Quadrajet jetting question

[Jaysonb]

I just about have my quadrajet tuned well. I recently installed a goodwrench 350, and it runs well, but it is a little weak. I ordered up a summit 1102 cam, and some headers to hopefully get a little more torque. When I had my engine dynoed, it was border line lean in cruse mode, so today I opened up the apt a little and it seems perfect now. So with the new cam and headers will I need to rejet to keep things good? I have 52m rods, and 71f jets in there now. When I placed my order for the cam and headers, I also ordered some 74 jets, and 48 rods. I figure that will give me a few options if I need them. Any input is appreciated.

[enaberif]

Just out of curiositys sake how do you know the truck was running lean? You never mentinoed a wideband o2 which is the only way you can really know.

[Jaysonb]

I had the truck put on a dyno.

[cadillac_al]

It sounds like you have a good handle on it. Back in the 80's I was tuning a carb on a Camaro or truck, I forget now. When I went to the dealer to buy some jets one of the mechanics told me if somebody comes in complaining about a lean flat spot that they put 74 jets in them. That's what I did and never touched it again. I always ran mild rv type cams. I think you will be right in the ballpark with those jets and if you need more you have the smaller rods too.

[enaberif]

Originally Posted by Jaysonb

I had the truck put on a dyno.

A dyno can't tell you if a vehicle is running lean or rich. It can only tell you hp and tq values.

Based off of these values you can see if you have areas that you can improve through various means but the only way to 100% sure tell what is happening is with a wideband o2 setup.

[Jaysonb]

Originally Posted by enaberif

A dyno can't tell you if a vehicle is running lean or rich. It can only tell you hp and tq values.

Based off of these values you can see if you have areas that you can improve through various means but the only way to 100% sure tell what is happening is with a wideband o2 setup.

I wonder how my dad, and grandpa set there carbs up back in the old days? The wide band set up is cool, but its not the only way to tune a engine. Believe it or not, back in ancient times guys used to have to pull spark plugs, and determine how there engine was running, just by the color of the plug!! Sounds crazy, I know!!!

[enaberif]

Originally Posted by Jaysonb

I wonder how my dad, and grandpa set there carbs up back in the old days? The wide band set up is cool, but its not the only way to tune a engine. Believe it or not, back in ancient times guys used to have to pull spark plugs, and determine how there engine was running, just by the color of the plug!! Sounds crazy, I know!!!

Plug checks for carb engines is STILL one of the easiest way to tune a carb. Whether it be on a truck or a bike. But its not always 100% accurate.

A wideband will show you your levels at all rpms so you can tune properly for varying conditions.