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Vacuum and Mixture Problems
https://www.slantsix.org/forum/viewtopic.php?t=5400		 Page 1 of 1
Author:  new2slant [ Sat Apr 05, 2003 9:47 am ]
Post subject:  Vacuum and Mixture Problems
I'm kinda new to the slant six and havin' a problem that I just can't crack. This is a stock 225, 2bbl from a '79 Aspen and other than PCV and EGR, there's no emissions stuff. Here's the scoop:

:? At idle vacuum is 17", but when put in gear it drops to about 10-8" and idle is bad. The fuel/air meter is sliding up and down during this, but mostly very lean. I've, done the following: replaced vac lines and plugs, disconnected/plugged brake booster, had carb rebuild (Recarbco) and new gasket, replaced PCV and EGR, resurfaced manifold and replaced gasket, adjusted timing, new Mopar distributor kit, plugs/wires, fuel pump/filter. Compression is good and even across cylinders.

Now, the F/A meter and idle will stabilize when I disconnect and block the PCV to the carb. Then the vacuum is 18" at idle out of gear and 11" in gear, and smooth. Not sure, but this may just reduce air enough to keep F/A stable and may not be the source of the real problem.

There was a questionable rebuild by an unknown person and I'm wondering if I should take the head in for machining and rebuild. Any help would really be appreciated. :wink:
Author:  Doctor Dodge [ Sat Apr 05, 2003 10:11 am ]
Post subject: 
Do you know if this is a mechanical cam engine? (it should be)
Have you adjusted the valves?

Pull off the valve cover and do a valve adjustment, then work on the carb. to richen-up the mixture. That should help a bunch.
Where is the timing set at? How much total advance does the engine see?
DD
Author:  new2slant [ Sat Apr 05, 2003 10:29 am ]
Post subject: 
I think it is a mechanical cam. How would I check for sure? The core engine was 1bbl, '87 van and I added the 2bbl set up from an Aspen. Valve adjust is about the only thing I haven't done, short of taking the head in. I've tried a variety of timing selections with about the same results.

I really like the van and engine, but my buddies are giving me a hard time about my mechanic skills. Ironically I bought the van to make a mobile lounge, but all I've done is work on it! It's fun though. :)
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