Keep Dellorto DRLA 45s and Bosch 009? Options

[98101]

I suddenly find myself owning 1970 4-cylinder 2.4 with Web hot street Cam idles nicely and pulls hard at WOT. Part throttle response is not great, often with carbs coughing and even backfiring on trailing throttle. My use is mostly street, so I'd like to get this part throttle stuff sorted.

Here's pictures of the stuff that's in there now. I guess that's the infamous Bosch 009 with no vacuum advance and a PerTronix 1847A. The carbs are Dellorto DRLA 45s with short velocity stacks and these tall foam things that don't seal against the air cleaner housings. I'm willing to learn about the carbs but I don't have much confidence in the 009 for running nicely on the street. Please correct me if I'm wrong about any of this stuff.

Also from other threads I gather that switching to EFI such as MicroSquirt would cost $5K or so ... though I'm not ruling this out completely. Correct me if I'm wrong about that.






Is this kind of linkage OK?


Here's the idle you may have seen in another post:

https://www.youtube.com/watch?v=-AC53RRrXOU


Any help you can provide is appreciated!

--Michael in Seattle

[98101]

I couldn't see how changing the linkage and adjusting it better than it ever had been before would cause these problems. Maybe I had messed something up when I had the carbs out, using carburetor cleaner on the jets (should I have used brake cleaner?), trying to get the muck off of the exterior, or installing the new throttle arms? Or had I altered the mixture when I closed off the vacuum advance ports that had been wide open before? Had I knocked a spark plug wire loose?

The weirdest thing was the airflow into cylinder #3. It had always been slightly less than #4 on the same carb. But now it was *very* different. I believed it wasn't just a measurement error because spraying carb cleaner into #3 had much less effect than spraying into #4. Note that #4 was perfectly in sync with #2 on the other carb.