455 spark plugs

E

emerystora

New member
Apr 6, 1999
14,608
1
1
Dick Paterson has long recommended the NGK # XR51X (7355)
spark plugs for the Olds 455 engine gapped at .038 to .040

I went onto the internet to check prices. I had bought them in the past at O’Reilly.
Their price is currently 8.99 each at the store.

Amazon is 10.01 with free shipping.
Summit is 9.99 plus shipping.
Rock Auto is $5.18 each with 6.99 for shipping of 8 plugs (6.05 each including shipping).

I was a bit surprised at Rock Auto’s price. It is their everyday price not a sale.

Emery Stora
77 Kingsley
Frederick, CO
 
I forgot to say that Dick Paterson recommends always using a torque wrench when installing plugs.
Most of us just spin them in and lean on the wrench.
Dick says to torque them to 26-30 ft-lbs.
Over torque can distort the thin base and fracture the “gas tight” seals between the porcelain and metal base.

Emery Stora
77 Kingsley
Frederick, CO
 
Also the gap not to exceed .040.
There are books that call for .080, that was changed by GM, but it cannot
be erased, just like the front wheel alignment specs.

On Wed, Dec 11, 2019 at 9:10 AM Emery Stora via Gmclist <

> I forgot to say that Dick Paterson recommends always using a torque wrench
> when installing plugs.
> Most of us just spin them in and lean on the wrench.
> Dick says to torque them to 26-30 ft-lbs.
> Over torque can distort the thin base and fracture the “gas tight” seals
> between the porcelain and metal base.
>
> Emery Stora
> 77 Kingsley
> Frederick, CO
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

--
Jim Kanomata
Applied/GMC, Newark,CA
jimk
http://www.appliedgmcrvparts.com
1-800-752-7502
 
What did Dick say for an Olds 403 engine??
JR Wheeler 78 Royale 73 Painted Desert

On Wed, Dec 11, 2019 at 12:28 PM Jim Kanomata via Gmclist <

> Also the gap not to exceed .040.
> There are books that call for .080, that was changed by GM, but it cannot
> be erased, just like the front wheel alignment specs.
>
>
> On Wed, Dec 11, 2019 at 9:10 AM Emery Stora via Gmclist <

>
> > I forgot to say that Dick Paterson recommends always using a torque
> wrench
> > when installing plugs.
> > Most of us just spin them in and lean on the wrench.
> > Dick says to torque them to 26-30 ft-lbs.
> > Over torque can distort the thin base and fracture the “gas tight” seals
> > between the porcelain and metal base.
> >
> > Emery Stora
> > 77 Kingsley
> > Frederick, CO
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
> >
>
>
> --
> Jim Kanomata
> Applied/GMC, Newark,CA
> jimk
> http://www.appliedgmcrvparts.com
> 1-800-752-7502
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
Since I don’t have a 403 I didn’t ask him. It’s likely the same plug but perhaps you should email him and ask.

Emery Stora
77 Kingsley
Frederick CO

>
> What did Dick say for an Olds 403 engine??
> JR Wheeler 78 Royale 73 Painted Desert
>
>
> On Wed, Dec 11, 2019 at 12:28 PM Jim Kanomata via Gmclist <

>
>> Also the gap not to exceed .040.
>> There are books that call for .080, that was changed by GM, but it cannot
>> be erased, just like the front wheel alignment specs.
>>
>>
>> On Wed, Dec 11, 2019 at 9:10 AM Emery Stora via Gmclist <

>>
>>> I forgot to say that Dick Paterson recommends always using a torque
>> wrench
>>> when installing plugs.
>>> Most of us just spin them in and lean on the wrench.
>>> Dick says to torque them to 26-30 ft-lbs.
>>> Over torque can distort the thin base and fracture the “gas tight” seals
>>> between the porcelain and metal base.
>>>
>>> Emery Stora
>>> 77 Kingsley
>>> Frederick, CO
>>> _______________________________________________
>>> GMCnet mailing list
>>> Unsubscribe or Change List Options:
>>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>>
>>
>>
>> --
>> Jim Kanomata
>> Applied/GMC, Newark,CA
>> jimk
>> http://www.appliedgmcrvparts.com
>> 1-800-752-7502
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
Jerry,
I wrote a complete spark plug guide for the 455 and 403 and including Onan
& Gererac generators. I am presently in AZ for the winter and don't have a
copy to current version on my laptop. I had worked with Dick Paterson on
the current plugs that he recommended. If anyone out there has a PDF of
the doc please send it to Jerry or post it. The current version onn GMCMI
does not work and I will be contacting Kim to try and correct it.

J.R. Wright
GMC Great Laker
GMCGL Tech Editor
GMC Eastern States
GMCMHI
TZE Zone Restorations
78 Buskirk Custom 29.5' Stretch
75 Avion (Under going Frame up Restoration)

On Wed, Dec 11, 2019 at 12:58 PM Emery Stora via Gmclist <

> Since I don’t have a 403 I didn’t ask him. It’s likely the same plug but
> perhaps you should email him and ask.
>
> Emery Stora
> 77 Kingsley
> Frederick CO
>
> > On Dec 11, 2019, at 12:30 PM, Jerry Wheeler via Gmclist <

> >
> > What did Dick say for an Olds 403 engine??
> > JR Wheeler 78 Royale 73 Painted Desert
> >
> >
> > On Wed, Dec 11, 2019 at 12:28 PM Jim Kanomata via Gmclist <

