Hey guys, Ive got a couple of issues with my carbed 355, and Im hoping yall might be able to shine some light onto the subject as I know squat about carbs.

Alright, here's the situation.

Motor : 355 Cu In block, Edlebrock 73cc heads, Comp cams 292h, air gap intake. have mini starter on block, Powermaster i believe.

Carb : Holley Street Avenger 750cmf Vac Secondary.

Issue :

Have been smelling fuel when the windows were down heavily. Was driving home last Saturday and turned a corner a bit fast and the car started acting like it didnt wanna keep running. Car then stalled 2 times, and I popped the clutch to get her running both times since I was in motion already. Was able to get her home, without stalling by keeping on the gas some.. Didnt matter if it was in neutral or gear, as long as motor was running at higher than idle speeds.. got home, decided to see if it'd idle. It stalled out. Wouldnt re-start. not even a turn over but no fire/fuel sound just a CLUNK, and that was it. Like hydro compression almost.

Get out, popped the hood, wife and I heard what was like dripping water. I unscrewed the air cleaner took it off, examined the carb. sure enough the back bowl was dripping fuel at a constant rate... drip drip drip drip drip drip from both of the jets(i guess thats what they are) So since it was 1130 pm ,a nd i dont have a a garage, I went ahead and left it over night. Came back out the next day around 11-12 in the afternoon, and it's still dripping. Take the back bowl screw out of the side of the bowl, and it pours fuel out. I took the top screw off it as well and it fountained fuel up. Put the screws back in place, disconnected the fuel feed line, and took the carb off the car. I believe there to be a problem with the rear float, at least thats what my neighbor who knows stuff about carbs said.

What you think is the issue? ive described it as best I could.. like I said, The most i know about carbs is I have one, I have used this model since I put the v8 in the car, This is the second of this exact model Ive gone through. The first one we couldtn fix so i had to replace it. I dont have the $ to buy a new carb at this time, and I was really hoping to get the car to the fbody gathering in atlanta this may.. so times running out..

Any and all help is greatly appreciated..


I had accidently posted this in the Tech/general motor area, but then i found this sub-forum.. sorry for the confusion.

Thanks.
Steve

 

Sounds like you sunk a float or your float needle/seat is worn out. This is a very, very common problem with Holley carbs. It could be as simple a fix as readjusting the float level (maybe the float is not damaged afterall) but usually when they start dripping like that you need a carb rebuild.

 

thanks... so how hard is it to rebuild a carb?
-steve

 

rebuilding a carb is not easy if you have not done it before lol.. But I had that exact same problem with my holley. turned out i just needed a new needle and seat and then readjust the float.. you could get a new float and that should solve that particular problem. Rebuilding a holley unless you have a book on how to do it is not the best thing to do. since holley does not give you any decent instuctions with a rebild kit (been there and done that) Another thing is how old is the carb itself..

But yea.. had that problem before... float level is out of adjustment and what is happening is (not sure if yours has it... but it could.. i should pay more attention to the different ones) is two overflow tubes.. one for the front and on in the rear by the bores. basically what will happen is when the needle/seat sticks open fuel will keep coming into the fuel bowl and the overflow tube is there to push the eccess fuel out of the fuel bowl and let it drain into the bores.. most times it will kill the engine. well. actually almost everytime.

 

*removed by me.. reposted*

 

well i got the carb disassembled and everything looked good. the float seemed fine, but i bought a rebuild kit anyways and replaced the needle for the float anyways, put it all back together, and it started to run, albeit not very well. Had to shut her down as i detected a leaky valve cover. Hoping to get that fixed tonight, and go from there. When I pulled her apart, i found a dead fly that i think fell out of it. Im not srue for sure.. but it appeared it had been in the bowl. I acnt be positive though. Will keep yall updated.

I know i have to adjust the float level now, and see if that helps any.

-steve

 

if there was a fly in the bowl.. that was more than likely your problem.. it would get stuck in the needle/seat pretty quick

 

I would be concerned with how the fly got in there in the first place... you got a fuel filter on that thing right?

BTW I will be in Atl, plan to take home the '70-'77 Super modified plaque... there were no entrants in that class last year

Which car are you taking?

 

If the air cleaner was ever off it could have gotten in through the vent tubes.

 

yeal its got both a stock filter and an inline clear up before the carb under the hood.

