 Bigger valves in 1.8 heads? |
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| Korijo |
 Jul 16 2005, 06:23 PM
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#1
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[]D o [] o []V[] o []D  Group: Members Posts: 1,308 Joined: 16-July 03 From: North Bend, WA Member No.: 914  |
can you use a 2L exhaust valve in a 1.8L head? [after machining, of corse (IMG:http://www.914world.com/bbs2/html/emoticons/dry.gif) ]
i was thinking [ (IMG:http://www.914world.com/bbs2/html/emoticons/smoke.gif) ] of only bumping the exhaust up to 36mm, and leaving the intakes at 41mm? common practice? weird? i have a set of loaded, rebuilt 2L heads; but i want to use the Solex PII 40's Joe Sharp gave me*, so i'm gettin' some 1.8L heads... * [thanks again joe (IMG:http://www.914world.com/bbs2/html/emoticons/pray.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/clap.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/boldblue.gif) ] |
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| qa1142 |
Jul 16 2005, 06:28 PM
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#2
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Whiplash Group: Members Posts: 1,514 Joined: 1-June 04 From: Lake Zurich, Illinois Member No.: 2,140 |
Valves are not the problem. The porting angles and flow of the 2.0 heads are just that much better. Plug location and angle is different also. This is why I am rebuilding a 2.0 to replace my 1.8 (IMG:http://www.914world.com/bbs2/html/emoticons/smilie_pokal.gif)
Stick with your 1.8 and save $ for 2.0 heads and or motor |
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| anthony |
Jul 16 2005, 07:55 PM
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#3
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2270 club Group: Benefactors Posts: 3,107 Joined: 1-February 03 From: SF Bay Area, CA Member No.: 218  |
You can also have the 1.8 spark plug holes welded up and relocated to the 2L position. You can also go for smaller diameter spark plugs so that they don't crack in the future.
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| Korijo |
Jul 16 2005, 08:39 PM
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#4
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[]D o [] o []V[] o []D Group: Members Posts: 1,308 Joined: 16-July 03 From: North Bend, WA Member No.: 914 |
see my 1st post, already have 2L heads (IMG:http://www.914world.com/bbs2/html/emoticons/blink.gif) , but thanks for yur post.
"I did not know this..." gud reply. |
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| tat2dphreak |
Jul 16 2005, 09:08 PM
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#5
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stoya, stoya, stoya Group: Benefactors Posts: 8,797 Joined: 6-June 03 From: Wylie, TX Member No.: 792 Region Association: Southwest Region |
(IMG:http://www.914world.com/bbs2/html/emoticons/agree.gif) I think Jake said that he preferred this... the smaller plug keeps the little cracks from happening too... IIRC, anyway... |
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| Jake Raby |
Jul 16 2005, 09:48 PM
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#6
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Engine Surgeon Group: Members Posts: 9,394 Joined: 31-August 03 From: Lost Member No.: 1,095 Region Association: South East States |
1.8 heads don't have the spark plug cracking issues of the 2.0 because of plug location. We flycut 1.8 heads down almost to the sparkplug on F prod engines and no crack issues..
Going to the 36mm exhaust without upping the intake valve will imbalance the head quite a bit.. 42x36 valves(stock 2.0 size) can be used in a 1.8 head and still be supported by stock ports. Porting will help, but is not necessary.. Spark plug relocation has given us 8% more power+ in every instance that we have tested it.. |
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| Korijo |
Jul 17 2005, 01:49 PM
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#7
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[]D o [] o []V[] o []D Group: Members Posts: 1,308 Joined: 16-July 03 From: North Bend, WA Member No.: 914 |
i can use 2L valves in a 1.8 head WITHOUT changing guides, seats, or porting the chambers? (IMG:http://www.914world.com/bbs2/html/emoticons/wacko.gif) [i will have it done regardless]
if i use the 1.8 head, it will have the plugs relocated. any advice on welding the exsiting plug holes? |
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| gregrobbins |
Jul 17 2005, 03:57 PM
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#8
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Member: Team NARP Group: Members Posts: 1,515 Joined: 23-March 04 From: Arizona Member No.: 1,844 Region Association: Southwest Region |
Why don't you use the 2.0L heads? Carb manifolds for 2.0L heads are cheap enough. I have a pair I would swap you for 2.0L FI runners if you have extras.
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| Korijo |
Jul 17 2005, 04:56 PM
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#9
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[]D o [] o []V[] o []D Group: Members Posts: 1,308 Joined: 16-July 03 From: North Bend, WA Member No.: 914 |
b/c i want to try to use the short manifolds w/ the solex 40's... if'n it doan wurk... |
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