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Rough running untill fully warm #2149035
09/06/16 07:03 PM
09/06/16 07:03 PM
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Norway
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General 68 Offline OP
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440, 915 heads, Lunati voodoo 302 hyd. cam, Edelbrock 800 Thunder AVS, Torker 2, FBO ignition, 2" headers, manual trans:
Starts easy and idles ok also after choke is fully open but driveability is not good untill engine is fully warmed like after 10 minutes or more of driving. Car needs lots of attention to clutch- and accelerator pedal use to function ok without lugging or bogging down at rpm,s below 2000. Going idle to wot before it is fully warmed will make a huge bog - It completely dies. Acc pump set for longest stroke and a huge .043 squirter still makes this happend. A/F meter reads low 14's at idle and cruise, 13,5 loaded and around 12,5 at wot. Best idle micture setting with the screws out about 1,5 turns.
Prior to installing the a/f meter I had bigger jets in the carb but it acted the same when not fully warm. Even when warm it feels like it is on the edge of running too lean and might sometimes bog some when floored. All sympthoms tells me it is to lean but the a/f meter don't... and it has been calibrated.
Am I overlooking something? Thinking lifter preload, pcv valve or other not obvious things that can make for thermic problems?
Also need to mention that I can not tune away a small lean surge going slowly from cruise to heavier load. Tried different springs and jettings to no vail. Works best with purple spring. What do you suggest?

Re: Rough running untill fully warm [Re: General 68] #2149041
09/06/16 07:09 PM
09/06/16 07:09 PM
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Tacoma, Washington USA
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Don't know of I'm missing something here but every carbureted vehicle I've ever owned will bog down under acceleration when cold and will not function correctly till warmed up

Re: Rough running untill fully warm [Re: General 68] #2149060
09/06/16 07:43 PM
09/06/16 07:43 PM
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central texas
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that's the way both of my cars are too, no choke. carbs.
they are lean until it warms up, they will idle but it's a little slow, then the idle comes around as they warm up.
off idle transition is lean so it's a little tricky, if i try to really give them a stab of the throttle then they do the lean backfire or stumble/stall.

to drive them when cold they like to have the rpms around 1500-2000 rpm or so, once they get some heat in them i let the trans shift into third and let the rpms drop...

Last edited by krautrock; 09/06/16 07:44 PM.
Re: Rough running untill fully warm [Re: Adam71Charger] #2149062
09/06/16 07:48 PM
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In some grade yes but this is bad and the driveability is on the edge until it reaches 180-190 F. If that is normal I am fine with that but it sure would have been nice to make it run good quite a bit earlier. Ofcourse the manual trans makes it more pronounced.

Re: Rough running untill fully warm [Re: krautrock] #2149069
09/06/16 07:54 PM
09/06/16 07:54 PM
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So I am not alone then:) The colder climate here also makes it worse. My other 440 car with a 800 Carter AVS wakes up a lot faster. Thinking the Carters and Edelbrocks might struggle more with this. I had a couple of cars with Holleys and they drove a lot better until fully warmed but that might be in their nature - always pouring plenty of gas:)

Re: Rough running untill fully warm [Re: General 68] #2149181
09/06/16 10:05 PM
09/06/16 10:05 PM
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Hamilton, Ontario Canada
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It is the intake manifold that must be warm. You can fully warm up the intake and with the short block, oil and even water cold. It will not bog.

I find big port intakes are the worst offenders. You either need to choke the carburetor which Im not recommending or switch to fuel injection.

This is not the solution you are asking for but I think throttling up a cold engine is bad news.


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Re: Rough running untill fully warm [Re: General 68] #2149195
09/06/16 10:19 PM
09/06/16 10:19 PM
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central texas
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Originally Posted By General 68
In some grade yes but this is bad and the driveability is on the edge until it reaches 180-190 F.


that sounds annoying, mine are auto cars with holleys. so yes maybe the manual trans and the edelbrocks are just more finicky. or maybe you are the edge of too lean fully warm and that is making the cold driving even worse...

