The Ford Barn

justpassinthru · 03-13-2011, 02:25 PM

I have seen a number of threads on this issue and it seems the popular plug choice is the NGK B6L plug. That plug has a 7/16" reach, which may be fine for stock heads. My Offy 8BA-425 heads measure 1/2" from the plug seat to the inside of the chamber, so wouldnt a spark plug with a 1/2" reach, such as the NGK B6HS be a better choice? Its still the same heat range, 14mm thread, non protuded tip, non resister as the NGK B6L.
Bill

JM 35 Sedan · 03-13-2011, 04:27 PM

I can't answer your question but I do have an Excel Spread Sheet/Matrix that gives all NGK plug numbers and all sorts of tech info for each pn, such as reach, etc. It also compares NGK to other well known plug manufactures and their plug numbers. I could email you a copy of this if you PM me your addy.

ps...one thing I failed to mention was I'm using the NGK B6L plugs in my Offy heads on my 59 engine. I chamfered a little material away inside the chamber at each threaded plug hole until the reach was right for the B6L's. Then I CC'd the chambers to make sure they were all the same. I'm not necessarily recommending that you do this but that's what several folks suggested that I do when I asked the same question. Maybe some of the engine building gurus here can comment more on this.

4dFord/SC · 03-13-2011, 04:31 PM

Don't know the exact measurements, but I've had good luck with Autolite 437's in my Offenhauser heads.

barnfind08 · 03-13-2011, 04:38 PM

All flatheads with 14mm plugs were in the old days H10 why would we not use these. The champion replacement is H10C. They are available and I have some coming on Monday. They will be going into eddie meyer heads.

JM 35 Sedan · 03-13-2011, 04:57 PM

Quote:

Originally Posted by barnfind08

All flatheads with 14mm plugs were in the old days H10 why would we not use these. The champion replacement is H10C. They are available and I have some coming on Monday. They will be going into eddie meyer heads.

New Champion plugs have received a lot of bad press after they moved their manufacturing to Mexico.

justpassinthru · 03-13-2011, 07:54 PM

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Im not trying to figure out which spark plug manufacturer is better or not. That could be argued for ever. What I am interested in is the reach of the plug. The Champion H10C is a 7/16" reach plug with out a protruded tip. If that plug was to be used in a head with a 1/2" deep hole, the electrode of the plug would be up inside the hole quite a bit. I cant see how that will work good. The Autolite 437 is also a 7/16" reach plug but with a protruded tip. That may put the electrode where it shoud be, but would leave a pocket at the bottom of the plug which could cause firing problems? Not sure.
Bill

Walt Dupont--Me. · 03-13-2011, 08:37 PM

I just used a set of ATL414 autolights in a new set of Offy 400 heads, 1/2in reach same heat range as H10 or 216 autolight. Walt

Flathead Fever · 03-14-2011, 04:24 PM

Here is a link to the H.A.M.B site about the plug length for Offenhauser heads

http://66.154.44.164/forum/showthread.php?t=365381

52merc · 03-14-2011, 05:47 PM

i had to champer out around the plug hole as the tips of plugs didnt go right through this was on a new set of edelbrocks

03-13-2011, 02:25 PM	#1
justpassinthru Junior Member Join Date: Mar 2011 Location: Chicagoland Illinois Posts: 26	Offenhauser head spark plug length I have seen a number of threads on this issue and it seems the popular plug choice is the NGK B6L plug. That plug has a 7/16" reach, which may be fine for stock heads. My Offy 8BA-425 heads measure 1/2" from the plug seat to the inside of the chamber, so wouldnt a spark plug with a 1/2" reach, such as the NGK B6HS be a better choice? Its still the same heat range, 14mm thread, non protuded tip, non resister as the NGK B6L. Bill

03-13-2011, 04:27 PM	#2
JM 35 Sedan Senior Member Join Date: May 2010 Location: Near Rising Sun, Maryland Posts: 10,858	Re: Offenhauser head spark plug length I can't answer your question but I do have an Excel Spread Sheet/Matrix that gives all NGK plug numbers and all sorts of tech info for each pn, such as reach, etc. It also compares NGK to other well known plug manufactures and their plug numbers. I could email you a copy of this if you PM me your addy. ps...one thing I failed to mention was I'm using the NGK B6L plugs in my Offy heads on my 59 engine. I chamfered a little material away inside the chamber at each threaded plug hole until the reach was right for the B6L's. Then I CC'd the chambers to make sure they were all the same. I'm not necessarily recommending that you do this but that's what several folks suggested that I do when I asked the same question. Maybe some of the engine building gurus here can comment more on this. __________________ *John* *"Never give up on what you really want to do. The person with big dreams is more powerful than one with all the facts". Albert Einstein* Last edited by JM 35 Sedan; 03-13-2011 at 04:55 PM.

03-13-2011, 04:31 PM	#3
4dFord/SC Senior Member Join Date: May 2010 Location: Columbia, SC Posts: 1,579	Re: Offenhauser head spark plug length Don't know the exact measurements, but I've had good luck with Autolite 437's in my Offenhauser heads.

03-13-2011, 04:38 PM	#4
barnfind08 Senior Member Join Date: May 2010 Posts: 893	Re: Offenhauser head spark plug length All flatheads with 14mm plugs were in the old days H10 why would we not use these. The champion replacement is H10C. They are available and I have some coming on Monday. They will be going into eddie meyer heads.

03-13-2011, 07:54 PM	#6
justpassinthru Junior Member Join Date: Mar 2011 Location: Chicagoland Illinois Posts: 26	Re: Offenhauser head spark plug length Sponsored Links (Register now to hide all advertisements) Im not trying to figure out which spark plug manufacturer is better or not. That could be argued for ever. What I am interested in is the reach of the plug. The Champion H10C is a 7/16" reach plug with out a protruded tip. If that plug was to be used in a head with a 1/2" deep hole, the electrode of the plug would be up inside the hole quite a bit. I cant see how that will work good. The Autolite 437 is also a 7/16" reach plug but with a protruded tip. That may put the electrode where it shoud be, but would leave a pocket at the bottom of the plug which could cause firing problems? Not sure. Bill

03-13-2011, 08:37 PM	#7
Walt Dupont--Me. Senior Member Join Date: May 2010 Location: Gardiner Me. Posts: 4,200	Re: Offenhauser head spark plug length I just used a set of ATL414 autolights in a new set of Offy 400 heads, 1/2in reach same heat range as H10 or 216 autolight. Walt

03-14-2011, 04:24 PM	#8
Flathead Fever Senior Member Join Date: May 2010 Location: Yucaipa, CA Posts: 1,093	Re: Offenhauser head spark plug length Here is a link to the H.A.M.B site about the plug length for Offenhauser heads http://66.154.44.164/forum/showthread.php?t=365381

03-14-2011, 05:47 PM	#9
52merc Senior Member Join Date: May 2010 Location: new zealand Posts: 1,054	Re: Offenhauser head spark plug length i had to champer out around the plug hole as the tips of plugs didnt go right through this was on a new set of edelbrocks

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