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D-jet? J-Jett? L-jet? How about Q-jet?

Mike Goble

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I've had this euro 4-bbl manifold for several years and I finally decided to put it to use. It had a Solex 4A1 on it when I got it, but it looked kinda funky. I noticed that the bores matched a Quadrajet very closely so I decided to go that route. I have a dozen or so of them so I decided on the 7029207 one that came on the 69 Chevy 325 and 350 horsepower 350's . It's all stock jetting and I'm foregoing the choke for now. The stock booster is too large to fit with this manifold so I got one from an 88 VW Fox and adapted it so the M/C is in the same place. This involved making some spacer bolts to account for the thinner VW booster. I made a 2-piece phenolic adapter plate with the 4A1 bolt patten on the bottom and the Q-jet pattern on the top. The throttle linkage was adapted using some ball and socket parts from a diesel MBZ. Found some radiator hoses on a Ford Explorer and a VW Jetta that gets the water where it needs to go. Haven't driven it yet but it fired right up. Gotta bleed the brakes after I get some more brake fluid.


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Dick Steinkamp

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I'm anxious to see how it runs and drives. Being a hot rodder at heart, it seems to me that this is the best choice for at least as good, if not better, driveability and performance and none of the headaches of multiple carbs.
 

Stevehose

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I’ve read about fuel distribution issues given the unequal manifold lengths, are you reducing the inner cylinders’ secondary throttle bore to compensate for varying mixtures?
 

Mike Goble

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I’ve read about fuel distribution issues given the unequal manifold lengths, are you reducing the inner cylinders’ secondary throttle bore to compensate for varying mixtures?
It's a stock manifold. I'm just going to drive it.
Inner cylinder's secondary throttle bores? The secondary throttle bores feed three cylinders each.
I've had a 4-bbl Mopar slant six with the same disparity in runner lengths and never worried about that one either.

Didn't some M30 equipped BMW come with the 4 barrel standard?
Yes. Euro 5, 6 and 7 series from the 70's. I think that there might have been some others.
 

Mike Goble

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Well, got the brakes bled and fixed a vacuum leak, set the idle speed and mixture and went for a test drive. It runs really well. Off idle throttle response is very smooth and the secondary transition is excellent. Got that traditional Q-jet 'wooooop' when you nail it. From a tuning standpoint it is very simple with no balancing or multiple linkage adjustments. The wiring diagram is also very simple.
 

dang

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Very cool Mike. I'm anticipating how you'll adapt the stock BMW air cleaner to that carb. ;)
 
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