Re: Rough running untill fully warm [Re: General 68] #2149305
09/07/16 12:40 AM
09/07/16 12:40 AM
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Pittsburgh,PA
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Have you checked for an intake manifold/carb base leak?These will sometimes seal after warmup.I'd do a cold engine leak-down test as well to check primarily for leaks beteen cylinders.What head gaskets does the engine have,steel possibly that need retorquing?How old is the engine build? ~RT

Re: Rough running untill fully warm [Re: General 68] #2149344
09/07/16 01:37 AM
09/07/16 01:37 AM
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Northern Calyfornua
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Are you directing any exhaust thru the intake manifold to warm it up, or are the crossover ports blocked? If not, it will take a much longer time for the intake to warm up. That's what heat risers are designed to do.

Is the Torker 2 a single plane intake as I believe it might be? If so, that compounds the problem over a dual plane on a cold manifold.

Without exhaust crossover in a cold climate, likely an intake will not even reach room temperature. I existed for 30 years in our state of Nebraska,,,not Norway but close enough for government work.

Re: Rough running untill fully warm [Re: General 68] #2149346
09/07/16 01:41 AM
09/07/16 01:41 AM
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can you borrow another carb to quickly elim or confirm it as the culprit? I would put some thin superformance gaskets on either side of the metal valley pan (vac leak). what is your timing & ported or manifold. there is definitily an issue that I wouldn't be comfortable with


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Re: Rough running untill fully warm [Re: RapidRobert] #2149385
09/07/16 03:21 AM
09/07/16 03:21 AM
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Wow - I'll try to answear your questions:

-I am not going to race a cold engine. Working on this to get the most out of my gear (it's part of our hobby, right?)

-Engine and carb has been in the car for 10 years but not ran much and has always been like this. No vacuum leaks as far as I can see. I run gaskets on both sides of the valley pan, changed out a bad pcv valve last year. It's a 68 Charger so I always check the vacuum lines out of the carb.

-Don't know what head gaskets were used

-The build is at least 10 years old but hasn't been driven more than 200-400 miles pr year.

-Torker 2 is a singel plane with no heating.

-I do not have easy access to another carb.

Re: Rough running untill fully warm [Re: General 68] #2149394
09/07/16 05:36 AM
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What are outside temperatures when experiencing your concerns. If 70 degree 'F', engine start and initial performance will be dramatically different than at 5 degree 'F'. I will leave it to you to do the Celsius conversions.

The intake that you are running unlikely will ever give you decent cold weather performance or economy given its lack of crossover exhaust porting to quickly warm it up,,,and is unlikely to ever warm sufficiently for optimum economy.

In warmer weather you should not even need a choke to start the engine. The fact that you indicate that it is closed when starting the engine suggests that your poor performance is occurring in very cold weather. Hence the need for a rapidly warming up intake, which you do not have.

In warmer weather, intake manifold warming even without crossover or heat riser will be quite rapid,,,even with a single plane intake.

Your other option is to leave the choke closed for an extended period of time until engine finally warms up,,,,just not a good option,,,poor performance and economy and rapidly polluted oil and a likely more quickly rusted out exhaust system if you use for a lot of shorter trips.

Re: Rough running untill fully warm [Re: Sxrxrnr] #2149405
09/07/16 08:29 AM
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I only drive the car in summer season and outside temps will wary from 50 to 80 F. Choke works best between 0 and -2 (lighter spring tension) on the housing. Setting it firmer makes it too rich after a minute or so.

Re: Rough running untill fully warm [Re: General 68] #2150024
09/07/16 11:24 PM
09/07/16 11:24 PM
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Freeport IL USA
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The intake manifold is your biggest issue. Between 40 and 60 is about the worst temp range to adjust a carbed motor. its too cold without a choke, and its too warm for the choke to stay on long enough to get past the lean stumble. Opening up the exhaust crossover in the intake would probably solve most of your problem.

