Spark Plug Question

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70SwingerGuy

70SwingerGuy

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So Im looking at replacing my plugs. I have a mildly built 340, Edelbrock AVS2 650, LD340 intake, MSD 6AL2 ignition/distributor, Edelbrock heads, unsure of cam but am told its a mild roller, TTI long tube headers, 4spd. Currently the plugs in it are NGK 7496 BCP5ES gapped at .040, which have been discontinued, but NGK recommends the 6130 BCPR5ES as a replacement. Anyone have any opinons on this or recommendation for a better plug?
I know I may be opening up a Pandoras box here. :)
Thanks FABO!!
 
I have been using Autolite 65s in my 69 340 Barracuda for about 30 years. Our engines are quite similar I have a 340 built to about 375 HP, Headers, complete MSD setup (including their Manual advance distributor, coil and wires), Edelbrorck Air Gap and Edelbrock 650 Thunder series carb. The Autolites have always performed very well.
 
harrisonm said:
I have been using Autolite 65s in my 69 340 Barracuda for about 30 years. Our engines are quite similar I have a 340 built to about 375 HP, Headers, complete MSD setup (including their Manual advance distributor, coil and wires), Edelbrorck Air Gap and Edelbrock 650 Thunder series carb. The Autolites have always performed very well.
Click to expand...
Thanks for the info! What do you run your gap at with the MSD?
 
The 'new' NGK plug is the same as the old one except one except now it has a resistor. Never heard of one of these causing a performance loss, & D. Vizard did some testing & found the same thing. In fact, in the test below, all the plugs tested were resistor plugs except the one with the lowest hp...which was non-resistor.
Everybody frets about a 4-5k ohm resistor, but never worry about 30 k ohm plug leads or plug & rotor gaps of hundreds of thousands of ohms ...

img331.jpg
 
The resistor plugs made no difference in
our testing. In our MSD 6 Street/Strip cars
we run .040 with a plug with that ground strap.
We did not find any power in those car from a
wider gap and I believe it puts more strain on
the rest of the ignition system.

\My .02 = For Free
 
GTX JOHN said:
The resistor plugs made no difference in
our testing. In our MSD 6 Street/Strip cars
we run .040 with a plug with that ground strap.
We did not find any power in those car from a
wider gap and I believe it puts more strain on
the rest of the ignition system.

\My .02 = For Free
Click to expand...
Plug of choice?
 

What's the static compression? If it's 10:1, a 5 heat range seems a little hot. I'd go for a 4.
 
NGK plugs the lower the number the hotter the plug, 4 is equivalent to the old J14 Champion plug
 
harrisonm said:
I have been using Autolite 65s in my 69 340 Barracuda for about 30 years. Our engines are quite similar I have a 340 built to about 375 HP, Headers, complete MSD setup (including their Manual advance distributor, coil and wires), Edelbrorck Air Gap and Edelbrock 650 Thunder series carb. The Autolites have always performed very well.
Click to expand...
So I got some 65's and went to put them in tonight, found out that I cant use them with my Eddy heads, the heads need the smaller 5/8 hex plug, the 65's are 13/16.
After some research, I found the Autolite 3926 are the correct hex and appear to be almost identical to the 65, but the heat range is a 7 compared to the 8 of the 65's, whats your opinion on that? I dont really want to go to a colder plug.
 
Sorry to hear that. I guess I missed that you had Edelbrock heads. I would think that it would be fine. Although I am not an expert, I had always heard that going one stage colder was a good move for performance. Hopefully someone with more knowledge about plugs than me can chime in. @67Dart273 is an electrical whiz. Maybe he will know.
 
harrisonm said:
Sorry to hear that. I guess I missed that you had Edelbrock heads. I would think that it would be fine. Although I am not an expert, I had always heard that going one stage colder was a good move for performance. Hopefully someone with more knowledge about plugs than me can chime in. @67Dart273 is an electrical whiz. Maybe he will know.
Click to expand...
No problem! Good thing they arent that expensive...haha
I left a message on the Autolite site asking them for the 5/8 equivalent, hopefully they get back to me.
Im thinking about going up a heat range also, Ive had some sooty plugs lately, so this is just part of what Im looking into to correct it.
Thanks again
 
NGK BCP4ES!!

Sometimes there is an extender [ -11 ] on the end of the part #. That means it has been pre-gapped to 1.1mm = 0.044". You can bend the grd electrode if you want to alter the gap.
 
Bewy said:
NGK BCP4ES!!

Sometimes there is an extender [ -11 ] on the end of the part #. That means it has been pre-gapped to 1.1mm = 0.044". You can bend the grd electrode if you want to alter the gap.
Click to expand...
Im currently running the NGK BCP5ES(which is discontinued, BCPR5ES is the replacement), why do you recommend the 4ES plugs?
And thanks :)
 
Because of the letter 'E'.......Edel heads...which are alum. Alum absorbs & transmits heat much faster than c/iron. That heat of course goes into the coolant....
The point is that with alum heads, all else being equal, the plugs in alum heads will lose heat quicker....which could lead to fouling because the centre electrode has lost heat & is not able to burn off the deposits. So use one grade hotter.

The R means a resistor plug. No problem using those.

In the test below, the NON-res plug lost power!!

img331.jpg
 
In my Eddies, I run Champion coppers, heatrange 12 , with the small hex. And I run an old sq-top Accell Supercoil. I think they were installed at 040, back in 1999.
The plugs last forever, but, I changed them a few miles ago just because..

IIRC, the number mightabin, RCJ12YC or something like that, not sure.
 
My oldness will show thru but what plug equals the old n63y or rn63y. Thanks guys.
 
Bewy said:
Because of the letter 'E'.......Edel heads...which are alum. Alum absorbs & transmits heat much faster than c/iron. That heat of course goes into the coolant....
The point is that with alum heads, all else being equal, the plugs in alum heads will lose heat quicker....which could lead to fouling because the centre electrode has lost heat & is not able to burn off the deposits. So use one grade hotter.

The R means a resistor plug. No problem using those.

In the test below, the NON-res plug lost power!!

View attachment 1716435814
Click to expand...
Thanks for the info, but isnt the 4ES colder than the 5ES?
 
harrisonm said:
Sorry to hear that. I guess I missed that you had Edelbrock heads. I would think that it would be fine. Although I am not an expert, I had always heard that going one stage colder was a good move for performance. Hopefully someone with more knowledge about plugs than me can chime in. @67Dart273 is an electrical whiz. Maybe he will know.
Click to expand...
Sorry, no. Don't know And now that Champion and AC are sorta in the background, I am not at all fluent with Autolite/ NGK, etc heat ranges
 
So I go to Summit and try to get these NGT plugs and I get this messge:
"Due to State, Country or Carrier restrictions some of the parts in your shopping cart cannot be shipped to the address provided. Please remove them from your shopping cart or change your shipping location.
The part NGK-1086 cannot be shipped to your billing/shipping location at this time."
Anyone know what the hell this is all about??
Anyone else from Canada have any issues with Summit? I messaged them and it will be interesting to see what they say.
 
Last edited:
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