Carb issues?

[Masonite]

So coming home from the meet yesterday, I noticed a slight hesitation when giving it gas at low RPMs. Once it got past 1500, the car revved fine. Throughout the night, the problem seemed to worsen--it eventually got to the point that it felt like I was losing torque at random points in the RPMs, almost like it would pull, hesitate, then repeat. Almost like a subtle bucking feeling. I THINK it's my carburetor, but I'm not totally sure. Any ideas/suggestions would be fantastic. Please keep acronyms down to a minimum--I'm a bit of a noob when it comes to auto repair. Oh, and this morning, the car would crank but wouldn't start until I pumped the gas a couple times (usually takes only one pump prior to starting).

Anyway, the reason I'm posting this in the lounge is because if it's an issue with the carb, I'm in luck. I just found a Holley 750 double-pump carb in my garage (I think these are illegal on the road!) that MIGHT work. Sweet.

[Mulletbird]

I had that...

check choke (that's what happened to me ... choke wouldn't open) - I just used duct tape and bailing wire to hold 'er wide open (this is for if the choke is fully closed 24-7). Then, just tune it. You'll be surprised how bad a car on a winter tune will run when it gets 80+ out. It's gotten very hot very fast, and it messes with carb'd engines real bad.

[Masonite]

I had that...

check choke (that's what happened to me ... choke wouldn't open) - I just used duct tape and bailing wire to hold 'er wide open (this is for if the choke is fully closed 24-7). Then, just tune it. You'll be surprised how bad a car on a winter tune will run when it gets 80+ out. It's gotten very hot very fast, and it messes with carb'd engines real bad.

Great advice, thank you. I will try that and let you know how it works. I'm going to put the Holley on, anyway, for that little extra power ;-).

[Jersyboyy]

A holley 750 on anything smaller than a worked 383 or a seriously worked 350 355 357 IS NOT A GOOD IDEA
Your throwing way to much fuel at a 305 that got more than enough to start with.
A 4 barrel 750 double pumper is not illegal on the road but its not for your car bro you will probally not get any performance gain from a stock motor NO you WONT and you WILL lose MPG.

Take your car to a shop to have the stock carb looked at it may be something simple, debri lodged somewhere in their or a simple adjustment could fix it and youll be good to go...if you want more power the smart way get a edelbrock 650 nice and simple...holleys (as much as I love them and will be running a 750) are a pain in the ass to tune and are better suited on motors making good-serious power.

[Masonite]

A holley 750 on anything smaller than a worked 383 or a seriously worked 350 355 357 IS NOT A GOOD IDEA
Your throwing way to much fuel at a 305 that got more than enough to start with.
A 4 barrel 750 double pumper is not illegal on the road but its not for your car bro you will probally not get any performance gain from a stock motor NO you WONT and you WILL lose MPG.

Take your car to a shop to have the stock carb looked at it may be something simple, debri lodged somewhere in their or a simple adjustment could fix it and youll be good to go...if you want more power the smart way get a edelbrock 650 nice and simple...holleys (as much as I love them and will be running a 750) are a pain in the ass to tune and are better suited on motors making good-serious power.

Duly noted. I have another quadrajet laying around, too. Might start with that, then. Thanks!

[Mulletbird]

I'd try fixing it yourself first. With my Firebird, I asked about how much for an ignition timing adjustment and carb tune (it was really out of whack ... I told them I'd supply parts, all they had to do was tune it) and shops wanted $300+ labor for that simple job. If you can't tune it out, then yes, go to a shop or (if mechanically inclined / have a friend who is / willing to offer beers) do it yourself. You'll save a ton of money that way - beers for 4 people, maybe $30, shop labor, $300.

[bad64chevelle]

A holley 750 on anything smaller than a worked 383 or a seriously worked 350 355 357 IS NOT A GOOD IDEA

Oh really? My car picked up so much going from a 600 to a 650 holley DP, then more to a 650 Demon, and it really jumped going to the 750 DP. And I run a measly 327 :lol:

I agree with the rest of your statement, but I have heard that all too much. My buddy said that about his 327 also that is set up similarly, and he picked up quite a substantial et and mph out of his car.

[Jersyboyy]

oh word i forgot about the 327s but i dont think a 305 would ever need anything bigger than a 650 no matter what you do to it. a 327 or a 350 with a 650 dp even with just slight mods probally will result in more power if tuned right :)

"I'd try fixing it yourself first. With my Firebird, I asked about how much for an ignition timing adjustment and carb tune (it was really out of whack ... I told them I'd supply parts, all they had to do was tune it) and shops wanted $300+ labor for that simple job. If you can't tune it out, then yes, go to a shop or (if mechanically inclined / have a friend who is / willing to offer beers) do it yourself. You'll save a ton of money that way - beers for 4 people, maybe $30, shop labor, $300."
Wow didnt relize it would cost that damn much at a shop!

I got a guy up here in sayreville/south river thats an old school gear head. Hes about to open up a performance shop in south river too right where the old "Ask Franks" was.
If you want I could talk to him, he rebuilt my carb and tuned it on the car for 75 bucks so it should def be cheaper for just a quick tuning of the carb.

[Tru2Chevy]

Since you don't state any differently, I'm going to assume that you still have the stock computer-controlled Q-jet on your car. Swapping that for a non-cc q-jet, edelbrock, holly, etc will throw a code (or several). I am pretty sure there are ways to use a standard carb and have the computer still control timing with the stock distributor, but I don't know what all that entails.

Your best bet would be to check the basics out first....make sure you are getting an adequate fuel supply to the carb, and do a quick visual inspection of the carb to make sure there is nothing obviously causing a blockage that you can see.


A holley 750 on anything smaller than a worked 383 or a seriously worked 350 355 357 IS NOT A GOOD IDEA
Your throwing way to much fuel at a 305 that got more than enough to start with.

While a 750 Holly DP sure isn't ideal for a stock or near stock 305, remember that the factory computer controlled Q-jet was also rated at ~750 cfm ;) The biggest difference is the fact that the q-jet has smaller primaries for part-throttle cruising, with the larger secondaries to get a proper amount of air into the engine when you go to WOT, where as most other carbs are designed around primaries and secondaries of the same size.

- Justin

[Masonite]

Thank you all for your advice. I tried Mulletbird's tactics first, and that fixed the problem. The choke didn't want to open all the way, so for now, I have a zip tie keeping it fully open. Might not be the best for cold days (although I'm not anticipating any more for awhile), and it's a little iffy on a cool start for the idle, but once warmed up, the car performs better than ever.

Also, looks like I'd have to throw in some adapters to even get a holley 750 on--the quadrajet that's on there now doesn't have the primary/secondary fuel bowls that the holley does. it's practically all electronic controlled, where the holley isn't.

Thanks again for the advice!

[WildBillyT]

Thank you all for your advice. I tried Mulletbird's tactics first, and that fixed the problem. The choke didn't want to open all the way, so for now, I have a zip tie keeping it fully open. Might not be the best for cold days (although I'm not anticipating any more for awhile), and it's a little iffy on a cool start for the idle, but once warmed up, the car performs better than ever.

Also, looks like I'd have to throw in some adapters to even get a holley 750 on--the quadrajet that's on there now doesn't have the primary/secondary fuel bowls that the holley does. it's practically all electronic controlled, where the holley isn't.

Thanks again for the advice!

Your Q-Jet is a spread bore carb, and the 750DP is square bore. You will need an adaptor for that.

As for carb size, there are rules of thumb that people follow, and sometimes the engine just likes a lot more carb than one would think. For a stock 305 you should be fine with a Qjet or 600-650 holley.