Hi, i'm running a rebuilt qjet 4bbl on my 350 and there's a lot of strong white/grey exhaust at start up. it lessens after the car is run but its never had this much exhaust. i had this qjet on before it was rebuilt and never ran like this. swapped it out for a edelbrock and again, no strong exhaust. car starts up fine and then as it warms up a bit these clouds of grey/white exhaust come out. i ran the car good last year and then checked the plugs and they showed no evidence of fouling. if anything they were running a bit lean. tried adjusting the qjet with the adjustment tool (air fuel screws) but had no affect.

short of putting the edelbrock back on or taking it to a shop is there anything i can try.

has an edelbrock performer intake, hooker headers, 7a heads, flowmaster delta 50's.

thanks for the help

 

just wanted to add i just took the car for a bit of run. its driving fine but when i got back the exhaust issue was still prevalent.

 

If your idle is set too high, the 2 A/F mixture screws won't do anything. If there is a vacuum leak it will also make it difficult to adjust.

 

Is there a smell from the mist? Antifreeze is the smell of head gaskets here. I will admit that a carb change should not have an effect on mist from the exhaust. A mist or even water from the exhaust on a cool or cold start is normal, but that mist will not be present from an engine that has been run (thoroughly warm).

 

Idle while in park is around 850 rpm.

i have a vacuum gauge, what would be the correct means of determining a leak. i've sprayed around where the heads meet the intake with WD40 and there was no increase in rpm.

the car does not run smoothly when its cold, kind of sounds like its got a rough cam in it but it has a rather mild lunati cam in it for a while. when its warmed up it runs smooth, good acceleration torque for my needs.

 

no i don't think i smell that. its just a very strong exhaust smell. stronger than normal.

 

Have you sprayed around the base of the carb? Is your choke opening all the way? Can you drop the idle a bit to see if you regain adjustability for your A/F mixture screws? If you look down the throat of the carb with the engine running do you see fuel dribbling? Is your vacuum gauge steady or jumping around?

 

i'll check on those things and will update. many thanks.

 

I'll give you my take with an assumption or two.

Your car has set all winter. It probably has at least some of last years fuel even though you used a fuel stabilizer and new fuel. Lastly, your engine has a few miles on it. Just guessing.

Give it a little while, and few hundred miles of fresh gas. I think its coked up a bit, sticky rings, carbon, etc. Things happen when cars just sit there. They like to run.

My theory, it just needs to loosen up a bit. Why not get some sea foam and follow the directions, while keeping an eye the other suggestions and stuff.

 

Sounds like the choke pull off isn't opening enough, open it more. I bet it will smooth out and have less smoke.

 

yeah i think the choke is playing a part but after the car is fully warmed up the choke wouldn't come into it would it? after fully warmed up there is still quite a lot of white/grey puffs of strong exhaust coming from both tail pipes.

 

this was happening last fall before the car got put away but otherwise yes it has set all winter. i fired it up about once every two weeks, now its warming up finally and getting it out on the road.

 

Is the choke fully open once the engine is warmed up?

- Eric

 

Factory carb? Your float level could be too high.

 

What MD says.
More info. Who did the rebuild, what style choke does it have,electric or heat stove? No response from the A/F adjustment needles means a vacuum leak(or high idle). What is the vacuum reading at warm idle? What style of gasket do yo have on the intake? A 4 holer or all cut out?
If one carb runs good and one doesnt the prob is narrowed to the bad carb.
It sounds like its rich. Choke adjustments too tight. The choke should just shut when the accelerator is depressed on a cold start. Then as soon as vacuum is built up the pull-off should pull the choke open, slightly like 1/16". This is by design so the air fuel charge isn't over enriched, the engine needs some air. Then as the choke warms up it slowly opens with the temp rise. Re-read the plugs Ill bet they are black. Is it using coolant?

 

yes choke is off when warmed up. choke plate standing straight up. i adjusted the choke a bit and that seemed to improve things at initial start up with the fast idle but there's still a lot of exhaust. Sprayed wd40
all around intake, heads, carb base and no increase in rpm. vacum is reading a steady 14.5, is that a good amount? its rock stock steady.

 

a carb rebuilder who says he's been doing it for 40 years rebuilt it. i'm going to call him tomorrow to see what he says. choke is electric and i've adjusted in a bit but with it fully open there is still a lot of exhaust. got back from a nice drive and parked in the driveway. the exhaust was still prevalent but not as bad but as i let it run int he driveway to check vacum and the choke etc. it started to increase again.

no not using any coolant, level remains constant. that's what you meant right?

intake gasket is the valley pan, have used this before with no problems. or did you meant gasket between carb and intake?

yeah i agree with you, i think its the carb. i'm tempted to swap it out with the edelbrock this weekend.

 

i don;t know the history of the carb. the engine wasn't original when i got the car, had #8 heads on it and its number matches one of those 73 - 76 blocks or whatever the dates are, it was painted blue.

can the float be adjusted on a qjet with the carb on the car?

