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1911tex Samba Member
Joined: June 14, 2014 Posts: 63 Location: Central Texas
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Posted: Sat Jul 12, 2014 8:28 am Post subject: POP (not a backfire) >>> |
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All stock '74 engine/carb. Timed, valves adjusted, spark plugs clean/gaped. Every once in a while on acceleration, the is a single pop from the carb...I adjusted mixture by ear...turned in till engine lugged, then out 1 turn. Is it too rich, too lean? Which way on the mixture screw lean or rich (in or out). Thanks all! |
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tkelley Samba Member
Joined: January 10, 2006 Posts: 1597 Location: Where Pterodactyls crash and burn...
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Posted: Sat Jul 12, 2014 12:38 pm Post subject: |
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Turning the screw to the right (tightening) is leaning
the mixture out. Turning the screw to the left (loosening)
is richening the mixture.
Did you see if you have any vacuum leaks?
Tom _________________ When the sun doesn't rise, we'll replace it
with an H-bomb explosion or a painted jail cell... |
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1911tex Samba Member
Joined: June 14, 2014 Posts: 63 Location: Central Texas
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Posted: Sat Jul 12, 2014 1:30 pm Post subject: |
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Tom, we checked and rechecked for vacuum leaks...non found. I am going to enriched 1/4 turn a trip and see if the setting was too lean...thanks for your clear description of the air mix screw! |
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tkelley Samba Member
Joined: January 10, 2006 Posts: 1597 Location: Where Pterodactyls crash and burn...
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Posted: Sat Jul 12, 2014 6:59 pm Post subject: |
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You're very welcome. Please keep us posted on any progress.
Tom _________________ When the sun doesn't rise, we'll replace it
with an H-bomb explosion or a painted jail cell... |
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[email protected] Samba Member
Joined: February 12, 2003 Posts: 510
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Posted: Sat Jul 12, 2014 7:49 pm Post subject: lean/enrich |
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Thanks for that bit of info, in playing with my carb I was wondering the same thing, was going to post the same question. |
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[email protected] Samba Member
Joined: February 12, 2003 Posts: 510
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Posted: Sat Jul 12, 2014 7:49 pm Post subject: lean/enrich |
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Thanks for that bit of info, in playing with my carb I was wondering the same thing, was going to post the same question. |
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[email protected] Samba Member
Joined: February 12, 2003 Posts: 510
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Posted: Sat Jul 12, 2014 7:49 pm Post subject: lean/enrich |
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Thanks for that bit of info, in playing with my carb I was wondering the same thing, was going to post the same question. |
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doublecanister Samba Member
Joined: September 23, 2008 Posts: 1184 Location: Richmond, Va
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Posted: Tue Jul 15, 2014 1:46 pm Post subject: Re: lean/enrich |
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[email protected] wrote: |
Thanks for that bit of info, in playing with my carb I was wondering the same thing, was going to post the same question. |
Hey Guys, I may have posted this for you but will do again as I can swear by it now it works!
(From a prev post)
I read that mucking with the carburator adjustments, even mi-nute ones can cause extreme exhaust fumes. I have a pict 30/31 & 009 dizzy on a 1600 engine.
Well I can say that "mi-nute changes can cause extreme exhaust" is correct cause before i knew what I was doing i was crankin them screws willy nilly, pretty much "Trying" to set the carb by ear.
Well, in prep for last year's driving to Dover's "Thing show", I did a tune up.
did a valve adj
Timing adj
points and dwell
After all that I put on a 'vaccume guage"
One of those 1man brake bleeder tools that doubles for a vac guage;
(attached it to a vacume port below the carb) and used it to help adjust the carb.
I set the carb by the book to the default screw turn outs, then using the vac guage adjusted them to get the Highest needle/most stable needle settings i could.
I had to do this about 3 times but I got it finally and I noticed for the FIRST TIME EVER I had no exhaust fumes entering the cabin.
Now, fast forward about 500 miles later, I noticed last weekend i got a slight wiff of exhaust, but sundays drive with the top down i didnt notice any.
(update) July 2014 she's still running smooth, no stinky exhaust note.
I learned this method from working on my 51 Ford truck, and just had to reset the carb from a recent rebuild on that. It runs even better now!
I did it to all my vehicles and made them run way better and not stink from exhaust so much.
(the Mustang was the worst with exhaust smell)
The Book that comes with the 1 man brake bleeder tool (got from PEP BOYS) actually demos the needle patterens as to what's causing it , out of adj carb, leaking valves, blown head gaskets, etc. Nice little tool.
Hope it helps you guys out.
I can say I never EVER tried a vaccume guage before, we always set carbs by ear, test drives, etc, I was really amazed on how it helped the VW and the old 51' Ford, the Mustang was so bad that I bumped it back to electronic ignition to "take it a step further'.
anyways, good luck and try it!
T _________________ ****************************************
2020 - Mustang Eco Boost [High Performance]
1973 - Thing
1966 - Mustang GT- Fastback
1951 - Ford F1 pickup Flathead V8 |
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1911tex Samba Member
Joined: June 14, 2014 Posts: 63 Location: Central Texas
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Posted: Sat Jul 19, 2014 6:42 am Post subject: |
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Tom and all..thanks. As above indicated, and per your instructions, I enriched (counter clockwise) 1/4 turn...and I must have nailed it the first trip as I have not a single popping sound on acceleration or deceleration...amazing how such a fine adjustment can make such a difference...as indicated by doublecanister. |
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