Spark plug suggestion

[Sonny]

My 440 build is really starting to come around now. Just discovered that my original cast iron intake manifold was leaking at three of the runners. Added a new Edelbrock manifold and the change is unbelievable. The new 650 CFM brawler carburetor ain’t bad either!

Now I am fine-tuning things and my spark plugs look pretty good. I have been experiencing some spark knock when I hit the gas though. My timing was set to initial at 19, I reduced it down to about 16, and the knocking is better but still barely there. I did lose some seat of the pants acceleration though. I am running auto light number 25 spark plugs. Is this a hot or cold plug? Is there a better plug out there for my street 440? I upgraded to a electronic ignition also. Has Kieth Black raised pistons (9.5 to 1 or so compression), 1/2” lift cam, headers.

 

[Lionized]

NGK XR5
I also increased my gap to .045 - .050. I'm running a Pertronix coil and bypassed ballast.

 

[Sonny]

My 452 heads use the tapered seat.

 

[PurpleBeeper]

Your plugs look good to me. As far as your spark knock issue:
a. What octane gas are you running?
b. If you're having any "ping" at all, that ain't good and you need to keep retarding your timing (or running higher octane fuel). That's important. Measure your initial & total timing and at what rpm that total timing happens along the way.
c. Since you mentioned you lost some "seat of the pants" feel, you may be able to do something like limit your mechanical advance & turn back your initial advance to 19-degrees OR start playing around with advance weights/springs inside the distributor & re-curve it to make the mechanical advance come in faster, etc, etc. But, I suggest you eliminate any "ping" first and work from there.

 

[Sonny]

Your plugs look good to me. As far as your spark knock issue:
a. What octane gas are you running?
b. If you're having any "ping" at all, that ain't good and you need to keep retarding your timing (or running higher octane fuel). That's important. Measure your initial & total timing and at what rpm that total timing happens along the way.
c. Since you mentioned you lost some "seat of the pants" feel, you may be able to do something like limit your mechanical advance & turn back your initial advance to 19-degrees OR start playing around with advance weights/springs inside the distributor & re-curve it to make the mechanical advance come in faster, etc, etc. But, I suggest you eliminate any "ping" first and work from there.

 

[Sonny]

I’m running 93 premium. Would it hurt to try a colder plug?

 

[PurpleBeeper]

I’m running 93 premium. Would it hurt to try a colder plug?

I don't think it would help or hurt. I think you just have too much total timing advance (initial + mechanical + vacuum) at the point when the "ping" occurs. The real "trick" would be to keep that high initial advance (if it is really faster, not just seat of the pants) and eliminate the "ping" by re-curving the distributor...…...but, that little "ping" is doing a lot of damager to your engine, which is why I suggest you take the "brute force" approach and just turn back the initial timing a little more for now until you can "dial in" the advance curve. You're running just about the best "pump gas" you can get & your static compression ratio isn't crazy at all....must be timing.

 

[BSB67]

Try 23's. It will make a difference. Just don't know if it'll be enough.
Does it ping at WOT above 3500 rpm?

 

[Sonny]

Try 23's. It will make a difference. Just don't know if it'll be enough.
Does it ping at WOT above 3500 rpm?

No. Under load after 2nd kicks in.

 

[Dennis H]

Plugs look better than mine. NGK XR5.

 

[PurpleBeeper]

Are you using the vacuum advance? Unless it's a "too much vacuum advance" issue, I think you just still have a little too much total initial advance + mechanical advance, so maybe dial back that distributor another couple degrees?

 

[Sonny]

Are you using the vacuum advance? Unless it's a "too much vacuum advance" issue, I think you just still have a little too much total initial advance + mechanical advance, so maybe dial back that distributor another couple degrees?

I’ll dial it back 2 more tomorrow. I’m waiting to get it right before hooking up the vac advance. At 16 my total is about 38 (22 mech). I’ve got some old MSD springs floating around. I may replace the stock thick spring with the “loop” with a blue or silver spring to get total near 34-36.

 

[1967coronet]

I’ll dial it back 2 more tomorrow. I’m waiting to get it right before hooking up the vac advance. At 16 my total is about 38 (22 mech). I’ve got some old MSD springs floating around. I may replace the stock thick spring with the “loop” with a blue or silver spring to get total near 34-36.

If you have any older points RB distributors around some have a 9.5 advance plate in them.
I found a 9.5 in one of my old distributors so I didn't have to do any slot welding to limit total.
But like purplebeeper said back it off until you get it figured out.

 

[Sonny]

This is the ignition upgrade I used on my 440. The instructions say to set your initial timing at 5°, take a test drive, and if everything runs correctly hook up the vacuum advance. Do you think they are referring to manifold or ported vacuum advance? 5° seems really low for using ported vacuum advance.

 

[Sonny]

View attachment 715178 This is the ignition upgrade I used on my 440. The instructions say to set your initial timing at 5°, take a test drive, and if everything runs correctly hook up the vacuum advance. Do you think they are referring to manifold or ported vacuum advance? 5° seems really low for using ported vacuum advance.

Nevermind. The light bulb just came on! This means my dizzy has 31 degrees mechanical. I will crank it back until I can save up for a new “ready to run” dizzy. Do y’all prefer those over dizzy plus ignition box?

 

[BSB67]

Focus on getting your total timing at 38° or so at 3000. Then adjust everything else for the curve below that. You simply shorten up the slots in the advance to get the initial where you want it. No need to purchase anything

 

[Bee1971]

The first two threads on that spark plug look black pig rich

Possibly at idle , what jetting and or choke system are you running

Based on your ground strap your running to much total timing already like Purplebeeper mentioned , especially with pinging

You would have to pull the distributor apart to find the stamped number on the advance plate

Probably a 13 or 15

I have a 9 that I pulled out of a slant six distributor many moons ago

Another option is this plate instead of welding up the slots to limit advance

https://www.manciniracing.com/fbomodilipl.html

 

[Bee1971]

Focus on getting your total timing at 38° or so at 3000. Then adjust everything else for the curve below that. You simply shorten up the slots in the advance to get the initial where you want it. No need to purchase anything

He mentioned pinging at 38 degrees total already , and looking at that spark plug

Would bee nice to have better pictures

And if he is running any decent compression I would say look at 34-36 degrees total timing

Agree Yes / No ?

 

[Sonny]

Focus on getting your total timing at 38° or so at 3000. Then adjust everything else for the curve below that. You simply shorten up the slots in the advance to get the initial where you want it. No need to purchase anything

Obviously I can file away the welds after to add timing. So how much should I weld up to begin with?

 

[Bee1971]

Obviously I can file away the welds after to add timing. So how much should I weld up to begin with?

You need to find out what number is stamped on your advance plate first , that determines mechanical advance X2

Another option instead of welding , filing , welding , filing

https://www.manciniracing.com/fbomodilipl.html

Or just find a stamped #9 advance plate out of another distributor