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Re-tuning after smog check


silasmoon

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Howdy! My car - 1976 49 State - passed CA smog! Woo! Okay now let's make it purr. The engine right now likes to ping / pop when I decelerate from 4,000 rpms to ~3,500 rpms. I put in 93 octane gas, but it still happens. I have a 32/36 Weber (not sure on the jet sizes yet) and I have an electronic ignition. The distributor cap was changed and I have new spark plugs. 

So! A few questions:

  • Should I attempt any tuning while the smog equipment is attached? Or will that disrupt the balance? 
  • What was likely done to make it pass smog that killed performance? I figured they would've leaned out a bit too much (hence pinging)?
  • What is the order of operations for general tuning? Distributor Timing? -> Idle screw? -> Enrichener screw? Floats? -> Measure jet sizes? 
  • Possible gotchas? I need to check all the vacuum hoses are sound and that contacts are solid. 

I am reading all the articles I can find, but none found so far that address what they would've done to help pass smog. 

Thanks! 

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Uh, you passed with a Weber?  Does it have a CARB tag on it?

 

I thought you had to have the stock Solex...

 

I'd start with a timing light, to see where timing is set right now.  So you can get BACK there in 2 years for your next smogging.

 

...

 

t

"I learn best through painful, expensive experience, so I feel like I've gotten my money's worth." MattL

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There is a CARB approved  Redline Weber 32/36 kit

 

Could be the smog checkers don't even know what they are looking at, so it passes visual then it passed the tests, so it's good to go

I took a 76 in for smog and they could not figure out how to check the timing. After I explained what to look for,they thanked me for bringing it in since they had never seen one before

Toby has a good suggestion to see where the timing is set  and make note of it. Then start playing with the timing and maybe pull the connections on the firewall switches to see what kind of improvement you can make.  Doubt the carb jetting needs any changes.

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You can remove the drive belt for the smog pump and re-install it 2 years from now when you need to pass smog again.  I would also run the vacuum advance line from your distributor to your Weber carb and bypass the connections to the two magnetic valves on the firewall.  The Weber doesn't have a dashpot, so the White Magnetic valve isn't doing anything.  Set the dwell (point gap), timing, adjust the valves, and confirm the vacuum advance is working and you should be good.

 

Have fun,

 

 

Mark92131

 

 

post-33686-0-53728900-1455565413_thumb.p

1970 BMW 1600 (Nevada)

 

 

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You can remove the drive belt for the smog pump and re-install it 2 years from now when you need to pass smog again.  I would also run the vacuum advance line from your distributor to your Weber carb and bypass the connections to the two magnetic valves on the firewall.  The Weber doesn't have a dashpot, so the White Magnetic valve isn't doing anything.  Set the dwell (point gap), timing, adjust the valves, and confirm the vacuum advance is working and you should be good.

 

Have fun,

 

 

Mark92131

Mark - where on the 32/36 weber would I attach the vacuum advance? Also - it looks like there is a vacuum from the white magnetic valve running to the manifold. Should I plug that hole on the manifold? 

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