 carbs popping, and bonus clutch question |
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| vitaminC |
 Jan 5 2013, 10:22 AM
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#1
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searching...  Group: Members Posts: 49 Joined: 29-August 10 From: NorCal Member No.: 12,121 Region Association: Northern California  |
In my quest to drive every 914 I can, yesterday I drove a 73 1.7 that has recently been refitted with a 2056 with Weber 40's. The car started and idled fine, and overall drove quite nice. However, when I was on the freeway there was some popping happening in the carbs. It seemed to occur more at a steady throttle vs accel or decel. Any thoughts what might cause that?
And on an unrelated topic, where is the 'typical' clutch engagement point? The '73 seemed okay, but the '71 I drove earlier engaged right at the top of the travel (i.e., I hardly needed to push the pedal) and that didn't seem quite right. Thanks. |
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Replies(1 - 11)
| Mike Bellis |
Jan 5 2013, 10:37 AM
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#2
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Resident Electrician Group: Members Posts: 8,347 Joined: 22-June 09 From: Midlothian TX Member No.: 10,496 Region Association: None 
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You need a WB O2 sensor to verify but popping usually indicates a lean condition.
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| ArtechnikA |
Jan 5 2013, 10:45 AM
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#3
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rich herzog Group: Members Posts: 7,390 Joined: 4-April 03 From: Salted Roads, PA Member No.: 513 Region Association: None |
Agree with Mike on leanness but popping is also a symptom of out-of-sync carb / linkage. And/or plugged idle jets. Both of which are just ways of producing leanness...
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| IronHillRestorations |
Jan 5 2013, 11:48 AM
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#4
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I. I. R. C. Group: Members Posts: 6,813 Joined: 18-March 03 From: West TN Member No.: 439 Region Association: None
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I'll 2nd what Rich said. Do a search on this website for carb tuning.
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| gothspeed |
Jan 5 2013, 12:30 PM
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#5
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Senior Member Group: Members Posts: 1,539 Joined: 3-February 09 From: SoCal Member No.: 10,019 Region Association: None |
More than likely it is a lean condition ........... also make sure your timing is spot on (IMG:style_emoticons/default/smash.gif)
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| Elliot Cannon |
Jan 5 2013, 01:23 PM
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#6
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914 Guru Group: Retired Members Posts: 8,487 Joined: 29-December 06 From: Paso Robles Ca. (Central coast) Member No.: 7,407 Region Association: None
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Those symtoms are indicative of clogged idle jets. Pull out the jets, hold them up to a strong light and take a look. If clogged they can be cleaned with air pressure. There are small "O" rings aroung the jets. Don't drop them. (IMG:style_emoticons/default/laugh.gif) This is probably the easiest and quickest trouble shoot. I'm not an expert. I'm just sharing my own experience.
Cheers, Elliot |
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| rhodyguy |
Jan 5 2013, 01:51 PM
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#7
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Chimp Sanctuary NW. Check it out. Group: Members Posts: 22,240 Joined: 2-March 03 From: Orion's Bell. The BELL! Member No.: 378 Region Association: Galt's Gulch |
LOUD snapping or light sneezing? at 60ish on the fw your right in the transition between main and idle circuitry and the series of progression ports. the sneezing may be solved (low speed, but with the throttle plates not above progression ports) with the air by-pass on the offending barrel. the idle/air mixture screws are just that. they allow more FUEL to be drawn in when the throttle plates are CLOSED. once the throttle plates start to raise above the prog ports the draw on the idle air mixture screws lessens and fuel is drawn directly into interior carb wall. the ports are drilled into the well that feeds the iams.
with the tops off of the filters you can usually note the the offending barrel when you increase the engine speed by hand with the linkage. listen and watch from aside. with a sneeze you may see a momentary puff of atomized fuel or a flame with a bang. DON'T BE LOOKING DOWN THE BARRELS during your observations. k |
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| URY914 |
Jan 5 2013, 03:33 PM
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#8
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I built the lightest 914 in the history of mankind. Group: Members Posts: 126,349 Joined: 3-February 03 From: Jacksonville, FL Member No.: 222 Region Association: None |
You could also have a air leak between the heads/manifolds or manifolds/carb.
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| rhodyguy |
Jan 5 2013, 03:50 PM
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#9
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Chimp Sanctuary NW. Check it out. Group: Members Posts: 22,240 Joined: 2-March 03 From: Orion's Bell. The BELL! Member No.: 378 Region Association: Galt's Gulch |
that too. the solution is usually pretty simple but it can be a long away around the mountain. judging by his drive comments it doesn't sound like there are terrible issues. no banging on decel and low engine speed carb noises narrows the field quite a bit.
i sat down and went thru the "how they work" chapter of thomlinson's again. it's a must read. esp before you put a wrench or screwdriver to a set of webers for the first time. k |
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| vitaminC |
Jan 5 2013, 04:10 PM
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#10
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searching... Group: Members Posts: 49 Joined: 29-August 10 From: NorCal Member No.: 12,121 Region Association: Northern California |
Thanks for the replies. Mainly I was just curious as whether it was something serious or not, and it sounds like it will take some effort to get right, but isn't a major issue.
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| rhodyguy |
Jan 5 2013, 04:12 PM
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#11
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Chimp Sanctuary NW. Check it out. Group: Members Posts: 22,240 Joined: 2-March 03 From: Orion's Bell. The BELL! Member No.: 378 Region Association: Galt's Gulch |
it's not like it's dirty work.
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| gothspeed |
Jan 5 2013, 07:42 PM
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#12
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Senior Member Group: Members Posts: 1,539 Joined: 3-February 09 From: SoCal Member No.: 10,019 Region Association: None |
One more thing, make sure your valves are adjusted with proper gaps. (IMG:style_emoticons/default/smile.gif)
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