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914werke
Samba Member
Joined: August 25, 2012
Posts: 21
Location: PNW
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 Posted: Thu Jul 14, 2022 2:16 pm Post subject: L-Jet troubles |
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OK Im resurrecting this ancient thread. Im not working with a T2 but a 914.
Regardless it shouldn't make a difference.
Problem:
2056 was running Carbs but is now switched to a L-Jet system from the 1.8L 914.
AFM has been opened & altered from OE settings.
Only other non-stock elements are new injectors (SMP) 2.0L intakes (to match 914 2.0L heads) & new GoWesty throttle body.
Everything else in new (hoses lines) or tested to be in spec. (CHT, AAR thermo-time)
I smoke tested the motor & its sealed up with no Vac. leaks.
When the motor was rebuilt it did have a non-stock cam installed & I think this is a significant part of my problem.
It has either a Raby 9530 or 9580 cam installed which both have significantly more duration that a stock cam.
I timed the motor to spec & am now fighting to get it to IDLE or adjust it to pull smoothly through gears under load.
I've got a an LM-1 installed so I am able to monitor (while driving) the AFR.
Symptoms:
once motor is warmed & idle is adjusted to 1000-1100 RPM it seems to taper off & stall every time.
If adjusted up enough to stay lit & driven it encounters a couple of "flat" spots...but when monitoring the LM-1 the motor is going VERY RICH when that is encountered.
Overall the AFR is rich at idle & isn't too far off under load (14.-16.)
I've been going back & forth & chasing my tail...
I'm hopeful there are some of you that have BTDT~
& can provide some guidance. |
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Starbucket
Samba Member
Joined: April 30, 2007
Posts: 4025
Location: WA
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| Posted: Thu Jul 14, 2022 4:06 pm Post subject: Re: L-Jet troubles |
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| Post in the Bay window forum as there are a lot of L-Jet pros there. A cam usually requires a different timing point than stock. Have you checked the quality of your spark (Blue not Yellow) as there are a lot of bad condensers out there from China. |
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[email protected]
Samba Member
Joined: December 28, 2016
Posts: 279
Location: atlanta ga
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| Posted: Fri Jul 15, 2022 8:56 am Post subject: Re: L-Jet troubles |
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| yup non fuel injected cam, always causes that problem |
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Alan Brase
Samba Member
Joined: March 28, 2004
Posts: 4532
Location: Cedar Falls, Iowa
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| Posted: Sun Oct 23, 2022 11:15 am Post subject: Re: L-Jet troubles |
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The cam probably has too much intake duration to keep the air flowing smoothly at low (idle) speeds. So it is causing a bit of back flow, reversion until the higher speed momentum of the air just smooths out the flow.
As a short term fix and possibly trouble shooting tip, might try to just set the valves a LITTLE loose. As much as .008-.010" lash would lower the duration a little. much more an you will hear clatter, which may or may not cause damage.
Keep in mind some HP American cars used as much as .030" valve lash. (365/375hp Chevy 327s and DZ 302 Camaros.)
Actual 912E's used an AFM that had a DAMPER in it. (Bosch guy told me this. that's all I know)
912E was the ONLY 2 liter type 4 Porsche spec motor with L-Jet. others used D-jet. Manifold pressure.
_________________
Al Brase
Projects: 67 sunroof bug, 67 Porsche 912 Targa, 70 Westy
Dec 1955 Single Cab pickup WANT 15" BUS RIMS dated 8/55, thru 12/55
To New owners: 1969 doublecab, 1971 Dormobile
Vanagons:
80 P27 Westy JUL 1979, 3rd oldest known US
83 1.6TD Vanagon, 87 Wolfie Westy daily driver, swap meet home |
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