My camera is at work but I will get some photos taken in the next day or so and let you have them.
May be a bit grubby but I will try and clean them off.
Regards
Chris
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1987 Alfa Sprint Veloce |
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Spyderman
Alfasud
Joined: 04 Sep 2003
Posts: 48
Location: Hampshire
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| Posted: Fri Dec 31, 2004 10:43 pm Post subject: |
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Cheers 
If you have any of the piston tops it would be useful too
Thanks
Guy |
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Knight
Guest
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| Posted: Wed Jan 05, 2005 6:14 pm Post subject: pics |
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| do you mind me asking why you want pictures of this?.....are you trying to measure tha valve to piston clearance???.....look in the expensive mistake section for some pictures of the 16v combustion chamber......I have never seen an 8v combustion chamber. |
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Alan
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| Posted: Fri Jan 07, 2005 2:05 pm Post subject: |
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Hi,
I won't bore you with the (expensive) reasons, but I've got a 16v and 8v engine in bits at the moment, and have heads and pistons. So if you can't get piccys from anywhere else, let me know (alan.abbey@ntlworld.com). I'll have to scrouonge a digital camera to do the honours but that's not too much of a problem.
Cheers,
Alan |
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Spyderman
Alfasud
Joined: 04 Sep 2003
Posts: 48
Location: Hampshire
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| Posted: Sat Jan 08, 2005 1:46 pm Post subject: |
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| Was asking as wondered if 8v pistons could be used in a 16v motor to lower the compression ratio if you pocketed the 8v pistons. |
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Alan
Guest
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| Posted: Mon Jan 10, 2005 1:20 pm Post subject: 16v pistons |
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| Spyderman wrote: |
| Was asking as wondered if 8v pistons could be used in a 16v motor to lower the compression ratio if you pocketed the 8v pistons. |
Spyderman - the height from gudgeon pin centre to piston top face on the 8v a lot greater than the 16v piston. So if you put an 8v piston in a 16v block with 16v crank, the 8v piston would stick out of the top of the block a long way - several mm.
I've done the opposite swap - I use 16v pistons in an 8v block / crank, and have then fitted 16v heads. Because the 16v pistons were a lot shorter, I had to have approx 2.5 mm taken off the block to get the correct comp ratio again.
Hope this helps.
Alan |
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RFlower
Alfa 33
Joined: 17 Feb 2004
Posts: 432
Location: S of France
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| Posted: Mon Jan 10, 2005 2:02 pm Post subject: |
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I don't know if this is of any use, but a friend lowered the CR of his Triumph Trophy 'bike, (to drive from Australia to UK via India, many years ago), by fitting two head gaskets.
This lowered CR enough to run on almost paraffin, but these were thick copper asbestos gaskets. The advantage was he could change it back easily when he could get good fuel again.
Don't know if this would work with Alfa engine, depends if enough slack in the cambelts. (and how much reduction in CR you need)
_________________
Dick Flower, Nr. Carcassonne. '94 Trofeo 1.4 ie (F), '93 Imola 1.3/1.4 ie (now for breaking) (F), '91 1.7 ie (GB)(spare car), '86 Sprint 1.5 QV (F). '87 VW Syncro camper (F), '73 NSU Ro80 (F), '99 Fiat Seicento (F) |
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Laki
Alfasud
Joined: 06 Sep 2004
Posts: 74
Location: Ljubjana
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| Posted: Tue Jan 11, 2005 1:30 pm Post subject: |
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I have som pictures from when I was converting my 1.7 to 16V....Not higres, but It might help.....dont know where to put them though
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-- ALFA ROMEO 33 Q4 --
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Guest
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| Posted: Wed Jan 12, 2005 9:56 pm Post subject: |
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Spyderman
Alfasud
Joined: 04 Sep 2003
Posts: 48
Location: Hampshire
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| Posted: Sat Jan 15, 2005 8:18 pm Post subject: |
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Alan you replied with
"Spyderman - the height from gudgeon pin centre to piston top face on the 8v a lot greater than the 16v piston. So if you put an 8v piston in a 16v block with 16v crank, the 8v piston would stick out of the top of the block a long way - several mm.
I've done the opposite swap - I use 16v pistons in an 8v block / crank, and have then fitted 16v heads. Because the 16v pistons were a lot shorter, I had to have approx 2.5 mm taken off the block to get the correct comp ratio again. "
Does this mean there are differences in throw on a 16v crank to 8v. Or is it conrod differences.
I got the impression just the heads and piston were different |
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Sprintervention
Alfasud
Joined: 30 Jul 2004
Posts: 60
Location: York
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Laki
Alfasud
Joined: 06 Sep 2004
Posts: 74
Location: Ljubjana
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| Posted: Mon Jan 17, 2005 3:32 pm Post subject: |
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Here you can lower the heads still another mm...
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-- ALFA ROMEO 33 Q4 --
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Alan
Guest
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| Posted: Tue Jan 18, 2005 12:34 am Post subject: |
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| Spyderman wrote: |
Alan you replied with
"Spyderman - the height from gudgeon pin centre to piston top face on the 8v a lot greater than the 16v piston. So if you put an 8v piston in a 16v block with 16v crank, the 8v piston would stick out of the top of the block a long way - several mm.
I've done the opposite swap - I use 16v pistons in an 8v block / crank, and have then fitted 16v heads. Because the 16v pistons were a lot shorter, I had to have approx 2.5 mm taken off the block to get the correct comp ratio again. "
Does this mean there are differences in throw on a 16v crank to 8v. Or is it conrod differences.
I got the impression just the heads and piston were different |
Spyderman - the 1700 uses the same rods as the 1500, and the crank has increased stroke ... around 72mm I think ... hence the need for lower pin to crown height on the pistons. I've actually used some 1700 rods in my engine - no special reason, just that they were available.
Cheers,
Alan |
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Spyderman
Alfasud
Joined: 04 Sep 2003
Posts: 48
Location: Hampshire
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| Posted: Sat Jan 22, 2005 4:19 pm Post subject: |
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| Does that mean you were building a 16v 1500 as that would make more sense |
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Alan
Guest
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| Posted: Mon Jan 24, 2005 9:40 am Post subject: |
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It's a 16v 1600 ..... 87mm pistons from 1700 in a bored out block from a 1500, and 1500 crank ... equates to 1598cc. Done this way because it's for a rally car, for the up to 1600cc class.
The 1500 block can be overbored to 87mm .... I built mine in 1997 and it survived until November last year when it cracked in two bores. So now I've just collected a freshly machined block, and will start the rebuild this week..... |
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Serpent33
Alfa Sprint
Joined: 06 May 2003
Posts: 210
Location: Singapore
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| Posted: Sun Nov 20, 2005 2:40 pm Post subject: |
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Hi there, another way is to use 8V con-rods. It will be useful for forced induction but short fall is lower rod ratio, which increases lateral stress. Might want to try this if changing of piston is not adequate.
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Each time I speed I say, "Dear lord, make me fast and accurate..." |
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rallyboy77
Alfasud
Joined: 08 Apr 2003
Posts: 76
Location: Sydney
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| Posted: Thu Nov 24, 2005 7:47 am Post subject: |
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Yo Alan,
Where do you rally?
J  |
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