Short of changing the intake, or setting up the choke more rich, the only other option is to introduce warmer air into the intake.
A few ways to do that, off the top of my head:
1, If you running an open air filter, get one that is closed for your winter driving. Restricting the amount of cold air available to the carb will help your lean condition.
2 Pull warm air off the exhaust and run it through the thermostat controlled snorkel on the closed air filter housing, if you have a dual snorkel housing, one heated snorkel should be enough to do the job. This will require a vacuum source for the thermostatic air door to open and close, and a tube attached to the header/exhaust manifold duct-ed to the snorkel.
3, If your running a heater core with functioning heat, you can pull a heater hose close to the carb to warm up the carb.
4, Another thought is that maybe you can run a copper tube filled with engine coolant between the bottom of the intake and the valley pan to warm up the intake. This could be controlled to shut off once the engine reaches operating temp.

#1 & #2 are better options. Gene

Re: Rough running untill fully warm [Re: General 68] #2150062
09/08/16 12:04 AM
09/08/16 12:04 AM
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The factory didn't use an electric choke like the Thunder uses. So part of the problem is that it has no idea what the engine temp is.

I ran an Edelbrock Performer on my 64 300, but I used a manual choke. Pull it out, drive till it warmed up and pushed it in. Ran fine in all weather, even below freezing. On my 413 you'd know when it needed pushed in because it would bog with the choke on and it warmed up. Open element air filter (no warm air), stock intake (with exhaust crossover).

Tuning to an AF ratio is not best. Tuning to what the engine wants is best, you can note the AF ratio if you want, but if it needs more fuel, then it needs more fuel. Especially when running an unheated intake that doesn't help fuel atomization.


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Re: Rough running untill fully warm [Re: Supercuda] #2150200
09/08/16 08:34 AM
09/08/16 08:34 AM
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Supercuda: Nice to hear your opinion on a/f readings. I have been thinking the same thing and I know the car was more forgiving with bigger jets in it even thou the a/f would read about 1.0 richer than where I am at now. Still finky when col thou.

Robert: Forgot to answer one of your Q's: I run 20 degrees initial on manifold vacuum. Distributor is set up for that and if I remember right it will idle at 28 degrees. It will instant drop to 20 when opened up. Total is 35-36 all in by 2.500 rpm.
Car runs ok otherwise. Heavy Charger, runs 8,70 in the 1/8 mile.

Another thing I just noticed was at outside temps about 60F I parked the car for 1,5 hours after warmed and it had crisp and clean throttle respons when fired back up but got a slight bog after driving a minute before it got ok again. Thinking this points to the suggestions for a too cold intake. Like the intake stayed heated under the hood in the warm car for more than an hour but got cooled down enough to bog when the car got directly up to speed.
Going to put the bigger jet back in tonight an note the difference in driveability and a/f readings.

Re: Rough running untill fully warm [Re: General 68] #2150567
09/08/16 07:42 PM
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Actually I wrote something wrong - the Torker 2 HAS heat crossover ports. But on my engine a heat crossover blocking valley pan was used. I guess it is a good idea to open up the heat crossover! With the issues I have it might be worth the hazzle.

Last edited by General 68; 09/08/16 08:18 PM.
Re: Rough running untill fully warm [Re: General 68] #2150591
09/08/16 08:07 PM
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Well, it couldn't hurt and could be a cheap fix.

edit - I see you have headers, not too sure how well it'll function with headers. But you can try.

Last edited by Supercuda; 09/08/16 08:36 PM.

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Re: Rough running untill fully warm [Re: General 68] #2150630
09/08/16 09:09 PM
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That's what those ports are there for. It is not recommended to close them off for street use except for special circumstances such as racing and other such performance purposes.

Re: Rough running untill fully warm [Re: General 68] #2150776
09/09/16 12:21 AM
09/09/16 12:21 AM
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Even with headers, I believe you will get enough heat to the intake to help. It may take a little longer to get the intake warmed up, then it would with the manifolds & the heat riser functioning, but it still should be a noticeable improvement. Over time, you may have to pull the intake and clean the carbon build up out the crossover ports since you won't have the forced hot air passing through that the hear riser causes. Gene

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