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NGK Spark Plugs
Posted by: JimBrandberg ()
Date: January 03, 2018 04:28AM

I'm thinking of switching to NGK spark plugs. In searching here, there seems to be a little discrepancy in what people are using.
I was thinking B5HS (4210) in 80 and 95 HP engines and B6HS (7534) in 102, 110, 140 and 180 HP engines. Some folks seem to use the hotter B5HS in everything.
What do you think?
Jim Brandberg
Isanti, MN
CorvairRepair.com

Re: NGK Spark Plugs
Posted by: vairmech ()
Date: January 03, 2018 05:02AM

The hotter plug most times will work in all engines but is needed in the low HP engines to keep the plug tip clean.

With the higher HP engines the engine made enough heat to keep the plug tips clean and therefore could run a cooler plug. Keep in mind that the hotter plug can contribute to detonation and one of the reasons GM went to the 44FF.

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com

Re: NGK Spark Plugs
Posted by: Phil Dally ()
Date: January 03, 2018 05:07AM

I ran B5HS in my racecar to warm it up in the pits.

Then changed out to B7HS before we pushed up to run.

Dwight uses B9HS plugs in his landspeed Corvair.

Re: NGK Spark Plugs
Posted by: DAVECS1 ()
Date: January 03, 2018 06:52PM

I had a heck of a time with B5s and detonation on long trips when I was running a carb. I. Actually had two paint mars on my dizzy so I could tune it back quickly on hot days. We had a cycle shop go out of business and I bought all the B6 stock they had. Those worked great but had to be changed at the end of the season as they sooted up. With EFI I no lknger have the soot issue and just run B6s

1964 Monza Convertible
110 4 speed
Peoria, IL

Re: NGK Spark Plugs
Posted by: JimBrandberg ()
Date: January 04, 2018 04:39AM

What main jets were you running when you had some soot with the B6HS?
Jim Brandberg
Isanti, MN
CorvairRepair.com

Re: NGK Spark Plugs
Posted by: DAVECS1 ()
Date: January 04, 2018 09:18AM

I will pull the carbs off the shelf and look.

1964 Monza Convertible
110 4 speed
Peoria, IL

Re: NGK Spark Plugs
Posted by: DAVECS1 ()
Date: January 04, 2018 10:22AM



If I had to guess it is a 5335 I could not see those numbers with my eyes

1964 Monza Convertible
110 4 speed
Peoria, IL




Edited 1 time(s). Last edit at 01/04/2018 10:55AM by MattNall.

Re: NGK Spark Plugs
Posted by: RobertC ()
Date: January 04, 2018 12:22PM

DAVECS1 Wrote:
-------------------------------------------------------
> [i63.tinypic.com]
>
> If I had to guess it is a 5335 I could not see
> those numbers with my eyes


Jet is 53 - stamped twice...

Re: NGK Spark Plugs
Posted by: American Mel ()
Date: January 04, 2018 01:17PM

It may be a 53, but it does not say 53 twice.
That definitely says 53 on one side, and 35 on the other.
So how ever you want to read it.
53 & 35
5335
3553
???

.
-----------------------------------------------
WA. state, 1 mile south of the Canadian border,
I am not at the end of the world, but you can see it from here.
'66 Monza Coupe - 4spd, 140 Daily driver beater
'67 Monza Vert. - PG, 140 Daily driver beater

Re: NGK Spark Plugs
Posted by: DAVECS1 ()
Date: January 04, 2018 02:14PM

I never changed them as it ran 13.7 most the time. My assumption is they are stock for 64 110 manual. I tried to back it out and it is stuck. Gonna be a game of heat and penetrating oil if it ever needs done.

1964 Monza Convertible
110 4 speed
Peoria, IL

Re: NGK Spark Plugs
Posted by: RobertC ()
Date: January 04, 2018 03:08PM

Rochester carb jets (Corvair and other GM carbs of the era) are referenced by a TWO digit number. It matches the size of the jet.

For example a 50 jet is .050". A 71 jet is .071".

The GM Part Number is 70026nn where nn is the jet size.

Attached is a pic of a few Rochester jets that I have. They are stamped similar to your jet.

FWIW 53 was not the stock jet. People here recommend going to a larger jet because of ethanol gas.

