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Old April 17th, 2016, 06:21 AM
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Default Re: Black Widow Build (1960 1/2 ton)

Although my last entry said "running driving truck", that's not quite right. Before the clutch went out I was tuning a Rochester 2jet, trying to get it to run on my single barrel manifold.

I was using a jinky adapter. I say jinky because it was a $14 item that, well, looked like it was produced as an after thought.


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Too its credit, the adapter did it's job. But I was experiencing hesitation during acceleration from a stop. Which, my research said, was probably a vacuum leak. Sure enough, the vacuum can on my distributor was shot. Replaced it.

Adjusted the points. Adjusted engine timing. Still hesitation during acceleration from a stop. Good 'ol hose-to-the-ear-trick revealed a vacuum leak at the base of the adapter.
Well, bummer, but not too surprising. The gasket there was very thin. In fact I had a second gasket on there that I'd cut out of thin cardboard.

Figured the ultimate test was to replace the gaskets with a gasket sealer. Yep, I did that. Very carefully. And only as a test - wanted to know if that would cure the leak. But, alas. Still sucking air - less than before, but still a leak. Still hesitating on acceleration. Uh-oh, looks like more than a vacuum leak...

Started thinking that maybe the adapter isn't a good match with the intake manifold. Figured I'd need a new gasket, a good one, and maybe clean each surface real good. Possibly check the base of the adapter, make sure it was "level" or flat or whatever.

That means removing the intake manifold.

Dang, I only wanted to remove the intake in order to replace it with the new-to-me 2 barrel manifold I picked up a while back. But, that manifold doesn't directly fit my 2jet either. Bummer. But heck, gaskets are cheap, right? Keep the two-barrel on hold a while, clean and adjust the surfaces. Fix the vacuum leak, then proceed to checking the carb.

But that means removing the intake manifold.

Browsing around the net I found some quality adapters that might actually work with my 2jet and two-barrel manifold. After much reading, the manifold fits a "small Rochester" carb as-is. Good to know. But my 2jet is the "large" variety. After more reading, turns out that

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sells an adapter for a "small Rochester" manifold to a "large Rochester" carb. Nice stuff too.

Luckily, I had the money. Bought a Dashman's adapter and ... the two barrel manifold is in action.


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Man, I had to fight my way through 40-odd years of gunk!


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Still, hope I'm not shaving a yak here. Even if the new adapter/manifold swap cures the vacuum leak, the hesitation on acceleration hasn't been totally addressed. Likely something with the carb. Since I rebuilt it, I wouldn't be surprised something's amiss. I guess it's time to break open the 2jet again.
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