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Change Carb Jets .049" to .050" 102hp '63
Posted by: MonzaJPD61 ()
Date: March 20, 2020 07:09AM

I've only had this car about 2 years. Spark plug tips generally look grey, not brownish tan like I'd expect. Circular base - sooty black, mostly city driving.

Would you re-jet to .050" or not (elev. ~750ft)?

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Re: Change Carb Jets .049" to .050" 102hp '63
Posted by: joelsplace ()
Date: March 20, 2020 08:30AM

What plugs are you using? Picture?

Joel
Northlake, TX
5 Ultravans, 114 Corvairs and counting...

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Re: Change Carb Jets .049" to .050" 102hp '63
Posted by: JimBrandberg ()
Date: March 20, 2020 01:49PM

I think #49 jets (not .049) would be lean in a 102 HP. It's a fairly aggressive engine and 64 and earlier carbs do not have high speed enrichment circuit.

Jim Brandberg
Isanti, MN
CorvairRepair.com



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Re: Change Carb Jets .049" to .050" 102hp '63
Posted by: joelsplace ()
Date: March 20, 2020 01:55PM

Also matters if you are using Gasoline or Gasohol.

Joel
Northlake, TX
5 Ultravans, 114 Corvairs and counting...

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Re: Change Carb Jets .049" to .050" 102hp '63
Posted by: Ratt643 ()
Date: March 20, 2020 02:23PM

There is also a difference between jet sizes of the automatics and the manual trans. Yes, we need a pic of the plugs. Could be something other than the jet size since you said there was some black on the base of the plugs.
What brand and part number of spark plug are you using? Are you using a mechanical fuel pump? How long ago since the carbs have been overhauled?

1964 Monza Coupe
1965 Corsa 140
1967 Monza Coupe

Maryville, TN
U.S. 129 The"Tail Of The Dragon"

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Re: Change Carb Jets .049" to .050" 102hp '63
Posted by: MonzaJPD61 ()
Date: March 20, 2020 02:49PM

Powerglide car. Carbs rebuilt within past year. Clark's mechanical fuel pump. Stock ignition setup. Spark plugs AC Delco R44F gapped 0.035" dewll 31, timing 12 degrees BTDC. Alternate ethanol & ethanol free fill-ups.



Edited 1 time(s). Last edit at 03/20/2020 02:50PM by MonzaJPD61.

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Re: Change Carb Jets .049" to .050" 102hp '63
Posted by: joelsplace ()
Date: March 20, 2020 03:37PM

That electrode looks great to me.
The different fuels will want different jets.

Joel
Northlake, TX
5 Ultravans, 114 Corvairs and counting...

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Re: Change Carb Jets .049" to .050" 102hp '63
Posted by: Ratt643 ()
Date: March 20, 2020 04:39PM

I would go with a 50 jet...just my .02

1964 Monza Coupe
1965 Corsa 140
1967 Monza Coupe

Maryville, TN
U.S. 129 The"Tail Of The Dragon"

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Re: Change Carb Jets .049" to .050" 102hp '63
Posted by: vairmech ()
Date: March 21, 2020 05:39AM

Are you having any spark knock issues? Any other running issues? If not leave it alone.

Todays fuels will not look the same as old school spark plugs readings when there was lead in the fuel. The black sooty is sort of normal for a street engine.

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com

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Re: Change Carb Jets .049" to .050" 102hp '63
Posted by: MonzaJPD61 ()
Date: March 21, 2020 07:08AM

12 deg BTDC is all the timing it'll stand without spark knock when warmed up. Otherwise, I guess it runs ok for a PG car.

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Re: Change Carb Jets .049" to .050" 102hp '63
Posted by: Wagon Master ()
Date: March 21, 2020 07:13AM

What octane grade of ethanol/ethanol free fuel?

'29 Ford Model A Tudor
'61 700 Lakewood 110 4 speed
'69 Monza Convert. 140 Auto.
'70 Dodge Challenger R/T 440 4 speed

Been aircooled since 1973
Northwest Ohio

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Re: Change Carb Jets .049" to .050" 102hp '63
Posted by: MonzaJPD61 ()
Date: March 21, 2020 07:18AM

I believe their both 87.

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Re: Change Carb Jets .049" to .050" 102hp '63
Posted by: MattNall ()
Date: March 21, 2020 07:20AM

A healthy 145/102hp needs at lead 89 octane! 9.25:1 CR??

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Re: Change Carb Jets .049" to .050" 102hp '63
Posted by: JimBrandberg ()
Date: March 22, 2020 08:26AM

Richer jets may help the pinging and allow you to advance the timing to spec.

I would run 87 octane in a 80 or 95 HP 8/1 C/R engine but probably not in a 102,110,140 or 180. I might if I was driving it a lot and cognizant of the throttle limitations.

Around here 89 used to be just a few cents more than 87, it's a shame that it seems to be more like a dime now. It's also a shame that they might be getting the extra octane from more corn squeezings.

I usually put 91 non-oxy in Corvairs I see and it's their business if they follow up. I think it stores better for cars that don't get driven all the time but I could be wrong.

I would probably try to run 89 in a 102 I was driving all the time. I would probably have 51 jets in it, maybe 50 if it will take it. Results and geography may vary.

Jim Brandberg
Isanti, MN
CorvairRepair.com



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Re: Change Carb Jets .049" to .050" 102hp '63
Posted by: MonzaJPD61 ()
Date: March 22, 2020 04:51PM

Put in the #50 jets. Left everything else as it was and it seems to have helped the tendecy to spark knock under load and throttle. Will wait till mid summer heat settles in to see if I need to move up to #51. Have driven it about 50 miles since - still like taking it out for a drive!

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Re: Change Carb Jets .049" to .050" 102hp '63
Posted by: JimBrandberg ()
Date: March 22, 2020 07:28PM

Good deal, one step at a time with jets is good practice.

Jim Brandberg
Isanti, MN
CorvairRepair.com



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Re: Change Carb Jets .049" to .050" 102hp '63
Posted by: junkman ()
Date: March 22, 2020 08:56PM

I have switched all my cars to NGK plugs, and the engines like them a lot more. My Spyder ran terribly before I changed it over, and now it runs great, except on extremely hot days, when it starts pinging.

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