Inliners International Forums General Discussion Engines Stuttering

Hey guys. I've noticed in the past week that my engine likes to stutter consistently when I'm at this particular point into the throttle. Like at 2/5 throttle, the engine starts sputtering and it sounds like a machine gun. It's not random and it happens at the same place in the revolutions (like a cylinder or 2 aren't firing) at the same place in the throttle. If it has to do with the distributor, I'll know soon enough because I just bought an HEI from 56er and already sent payment so it should be here soon.

That could be, I had a Volkswagen do that when the distributor shaft bushings wore out.

It could be in the carb though, a partially blocked circuit could do that too.

As the dizzy is already paid for, I would start there.

Does it loose power like it is down a few cylinders?

Good luck.

Well I've rebuilt the carb like twice and given it a pretty good cleaning both times and it has a fuel filter that is only like 5 or 6 months old. I'm pretty sure it isn't the carb.

It feels like a few cylinders stop firing consistently and it makes the engine shake somewhat violently.

Let us know how the distributor change turns out, it sounds promising.

Good luck.

Spark plugs or wires are a possibility too.

It wouldn't hurt to check the fuel filter anyway.

Tim

Once the HEI is installed and if it still acts up - for a test, wire the hei direct to the battery - if the problem goes away - change the ignition switch.

Nexrussian - Will do. 56er said he'll ship it ASAP

StrokerSix - I've checked the wires for resistance and the short were under 3K ohms and the long were under 6K ohms so they should be fine. I replace my plugs with E3s like 3 months ago so that shouldn't be the problem either.

Titen - True true. I'll try to remember to do that today.

efi-diy - Hadn't though about it being the switch. That's a great idea. Actually there's a good chance that's the problem because I know it's broken. I don't need the key to turn the car on so I know something is wrong there.

efi
Ignition switch? Seems like if the switch was bad, then the problem would be consistent and regardless of throttle position. Very curious and interested how the ignition switch could be causing this problem.
I'm having a similar problem - I have a stutter when throttle position is steady and I'm at 3-4inches of vaccuum. I was thinking that mine was in the distibutor.

Snowman,
Do you have a vaccuum gauge hooked up? I wonder if your problem is happenning at the same amount of vaccuum, like mine does.

Good luck

I don't have one. I just have that port plugged up. I really should get one though.

The HEI shouldn't be much longer so I'll report back once I get it installed

I used to have a 194 that snorted and bucked at certain speeds. It turned out to be the wire that supplied the ignition system; it runs along the length of the valve cover in metal clips. At certain speeds the engine would rock just enough at the right frequency to pull the ballast to coil wire back and forth slightly through the clips. It had eventually wore out the insulation and the ignition power would intermittently short to engine ground. You couldn't see the worn spots in the insulation without pulling the harness through the clip enough to see what is hidden by the clip itself.

I've seen a v8 distributor where the internal components were not clocked properly. This resulted in misfire at certain combination of rpm and vacuum. I think the effect was the rotor wasn't lined up with the distributor cap and the spark was lost trying to jump the gap.

I don't know the root cause. Twisted shaft, sloppy weights, too much or little vacuum advance, not sure. I swapped distributors and the problem went away.

If you are running points you might try adjusting them either open or closed a bit from spec and see if it helps. Reset timing of course. This should change the relative position of the rotor and cap. Or you could alter or remove the key from the bottom of the cap so you can rotate it on the distributor body.

Stroker,
Thanks for the input. I modified the weights that I'm using to get an extra 4 degrees of mechanical advance. My system for modifying them could be considered crude. I removed and reinstalled them about 6 times before I got them to advance as far as I wanted. BUT, I have another three sets of sets. I'll try another set, unmodified, and see if the problem is gone.

My goal was attempting to get away from such a high intial timing setting.

Years ago GM had a service bulletin out that said a miss at constant speed light throttle was caused by a bad bearing in the distributor allowing the shaft to wobble the cure was to replace the bearing and the permanent cure was to install an extra bushing while you had the distributor apart. These bushing used to be about a dollar each. I don't even know if they are still available. They discovered this problem in the early 70's six cyl trucks and it seem to be worse in standard shift vehicles. My 69 chev 1/2 ton did it and I installed the dble bushing and it ran better than new.

Thanks for the suggestion. Like I said, I'm getting an HEI soon and I'll replace the parts that need replacing and keep this in mind. I'll let you guys know