carbs popping, and bonus clutch question Options

[vitaminC]

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.

[Mike Bellis]

You need a WB O2 sensor to verify but popping usually indicates a lean condition.

[ArtechnikA]

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...

[IronHillRestorations]

I'll 2nd what Rich said. Do a search on this website for carb tuning.

[gothspeed]

More than likely it is a lean condition ........... also make sure your timing is spot on (IMG:style_emoticons/default/smash.gif)

[Elliot Cannon]

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

[rhodyguy]

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

[URY914]

You could also have a air leak between the heads/manifolds or manifolds/carb.

[rhodyguy]

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

[vitaminC]

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.

[rhodyguy]

it's not like it's dirty work.

[gothspeed]

One more thing, make sure your valves are adjusted with proper gaps. (IMG:style_emoticons/default/smile.gif)