Hopefully someone can help with this. I have a 87 305 with a 4 brl rochester. My problem is the idle. In park it idles around 1500 and drive around 1100-1200. When you sitting still you can feel the rpms jumping up and down. The timing is set and the idle screw is backed all the way out. You can smell gas real bad, and I get white smoke when I first start the car. Is there something wrong with my carb. perhaps the tps, or m/c solenoid. I was thinking the tps since that controls the idle speed. When I shut the car off after driving for a while it diesles real bad. I've been trying to fix this for months now and any ides would be appreciated. Thanks

 

never fooled with a q jet on a ecm controlled car, but i'd guess the idle screw all the way out isn't good. try setting the tps and maybe look at the fuel and air filters

 

Sounds like your choke is stuck on...

 

The choke being stuck can cause all of the idle problems? How do I find out if it is sticking or not?

 

Take the air cleaner off while the engine is running, after it's hot, and look at the top of the carb... see if the primary barrels of the carb are closed off by the choke blade. The secondary barrels (the 2 rear ones) have their own valve which should always be closed, but the one over the primaries should be open whenever the engine is hot.

 

I have exactly the same problem. Mine gives a bit of a smoke at startup which I attribute to valve guides being shot. Mine idles about 1400 and gas smell real bad also. I also have the extra run after I shut it off. I hate it, I have timed mine as well and my screw is all the way out too. I also have an 87 305 4bbl. I have been looking at replacing the tps too, but haven't yet. I called carbs unlimited and the guy there told me the carb needed to be rebushed? He said that is what my problem is. I did the choke thing and I have mine wired open at all times so I know it is not the choke stuck on. Please anyone help us! Or is the guy at carbs unlimited correct? Just didn't sound right to me. Any help would be great!
:hail:

 

Hey 350ss, if you want the link to that website where it shows you a blown up view of the parts here it is. http://www.carbs.net/Quads/E4MC.htm

 

Thanks for the link. Yeah my choke is open when the engine is hot. So I'm pretty sure it works correctly. It's gotta be the tps. I took another rochester apart yesterday to get at the tps and it is not all that difficult. It's about a 10min job. So I'm gonna replace my tps with another and see what happens. I have to start somewhere and I guess this is as good as any. 1987fbd I will let you know what happens. Sounds like you have the exact same problem. Wish me luck.

 

I think you are on the right track there. At leat that is what I was going to do also. Doesn't sound as if anyone here has seen this which seems strange if we both have the same problem. I appreciate you keeping me posted on how it turns out. I will probably tackle mine this weekend. Do you have the book by roe on carbs. I just ordered it. I was told it was a must if you have these carbs. Good luck man!

 

No I don't have a book yet. I was gonna switch to TPI, but that's just too expensive. I'm just gonna put the TPI on my camaro and leave the rochester on my ss. Yeah I'll be doing mine this weekend as well. I have to pick up some connecting rods today. Let me know what happens.

 

Hey 350ss,

I was just talking to five7 about this because he seems to be the guru on these cc cars. He thinks it is the choke thermostat and linkage. I just got back from Napa, I bought a carb kit and choke thermostat. The two came to 98.00. Ouch! I also priced the tps you are getting and they wanted 58.00 for it. Well anyway I wanted to let you know I got those and still plan to get it done this weekend. I just popped the hood and checked it out and the choke is pop riveted in there so I guess I will need to drill it out and rent or buy a rivet gun. Also looks as if I am gonna need to take the carb out to do it. I was kinda hoping I could try the thermostat with it still in and see if it changed it any. Owell, maybe between the two of us we will get to the bottom of this ****. Talk at ya later!

Mark

 

Man ouch is right. The Tps here is around 25.00 and I was looking at the choke stuff and it was around 40-50.00. I have another rochester that ran fan. So i'm gonna take the tps out of that one and put it in mine and see what happens. Let me know about that choke thing. If it helps any I might as well do that. I'll have to wait tho. I just paid 200.00 out for my pistons and rods at the shop. I'm building up a 355 and I want this carb to be working right when it comes time to put it all in. I hope to *** this works. I've tried everything else. But yeah let me know what happens. I'll do the same

 

I thought a rich running motor blows black smoke...not white! Could this be another problem? Maybe intake gasket?

 

Hey 1987fbd, you don't need a rivet gun, the carb kit should come with some little screws to replace those rivets after you drill them out.

 

Hey Riley,
I thought that as well at the beginning too. I have checked all around it and there is no leaks at all. And no vacume issues either.