> >
> >> Also the gap not to exceed .040.
> >> There are books that call for .080, that was changed by GM, but it
> cannot
> >> be erased, just like the front wheel alignment specs.
> >>
> >>
> >> On Wed, Dec 11, 2019 at 9:10 AM Emery Stora via Gmclist <

> >>
> >>> I forgot to say that Dick Paterson recommends always using a torque
> >> wrench
> >>> when installing plugs.
> >>> Most of us just spin them in and lean on the wrench.
> >>> Dick says to torque them to 26-30 ft-lbs.
> >>> Over torque can distort the thin base and fracture the “gas tight”
> seals
> >>> between the porcelain and metal base.
> >>>
> >>> Emery Stora
> >>> 77 Kingsley
> >>> Frederick, CO
> >>> _______________________________________________
> >>> GMCnet mailing list
> >>> Unsubscribe or Change List Options:
> >>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
> >>>
> >>
> >>
> >> --
> >> Jim Kanomata
> >> Applied/GMC, Newark,CA
> >> jimk
> >> http://www.appliedgmcrvparts.com
> >> 1-800-752-7502
> >> _______________________________________________
> >> GMCnet mailing list
> >> Unsubscribe or Change List Options:
> >> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
> >>
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
The way I see it, there are three factory engine scenarios. A 455 with the points ignition, a 455 with HEI, and a 403 with HEI.

Dick Patterson's position is that they all get the same plug and the same gap. I talked to him about this in October.
--
Ty Hardiman, Norman, OK / Member FMCA-GMCMI-GMC Classics / August 1977 Kingsley TZE167V102390 / 26' / 403 / 3.55 / 16" Wheels / Quadrajet / HEI /
Previous Owners: Basil LeBlanc, Dan Ramker / Original Owner: William Strahm, Loveland, CO
 
> The way I see it, there are three factory engine scenarios. A 455 with the points ignition, a 455 with HEI, and a 403 with HEI.
>
> Dick Patterson's position is that they all get the same plug and the same gap. I talked to him about this in October.

I have been running NGK XR451X for a very long time. I did not even replace them during the recent overhaul. At Marco, we did a lot of testing for
NGK.
At McCord, we made all the gaskets for Champion and A/C for years. The most reliable way to seat the gasket was torque and turn and not torque alone.


Being an ex-engine lab rat, that is why I don't have one of those as listed above.
GM's attempt with HEI was to use the spark energy to reduce misfires that were a big problem in emissions in the early game. If you can do it, it can
work in your favor for both emissions and fuel economy. I have done both created my own data and seen the test results. So, I almost redid what we
did then that was successful. I say almost because the test engines had an Mallory optical trigger instead of points and it was unreliable even in
the test cell. That is why I went with Pertronix as soon as I got the rest of the coach right. I still have it. At first it had a MSD CDI attached
to it, but that crashed. So, I dug around in my barn, (those that have been in my barn will believe) and came up with a Mark X CDI by Delta C.1974.
It failed the C1 about a year later but I had already procured a Mark XB. It is very similar device with minor improvements. It has been firing
those XR451X set at 0.060 for at least 50K mi, and maybe more. (It is cold out where the coach's maintenance log is right now.)

I will put in the warning right now. There are two big issues with this game that you should know about.
First is that the secondary ignition has to be top notch. If it is not, it will not just leak, but common parts may just blow up.
Second is that if you are not a electric shock masochist, stay away while it is running. That level of secondary voltage is out to get you. GOOD!!

The thing I am still missing is how to do an knock controlled spark, but I am working on that. I don't want to have to hammer the air filter housing
to fit in the later model distributor.

Matt - The refugee from Dyno-Land

--
Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan
OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit
 
Matt, you reminded me with you talk of some 'electric shock therapy' of a little competition orange Fiat 600 I had in the early 70's. It had the 600
cc motor .040 over with a little head work, a custom Isky stick, headers, Webers and a Vertex magneto that would let you taste the fillings in your
mouth when you got too close-and I did a few times I'm afraid. Fun times and memories.
Hal
--
1977 Royale 101348,

1977 Royale 101586, Diesel powered,

1975 Eleganza II, 101230,

1974 Eagle Bus 45',w/slideout,

Rio Rancho, NM
 
Ah yes, Scintilla/Vertex magneto's. Been there, done that. Got the memories
as a reminder to not get intimately involved with them. They will light
your fire, properly set up. The faster they turn, the more spark they make.
Jim Hupy
Salem, Oregon

On Wed, Dec 11, 2019, 9:04 PM Hal StClair via Gmclist <

> Matt, you reminded me with you talk of some 'electric shock therapy' of a
> little competition orange Fiat 600 I had in the early 70's. It had the 600
> cc motor .040 over with a little head work, a custom Isky stick, headers,
> Webers and a Vertex magneto that would let you taste the fillings in your
> mouth when you got too close-and I did a few times I'm afraid. Fun times
> and memories.
> Hal
> --
> 1977 Royale 101348,
>
> 1977 Royale 101586, Diesel powered,
>
> 1975 Eleganza II, 101230,
>
> 1974 Eagle Bus 45',w/slideout,
>
> Rio Rancho, NM
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
So it should retard the spark when a knock or knocks is/are sensed? does the system need to do anything else such as rich up the mixture, or goose
the waste gate a bit?

--johnny

--
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
 
ebay has the BOSCH PLATINUM # 4023 for $1.26 each with free shipping.
--
1977 Kingsley 455 as stock as it gets except lots of Ragusa parts
 
You must log in or register to reply here.
Applied GMC
GMCMI Spring 2026 Rally

Share this page

Share this page
Top Bottom
Back