Ford CMP Spark Plugs

[Mark Sierant]

It is comming up to Christmas and I have decided to give my two Fords Blitz farm trucks a full service but have come up with a real issue on spark plugs. I have two trucks and a combination of 16 different spark plugs which one is correct? I have rang all spare part shops in town tryng to find a match for a Flat Head Ford motor running a 12 volt ignition system. No one has a clue what heat range or plug type to use in fact many of the younger counter jockeys have asked what is a Flat Head Ford. No one has in stock the short thread type associated with the flat head so I cant even pick a packet of "She'll be Right Plugs" they need to order things in down under.
In Australia I have access to the NKG and Bosh brands are there any sugestions out there that will be nice to my flat heads?

[Mike K]

Mark ,

Try asking for Lawn Mower spark plugs , don't laugh as they have the short reach you need and they work under all temp ranges that a hard working mower requires .

I think The Champion J8 was the plug commonly used in SV Fords and many other side valve engines , but I could be wrong .

Try looking for 7/8" thread plugs . . . my old compressor uses these plugs in its Waukesha engine .

Mike in Gippsland

Originally posted by Mark Sierant
It is comming up to Christmas and I have decided to give my two Fords Blitz farm trucks a full service but have come up with a real issue on spark plugs.
In Australia I have access to the NKG and Bosh brands are there any sugestions out there that will be nice to my flat heads?

Hi,

I went round this for Ballard and the DTB F15 Polsten; years ago.

Now the plug spec hides in the "Instruction book" - Driving - Maintenance - Repairs, not in the workshop manual.

It gives Champion H9, H10 and J10, only the H10 cross refers in the excellent NGK catalogue to B6L.

Our local wholesaler keeps a fair range on the shelf but not the B6L (or indeed BKUR6ET-10 for my 16V Golf until recently), however we're alright for Morris-Commercials as they always keep the NGK A6 (18mm), probably as Ballard Jr. has bought two boxes for his M-Cs and thus truly foxed the re-order computer.

Anyway, B defines 14mm, 6 is the heat range and L defines a 11.2mm reach. Modern plugs are very tolerant and it is obvious reading the cross-reference tables that handfuls of old types are replaced by one modern one.

We met the NGK tech rep by chance whilst grimbling about the shelves and he confirmed the position and suggested that either we order and wait for the B6L or use the common B4LM already there. The change in heat range is minimal (4) and the important mechanical configuration is identical (B & L). The M gives a shortened 18.5mm outer insulator as this is a lawn mower plug but the short insulator doesn't look out of place in the dark recesses of the Ford engine bay.

Looking at the applications its also obvious that in power/cc the average Briggs & Stratton is very nearly identical to the Ford V8.

Ballard's DTB F15 has done thousands of miles now on the NGK B4LM and always goes hot or cold with minimal difficulty, so much so that I had to call in a moment ago and pull the engine cover to ascertain what we had actually used since they've been a fit and forget.

It more than can be said of the aftermarket "Classic" plug suppliers, their Polish made "equivalents" were troublesome and grossly over-rich hot starts with the typical Ford fuel percolation hassle was nearly a non goer.

I did try to "back" refer the B6L to Bosch in the NGK conversion tables by scanning the listings but there seems to be none.

R.

[cletrac (RIP)]

The J8 is the plug used by the old flatties. These engines are very forgiving when it comes to spark plug types and they'll run good on almost anything that'll screw into the hole.

[David_Hayward (RIP)]

I find the postings fascinating as I grew up from early teens with sparking plugs and as a result when I was working for MOTORCYCLE MECHANICS magazine [30 years ago] on their advice column, I was able to advise on plugs.

My mum worked for Champions near London Airport for many years and she used to get me free plugs, some including the latest at the time Gold-Palladium, were brilliant when used in my two-stroke motorcyles. That is why I stuck with Champions, and grew to respect them, the company and the expertise. The company used to produce a little booklet with recommended sizes for every make, and hot and cold versions either side of the norm. Champions were taken over by Coopers years ago but I bet that they still have their central office that deals with queries of this nature. [THEY ARE NOW PART OF FEDERAL MOGUL of the USA]

May I take it that the position with regards to Chevrolets is better? I had an original, 1944 boxed AC that was fitted to CMPs. Do I take it that modern ACs equate to WW2 versions?

FURTHER COMMENT: I just checked on the web and see that other flathead users have tried the Champion H10, although there were comments that an Autolite equivalent was better. Do we know what the H10 translates into in the Autolite range? Types 216 and 437 were discussed on one site...437 for tuned engines, and 216 for stock.

