Finally got some nice WOT pulls in on the new engine and I'm a little lean still and looking for a little jetting advice so I don't end up with a stack of jets I'll never use...

Motor...
460 CI with 8-71 blower(5 psi boost) dart heads JE pistons eagle rods

Carbs...
Twin 850 holley's with 84 primary jets and 92 secondarys...secondary PV blocked off and 10.5 power valve in the primary side

Air/fuel readings...
idle to 1200...12.5-13
1200 to 3500ish....12.5-13.2
WOT 12.3-13.1 when I shut it down

Timing...
12 degrees at idle 30 degrees full in at 2800

My next move...

I'm thinking go up one to 85's maybe 86's in the primarys and up 3 to at least 95's in the secondarys

What's everyones thoughts?? Too much?? Too little??

Thanks

Stewart

I would go bigger to get safer and work backwards.

Here is what I looked at when jetting.
I mark a spot on my throttles where the secondaries open. Open hatch and visually look when they crack, I can feel it in my throttle.
1. Idle... Quality, where ever it falls (don't care)
2. AFR 12.5-Getting on plane, with or without secondaries. (I don't get into the secondaries getting on plane) High torque on engine watch timing and listen
3. AFR 12.5-Boat planed thru cruise speed. ~2800-3800 RPM (end of primaries to the secondaries mark on throttle)
4. AFR 12.3-3800-WFO (primaries and secondaries)
It helps me to see what jets are affecting my AFR.

Makes total sense...mine is the same..no secondarys on acceleration..i can get on plane and up to 3500 or so without the secondarys which is preferred for me anyway since I'm only running an XR don't want to stress it more than I have to....

My biggest concern was top end but I guess cruise AFR is important as well....would the cruise AFR be determined by the primarys?? I was always under the impression that off idle until the secondarys open is all the primary circuit...is that correct??

What would you suggest as a starting point for this then?? Already did one jet change to what I have as it was waaayyyy lean at first

One more thing...here is my knowledge from what I've read on A/F ratios....

idle...12-13 ish
cruise...12-12.5
WOT...11-11.5
Do those number sound like a good goal to shoot for?? I understand not to get hung up on chasing magical numbers and its all about what the engine likes but I do want to keep it safe until I can do final tuning

Thanks

Stewart

I've never tuned a boosted application so I will not make a suggestion. I have read similar to what you wrote.

Fair enough lol

Trust me if holley had a dual EFI kit that would work on a roots blower that would be my next move when money allowed....I looked at those kits but the ones I saw only had like 2 or 3 of every jet so I would need 2 kits just to jet it once....probably better in the long run to have the assortment but honestly this will probably be the last carb I jet for a looooong time...I hope lol

I was actually just looking on ole fleabay and there are quite a few sellers that have 20 packs of whatever combo of sizes you want for really cheap...probably end up doing that..if I can figure out what sizes I would need lol

Can you elaborate a little on how secondary jetting would affect primary jetting?? Just simple quick explanation so I can wrap my head around it

Thanks