Hi, I'm new to your group and came here looking for an answer. I have a 1956 Victoria with 292 bored 60 over, '57 intake, 1850 600cfm carb. manual choke, '59 distributor with petronix ignition, with a ton more done to it but I think that is all you'll need to know to hopefully answer this question. I'm getting a hesitation or hiccup like the car is jerking or stalling a bit at a constant speed around 60mph. Almost feels like hitting bumps in the road. If I accelerate or decelerate, this hiccup disappears. Any ideas? Please help. If you need to know anymore information on the car to identify the problem, just ask. Thanks, Brooks.

Brooks

Brooks;

I don't have an easy answer, but you can start with checking some things and narrow down the possibilities. I have a similar set-up in my '56 Customline. I would double check the air gap on the Pertronix and the gap on the spark plugs. I don't know what type of plugs you are running, but with my Pertronix I set the plug gap at about .042"-.045". When you pull the spark plugs you can also see how they are burning. If the hiccups go away on acceleration, it's probably not the fuel pump or ignition timing.

Just my 2 cents worth

Rono

  Ron Lane,  Meridian, ID

Sounds to me like the vacuum advance is kicking in and over advancing the spark.

If you put a lot of early mechanical advance in an engine - you can't add vacuum advance without limiting the "top end" a bit. Say you have a quick curve in there and it has 36° total mechanical advance (initial plus centrifugal) at crusing speed - if you let the vacuum kick in on top of that - and you go way up over 55° or something like that - the engine will lean out drastically. 

 
 Steve Metzger       Tucson, Arizona

Hi Brooks,  Steve is right, it sounds like you have a "lean surge" problem.  It's possible that you could have a leak at one of the intake manifold gaskets or that your carb is too lean.  I'd try blocking off the vacuum to the distributor and take it for a drive and see how it acts.  Good luck, Nick Brann - K.C., MO

Thanks to everyone so far with your help. I did already try this, if I did it correctly about a month ago. I separated the vacuum advance line to the carb from to distributor. I just left the hard line on the dist. and plugged the hole at the carb to not lose vacuum. I didn't plug the line to the distributor. Would I have to do that? Did I do the whole process right? If I did there was no change, if anything it got slightly worse. I took it down the road and no good. The man i purchased the car from in '97 had thought the same as ya'll did. The car was built and is still the same as it was since the mid 70's with the exception of the Pertronix and complete tune up of course. Plugs are NGK and the carb has never been touched, but it has never sat for more than over winter. I only did the Pertronix to hopefully fix this still existing problem. The problem was there at times even with the other owner(he recently stated) who has owned the Vic since '69. I noticed it a couple years ago on a trip to Iowa to a regional meet for our C.V.A. club. I've done a complete tune up, Petronix, set timing and recently pulled the vacuum advance line, all with no success. Please, if anybody has any more idea's, I'll try anything to fix this issue.

Brooks

I've had the same symptoms and it turned out to be an ignition problem. In my instance, it was 7 year old wires.


Lawrenceville, GA

Hi Brooks,  Yes you did a proper job of blocking off the vacuum to the distributor without messing up your carburetor.  It still may be a lean situation with your carb.  I'd try changing the jets in the primary side of the carb, go larger by 3 or 4 sizes.  I'm not an expert on Holley carbs by any means.  Also, what is the gap on your spark plugs?  A too small of a gap (like .015" to .025") can cause a rough running engine, but that usually shows up at idle.  Good luck, Nick Brann - K.C., MO

Ignition parts first, Go through rotor and cap, leads, Get a set of new plugs and set them at .36 - .38 no need to go further [Steve will tell you that] . Whats your timing like, Sounds like it not a vacuum advance ? . To the carb , Set the float levels right, Im running 64 jets witha blue pump cam on position 2, when was the last time the fuel filter replaced?



"Came too close to dying to stop living now!"

Opps.. make that .036 - .038 gaps



"Came too close to dying to stop living now!"

On the ignition I’ll suggest checking that both the mechanical and vacuum advance curves function by observing the timing mark with a timing light aimed at the damper while running the engine at various speeds.  Check the ignition timing with the vacuum advance hooked up and not hooked up to determine if both ignition advance mechanisms are working.

 

On a different train of thought, have you checked the fuel float levels at the carb?  Rear float level is just as important as the front level at this point.   Fuel pressure and volume are also worth checking.  Also check the fuel tank vent behind the license plate for being open and not stopped up.

Lorena, Texas (South of Waco)