[Mark Sierant]

Gee I have got a good bit of information on spark plugs today. I have ordered in 24 of the NGK B4LM from a local agent they should be here in a couple of days, enough for a couple years motoring. The B6LM is now discontinued in Australia, but a B2LM is available, a higher heat range plug. The Champion BCJ8 is available but I have decided that in the past I have had fewer problems with NGK plugs. But in all fairness to the Champion BCJ8 Plug I have these fitted in water pumps and a couple of mowers they are subjected to higher operating temps and exposure to the elements year round that could help leed to earlier than expected failures. Thanks all on the forum for your help.

Originally posted by cletrac
The J8 is the plug used by the old flatties. These engines are very forgiving when it comes to spark plug types and they'll run good on almost anything that'll screw into the hole.

I think you're right, so long as it doesn't hit anything (too long) then they will run perfectly well on almost anything.

Its surprising the J8 isn't listed in the CMP manual but these old Champion designations are now almost one type anyway.

I have to say over the years we've had continual success with NGK plugs in all manner of old stuff.

Of course it helps the Ford to ditch that iffy original coil with its ballast resistor and just use a modern 6V one; in fact the original can stay in place for show with dummy wiring too.

Here's a couple of handy references:
http://www.spark-plugs.co.uk/pages/t...ymbol_code.htm

and

http://www.spark-plugs.co.uk/pages/t...on860-n288.htm

R.

[Pete Ashby]

Over the years I have run J8's, AC's and latterly NGK's in a number of different WW11 truck engines.

I agree with you guys the old J8 just keeps doing it's stuff but I had some issues with hot starting.

The AC however gave poor results for heat resistance during running and this was in several jeeps !!, not renown for over hot running here in the UK , poor hot start as well.

I run the 216 on NGK and they run real hot inside a 12 cab engine bay with no problems at all,..... they get my vote for best all round performace.

Pete

Originally posted by Pete Ashby
Over the years I have run J8's, AC's and latterly NGK's in a number of different WW11 truck engines.

I agree with you guys the old J8 just keeps doing it's stuff but I had some issues with hot starting.

The AC however gave poor results for heat resistance during running and this was in several jeeps !!, not renown for over hot running here in the UK , poor hot start as well.

I run the 216 on NGK and they run real hot inside a 12 cab engine bay with no problems at all,..... they get my vote for best all round performace.

Pete

I'd agree with Pete, and it seems over the years my old car and modified specials friends would say the same too. I just wish NGK did a RSN13-P replacement. . . . . . . . . .!

The Ford hot-start hassles we can't blame entirely (in the UK anyway) on the old flat-head although they were never good at it; the EU-law specified high volatility fuel does not help and set to get worse as they are about to jack up the RVP again in a further low-pollution effort. Let's just hope they don't get the US alcohol (MTBE) idea - all very well in a continuously computer tweaked, closed-loop injection system but likely a re-jet hassle in an old carb. (and has just happened to a US friend with carburated UK MVs)

Ballard's F15 seems to favour the technique defined on a windscreen sticker found in the last carburated Ford cars here, half throttle and crank, keeping the revs well up when it fires and steadily backing the throttle over several seconds for a fast idle as the engine clears itself and settles.

I re-fitted his truck with really meaty, 1" dia core, starter cables of self-manufacture and kept the length to a minimum, not forgetting you not only have to get huge amps into the starter on a 6V system but get them back to the battery too, so similarly huge chassis/engine bond and continued back from there to the battery.

The starter is lucky to even see 4V when cranking on these old 6V systems and hence the trick 8V batteries we hear of from down under. Its never failed yet but you do have to whirr it around for several seconds after a run on a really hot day and there's always that moment of anxiety.

R.

[Bob Moseley (RIP)]

NipponDenso W 20S-U. There are 8 in our Carrier's Mercury and all going well.

Bob

Originally posted by Bob Moseley
NipponDenso W 20S-U. There are 8 in our Carrier's Mercury and all going well.

Bob

Which translates to NGK B6S:
B = 14mm plug
6 = heat rating
none = 11.2mm thread depth
S = Copper core

I should explain, after the heat rating number you can only have E, H, L & EH, the appearance of an S means the default for thread depth applies depending on the first letter as A, B/BM or G.

The same as a B6L where L defines 11.2mm thread depth, its another way of saying B6LS I suppose.

We don't see N-D plugs at all here.

R.