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Carburetor adjustment  Rating:  Rating
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 Posted: 09-01-2009 03:49 pm
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sjensen24
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My Strombergs seem to be running too lean (per the air valve lift test).  I have maxed out the enriching adjustment and they still seem to be too lean.  I just read in the stromberg book that screwing the idle trimming screw in enriches the mixture.  It is apparently screwed out on new engines and needs to be screwed in as the engine loosens.  Does anyone have experience with this?

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 Posted: 09-02-2009 01:02 pm
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Mitch Ware
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Have they ever been rebuilt? As the bronze shafts and guides wear they will start allowing air to enter through those gaps, causing a too lean issue. The only way to cure it is to rebuild or replace them

Mitch Ware
#19670

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 Posted: 09-02-2009 01:52 pm
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sjensen24
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I just got the rebuild kits in the mail from Delta.  I did find a vacuum leak.  Fixiing that helped but it still feels like something is holding back.  By the way, the Stromberg book says there is an idle trimming screw, but I do not see such a thing on my carbs.

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 Posted: 09-05-2009 05:39 am
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dwalls1
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Have been watching this thread as my problem is the opposite from sjensen24's. 17798 is a gas hog. Wasn't so bad when I first brought it from San Diego, but since I kitted the carbs it's thirst has been unquencheable. I have fiddled them back to almost where they were before I tried to improve them, but they are still way rich. I hesitate to adjust the needles any leaner for fear of unscrewing them from the adjusters. Which is the way they were when I disassembled them for cleaning and kitting. Am going to try another quarter turn CCW, but a dasn't go any further. Any thoughts or comments welcomed.

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 Posted: 09-05-2009 02:40 pm
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Brett Gibson JH5 20497
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Float bowl level and condition of shutoff valve,plus check to make sure the choke lever is not contacting, all add to richness, and while your at it block of the bypass valve and temp compensator, thier more trouble than they are worth and you will have no ill effects if you do.

And one additional, spray some oil onto the the butterfly shaft seals while the engine is running, if the engine improves then you have a leak there as well, they are not a normal item in a rebuild kit but you can still purchase them.

Brett 

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 Posted: 09-05-2009 04:32 pm
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dwalls1
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Thanks for the reply, Brett! The kits I got had new inlet needles and seats, and also the shaft seals, but I may have goofed the install, somehow. AIUI the temp compensators open up and add air when hot. I have fooled with them and they are opening now as I think they are supposed to. Maybe that will help lean the carbs out. I hate to block the bypass after installing all those neat new pieces, but I like making things simpler. When you say "block off" are you refering to the vacuum line to them?I may just have to back up and redo the carb work, now that I have a little better idea of what I'm doing.

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 Posted: 09-07-2009 01:43 pm
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Brett Gibson JH5 20497
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Yes, remove the vac line and also the diaphram, replace that with a full gasket so it blocks off any holes in the carb body.

Brett 

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 Posted: 09-07-2009 03:23 pm
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dwalls1
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Thanks Again,
  I think you may have nailed a problem for me. I had blocked the vacuum line that goes to the bypass gadgets at the intake manifold, but had not removed the diaphragms or blocked any holes in the carbs. I will tend to this and let you know the result.

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 Posted: 09-13-2009 03:38 am
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dwalls1
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Well, I cut some dandy blanking gaskets and installed them next to the carb bodies, but I didn't have the heart to remove the diaphragms that I had just installed. I figure with the gaskets and the vacuum hoses blocked that should do what is needed. After a nice drive today, some 50 miles all totaled, I think I may have made an improvement. Idle is not quite as fussy and mileage seems to be better, though I haven't confirmed that yet. In reviewing my notes, it would seem the mileage dropped off after I changed the cam timing to the 110-110 setting. Can't say for sure, so probably shouldn't say at all. I do know my mileage records from our trip in July of 08 were showing 2-4 mpg better than any recent figures I have. Thanks all, for the good words and encouragement.

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