high RPM misfire 340 hp.

[Bruce W.]

Hey Guys, I have a high RPM miss fire at 5,000rpm. Have had the carburetor rebuilt, the distributor rbuilt and changed over to electronic. Valve have been adjusted. don,t think there is 1000 miles on the plugs. any ideas on what may be the problem, also I replaced the coil. appreciate your help.
Bruce

[Peter H.]

Re: high RPM misfire 340 hp.

Bruce. From My Experience With My 63 Misfire At High RPM,s I Replaced The Plug Wires And Success No Misfiring Even At 6500 . Just My 2 Cents Worth. Peter. Good Luck

[Mike M.]

Re: high RPM misfire 340 hp.

agree with Pete , especially if they are repo carbon core plug wires. mike

[Bruce W.]

Re: high RPM misfire 340 hp.

Mike, I know lectric limited wires are no good. Does anyone make a set of already cut wires. I am not interested in making a set which I did once?
Bruce

[Mike M.]

Re: high RPM misfire 340 hp.

don't know source for ready make steel core wires. i did buy a set for a street rod many years ago from the local parts store. good luck, mike

[Harry S.]

Re: high RPM misfire 340 hp.

Try Summit Racing. https://www.summitracing.com/parts/sum-g829b

The set in the link is going on a 63. The plug end is done. Just cut to length, run the wire and then finish the distributor end.

Call them and see if they have a steel core set made the same way.

[Dan H.]

Re: high RPM misfire 340 hp.

Used the Summit spiral wires on my 64 FI, cut to length and used LL top boots, runs smooth and no radio noise, Also bought the nice crimping tool and it makes the top connections super strong. Comes with a so so crimper, get the good one and treat yourself.
Dan

[Bruce W.]

Re: high RPM misfire 340 hp.

Dan, thanks i will check it out. seems like a logical conclusion about the miss fire in view of what I already have done. Think i will check a few plugs just to be sure
Bruce

[Dan H.]

Re: high RPM misfire 340 hp.

Bruce, read out the ohms on any wire with a bad plug, the wires get worse every time you move them.

[Bruce W.]

Re: high RPM misfire 340 hp.

Dan,
what should the ohms be?
Bruce

[Frank D.]

Re: high RPM misfire 340 hp.

Well - the Summit wires in the link above state 270 ohm/ft...
I just put Lectric Limited date-coded wires on my 63, I hope they won't be a problem..

[Dick W.]

Re: high RPM misfire 340 hp.

OEM wires are probably in the neighborhood of 3,500 or so ohms per foot. If I remember from my days of using a Sun 1120, 10,000 ohms was acceptable. Don't take that comment to the bank, it is just from my very feeble memory.

[Dan H.]

Re: high RPM misfire 340 hp.

Some of my LL dated wires read 50K ohms on the long ones, way too high. The summit ones run under 1K for long wires, really work, won't arc etc.

[Tim S.]

Re: high RPM misfire 340 hp.

What are you using for fuel? If you are running undiluted leaded race gas, you can lead foul the plugs in that amount of mileage. I know first hand.

The others are spot on about the plug wires as well. The LL's while they look the part........they sure do not play it. You can purchase AC Delco wires that are pre cut (black) and you can buy them at NAPA as well (although they will be blue). The Delco's and the NAPA's are a bit on the long side, but you can get them to work within the confines of the shielding.

I do agree with the others about buying a semi custom set, and cutting them to the proper length. While it's more work, you will have a better quality wire set that fits much better than the parts store offerings.

Tim

[Bruce W.]

Re: high RPM misfire 340 hp.

Tim, thanks for the input. I do run racing fuel undiluted never thought about that fouling plugs. I will pull a few and see how they look. Having said that I have owned the car 25 years and the plug wires were on it when i bought it. So who knows what they are? I have ordered a set of solid wire.
I am thinking they should be changed anyway. Hope that solves the problem.
Bruce