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9/29/12 10:01pm - Original Message: 'Vacuum Leak!'
daveo76
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Vancouver, WA - USA

Vette(s):
1976 Silver/Firethorn. L48, 4spd. Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.

Joined: 8/25/2005
Posts: 831
Oops! I've been driving around with a small vacuum leak since I put the motor in and didn't even know it.  For those familiar with Q-jets: I left out the little hose that goes from the carb to the choke pull-off diaphragm.  Noticed that missing last night and put it on.  It runs better than it did before, but it's surprising how well it ran without it.  The biggest improvement is how it runs right after a cold start.  Without the pull-off working it was probably loading up and it surged and ran crappy for about 30 seconds after start-up.  Now it runs good right from the git-go.  I was also able to lean the mixture a little bit and let it idle a little lower, maybe I'll save a little gas now.  Idle quality has slightly improved and I think it took care of a slight miss I was noticing.  The choke-pull off's other function is to prevent the secondary air valve from opening when the choke is on, but I haven't been getting on it much (especially when it's cold) with the engine break-in so I didn't notice that too much.  

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1976 Silver/Firethorn.  L48, 4spd.  Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.
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 Forums -> C3 Fuel, Emission Control, and Exhaust Systems
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