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our beloved (see hated with the fury of 1000 suns) 914 1.7 could use a little carb love (not the kind involving overweight cheerleaders and twinkies) any good tech articles on tuning webers you all have found?
our beloved (see hated with the fury of 1000 suns) 914 1.7 could use a little carb love (not the kind involving overweight cheerleaders and twinkies) any good tech articles on tuning webers you all have found?
I dont have anything handy but do some searching on the popular VW sites and you should find what you need.
The guys over at shop talk forums really like the Type4 motor like you have in the 914 so that would be a good place to start.
http://www.shoptalkforums.com/
We had horrible problems with ours (32/36) at BW on Saturday. The car was bogging on throttle and shooting flames out the back.
At about 10pm that night, after we had swapped the tranny and did other stuff, some drunks, er, revelers, came by and looked in. We asked if they had any Weber tuning advice, and they did. From our description he told us that we had it adjusted such that we were probably past the transition jets and likely into the primary mains even at idle, and that timing was off and was igniting fuel while the exhaust valves were still open. He advised setting the idle mixture screw to 1.5 turns out and the idle speed screw to one turn out, 1.5 max. The car should start with that. Then, advance the timing to 6-8 degrees.
I made the idle setting adjustments (our idle mixture was out 6 turns), started the car, let it warm up, then checked the timing. Our pulley does not have timing marks for other than -1 to +2 degrees, so I bumped the timing up a little, then checked throttle response, bumped it again, and so on, until the bog on throttle had just disappeared. The car ran great on Sunday! We were almost as fast as Spank's Mini down the front straight!
I learned a lot doing those adjustments. Thank you paddock stranger!
We'll tweak the tuning a bit more then will get it to EGR on the dyno to check A/F and maybe swap the primary and secondary jets.
Here is an article that might help - http://www.carburetion.com/Weber/adjust.htm
And here is a forum thread that might confuse, or might help, covering jetting, plugging some hole, and other stuff: http://www.opelgt.com/forums/aftermarke … tting.html
Yeah,
The holley 5200 book by Urich is rich with info, makes a good toolbox handbook - OUt of print - is the only book you'll need - the 5200 and the DGV are almost exactly the same, tuning procedures ARE the same, and the Holley book is GREAT - but expensive for 90 pages...
http://www.amazon.com/Holley-5200-Mike- … 0895860503
Failing that,
get the Braden Weber book and follow the setup instructions letter for letter!
http://www.amazon.com/Weber-Carburetors … 0895863774
~it will get you pretty close, and give some understandnign at the same time.
The Passini book is great on theory - but wouldn't make a good first go - I found it useful after a few tunes using Braden's though 'cause of the way it describes each circuit in the system - but generally it just isn't very good...
There are many online sources - almost all of them specific to a vehicle, and almost all of them written by an "Expert" who has never used a dyno or a gas analyzer. Beware.
Beyond that you MUST get a gas analyzer Beg borrow steal or buy an innovate LM-1 or LM-2. weld in an O2 sensor bung in the exhaust, collector area and get some track time on a test day. Open testing at the drag-strip using an LM-1 can be as effective as a dyno session - if you don't blow up.
Try this. He gives some specs for a 914 1.8 and 2.0L.
Before you do ANY adusting on the carbs, you need to set the float levels. Make SURE this is done Before you try anything else. The float bowls, and idle circuits need to be surgical clean too.
Try this. He gives some specs for a 914 1.8 and 2.0L.
Specs he gives are choke size for IDF - I hope you're not running IDF's! those would be worth more than the car...
It's a good basic intro to tuning, but not really what you are looking for.
I'd give you the numbers on my turbo-suck-thru 1600DP, but those would only be a baseline and probably only be different than what you have, not necc. better.
One thing - Fuel pressure is relevant! run 4~6 psi for repeatable results. More or less is NOT good.
So:
"Weber Baseline" for "Replacement conversion" - based on a 1600dp:
Aux vent (the venturi in the middle of the airflow, you need to verify this size) 3.5/3.5 ( with 1.7 or 2.0 you might be happier with a 4.5 in the secondary)
Main Jets (in float bowl) 137/140 (each tube - I would go 140/142 instead)
Emulsion Tubes F50 (if you have F16's they will do but tend to go lean "on top" a shade easier, otherwise F16/F50 are *virtually* the same)
Air correction jet (Above emulsion tube, holds them in) 165pri/160sec (I might try 140's in the secondary)
Idle Jets (in the sides of the body, screw in from outside and press into the screw) 60pri/50sec
Pump jet (the upside-down antler in the top) 50 (I'm running a 60)
FLoat valve (yep, the fuel inlet needle and seat are available in different sizes - if you run E-85 you MUST change this one!) std is 2.0 - if it's smaller expect issues at long-run high rpms.
These numbers should get you in the ballpark. As noted you might need to vary the main jets up a step or two and you might need to manage the air correctors up or down one or two steps.
~more than that means something is hideously wrong elsewhere! Like the aux vent size, clogged emulsion tubes or???
~ comparing "oem" numbers on 2liter euro cars - you might need to get the secondary air corrector down to 70 - as in microscopic - if you have a 3.5 aux venturi in it. If you have a 4.5 in the secondary the basic numbers seem to hold... The smallest air corrector I have in my jet box is 120!
...the rest of the numbers are, again, a pretty good baseline.
Before you do ANY adusting on the carbs, you need to set the float levels. Make SURE this is done Before you try anything else. The float bowls, and idle circuits need to be surgical clean too.
+1000
If you can find a "Redline high-performance master catalogue" from 1982, part number 99001.780, it contains a GREAT flow diagram and a plethora of try-me start points for 188cc cars, and one only for a 1600 type one.
What I posted above as baseline was derived from that book
I'll see if I can scan the 3 major info pages and post them somewhere. or email them.
...and if you want even more crap on your tech manual shelf, here's the Haynes Weber manual. I used it when working on my RX-7's Weber DCDs.
914's are cheater cars...
I'd like to build one for Lemons!
Whatever laps they give, certainly won't be enough!
KT
Phil, my DGV cost $15... with manifold that I promptly cut into a zillion pieces.
...then I found out the secondary shaft was frozen
- so called the local british car shop - who said "Yeah, we take those off MG's that people think they work well on, and then make the cars *actually run* using OEM SU's. Hang on... I've maybe a greasy one here you can have, for nada."
-Hard part about free is getting the reciept-
I then took the two of them apart and made one good one! Ok, well, one DGV that looks like it works the way it is supposed to. W/ 7 laps on it we don't really know.
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