rough running on climb-out

[Stumpy]

Re: rough running on climb-out

Tim,

Good to hear somebody else does that! Not a plug passes through my hallowed doors without intimacy with my fluke meter....even brand new ones. Only takes a second to do, and that eliminates one more issue. I generally put the ones that test 3k to 5k in the "use if needed" drawer...850 to 3k go in the plane...

[astjp2]

Re: rough running on climb-out

You ought to see the look on owners faces when I ohm a plug and then summarily smash it with a hammer so it does not wind up back on an airplane...

[Stumpy]

Re: rough running on climb-out

Ha!....amazing how folks overlook such a simple precautionary check...of course it only helps me on the 40E plugs on the bottom...running C26 old-school plugs on top so the fluke meter isn't much help on them...

[astjp2]

Re: rough running on climb-out

Its the same spec. for all the plugs that have a resistor, I don't know why the C-26 plug would not have the resistors, it causes problems in the mags..Tim

[Stumpy]

Re: rough running on climb-out

No resistors in an old C-26 plug...at least I don't think so (if wrong would be happily corrected)....they don't test as "resistor" plugs do anyway. I have several as-new and several that were restored per navy repair station and returned to service...

[astjp2]

Re: rough running on climb-out

Yeah, I has a brain fart, its high resistance that is a problem,not low.

[Hank Jarrett]

Re: rough running on climb-out

Them brain farts is really nasty since I got good seals around the cockpit! Sure glad I have the flip up windows. ;-)

Hank

[Stumpy]

Re: rough running on climb-out

Well...that wasn't soooo bad. After testing flow three ways through my carb plug at 3.3 gph I correctly guessed the culprit (but continued to do tests through disassembly). Even though we test our fuel religiously and soaked several original neoprene needles in our fuel for a couple of weeks last winter, apparently a slight swelling contributed to a reduced fuel flow via float/needle movement.

So-- double-checked that this carb body has the correct flange numbers for A-65/A-75 continentals, did a very thorough cleaning, installed 1 1/4" venturri, No. 49 jet and No. 65 air bleed, checked the jet location in bowl for proper machining, lapped a SS needle and correct seat, set correct fuel level, measured needle movement at 0.062" (minimum required is .048"), tested overnight at 40" head successfully, and went ahead and did S.B. 73 and moved the idle air bleed location for the heckuvit. Went through the mixture control carefully as well. might build an extended arm for it tomorrow to facilitate finer adjustment...they DO work when properly understood--sometimes anyway.
Just did two bench flow tests through the carb bowl with 12" head and measured it at 19.2 gph both times. Almost seems like more than it should be (anybody else do this kind of test and remember what they ended up with?)....but certainly a whole lot better than 3.3 gph me thinks. Post flow test she's happily holding fuel at the proper level according to my clear plastic tubing.

Reckon it's time to safety wire the outide bits, mount the Stromberg back up, test my fuel flow once again on the aeroplane, set the idle adjustments and see how she goes....unless someone can think of something that's been overlooked? Always a possibility sine I don't have Hank's flip-up windows for mental ventilation...