Typically, when you snap the throttle and have a bog, it usually means your squirters aren’t big enough and/or your accelerator cam is incorrect. It could also be that your pump isn’t all the way open when you’re at WOT and therefore not squirting as much as possible.
When I put my 830 on my 400 I had some work to do. The high speed air bleeds were too big so I had to go smaller. I was at 90+ on the rear and going lean at WOT. Going to a smaller HSAB forced it to suck more fuel. I also changed out the idle air bleeds and the Idle Feed Restrictor screws to get the throttle response back. However, I had an LM-1 wide band to help me tune so I had a better picture than just a plug. Don’t get me wrong, plugs are good but limited in what they show you.
I had to really advance my distributor too. Turns out my cam wasn’t straight up so I had to advance my distributor to get the idle right. I took the carb off and set the butterflies to expose just a slight amount of the transfer slot – should look like a square. Then I used my distributor to adjust idle speed which really sounds weird. However, it worked. I then had to go back and limit total timing so make sure you check that.
So my changes were:
- Smaller high speed air bleeds
- Bigger idle air bleeds
- Smaller idle feed restrictor screws
- Advance the cam
- 2.5 power valve
My cam specs are in my sig.
+1 for the Innovate motorsports web page. They do a lot of carb tuning with the wide band – good info.