 Had a a massive flat spot, more like a bog |
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| michel richard |
 Aug 17 2005, 03:46 PM
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Senior Member  Group: Members Posts: 1,291 Joined: 22-July 03 From: Longueuil, Québec Member No.: 936  |
I have indicated elsewhere that I used to run Mechanical Injection on the 2.2E engine in my 914. I switched to PMO carburetors because I had a huge flat spot, actually more like a through, a bog, an abyss, a souse hole, or a black hole, between 3,000 and 3,800 rpm, especially at WOT.
When the PMOs went on, I still had the bog, so I was massively disapointed. Early this afternoon I made arrangements with my main mechanic man, and we went for a test drive. Sure enough, the abyss was still there. He felt that it was probably ignition related. Back at the shop, he started fidling with a strobe light and reving the engine and figured out that the ignition was snapping to 72 degress advance between 3,600 and 3,800 rpm ! His immediate thought was that MSD box was causing the problem. I drove back home and wired in a Bosch CDI unit that I got as part of my Jon Lowe project purchase . . . and that solved the problem. Final diagnostic: bad MSD box. Moral of the story is: a lot of things that can look induction related to the amateur mechanic, are actually ignition. Make triple sure your ignition is 100% up to snuff before you start making big injection or carb changes. Hope this experience can benefit others. Michel Richard |
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Replies(1 - 6)
| ArtechnikA |
Aug 17 2005, 03:50 PM
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rich herzog Group: Members Posts: 7,390 Joined: 4-April 03 From: Salted Roads, PA Member No.: 513 Region Association: None |
1) yet another reason to hate MSD. i know a lot of you love them; i *used to*.
2) there is a reason the "MFI Ten Demandments" exist. glad you found & fixed your chasm ... |
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| michel richard |
Aug 17 2005, 03:54 PM
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#3
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Senior Member Group: Members Posts: 1,291 Joined: 22-July 03 From: Longueuil, Québec Member No.: 936 |
I must say the thought did cross my mind . . . Oh, and thanks for that extra synonym. M |
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| TimT |
Aug 17 2005, 04:00 PM
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retired Group: Members Posts: 4,033 Joined: 18-February 03 From: Wantagh, NY Member No.: 313 |
when I was a kid a wise old mechanic told me that many carb problems are solved in the distributor!!
thanks dad!! (IMG:http://www.914world.com/bbs2/html/emoticons/beer.gif) |
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| goose2 |
Aug 17 2005, 04:42 PM
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#5
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Senior Member Group: Members Posts: 976 Joined: 30-March 05 From: Eugene, Oregon Member No.: 3,847 Region Association: Pacific Northwest |
I have a friend who spent many agonizing days fiddling and cursing his Webers to no avail. Turns out someone had put a too long screw in the distributor and it was fouling the advance mechanism. 5 minutes and a 15 cent screw fixed it.
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| goose2 |
Aug 17 2005, 05:23 PM
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#6
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Senior Member Group: Members Posts: 976 Joined: 30-March 05 From: Eugene, Oregon Member No.: 3,847 Region Association: Pacific Northwest |
Pure Poetry (IMG:http://www.914world.com/bbs2/html/emoticons/clap.gif) |
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| michel richard |
Aug 17 2005, 05:28 PM
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#7
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Senior Member Group: Members Posts: 1,291 Joined: 22-July 03 From: Longueuil, Québec Member No.: 936 |
Hihi
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