[NYGTO]

I've been looking into the best fuel enrichment for the AFB used on early GTO's for street and strip.

I'm not sure what the typical jet change was from the popular speed shops and dealers like Royal for the AFB, naturally there's a lot more information on the tri-power cars

Can any of the veteran early GTO guys give me some direction on what worked on the strip? The stock jet was.091 and the metering rods were .0635 X .055.

The air is cold and dense now so I'm thinking a 100 jet with the stock metering rods would be a good place to start. The car is completely stock.

Thanks in advance for any ideas.

[Geoff]

That is for a 65 GTO, std trans.

Going from 91 to 100 on the pri jet is a HUGE increase, ridiculous.

Try a later AFB or Edel 092 jet.

[NYGTO]

The idea of a .100 jetting was for the convenience of using the metering rods to fine tune from that size.

I can use a wider rod for leaning and work my way thinner for whatever the air density circumstances are.

I've only had experiences with Holley carbs with slightly modified open exhaust engines so my pure stock GTO has me guessing for a starting point.

Thank you for responding.

[tom s]

Contact 61-63 on this site for jetting help with AFBs.Tom

[Skip Fix]

Hard to beat a wide band O2 sensor in the exhaust to tell for sure.

[61-63]

You sent me a pm and I responded but I'm wondering why you are asking if the car is completely stock, which suggests to me that it isn't a race car. If it isn't in fact a race car and it is running fine if it were me I'd just leave it alone. A stock '65 GTO 4 bbl car made 325hp which is a nice performing car. If you get an 02 sensor, some jets and metering rods, and fiddle with it you will be able to improve it some, but will the gain be worth the effort?

[NYGTO]

Yes, it's a completely stock car but in the spirt of fine tuning and enjoying the hobby of grass-roots hot rodding, I'd like to see how well I could make the GTO run. Just as several dealerships offered performance tune packages when these cars were new. I'm not looking to go beyond what the dealers did I appreciate your help.

[Dick Boneske]

I raced my '64 GTO when it still had an AFB carb. I tried larger jets with no improvement in ET's. A few thousandths of an inch larger jets will help a minimal amount.

After trying various things with the stock AFB, I bought a bigger one. I gained about 0.15 seconds with that bigger carb. Swapping to a Tri-Power setup got me from the 13.60's to 13.29 @109.75 with a stock '64 GTO 389.

[NYGTO]

Thanks D.B. --- that's flying for a stock GTO. I'll see what I can do next week at the track.

[Kenth]

With todays ethanol blended fuels it wouldn´t hurt enlarge idle tubes, primary and secondary jets about 5 percent.

[NYGTO]

Update:

I used 98 jets with stock metering rods and as best I can tell gained a small increase in mile per hour at the track. I had planned several changes but the day was cut short by the weather. I'll try again this early spring. Thanks