350, man I feel like they screwed me on the price then. The carb kit was like 38 and the choke therm was around 58. The item you bought they want 50 something as well. Guess I should have shopped around.
Oh and hey I found one of those books I was telling you about for 5 bucks on ebay. I did a search for rochester and it came up with like three of them all under ten bucks. I here it is the bible for this carb and everyone says to get it if you plan to keep that carb.
Are you going to swap out motors when you get that one built? That will be sweet. I want to find me a 350 to throw in mine. But I have body issues i am going to fix first. Nothing real bad just performance stuff.

Later, Mark

 

The 350 is going into my 87ss, which is going to be my track car. The 86iroc has an 87 305 truck motor in with tpi and pulls real strong. So that's gonna be my street car. I'll play with some mods for that to just not yet. I think I'll check on ebay to. I need one of those books. And I've checked for leaks and have found nothing. And black smoke is caused by oil. ie ring job, new valve seals. Blueish, white smoke is caused by running rich.

 

and white smoke means moisture getting in.....black smoke= rich...blue=oil

 

I had a problem smoking on startup, giving the classic valve guide seal symptoms. It turned out to be the choke pulloff valve. The function of the choke pulloff is to pop the choke butterfly open a little bit when the engine is cold until the choke itself opens the butterfly fully when the engine warms up. To check the choke pulloff, look at it on startup of a cold engine, it should immediately pull it's arm into it fully. If it doesn't you will run very rich until the chokes warms up.

The choke pulloff also serves a second purpose, it won't allow the secondaries to open until the engine is warmed up. If it's not defective, that is.

 

Hey all, problem solved. I put the carb kit in and also replaced the choke thermostat and now she runs sweet. By the way (redbird) the kit came with replacement rivets? I figured it would come with replacement screws as well. I went ahead used them.

 

Hey 1987fbd, glad to hear your good to go. I however am not. DId your replace the tps as well? I was trying to but the instructions talk about staking the tps so it will stay at a certain height. When I took it apart it wasn't staked whatever that means. Do you know what there talking about and how to stake the tps? Thanks

 

The TPS has a stiff spring under it. When you put the top of the carb on, the TPS can't move. Be careful to not loose the green pushrod under the accelerator pump lever .

 

Hey 350, No I didn't mess with the tps. I have the idle problem fixed. It was the choke thermostat like 57 said. I still have a few other issues however. One is the valve guides are gone in my motor so it tends to take out the o2 sensor and then my car runs too rich so then it throws everything out. So now you know what my next job is going to be. At least it is an easy fix. My motor has high mileage and I plan on rebuilding it this winter. I want to have fun with it while the weather is still nice. Hey let me know if i can be of any help at all. Good luck!

 

Ok then , so you just got a replacement choke thermastat? Well I guess that's what I'll be doing this weekend. Hopefully it will work for me to. Did you take the carb off to do that or leave it on? It looks as if you could just leave it on. Thanks for the info.

 

Hey 350,

I did have to take off the carb. I beleive it is possible to do it on, however there is factory rivets in there and you have to drill them out. So taking caution not to get metal shavings all over my intake I just pulled the carb. If yours has already been replaced, it may have screws, in which case it should be no problem to do it still on the manifold. Also you may just check to see if it moves on its own because they don't fail very often. It may just be linkage.

 

Well I watched it the other day while it was warming up and the choke opened up all the way on it's own. Does this mean my choke is working fine? If so then I don't know what my problem is. Thanks for the help

 

Hmmm, if your choke opened all the way then yes it is fine. Maybe you do have a vacume leak? Might be worth just pulling the carb and putting a 38 dollar rebuild kit in it. Set a new base gasket on it.

 

350SS, check your choke pull-off. Even though your choke opens all the way after you warm up does not mean that your choke is working properly on start up of a cold engine.

 

I think it may just be time for a new carb. For a rebuild here they want almost 900.00. But I can buy a rebuilt carb for 259. So I might just do that. I've been having so many problems with this one. I don't know maybe it's warped or something. Ever since I started working with it I've had more problems. Losing oil pressure, high idle, about nine miles per gallon. It's killing me. Thanks for the help. This one just may be shot.

 

$900.00 !!!! I think they need to be shot! You can buy 2 speed Demons for that price.

 

Yeah I thought that was kind of high to. He said it was because it was computer operated. Yeah whatever. Then why can you buy them rebuilt for 260. Obviously I'm not dealing with him.