High rpm upon startup

[trentonm]

Just a guess but it sounds like it was running on one carb then the second carb kicked in. The second carb has the throttle open too far so away it went. Back to basics. Valves, timing, carb static setup then airflow balance. That is incorrect float bowl to nozzle fuel line and it will give you a world of problems. Also you are missing hardware on the manifold throttle pivot point.

thank you for the response. i hadn’t known our lines from the float bowl to the nozzle were incorrect. what’s the correct way to connect the two?

[trentonm]

I'm not letting go of the "lean mixture" theory, especially after seeing those fuel lines. Get the proper tubing, not too long, and try it again. Those lines can kink inside and look fine on the outside. Pat

i hear you. i hadn’t known our fuel lines were incorrect. when you mentioned a kink before i naturally assumed it would be something i’d see on the outside. i appreciate your responses. what’s considered the correct tubing?

[trentonm]

I’m assuming you’ve already checked and don’t have a stuck hand throttle, accelerator or choke cable? Then, since it happened “out of nowhere” when it was otherwise running pretty good, there are really only two possibilities: Something is now jamming your throttle plates wide open or there is a major vacuum leak (likely from a hose that was knocked off).

Let us know.

i considered the vacuum but hadn’t thought about the throttle plates. i’ll check those out

[RBMann]

If your fuel line is not flexible then it could bind up the jet and choke/fast idle linkage causing the high idle. Someone here recommended this line at Amazon but I have not tired it. I can't find the thread right now.

https://www.amazon.com/dp/B07PQTBWY4?ps ... ct_details

[trentonm]

If your fuel line is not flexible then it could bind up the jet and choke/fast idle linkage causing the high idle. Someone here recommended this line at Amazon but I have not tired it. I can't find the thread right now.

https://www.amazon.com/dp/B07PQTBWY4?ps ... ct_details

well, only 10 bucks so i’ll give it a try

[spl310]

Go to Ace Hardware. They sell it by the foot.