New Holley 5200 and header....not running well. Lean?

[Anonymous]

Just installed a new transmission (C4) and a new Holley 5200 from Stovebolt on the Stovebolt adapter, plus a 6 into 1 header(still open at teh moment) on my 73 250.
Dont have the timing dialed in yet...but it cranks and idles well. When trying to accellerate from a stop there is a huge bog or stumble, enough to kill the engine when cold, then once rolling it accelerates well throuh first, but just at about the time it should make the shift to second...it starts to break up, really cut-out badly. I pulled the plugs, all are a very light gray or even white (this was at night with a drop light) and appear to have an ashy deposit on them. I suspect a lean condition, but where to look first? Float level? Jets? Fuel pump? The car was running pretty well before with the Carter RSB and stock exhaust manifold.
Any help would be appreciated.
Brad

 

[Titleist16]

I just put a H/W on mine and my mechanic had to drill the idle and main jets out because it was running lean. Mine also bogged down, especially around corners. There is a flat spot in my carb. My mechanic said he could make it go away by advancing the timing but then I could get detonation at higher RPM. I chose just to give it more gas around corners.

 

[Anonymous]

In my personal belief, carbs are infinitely adjustable if you know how to fiddle with 'em (check my sig for what I am doing with a 1946 1 bbl)

You can try all three things you mentioned...

I don't like to drill jets, cause once it is drilled you can't go back. If you think you can get jets pretty easily to replace the ones you drilled, then go for it.

Make changes slowly. Only change one thing at a time.

 

[Mustangaroo]

Before installing a Holley 5200 you should take the jets out and make sure they are installed correctly and NOT the Same SIZE, these carbs were on samller engines and most need larger jets to run well. The primarty jet should be a little smaller then the secondary jet, there are web pages on the internet on how to tune this carb correctly! It's not hard but if you think you can just bolt on any carb and your engine will run smoothly your are dreaming and need to wake up! They all need to be tuned to your engine!

 

[Anonymous]

if you think you can just bolt on any carb and your engine will run smoothly your are dreaming... They all need to be tuned to your engine!

 

[Anonymous]

if you think you can just bolt on any carb and your engine will run smoothly your are dreaming... They all need to be tuned to your engine!

That's pretty true. Especially when using carbs from a very different size engine. For instance, many Holley/Webers came on small four cylinders. Bolting it onto your six, you will need to do some adjusting to it.

 

[Anonymous]

Thanks for all the advice guys. The standard jets do appear to have been installed correctly as the secondary jet IS larger than the primary.
Mustangaroo, I certainly expected to do some amount of tuning, yet sought to draw upon the experience of those that may have already dialed in a similar combination. I am also quite awake, thank you.
Brad

 

[Mustangaroo]

Sorry Brad the commet about being awake is for anyone changeing carbs, they all need to be tuned. The Holley 5200 is a great carb on the 200 inline six, but it has to be tuned as the guys that rebuild them don't care what you install them on! If you want performance you have to be willing to tune your carb, otherwise it will not performe as expected!