Just when I thought it was all going so well

[paizao99]

Truck ran rough while driving on Saturday. Drove it on Sunday and nothing happened. Even drove it to the point of being warm on the temp gauge and nothing happened. Today it ran extremely rough. Changed out the fuel filter; it got better but still had a rough sound and hard vibration. The carburetor was recently overhauled and is now leaking slightly around the lower half of it (WW3). It has a new distributor, cap, spark plugs, and wires.

Filmed a little of it so anyone interested could hear it. Of course it sounds worse in person.

http://www.youtube.com/watch?v=DZJcf7edySQ

Would gladly listen to suggestions.

[j2007]

hello fellow North Dakotan,

I had a similar sound in a motor and found it to be a bad plug or plug wire. (both were contributing to the problem)

if this is not it, someone else with more experience should know

just my

[Trailmaster]

I'd try plugs and wires first, cap, rotor, points, and condensor if it's been a while since they were done. If that don't solve it a compression test might be in order to see what's going wrong.

[legacyABQ]

If a freshly rebuilt carb is leaking, it certainly would be reasonable to suspect the integrity of the carb as a whole.

[tinbasher]

whenever something goes bad, i always go back to whatever it was that i just fixed.

[paizao99]

Pulled all of the plugs out for inspection. Here is a pic of what they all pretty much looked like. This is after only a month, give or take, of light driving in a small town. Is that normal looking?

[dakotadave]

hard to tell from the pic, but they look a little dark and seem to have some goop near the threads (old rings?)

i never got my original carb to work right and i really did try; i used an edelbrock in the end and it is great.

i'm running 11's for spark plugs (thats a really cold plug, 15 is stock on mine) after replacing the ignition, carb, cam etc. it runs well.

if you are still running points (and no CD box) you can pull the plug wires off one at a time to see which cylinder is giving you grief, but i am wondering if you dont have a vacuum leak. it may be a plug but my money says each plug wire you pull at idle will drop the idle a few rpms - the way your engine runs sounds very familiar to me. good luck

[dakotadave]

i just watched your video right now and you are a likely candidate for a pretty unhealthy VACUUM LEAK or worse, bad valve seats! that sound brings back bad memories of my engine!

what is the history of this engine (rebuilt? hardened seats etc)

get rid of that sad old stromberg, it pained me to give up on mine but i wish i had SOONER as i have no regrets now!

also pull your manifold off and have it cleaned by a shop. they will look for cracks if you ask nice and even clean up that sludge factory in the middle. AFAIK there is a 4bbl manifold for that engine that is available(?? help me out here someone, a weiand maybe??)

[paizao99]

Thank you, Dave, for the info. I am going to see this through one way or the other.

I think that the ignition system is in need of the ole Pertronix upgrade. This will be first on the agenda. This will lead me to a few other routes. The valve seat idea is what may keep me up at night though. I don't have a clue about how to solve such a problem.

The Stromberg will be on it's way out too; however, the issue is how. To get an Edelbrock I would have to also purchase a 4 bbl manifold...I have been reading that those are a little on the scarce side, which of course drive up the price. It certainly appears as though the Edelbrock's are the primo product though. Now a 4 bbl drinks the gas a whole lot more too though, right?

In regards to the condition of the truck: it is all original. The previous, and original, owner did nothing but store it in his barn. He drove it on occasion but nothing like a daily, as I would like to use it. I have done more to the truck in the 7 months since purchased it than he did in the last 20 years. I replaced the distributor and all its parts, spark plugs a few times, spark plug wires, battery and cables, coil, ballast resistor, overhauled the Stromberg, clutch, slave cylinder, new tires and wheels, bled brake lines, and painted the rear bumper. Unfortunately, after all that it sits in the garage because it runs like junk.

I always appreciate any and all help. Thanks again.

[Hobcobble]

Have you rebuilt that Stromberg? If the throttle body
isn't in need of re-bushing, you might be able to improve
the engine's performance with a $15 jiffy kit. If not, you
could likely find a good Carter BBD 2bbl for it. I've run a
BBD on my '61 Poly for years. They're a bit less finicky
than a Stromberg. No need to re-invent the wheel on your
fuel delivery with a factory [very rare] or Weind [quite scarce]
4bbl manifold. If your truck was running good when you bought it
and began to run rough in a relatively short period of time, the
valves may be fine. You can run a compression check to confirm
this though. Just so you know.... Summit Racing sells a BBD for
a '70/'71 application. It would likely give you all the performance
you require.

As far as electronic ignition goes..... I'd suggest picking up the
MoPar Performance electronic ignition. I've seen many people
disappointed in the Pertronix system.... you get what you pay for
in some instances. Others have gone the boneyard route and
installed a system from another vehicle. Its a crap shoot.... I
personally like installing new electronic components and being
done with it in one session. I run the MP electronic ignition
on all my old MoPars and have been trouble free on every one of
them.
John

[dakotadave]

well the valve seats are the easy part, you bring the shop your heads and pay them :D

i dont know what it costs for a poly, but for my LA it was $250 - new valves, seats and springs on the exhaust side. i had brad do it here in fargo and he does well with mopars.

as a last resort you could always consider swapping a newer good running LA in there until you rebuild the poly. you might find a smacked up new yorker that runs fine for cheap or something?

[mopardwh]

As far as electronic ignition goes..... I'd suggest picking up the
MoPar Performance electronic ignition. I've seen many people
disappointed in the Pertronix system....

I agree.

viewtopic.php?f=33&t=22011


It sounds like you have a cylinder not firing. I would do a compression test and spark test on all the cylinders.

[paizao99]

Failed to mention that back in November a compression test was done. All but one valves came in at 125 psi. The one had a 120 psi.

[MountainMoparRobin]

Failed to mention that back in November a compression test was done. All but one valves came in at 125 psi. The one had a 120 psi.

thats fine as long as they are within 10 psi of each other your ok

[paizao99]

The much-talked about Mopar Performance Kit...is it this?

http://www.jegs.com/i/Mopar%20Performan ... ccessories

I only ask because the website for jegs and summit state that this is for a big block engine.

[Hobcobble]

The much-talked about Mopar Performance Kit...is it this?

http://www.jegs.com/i/Mopar%20Performan ... ccessories

I only ask because the website for jegs and summit state that this is for a big block engine.

You need the small block version.
John

[712edf]

The small block conversion kit part # ends with 426 instead of 428. Its on the same page in Jegs Mopar Performance Ignition section. Same price as big block. Only difference between the kits is the actual distributor itself. Small block rotates opposite direction from big block, plus the shaft isn't the same.

Bucky

[Bubb]

I was having ignition problems a while back. I bought the Summit Racing version of the Mopar Performance EI kit. Comes with all the same components and cost about $40 less. Just doesnt have the Mopar name on it. I have had nothing but success with it.

[BCW]

Also a easy way to check for vacuum leak . While you have it running spray WD-40 around the intake and base of the crab if there is a leak the engine will pick up in rpms . Just a check because it sounds like a vacuum leak to me.