Periodic miss is eluding me. Accepting random suggestions.

You can test the wires with a multimeter. Check the Ohms. I don't know what they should read, but I do know they should all read about the same.

 

when looking down the carb you see the venturis. they are the doughnuts in the middle of the bores. while the car is running. you may see a drip come out of the venturie. when you see the drip you will hear the miss.
the fact that scotts car does it while driveing also does point more towards an ignition problem. check to make sure that there is nothing loose in the distrubtor, inspect the cap for where or carbon trails. those second had plug wires would be highly suspect. back when i worked in a mazda dealership, miatas would come in with a bad miss right at 30,000 - 35,000 miles. they would always have bad plug wires. it wasnt worth pulling them in the bay just went to parts got some plugwires and put them in the car in the parking lot. the cars were still under warntee. mazada just missed engeneering them to last past the warntee period.

 

Curious. Could there be a place or a spot in the intake that could capture fuel and release it as a "drip"?

 

Lots of good suggestions so let me make a couple statements to help get my head around it all.

If it is a drip, wouldn't that be unnoticeable at cruising or acceleration speeds and only noticeable at idle? (hoping to cancel out the carb issue. I am not fond of hanging my head over a running car's carb for any length of time)

I don't know the history of the hand-me-down plug wires, so they are very suspect. Not a race car, so what do you guys suggest for a decent (and economical) wire that will be less prone to arcing over to headers, block, intake, etc. These wires are pretty much laying on metal for about 1/3 of their length.

Next time out, I will inspect all distributor components. They are all pretty new, less than 100 miles on them, but have sat around for the past 2 years with very little use.

Gap is at .044, if I recall correctly.
Taylor Pro 8mm spark plug wires
Stock distributor, with the larger cap on with the HEI type top. BWD distributor cap, spacer, and rotor.

And I agree completely with the engine being built for mid-to-upper range, and yet this is the area where the miss is most noticeable. It is just a periodic drop at idle. But when cruising at around 3500 rpms, it is more pronounced and more often, with a couple misses every few seconds.

Next payday, I will bite the bullet and replace the wires for starters.

 

I use factory wires or carquest high line. Same company that makes the Ford wires.
Prestolite OE Ford supplier.

 

I would check them first. I don't see getting anything better than the Taylor 8mm's you have now for less than $50, and for fifty bucks I'll bust out a multimeter any day.

There's a formula for knowing what the resistance should be. I know a guy who knows and I'll ask him today...

 

Seven Ohms per foot.

 

I will check that out.

Thanks!

 

i am not a fan of taylor wires. ive had many of there plug boots and termnials pull apart and they hadnt been on very long and had dieletric grease on them. from my experience and a good recomendation from somebody who is very creddible it use accell 300+ race wires. they have a life time warentee (summit racint is really good about warenting them for any reason) and my friend recomeded them because of his involvement on a race team that dynoed every pulg wire they could find and the 300+ made the most power. ive never had any problems with the boots or terminals pulling appart and ive warenteed them twice, once for a boot geting burnt on the header and the second time just becasue they were old and looking that way.

 

If you suspect the wires, just hit them with some water from a squirt bottle. Spray from end to end. If there is a bad wire, it will short and then your miss will be constant. I've done this many many times.

Remember, don't grab wet wires while the engine is running.

 

I have seen those 300+ wires at the local O'Reilly. So it shouldn't take long to get them if the ohms don't pan out.

I guess I got nothing else going on, I will hit those wires now with the ohm meter...

How far off of the 7 ohms/ft can the wires be before they are considered "toast"? Are we talking +/- 1 ohm or +/- .1?

 

I was going to suggest just that but at night or in a dark garage. Spray some water over the plugs and wires both wires running. I have seen real light shows with bad wires on teh Thunderbird we used to have. That thing went through plug wires every 10k no matter what I put on it.
I have had a bad experience with Taylor wires also and they were second hand. I have also had 2 experiences with bad plugs. Once was Autolite and the other Motorcraft. On the Autolites all 8 plugs were leaking where the ceramic met the metal. In a dark shop you could see a blue corona type bleed over. 390 ran like crap.
I have also had the floats too high and would get that drip every once in a while that would cause a drop in idle.
clint

 

I would expect it to be wildly off. When I've found bad plug wires this way, I didn't know the "7 Ohms/foot" rule, I just noticed that one wire had way more resistance than the others, or no continuity at all.

 

OK, I must be an idiot.

I cannot get a solid reading. It is bouncing from low 8s to high 10s on the ohm meter.

I even took the cable off and stuck the meter probes between the rubber and metal contacts, and set them on the garage floor, and after 3 minutes still bouncing all over the place.

What gives???

 

OK, regardless, the readings on the first two wires were 5.2 ohms/ft and 3.9 ohms/ft.

So nowhere near the 7 per foot I am supposed to have.

Just skip to the new wires?

I have fixed a couple computers this week for extra cash, so I can "splurge" on some wires.