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Idle-Jetting-Linkage / What in dwell? / Dead Stop... 120-130 1967

Hello All:

1967 Volvo 122S wagon. I did my first major tuneup yesterday, and Wendy is thrilled. She says Virginia is driving like a champ, and anytime Wendy is happy I am happy, which means I am happy darn near most of the time.

I have three questions, outlined below. Please feel free to answer any one, all of them, any combination, or none.

1) One of the mysteries for me is the relationship between the idle setting and the jetting of the twin SU (HS-6) carbs. I have ensured the choke mechanism is off and the fast idle screws are not engaging the cams, but what should the regular idle setting be when rejetting? If you completely disengage these two screws the engine will not run, but engaged they affect the ability to tune for "fastest idle", no? Particularly challenging when a relative newbie such as myself is trying to balance the carbs. I have also figured out that my last tune up was horrible due to the improper setting of the throttle linkage. I would love to see an article on that if anyone has one. I think I got it right this time but perhaps it could be better.

2) I thought I set the new points gap correctly (.16 feeler gauge go, .18 no go) but the dwell still seems a bit high, nearly 70 degrees. Is there any way to adjust this without resetting the point gap?

3) The car is running much better but I am still experiencing an interesting drop in revs as I disengage from the transmission, particularly at stop lights but also on downshifts. After a second or so the engine seems to "catch" itself and go back to the somewhat higher idle rev point. Those of you who have followed my travails might remember that I need to rebush my carbs, and I know that will make most problems go away but I am curious as to what might be happening in the world of physics to cause this. It seems to me that the needle piston might be "bouncing" off the bottom as it returns even though I am not observing that behavior with the air filters off. The throttle plate cannot be closing more than I would like due to the setting of the idle screws, so I would love to hear some theories. This is more of an intellectual exercise than anything else.

Cheers,

Jeff Pucillo






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