Quote:
Originally Posted by qscgyjl
I think the carb in the photo has the air filter adaptor fitted so it looks a bit different to a Fiesta carb. The 38DGAS can suffer with a flat spot from idle to progression when fitted on other engines than the Essex, I ran a couple on Opel engines and the progression drillings in the carb body were causing the problem. One I cured by using the 32/36 progressive linkage and the other by filing the butterflies to change the progression timing. The progressive 38 worked well but lost some low end torque and the other with filed butterflies nearly but not quite solved the problem. I moved to fuel injection so never really solved the flat spot completely on those combinations.
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A point we're both missing is that Webcon may have used a generic photo and it might not even resemble the exact carb in the kit.
As for the 38DGAS, there was something wrong other than the carb, biggest cause of flat spots on the 2.0 CIH Opel engine was incorrect points dwell and also the 38DGAS needed a few degees more adavance at idle to make it run properly through the rev range.
Shouldn't have needed to use the progressive 2-stage lnkage from a 32/36 and as you discovered, you lost low-end torque as a result of having to open the first butterfly more.
I'm guessing you also had the 2.0 CIH lump, originally fitted with the GM Varajet-II bucket?
The idle bypass is the screw that should control idle speed on them but too many people touch the throttle stop screw, completely messing the vacuum advance up. If that was the case and you went to a Weber without first getting the timing right because of messed up vac advance, you would have had incurable flat spots.
If memory serves the ideal figure for the vacuum advance was 8" H20 @600rpm, to be set (very carefully) with a water manometer.
Needed careful tweaking of the dizzy followed by careful tweaking of the throttle stop screw to get it right, especially if some muppet had played with the throttle stop screw instead of the idle bypass screw.
Once the right amount of vacuum was on the advance line, the igniton timing could be reset to where it should be and the idle speed brought up with the idle bypass.
First time i did mine took me a couple of hours and several episodes of drying the water off the plugs but it was worth it. Then i went for the 32/36DGEV, followed a short time later by the 38 DGAS, converted to a 38 DGEV using the same electric choke element and OE feed to the electric choke on the Varajet.
No flat spots or progression problems, just power all the way to 7200rpm in all 4 gears. Fuel economy was also improved on the DGES over the DGEV, nudging 30mpg which for a hard-driven car was pretty good.