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LONG TIME EVERYONE!! H4 question.

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steved033

steved033

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How many flats to a starting point on a set of H4 SU's?

I had SU's on my MGB, and it was something like 12 flats to the start, then adjust from there. The healey 100-6 doesn't seem to like that. anyone got a tip or a trick to a rebuilt set?

you can see the progress on the longbridge at my picasa site.

https://picasaweb.google.com/steved033/20100724BuffingIt#

thanks for your help in advance.

sjd
 
sorry...should have been more detailed. By flats, i'm counting adjuster nut flats as I turn the adjuster nut with the little SU wrench.

everything is clean, it looks like the jet is moving freely, the jet casing is slightly recessed in the aluminum casting (where it's pressed in, but both carbs are identical)

Basically, the problem I have is that the healey idles fine, seems to drive okay to about 3000 rpm, then seems to run out of fuel. the plugs say the mix is good, they're not greasy or sooty. the vacuum advance is dead, I know this for a fact, the mechanical advance seems to be working fine.

sjd
 
Is the 3,000 rpm in all gears? Then it starts misfiring? If so it sounds more like ignition than carburation.
What leads you to think it's running out of fuel? Symptoms?
 
at 3k when it starts to act up, if I give it a little choke, then everything mysteriously clears up. could this be masking the fact that i'm igniting too early? too much advance? I'll get it warm and re-time today.

as a note, I've taken everything apart again. I was at 15 flats on the rear carb, and 22 on the front.

the pistons float freely (they did before), and everything is super clean now.

sjd
 
Follow up! It was the front carb. I'm at 13/13 on the flats, and it pulls hard all the way to about 4200, where I clearly run out of ignition. it sounds great!

there's a miss somewhere around 2700-2800. THAT is ignition. I'll check the plugs again later.

Time to start venturing out of the neighborhood.

I got a neat treat in the mail. the original 1957 printing of the factory manual! it was found by the original owner's widow, and through the friends that got me the car, it was given to me.

sjd
 
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