 

Yes

The air horn or top will have to be removed.

 

yeah i just had it rebuilt so maybe the guy who did that would take a look at it for me. meantime i would put the edelbrock back on. if performance of the car stays the same with that on i would just keep it on and not bother with the qjet. never had any problems with that edelbrock.

 

Your Qjet should out perform that Edelbrock in every way, including mileage. If it doesn't, something is off.

 

i hear ya, but a carb swap is easy and it would help isolate the problem.

i have 14.5 steady vacuum, does that rule out a leak?

 

A reading of 14.5" on a stock engine is low. Was that idiling in park? I know my stock 307 ran closer to 20". My motors with 204/214 cam still pull 16-17" idiling in park.

 

Its low. Which could indicate a vacuum leak. Low but steady indicates retarded timing.
You should be up around 20hg at curb idle, warm engine with the timing set to spec or slightly advanced to obtain the highest possible vac reading. The A/F mix screws should be tweaked to obtain the highest vac reading as well. This is how you use a vac gauge to "tune".
You did an intake swap; whats the chances you have a slight leak and its pulling in oil from the lifter valley? Any "milk" in your oil? Is it "using" oil or coolant?

 

no milk in my oil. i'm not noticing a huge loss of oil or coolant so i don't think i'm losing any.

 

if in the course of trouble shooting i do decide to put the edelbrock performer #1403 back onto my performer intake #3711 can I do that with an adapter. the info on the edelbrock sight says the performer carbs won't fit a #3711 but it says nothing about adapters which i have. I used to have this edelbrock carb on the original intake with an adapter. wanted to ask before I take the plunge and sit on edelbrock's tech info line for an hour or more.

 

I believe the mount on that manifold is a spreadbore mount only, therefore the adaptor is necessary.

 

correct its spread bore. just wanted to know if there was any other reason it wouldn't fit, bolt holes not lining up etc. before i take that qjet off.

going to run my car good today and check the plugs and try and get a vacuum reading at the intake. not really seeing anything to connect to the gauge too but will keep trying. while i have the plugs out to check them i might as well do a compression test. i have the kit.

 

I believe the Edelbrock 2596 adaptor is the one you need for this.

 

What is the transmission control modulator and distributor vacuum advance canister lines hooked up to?
The trans should be seeing full unported intake vacuum. IMO so should the distributor vac advance can, but there are exceptions to that.

 

i just put my vacuum gauge on the distributor vacuum advance module, the thing that looks like a miniature version of a child's top correct? and it showed no reading at all. i put my vacuum gauge on the highest spout on my rochester carb and its reading around 15 - 16 now that i've increased my timing to 20 degrees. Is that my problem, a faulty distributor VA can?

i still don;t see a place to put my vacuum gauge directly on my intake. i'd have to take off the power brake line but that port seems too big.

 

vacuum advance can hose is hooked up to the carb, lowest nozzle on the left hand side. then i have a pcv valve going to the largest nozzle in the middle and the other nozzle on the driver's side is plugged.

 

Use the other nozzle on the carb, it should have vacuum at idle all the time.

 

sorry are you saying hook up the vacuum advance can to that other nozzle, the one on the driver's side?

 

We need some visuals here.
wcourt please purchase the large Chiltons or Motors service manual for your car as well as the assembly and fisher body manuals. They have great illustrations and all the specs etc...I am not being short with you here it just sounds like you need to do some reading rather then having us spoon feed you every little detail. Plus you'd be surprised at the wealth of info to be found in the above mentioned manuals. And it will make your Olds experience that much better.

The picture below shows the vac ports I'm describing. Keep in mind this is a 455 intake. The 350 will be somewhat similar as far as having a port or three. The 3 ports at the rear on this intake provide a direct vacuum source I haven't seen a 350 intake in a while but it should have at least one port on a 70-72. I believe on a 350 the base of the carb will supply the brake booster and the vac advance can or TVS. You may have/had the thermo vac switch (TVS) installed originally and someone deleted that?

(Padavano, https://classicoldsmobile.com/forums...um-switch.html)...
"The thermal vacuum switch is used on cars that run the vacuum advance off of ported vacuum. Since ported vacuum is zero at idle, this can cause the car to overheat when idling in traffic. The TVS senses coolant temperature and switches the vacuum advance to full manifold vacuum if the car starts to overheat. This increases vacuum advance at idle and lets the car run cooler. The use of ported vacuum for the vacuum advance is an early emissions control that was intended to reduce NOx emissions."

Hence those who aren't concerned about 100% originality remove said TVS device and run a straight manifold vac signal to the vac adv can. Better performance.

This is where the assembly and Chiltons will be of value to show what your application was originally and where the various hoses were routed.
You mentioned you have a 16" vac signal. Thats an ok but not a great a vac signal, 18-22 would be better. Is it steady?

