44-FF Spark Plugs NOT for Corvette

[Bob B.]

Hi all,

I keep seeing someone on eBay trying to sell 44-FF spark plugs for your FI Corvette. However, these are NOT Corvette plugs, or at least Chevrolet Engineering didn't think so. See the attached scan from a 1962 Corvette News article.

Caveat Emptor!

Bob

[Michael H.]

Re: 44-FF Spark Plugs NOT for Corvette

Bob,

I think AC 44FF plugs were Corvair.

[Jeffrey S.]

Re: 44-FF Spark Plugs NOT for Corvette

"FF" plugs are fully threaded with a 1/2" reach. They are Corvair plugs. Plain 44's are half threaded with a 3/8" reach. Do the math and beware. Of course, if it's on the internet it must be true.
Jeff

[Philip P.]

Re: 44-FF Spark Plugs NOT for Corvette

I found this on the internet hope it true.

ACDelco.Spark.Plug.Identification.Table

Prefix and suffix letters are used to identify a specific type plus the numbers relate to thread size and heat range. For example, the R45TS spark plug shown is:
R = Resistor
4 = 14 mm Thread
5 = Heat Range
T = Taper Seat
S = Extended Tip

Plug Identification Table Prefix
Identification Code	Description
B	Series Gap
C	Commercial
CS	Chain Saw
F	Fine Line 14 mm 5/8″ Hex
M	Marine
LM	Lawn Mower type
R	Resistor
S	Shielded (5/8-24 thread)
V	Surface Gap
Prefixes are sometimes combined e.g., VB, CR

Numbering

1^st number denotes THREAD SIZE
2^nd number denotes HEAT RANGE

Plug Identification Table Suffix
Identification Code	Description
A	Cap Gap
C	Copper Core Center Electrode
C	Colder Version of M44 Plub
E	Special Design Electrode Extended Tip
F	1/2″ (12.7 mm) reach
FF	1/2″ (12.7 mm) reach, fully threaded
G	Pin Gap (cold-running)
I	Iridium Center Electrode
J	Boot Release Agent, Anti-Seize Compound
K	Special Design
L	Long Reach 7/16″ (11.1 mm) reach, (14 mm) thread 3/4″ (19 mm) reach, (18 mm) thread 3/4″ (19 mm) reach, (14 mm) thread (fineline)
LT	Long reach, .715″ (18.16 mm), Tapered Seat
M	Special Design Electrode
N	3/4″ (19 mm) reach, 3/8″ (9.5 mm) thread length
R	Resistor (Sport Vehicle Plugs)
S	Extended Tip
S	7/8″ (22.3 mm) Moderate Long Reach 23/32″ (18.25 mm)
T	Tapered Seat Shell Design
TS	Tapered Seat with extended tip
XL	Extra Long Reach, 3/4″ (19 mm) fully threaded
Y	3-Prong Cloverleaf Electrode
Z	Special Gap (usually denotes wide gap)
5	.050″ (1.3 mm) gap
6	.060″ (1.5 mm) gap
8	.080″ (2 mm) gap
100	Iridium
600	Resistor Type
800	Platinum Type
900	Double Platinum Type
Suffixes are combined to form such AC suffix designations as FG, XLS, TS, FFM, TSX, SZ, etc.

Phil

[Duke W.]

Re: 44-FF Spark Plugs NOT for Corvette

Most plug manufacturer's numbering system can be used to decode the geometry and heat range, and you should be able to find this information in their online catalogs.

The one exception that comes to mind is Autolite.

A lot of guys talk about AC heat range as "44", "45"..., but as you can see from the breakdown, the first digit, in this case 4, means it's a standard 14MM, 3/8" reach with an 11/32" hex. The second number is the heat range, and in the case of AC the higher the heat range number, the hotter the plug. NGK and Champion conform to this convention, but Denso is just the opposite - a higher heat range number is colder.

Duke

[Graeme B.]

Re: 44-FF Spark Plugs NOT for Corvette

That's a small hex. Duke.

[Duke W.]

Re: 44-FF Spark Plugs NOT for Corvette

To late to edit, so make that an [edit] 13/16" hex.

Duke

[Michael H.]

Re: 44-FF Spark Plugs NOT for Corvette

To late to edit, so make that an 11/16" hex.

Duke

How about 13/16"? You folks on the left coast have weird spark plugs.

[Duke W.]

Re: 44-FF Spark Plugs NOT for Corvette

Yeah, that's the ticket! It's been so long since I used my 13/16" plug socket, I'm not even sure where it is.

Duke

[Page C.]

Re: 44-FF Spark Plugs NOT for Corvette

Also be aware of the repro AC44 & AC45 plugs in repro Delco boxes. Saw these at Corvette Carlisle this past August.

[John D.]

Re: 44-FF Spark Plugs NOT for Corvette

Page, I didn't know there were repro AC spark plugs.
The AC 44FF plugs have been mislabeled on Ebay for many years now. Once I notified the seller but was ignored. John

[Dave S.]

Re: 44-FF Spark Plugs NOT for Corvette

Page, I didn't know there were repro AC spark plugs.
The AC 44FF plugs have been mislabeled on Ebay for many years now. Once I notified the seller but was ignored. John

I saw those AC 44 and 45 reproduction spark plugs at Carlisle as well. For me its "never say never" just like distributor caps before this. I cannot believe someone would reproduce these AC plugs but I never thought anyone would reproduce Delco distributor caps either. It is apparent they did them without the permission of GM as there is no reference anywhere on the boxes. Only the red AC logo appears. In looking over both the boxes and plugs themselves the reproductions are easily detectable. Further the quality is likely to be very suspect. Rumor was they were looking for around $80/set which might work for the 44's but not for the 45's. At this time 44's can easily be found for $80 - $125/set and 45's can be found for $50/set all in NOS condition. The repros had 4 equal rings. Not very important as the wider green ring (if 3 equal and 1 unequal) is hidden by the spark plug boot.

[Bob B.]

Re: 44-FF Spark Plugs NOT for Corvette

John,

I also notified the seller and then I saw the plugs come up again and still advertised for Corvette. So, I sent another note and got a message that the seller had blocked me from sending messages to him! What does that tell you?

Bob

[Michael H.]

Re: 44-FF Spark Plugs NOT for Corvette

John,

I also notified the seller and then I saw the plugs come up again and still advertised for Corvette. So, I sent another note and got a message that the seller had blocked me from sending messages to him! What does that tell you?

Bob

Bob,

Would that be Tillyfour out of Rockford, IL? He claims that only the 1960 printing of the parts book shows the 44-FF plugs for Corvette. Here's a link.

http://www.ebay.com/itm/60-1960-Corvette-283-Fuel-Injection-New-AC-Spark-Plugs-44FF-4-Equal-Green-Rings-/310761097058?pt=Vintage_Car_Truck_Parts_Accessories&hash=item485ace0762&vxp=mtr

Also, I tried to reply to your private message but your mailbox is full.