The stock jet for 64 110 would be 50 or 51. The info would be in the 64 GM Shop Manual Supplement and in Bob Helt's book on Rochester Carbs.

Attachments:
Re: NGK Spark Plugs
Posted by: vairmech ()
Date: January 04, 2018 05:11PM

DAVECS1 Wrote:
-------------------------------------------------------
> I never changed them as it ran 13.7 most the time.
> My assumption is they are stock for 64 110 manual.
> I tried to back it out and it is stuck. Gonna be a
> game of heat and penetrating oil if it ever needs
> done.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

I have explained this before about getting jets out of a carb. You need a flat punch that fits the head of the jet, a hammer and a screwdriver.

You set the punch on the head of the jet squarely, take the hammer and smack the punch pretty firmly, (just a little more than just dropping the hammer on the punch). Take the screwdriver and turn the jet out. No heat, no chemicals and no cuss words or drill bits. After I started using the above method I can count on one hand the number of jets that I could not get out.

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com

Re: NGK Spark Plugs
Posted by: DAVECS1 ()
Date: January 04, 2018 05:29PM

Well I have wounded enough old carbs in the past, I knew better than to pull it out, if it did not move. As I am not using these carbs any more, I have no real reason to pull the jets. I reassembled the one and put thwm back on the shelf. Thanks for the info on the jets. I do not remember changing them, and the car was last driven in 1984 before I received it. I do remeber rebuilding the carbs and tuning them a bit, so it is possible I changed them.

1964 Monza Convertible
110 4 speed
Peoria, IL

Re: NGK Spark Plugs
Posted by: Frank DuVal ()
Date: January 04, 2018 07:20PM

Looking at the picture of the "53 35" jet and the pictures of the three loose jets, one can clearly see the jets are stamped with the two digit number three times. And there are two missing areas in the circumference, the slot cut into the jet. It seems the slot always removes some numbers. In the 53 case, it removed a 3 and a 5, so it looks like 53 35. But it really is a 53 jet.

Frank DuVal

Fredericksburg, VA

Re: NGK Spark Plugs
Posted by: RobertC ()
Date: January 04, 2018 08:16PM

vairmech Wrote:
-------------------------------------------------------
>
> I have explained this before about getting jets
> out of a carb. You need a flat punch that fits the
> head of the jet, a hammer and a screwdriver.
>
> You set the punch on the head of the jet squarely,
> take the hammer and smack the punch pretty firmly,
> (just a little more than just dropping the hammer
> on the punch). Take the screwdriver and turn the
> jet out.

Same method used by my Corvair mechanic from the 70's / 80's.

Except he used a modified (and shortened) large screwdriver - as a "punch" and for removal.

He ground a tip / end that exactly matched the size of the slot in the jet.

Re: NGK Spark Plugs
Posted by: American Mel ()
Date: January 04, 2018 10:37PM

Frank DuVal Wrote:
-------------------------------------------------------
> Looking at the picture of the "53 35" jet and the
> pictures of the three loose jets, one can clearly
> see the jets are stamped with the two digit number
> three times. And there are two missing areas in
> the circumference, the slot cut into the jet. It
> seems the slot always removes some numbers. In the
> 53 case, it removed a 3 and a 5, so it looks like
> 53 35. But it really is a 53 jet.


You are correct. thumbs up
That is exactly what is going on there.
RobertC's picture makes it much clearer.
So the number stamp has three sets of 2 digits on it.
That way no mater how the jet is oriented when it is stamped it will always have at least one complete set of numbers on it.
Very clever of them thar manufacturers. grinning smiley

.
-----------------------------------------------
WA. state, 1 mile south of the Canadian border,
I am not at the end of the world, but you can see it from here.
'66 Monza Coupe - 4spd, 140 Daily driver beater
'67 Monza Vert. - PG, 140 Daily driver beater

Re: NGK Spark Plugs
Posted by: JimBrandberg ()
Date: January 05, 2018 03:47AM

I was just wondering if it still had like a 50 jet in it contributing to detonation with B5HS.
53 is a little fat around here and may have had a role in soot situation with B6HS.
Of course 64 and earlier carbs need to be a little richer without the high speed enrichment system.

I bought a set of B6HS to install in a 140 Manual with 51 Primary and 49 Secondary main jets. My first step outside my Bosch comfort zone.
Jim Brandberg
Isanti, MN
CorvairRepair.com

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