morbidsunroof Posted November 7, 2009 Share Posted November 7, 2009 Hoping you can help? I just assembled a flattop > block w/ an N42 and triple 40DCOE's. With the > throttle plates closed, best idle is at 2k with 45 > f8 idle jets...went up to 160 mains and 175 air. > It pulls hard a 3/4 throttle, but at the mat, it > misses and goes flat. Waved the propane around > and don't see any leaks. I'm thinking it's alot > of compression for a stock cam, but I gotta > believe I can do better than this. Timing base set > at 10 deg. Plug check still indicate it might be > lean, but it's really hard to tell on pump gas. > If you can point me to a better jet scenario, I'd > appreciate it! Thanks!! > Nick Quote Link to comment Share on other sites More sharing options...
rags Posted November 7, 2009 Share Posted November 7, 2009 Best idle or lowest idle? Last time I worked on a set of triples that had an exceptionally high idle had bent throttle shafts. Pretty easy to diagnose, just put a flow meter on both barrels of one carb. If they are way different you have bent shafts. Obviously there are other internal engine problems that could cause this but if you are sure it's a carb issue, this is what I would look for. Joe Quote Link to comment Share on other sites More sharing options...
RB30X Posted November 8, 2009 Share Posted November 8, 2009 Can you repair a bent shaft?? Quote Link to comment Share on other sites More sharing options...
kiwi303 Posted November 8, 2009 Share Posted November 8, 2009 swap it out for a new shaft from a weber stockist. Quote Link to comment Share on other sites More sharing options...
morbidsunroof Posted November 8, 2009 Author Share Posted November 8, 2009 It was actually RICH. Went to 135 mains and it's now a rocketship! Still need to lean the idle more... Quote Link to comment Share on other sites More sharing options...
theghosttanker Posted November 8, 2009 Share Posted November 8, 2009 yeah 160 mains with 175 air is gonna be way too rich; as a rule of thumb, the main should be about 40 less than the airs. Quote Link to comment Share on other sites More sharing options...
morbidsunroof Posted November 9, 2009 Author Share Posted November 9, 2009 When the budget allows, I'm going to try 145 & 185 to get rid of a mild knock at WOT and heavy load. I did end up actually square once (165 & 165) on the race car due to a pressurized airbox. Nick Quote Link to comment Share on other sites More sharing options...
Lazeum Posted November 9, 2009 Share Posted November 9, 2009 I have the same setup except for the cam; to get rid of knock, you'll have to play with timing, AFR won't help you much I have scheinder cam (MSA stage II) in the car so far, with such a compression ratio you have to run big race cams to lower dynamic compression ratio to avoid knock. For your info, my setup tested with a wideband sensor gave the best results with: Main 135, Air 195, emulsion tube F11, Accel pump 45 Idle jet are 50f9 and work fine, idle is smooth at 850/900 rpm. This will also depend on your venturi size and other parameters. My car was difficult to tune until I noticed one needle valve was crushed, making fuel level in bowls not accurate. Quote Link to comment Share on other sites More sharing options...
morbidsunroof Posted November 9, 2009 Author Share Posted November 9, 2009 Thank you Lazeum! Gonna try sub stock timing and verify float level! Quote Link to comment Share on other sites More sharing options...
Lazeum Posted November 9, 2009 Share Posted November 9, 2009 Thank you Lazeum! Gonna try sub stock timing and verify float level! You're welcome I'm running 28-29° TOTAL timing vs. 34 or 36° stock which is lame. I have a mallory ignition that helps me to play with the curve. I have 10° at idle. My way to fix that is to get a new custom head (Braap) with new cam (Rebello) and some work done to it Quote Link to comment Share on other sites More sharing options...
morbidsunroof Posted November 9, 2009 Author Share Posted November 9, 2009 Best way fer me is to find a JOB first! BUT! I DO have a Mallory non vacuum with adjustable max that I'll be putting on right now! Nick Quote Link to comment Share on other sites More sharing options...
morbidsunroof Posted November 11, 2009 Author Share Posted November 11, 2009 The Mallory did the trick! Thanks! Nick Quote Link to comment Share on other sites More sharing options...
Lazeum Posted November 11, 2009 Share Posted November 11, 2009 I'm glad I was able to help you A spring set for the distributor helped me to add couple of degrees more into play mine was mostly knocling at high load (it's $20 if I'm not wrong...) Quote Link to comment Share on other sites More sharing options...
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