R66

I am chasing an intermittent miss. The 7 mm Packard wires on the 327 / 300 hp are about 8 months old with about 500 miles on them. Second set of new AC plugs.
I have terrible luck with 7 mm plug wires and AC plugs, these wires check good with an ohm meter but given the lack of separation in the wiring trough under the exhaust manifolds on both sides, I am thinking of putting 8 mm plug wires on it.
The problem is, I can't find replacement 8 mm rubber insulators for the stock GM wire supports. I don't want to drill out the holes in them as they appear to be the original and will retain them should the next owner want to return to 7 mm wires.
Does anyone know of a supplier for these 8 mm rubber insulators that will fit in the stock supports?

rtruman

I got mine to work it was tight but got everything under the chrome shielding .

Razzle

Always hard to diagnose without being there, but most likely it's not the wires.

R66

Thanks,
Did you run them though the stock rubber insulators on the wire supports?

rtruman

yea tight took some time got it to work I didn't use the medal supports above plug wires .Took them off both my corvettes they cause problems .The corvette's runs better with the 8mm wires and electronic ignition

R66

This is the Last item on the list, I have
rebuilt carburetor & put on a new carburetor
Plugged the heat passage in the intake, new gaskets each time.
new PCV valve and rechecked
Compression check 170 to 180 psi across the board
Valve seals and valve adjustment twice.
Timing checks and rechecks
Rebuilt distributor - new cap and rotor
Vacuum advance can checked good
Two new sets of points
Coil checked good, new NAPA coil added
Runs great off of idle, no backfires.

I have another thread on the Intermittent miss, just trying to wrap the ignition system troubleshooting up before I break down and go with a MSD box and magnetic pickup. I don't want to run 40,000 volts thru 7 mm wires designed for 25,000 volts.
Ron

rtruman

You don't need the box just the top of line ignition
Box would be waste of money unless you are drag racing it changing rev limiters all the time.

Jims66

As a test, try replacing with new 8mm wires (or use your current 7mm) and leave the shielding off. Just keep the wires separated and off the exhaust etc with plastic wire ties...., then you'll know if it's a "wire" problem or not. Also, try not to run #5 and #7 parallel to one another. Just my 2cents.... Good Luck with whatever you decide.

GUSTO14

Taylor makes a set of Ignition Wires (Taylor Cable 73051) that are 8mm and come in black (other colors are available) for the Small Block Chevy. They look for all intents and purposes stock. It is a universal set that you cut to length and assemble the distributor end to the wire after they have been run from the plugs to the distributor.



This makes them easy to run in the correct (SBC) routing before you put the distributor end on. Even though they are 8mm I have had no difficulty getting them in the looms. I do start with new rubber looms and spray them with a little silicone to make the very cooperative. They have a silicone inner and outer jacket that provides heat protection up to 600 degrees F, along with silicone spark plug boots with distributor grips.

I have had no difficulty fitting the stock shielding as well.



Good luck... GUSTO

Jims66

These are the exact wires I have on my L79..... They've been on a few years now and still feel "rubbery" and flexible. The best part of these wires are the boots (nice loud click when you put them on). I also bought Taylor's crimping tool which is worth getting if you don't already have one. I used these wires on my Big Block Nova bracket racer with no problems either.

R66

Started on it again this morning early. Found :with stupid: in my head. Forgot about keeping the wires well separated. Used a half a dozen more plastic insulators to spread them out. Started it up and little better, but then cleared my head of stupid and thought i have been idling the motor for over a week trying to work this out. Plus we only make short trips (less than 2 miles )with it.

Rather than burn my hands again on the hot motor, took it on a 10 mile run and came back. Idled great for about 2 minutes before I started getting the miss again, but only a slight miss and not as frequent.

On my prior thread, a knowledgable gentlemen said these carbs idle lean and with a weak ignition system, it may flutter on the lean cylinders. Really smart man.

I'm going to upgrade the wires to 8 mm and the ignition as well. Don't want to invest a lot of money for something we only drive maybe 1000 miles a year, but won't tolerate poor performance.

Until I get the ignition upgraded, I am going to drive the H#*LL out of it.

Thanks for your help gentlemen.
Ron

rtruman

Idle it in the dark so you can see it going to ground.

Scott Marzahl

You said you have new points, did you replace the condensor too? I saw you have #45 plugs, I'd use a #46 heat range or equivalent for street use.

bcwaller

New wires should not cross talk, but if they do you need to get better wires. You can make your own separators with zip ties. Loosely wrap one tie around the bunch of wires, then cross between the wires with a tie. Tighten most of the way and adjust for cosmetics.

rtruman

Cool idea

bcwaller

The zip tie idea isn't mine. I copied what Dick Guldstrand's shop did 20 years ago on my old site of wires.

Nowhere Man

You said about points but did you check the dwell?

SonnyAK

I may use that on my '66...I have 8mm stainless braided wires and have never found quite the right separators...

63 340HP

I run 8mm wires under the tin shielding, and through all of the stock brackets. I do not use the rubber four hole loom pieces.

I have never experienced cross fire with 8mm wires installed in this manner.

The idle test in a dark garage is a good tool.