power-valve diaphragm

[Chrille_GS]

Hello guys.
My car had been sitting for a while and I had a hard time starting it. Pumping the gas a couple of times didnt help it it just coughed and died over and over so I used "starting-gas" (is thats wat its called? You spray it down the carb to help the car start up) a couple of times. Well it helped but the car did backfire some and the engine ran pretty rough after that. Didnt see any black smoke at the time so I drove off to the shop to change the exhaust and didnt think about it that much, just thought it could be moist in the distributor.
It did do a strange thing though before i drove off. While raising the rpm to about 1800 it sudenly increased by itself to about 2300 and ran fine without stumble, as if some cylinders werent firing at first.
Anyway when I got home (still the same problem on the way back btw) I noticed the black smoke and the engine runs somewhat worse.
Could I be right here about the diaphragm? Sparkplugs?
Oh Its a Holley 850dp without choke and no vacuum :)
Thanks on before hand!

[DaWildcat]

My vote is the power valve diaphragms just as you said, especially if there was no problem previously.

Devon

[Chrille_GS]

Ok thanks, Ill take the carb off this weekend to have it inspected :TU:

[Chrille_GS]

What size would the powervalve be in a 850 dp? The one replaced (secondary) didnt say anything on it so I got the 6.5 from the dealer and he said its what most run? (Edit: And oh I dont have a vacuum gague to check what to run either.. :( )
Engine still doesnt run well and after 3 startups the carb had fuel ON it ?!
Could have been an overfill from my side but I gave up after that, so freaking hungry :)
Thanks!

[DaWildcat]

6.5 should do it unless you're running a killer camshaft.

Devon

[Chrille_GS]

No its not extreme. Its a Lunati 33304; 230 - 241 if I can remember right, I have the card here some where.
Could there be some other problem? Maybe I should have changed both.
The car just stumbels and dies 10 secs after fire up. I e The poblem has worsen...

[Chrille_GS]

Ok Ive been at it again. Re-asembled it, changed plugs (Campion 0.030, stock) and adjusted float in the secondary bowl to the point where the floatlevel adjusting screw is allmost through the locking nut (!)
Well the car did start abit easier but still not running when letting of the gaspedal and after a coulpe tries fuel came out of the secondary ventpipe.
The floater is about the same height in the sight-plug hole as in the primary (even though the extreeme adjustment, I mean if I turn another 1/4 it will not be fixed) and that one is not acting up. When I opened to check levels the primary was fine but in the secondary it just poured out...
Oh and some small backfire went on aswell but nothing harmfull I believe

And the thing is Ive never touched the float-level screw, just took the bowl apart from the main body and re-assembled it.

Could this hard-to-start-and-backfire problem be a combination of both carb and timing? I havnt checked the latter yet cause I havent got a light and never fiddled with the timing either since it ran good before.

Any replies appreciated, now of to :beers2: . Thanks!

[ralph sr.]

sounds like u may have a little trash in the needle and seat area. take it apart and clean it well. then when ur done readjust ur float level. good luck:beers2: ralph