I was hoping to bring the purple one to the gathering, as I think i could do real well in the super modified class for the 92 as well.. but if i cant get this carb thing ironed out i cant rightly drive her there..


Now ive replaced the needle, ive got her running again, all be it pretty crappy but it runs, and ive also tried to figure out how to set the carb.. if theres any insight as to why the car would be kinda "loading" up after it warms up i'd greatly appreciate it.

Also, is there possibility to get piston wash and have fuel in the oil if you had too much in the cylinders and cause oil pressure to not be right? if so, thats my problem too. cause now ever since it flooded out like it did, i havent gotten any good fuel pressure like i used to.. plus the oil smells like fuel.

-steve

 

if the carb is overly flooding the engine you can get gas in your oil. which would greatly effect the oil and is adviseable to change it before you run it or you could destroy the bearings and such in the engine.

As for why it is loading up... Make sure the choke is set properly to be all the way open when it is warm.. Make sure that you are getting the best vacuum while the engine is under load (by adjusting the Air/fuel ratio screws) and by making sure the floats are adjusted just right.. Holley did say if you seem to have exxssive fuel. you can go as low as 1/8 inch below the sight hole and be ok.. My be something to look into... other possibilities would be the jets are to large yet? Just throwing out ideas on how I tuned my holley.. Finally got it tunned perfectly. Also.. if you bought it used.. the a/f mixture screws might need new cork seals (mine were crap and i could ever maintain the mixture)

 

I'm going to have to try to adjust the float level again i suppose. Are the float levels supposed to be adjusted while the car is running or while it is off?

I'm planning on changeing the oil by this weekend too. If I have enough spare $ i'll do that soon.

I adjusted the Air Screws the following way. I took them and screwed them all the way in (clockwise) then I unscrewed them 1&1/2 turns out ( counter Clockwise) It seemed to not smell of fuel near as bad as it did before, so I was happy about that.

Problem that still exists is that after the car gets to around 180 degrees it starts idling like crap, borderline stall out, and i can see puffs of black fuel coming out of exhaust pipes. Im worried I may have fouled out a plug or two now, with all these fuel issues.

I havent adjusted the choke, as it was fine before I had the issue with the back bowl.. so unless something went horribly wrong there, I dont really see a need to adjust it.. what do you think?

The carb was new in box when I bought it so i dunno.

-steve

 

Its probably a good idea to check the plugs and see where you stand there. I doubt the choke is the problem because it was fine before. Your air/fuel sounds about right but the best way is to vacuum gauge it and set it that way. I adjusted my floats with the car off because everytime you crack open the adjuster fuel shoots up through the needle and seat and makes a bit of a mess. I would adjust it up or down, then run the car for a moment to run the fuel through and see where it stood after that. Might be a good idea to adjust the floats a bit lower as Angelis83LT suggested.

 

it says you are supposed to adjust it while the car is running to get the most accurate adjustment with the carb level. (on my car i had to actually jack a side up about an inch because the engine does not set level.. i figure it s an engine mount thing). Andway.. If you are careful. you can adjust the float without fuel spraying out.. you just have to turn the two pieces at the same and adjust them both at the same time.. I have done it more times than i can count... and only once did fuel go everywhere.. (forgot which way was which lol). The most you will get it a dribble... but then the instructions also tell you to adjust the float until it just dribbles out of the sight plug (to where it is at the exact bottom of the hole and ful just starts to come out.) Without fuel going into it.. it is impossible to adjust them properly becaues you can not get the fuel lvl in the bowls to rise or lower. th only way to adjust it with it off is to remove the fuel bowl, turn it upside down. and adjust it like that.

And yes. Vac guage the thing... best way to do it.. and remember... the adjustments to that are made when the car is in drive... not park or nuetral. (so haveing another person there to help you as a good idea.)

 

Ok fellers.. Last night, i adjusted the floats. the front one is just to the point that at idle some leaks out of the sight hole ever so little. the rear float is just below that.. almost but not quite letting any fuel out of the sight hole. I assume I have them pretty well tuned in.

Ever since I had adjusted the air screws she's started to pop through the carb when you get on it hard... seems like it may be too lean? should i turn those screws out again? it still is loading up after it gets hot. could it be the power valve? my buddy down the street things that it may be because of my cam the power valve needs to be smaller.. I dunno..

