Little help with a miss?

Hey all,

I was wondering if you all could help me. My engine has a miss that I can't figure out. I'm not sure if "miss" is the correct term.

It won't rev easily and runs very rough. It feels like it lost about 150 hp. The way it runs when this is happening reminds of a 351W I had a long time ago. The 351W had points ignition and when the points started sticking it ran the way I am describing. The motor will idle okay, but when you apply the accelerator it shudders and accelerates only slowly. This has happened two or three times in the last 6 months or so. The previous times it started running rough for no apparent reason, but the next day when I started it up it would run fine. This time it seems to be persistent.

When this happens it happens suddenly. I'll drive it one day and it's fine. The next day I start it up and it's running rough.

Here's what I have done:

- checked the timing. It's okay at about 18 degrees initial.
- checked to make sure the mechanical advance weights moved freely. They seemed to.
- swapped plug wires with a different set I have. no change.
- swapped a new cap on one of the vacuum ports on my carb. The old one was torn. I thought maybe I had a vacuum leak and this would be it, but it ran the same with the new cap.
- swapped the coil for another I have. No change.
- put a new fuel filter on it. no change.
- put a bottle of Seafoam in the gas tank. No change yet. I was thinking maybe I have crud making it's way through my carb.

Any ideas? Thanks.

paulie

Check the inside of the distributor cap for arcing. I would also replace the vacuum line, might be leaking a little there.

Originally Posted by blidzy

Check the inside of the distributor cap for arcing. I would also replace the vacuum line, might be leaking a little there.

I don't have any vacuum advance, but I'll look in the cap for arcing.

Thanks,

paulie

check for moisture in the dist cap. If you have headers, start it up and use a spray bottle with water and spray each header pipe. The pipe that the water does sizzle off is the one with the miss.

Originally Posted by Culcuhain

check for moisture in the dist cap. If you have headers, start it up and use a spray bottle with water and spray each header pipe. The pipe that the water does sizzle off is the one with the miss.

Interesting about spraying the header pipes. I never thought of that. I think moisture in the cap is a good possibility, too. It's rained a lot here lately.

Also, one thing I forgot to mention is I have a crappy BlueStreak cap on an old MSD rotor. The cap terminals look okay, but the rotor contact point looks a little worn.

As soon as I can get my wife and kids happy, I'll work on the ole' 428. I'll let you guys know what I found this afternoon.

Thank you,

paulie

A new cap and rotor (MSD 8442) fixed it. I didn't see any obvious signs of tracking on the old Blue Streak cap, but I did notice the whole cap would move around even when clamped down. The MSD cap doesn't do that. Whatever, it fries the tires up to 70 or 80 mph again. Thank you very much!


paulie