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Weber woes


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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

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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

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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.

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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 :mrgreen:

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