 

the onlt way to determine the power valve is to have a vacuum gauge connected to see whatvac you are pulling.. if it is anything above 12. then the 6.5 it comes with will work.. andy thing below 12 and you devide it in half to get the powervalve (ie a 10 would be a #5 powervalve). Again You have to do this when the car is in Drive. Also if you have backfired at all throuhg the carb.. you might need a new power valve anyhow unless your carb came with the power valve protection thing. a vacuum guage is pretty much a requirement for doing carb tuning. you can get one at a local parts place for probably 15$

 

yea, my neibhbor has one, just dont know what i'd be looking for / or where to hook it up at. i guess any vacumn port on the carb would work? how would i measure it in drive? its a manual.

-steve

 

ooh manual. hard to do it in drive them lol.. I guess for that just throw it in park and get the highest vacuum you can get. you can do it in drive. but you hvae to use a pretty good size piece of vac hose so you can have the thing in the car. Neve had to do it on a mnual.. but i would imagine that you would have to check the vac as soon as the car was fully engaged without giving it gas (which is very possible.) You would hook the vac guage up to any manifold vacuum source.. On my Performer intake i have a vacuum tree behind the carb i use.. comes in cery handy for that stuff.

 

Yea, its a 5 speed. Ill try to hook up a vacumn to it, just to see its hard to see idle in gear, as itll stall out on me if i release the clutch while holding the brake.. best i got is neutral..

what vacumn should i be looking for on the guage? how do i know what is good i guess is what im asking.
-steve

 

well.. on a sotck or mildly modified (no choppy idle cams) a vac around 22 in neuatral is what i get with the l69's... when in gear it is at 12 and 13. which is about right... as for putting the t-5 in gear. i meant. put it in gear and let it fully engage so you are moving forward.. (ie why i said you would have to have a really long chunk of hose so the guage could be inside the car when you did that.) but ussually.. you adjust the air/fuel screws to achieve the highest vac you can get.. and adjust them a little more till the vac just starts to fall off. then adjust back 1/4 turn

 

Ok, well we did all that after i changed the oil last night. the car is running like it used to for the most part. Im pretty pleased that the oil change and adjusting it with a vacumn guage worked as well as it did.. we're pulling down about 8&1/2 - 9 vac .. its a pretty stout cam. its a 292h by comp.. thats at idle though. we didnt do it in gear, but such is life.

Turns out I had crank saturation, so much fuel and what the extra quarts of oil i had put in the car was too much, it probably dumped out 7 quarts total out of the pan, once a change was done, it fixed her rightup.. Im so glad it seems to be runnign well again. I went ahead and did adjust the air screws and such just as you say angelis.

Thanks ever so much for your help, so far it looks like its running well. Im going to attempt to bring her out tonight to see how she does.

you guys all, thanks again. I couldnt have done it without your help.
-steve

 

np.. I hve a holley and I know they can be pains.. and 7 quarts. wow.... 5 quarts oil and 2 quarts fuel??? that would be scary lol.. the biggest thing is the vac guage. always helps lol.. Mine is a little stock cam.. but it does ok atm.. until i get get a few other things (headers. must get headers.. stupid exaust leak.....)

Anyhow Hope it runs nice and neat for you.. if you get any off idle stumbles it is probably the acelerator pump for the pump shot needs to be adjusted a little. again. not a big deal lol

 

well it took a **** on me again. Dang thing. I and my neighbor think its the damn power valve.. dunno though.. It sounds like its not firing right, or like a truck thats beat up or something at idle , i just dont get it it, then you revv her up, and it sounds like it always did.. so we're trying to fingure out what is going on with her.. I didnt have any problems with her running until the carb messed up origionally, so Im guessing its still a carb issue. I even changed the fuel filter under the car, no difference.

God im so frusterated with it right now.

-steve

 

well heres another developement as we disassembed the front bowl, we found the throttle plate was loose.. ugh.
-steve

 

disassembled the fuel bowl? that is not anywhere near the throttle plate.. unles you mean when you were taking the fuel bowl off you noticed the throttle plate was loose... that could cause problems as it would let air in when it shouldn't... tuning it would be a PITA at that point.

 

yea, the throttle plate was noticed as being loose when we were taking the front bowl off of her, all 4 screws (iirc) were loose. we replaced the power valve last night, new gasketed her up, after a full cleaning with carb cleaner, then we went ahead and put her back together. Tonight im going to try to put it back on the car and try it again. I hope it runs right after this. Im so frusterated at it its just not cool.

-steve