The vac adv canister hanging off the distributor needs to be supplied with a vacuum source from the carb (or TVS) or the intake, it does not have its own vacuum supply.
However if you did hook it up to a live vacuum source (not ported) you should see the timing advance by ~10-12*. You will hear it if the vac can is working. If the can is bad it will leak, as in a vacuum leak.
20* of base timing is a bit much. You should be experiencing pre-ignition(spark knock).

I like a direct intake vac source for the transmission modulator and vac can.

This still doesn't explain your original post you made with the exhaust smoke issue. So before we get off into the weeds any further we need to determine if what your seeing in the exhaust is normal or abnormal. Can you shoot a YouTube video of the smoke and of the intake showing some details?

 

i have all those manuals and thought you meant the transmission modulator which is attached to the transmission at the rear, has a rubber hose that goes to it, not a trans modulator port on an intake. i'm running a 3771 edelbrock intake that doesn't necessarily have those ports you listed in your photo except for one that the power brakes run to, i'll try and get a reading off that. yes i've upped the initial timing and I'm getting around a vacuum reading of 16. the exhaust is not normal, never seen it before including when i had this qjet on the car when i bought it. i'm swapping the carb out this weekend, if that ends the exhaust issue then that'll be it. thanks for trying to help me.

 

No, I was saying to measure your vacuum there.

 

yeah i don't seem to get any reading from there. only get a reading from the nozzle that is higher up on the carb. from that nozzle i'm now getting a reading of a steady 16 after i increased the timing. timing is now at 20 BTDC and rpm at idle/ car in park is hovering around 900 and its seemed to have smoothed out but the exhaust is still strong.

going to put that edelbrock on or this other qjet i have and see if that changes anything, then i'll know. cheers and thanks for your help, will let you know the outcome.

 

make sure u didn't crack the dizzy cap and its siting flat like it should and u have all the extra vacuum holes are plugged with those little rubber caps on ur carb

 

[QUOTE=wcourt3010;815915]i have all those manuals and thought you meant the transmission modulator which is attached to the transmission at the rear, has a rubber hose that goes to it, not a trans modulator port on an intake.

Humm...Im confused. Lets start over....We are not communicating very well here. There must be some language barrier? The transmission modulator(vacuum diaphragm) mounted on the transmission will have a vacuum line hooked to it coming from the intake manifold. It should not be hooked to the carb ports or nipples (nozzles as your calling them). I have seen instances when a modulator diaphragm will fail allowing transmission fluid to be pulled into the intake and burned in the combustion process, thus causing a white cloud of smoke from the exhaust with the unique odor of burning trans fluid.

The vacuum advance canister mounted to the distributor, not a dizzy!, is controlled and is hooked up to a vacuum source generally at the carb throttle plate or from the intake ports/nipples.

A carburetor generally consist of 3 main parts. The air horn(top), the float bowl(middle), and throttle plate (base or bottom). Any vacuum nipples/ports above the throttle plate are ported or timed vacuum sources. These nipples are not recommended for taking your vac readings, or to hook up a transmission modulator or distributor vacuum canister actuation. Ported means "restricted" by orifice size or by timing when its sees a vacuum signal due to throttle plate position.

It looks to me like the Edelbrock 3711 intake (3771 is a Ford intake) has 3 ports to tap for vacuum. One up front and 2 at the rear. Yes that's where you should be taking your vacuum reading from.

Heres is what Id expect to see if I was to walk up to your car to trouble shoot.
1. Look for any vacuum leaks, repair as needed.
2. Pull a plug or three and read them. Replace as needed.
3. Inspect the ignition and fuel delivery systems. Replace as needed.
4. Set curb idle @ 650-750, engine warm.
5 Set dwell to 30* on a dwell meter if you still had points.
6. See what the base timing is. Set base timing at 12* BTDC (to start out with). This is with the vacuum advance canister disconnected and the hose to it plugged off so there isn't a vacuum leak.
7. Now hook a vac gauge to a known direct vacuum source. Adjust the timing and air fuel settings to achieve the highest vac reading possible.
8. Connect the vacuum advance canister. Verify that it actually works by advancing the timing at idle approx 10 more degrees for a total of about 22* Re-adjust the air fuel to achieve the highest vac reading.
9. Now adjust the base timing to achieve the highest vac reading.
10. road test.

This is a base adjustment spec that should provide a decent running Olds 350 engine.
If not something is off. You have an intake/carb vacuum leak (the A/F needle screws will be unresponsive to adjustment).
The distributor is a tooth off.
The vacuum canister is unresponsive due to a breached internal diaphragm.
The carb has some internal problem. A cross leak, wrong needle and jet combination for your car or is the wrong CFM rating for your engine or the float level and drop settings are wrong.
If what you smell is gas the plugs should read rich.... the carb is the likely problem.
If the smoke smells sweet like antifreeze you have a bad intake seal on the heads. Remove and replace the intake gaskets.

Let us know if the carb swap gets rid of your smoke?
And your welcome for the help...I hope it actually helped.