Ultra XP850 Almost there!

[TT5.9mag]

all I can tell ya is cruising for me is anywhere between 2600 and 3200 RPM.
Why the hell did they can Newbomb?

It’s hard to tell but if you watch the AFR gauge you can see when the booster comes online. If you’re happy with the fuel “curve” while accelerating hard i would not mess much more with bleeds or emulsion. If you notice trends in the curve you’d like to fix, that’s where I’d go though. If cruising (on the booster) is still rich take main jet out. If you’re on the transfers and still rich you need more TSR. Sometimes it’s a little of both and that’s why it’s rich (and why you can time the booster with an air bleed change and it makes a big difference ). If you do take main jet out be sure to put that fuel back in with PVCR for hard acceleration. A little math will tell you how much to add.

 

[Ironmike]

It’s hard to tell but if you watch the AFR gauge you can see when the booster comes online. If you’re happy with the fuel “curve” while accelerating hard i would not mess much more with bleeds or emulsion. If you notice trends in the curve you’d like to fix, that’s where I’d go though. If cruising (on the booster) is still rich take main jet out. If you’re on the transfers and still rich you need more TSR. Sometimes it’s a little of both and that’s why it’s rich (and why you can time the booster with an air bleed change and it makes a big difference ). If you do take main jet out be sure to put that fuel back in with PVCR for hard acceleration. A little math will tell you how much to add.

Got it. Have you ever gone smaller than .062 on the TSR? Curious in case it leads me that way.

 

[Ironmike]

FINALLY! I think I'm there with this blasted Holley. Ended up with 028 MAB's up front and stuck with the 026's in the secondary side. Weather has finally cooperated and took a nice drive today. 86 degrees and humid.

Cruising on back roads around 45ish MPH and gauge says 14.0 - 14.5. At highway speeds (3000 RPM), it's 13.8 to 14. GREAT!

Hard acceleration with just primaries is a touch lean, like 14.5 to 14.9. WOT in 2nd and 3rd gear 13.2 ish.

So all I think all I'll do is up my primary main jets 2 sizes and I honestly believe that'll finally put me where i want.
Never touched all those damn emulsion bleeds.

I'll tell ya, these newer XP series carbs are absolutely the worst out of the box carbs I have ever seen in my life. What the hell happened to the old HP 950? They were great.


Holley tech? Unless it's FI, they don't know crap. Hate to bash them, but it's true..............at least in my experience.

Just for example, when I first called them about all these issues they told me "If you dyno'd 586 horsepower, you really just need a 650 CFM on there."

Boy have times changed!

 

[BSB67]

…..Hard acceleration with just primaries is a touch lean, like 14.5 to 14.9.

So all I think all I'll do is up my primary main jets 2 sizes……

Maybe increase the PVCR a little.

 

[Bewy]

If your cruise is correct, & you say it is, you do NOT increase the m/jets because that richens the cruise. As BSB says, you increase the PCVR which will richen WOT but not richern cruise.

 

[TT5.9mag]

Got it. Have you ever gone smaller than .062 on the TSR? Curious in case it leads me that way.

Yes. Lowest I’ve used is .055 or so if I remember right. But use what’s correct for your engine to be happy.

FINALLY! I think I'm there with this blasted Holley. Ended up with 028 MAB's up front and stuck with the 026's in the secondary side. Weather has finally cooperated and took a nice drive today. 86 degrees and humid.

Cruising on back roads around 45ish MPH and gauge says 14.0 - 14.5. At highway speeds (3000 RPM), it's 13.8 to 14. GREAT!

Hard acceleration with just primaries is a touch lean, like 14.5 to 14.9. WOT in 2nd and 3rd gear 13.2 ish.

So all I think all I'll do is up my primary main jets 2 sizes and I honestly believe that'll finally put me where i want.
Never touched all those damn emulsion bleeds.

I'll tell ya, these newer XP series carbs are absolutely the worst out of the box carbs I have ever seen in my life. What the hell happened to the old HP 950? They were great.


Holley tech? Unless it's FI, they don't know crap. Hate to bash them, but it's true..............at least in my experience.

Just for example, when I first called them about all these issues they told me "If you dyno'd 586 horsepower, you really just need a 650 CFM on there."

Boy have times changed!

Nice!! Glad you’re getting there. You have to determine if you’re on the mains or transfers while cruising to know where to add or subtract fuel. You can put main jet in it all day long if you’re on the transfers and not see it in the afr gauge. If you are on the mains, and don’t want to richen up cruise then I agree with the two posts above. Put the fuel in it with the pvcr. But if you’re not, then you can add main jet.

 

[Bewy]

Cruising at 45 mph with that carb [ big t/blades ], you are most likely still on the idle cct. Big-ger t/blades means you get more air with less opening, so a good chance you are operating on the idle cct.

Here is a simple test to find out without any disassembly. Find some wire about 0.025-.0.030" diam & push about 1/4" of it into the IAB. Wrap the other end around the vent tube. Do both IABs on the primaries. Secure with a tie wrap for a test drive.

If it is richer now at 45 mph cruise, you are on the idle cct. If no difference to the AFR, then it indicates you are on the main cct.

 

[Ironmike]

Maybe increase the PVCR a little.

Yep. Went from .077 to .082 primary only. Too friggin hot today to take a ride and see how it reacts.

Of course will update when that happens.


Oh yeah......I was very tempted to plug a couple emulsion bleeds, but since I'm so close I left them alone.

 

[Ironmike]

Long ride the other day. Cruising around, beating the snot out of it, just a real good eval of all the changes. ALL SEEMS GREAT!

As long as you guys think 14.6 ish to 1 is ok for cruising on flat level road.

Thanks to all your suggestions and insight.

A real big shout out to good ole Newbomb T for damn near forcing me to do what I thought was wrong.


As a side note: Don't believe the crap ya hear about these supercharged Mustangs. Young gun right beside us at the light, was feelin frisky. Honestly, I was a bit worried but it wasn't even close. I just LOVE those kids!

 

[TT5.9mag]

As long as you guys think 14.6 ish to 1 is ok for cruising on flat level road.

Hell yea it is. I like em even a little leaner than that. But at your hp level I’d say that’s great that it’ll cruise that lean.

 

[TT5.9mag]

How’s the fuel curve from converter flash to max RPM?

 

[Ironmike]

How’s the fuel curve from converter flash to max RPM?

Being a 4 speed car, I don't have much converter flash.

 

[Ironmike]

Why is it all these Chally, Mustang and Camaro dudes get mad at ya and tell ya they would kill you in a half mile? Yeah. No ****.... Who the hell races half mile? I've heard this now 4 or 5 times over the last couple years.

Anytime I've been stomped, I give the guy a thumbs up and a smile. This culture has changed over the years. A LOT! And not for the good.

Sorry for the off topic rant, but it's kinda sad.

 

[TT5.9mag]

Being a 4 speed car, I don't have much converter flash.

Ya know, I knew that when I typed it. Brain fart I guess. Same question though. How’s the fuel curve when you run it out a few thousand rpm in high gear?

 

[Ironmike]

Ya know, I knew that when I typed it. Brain fart I guess. Same question though. How’s the fuel curve when you run it out a few thousand rpm in high gear?

12.7 to 13.2. Nephew says I ran it to 5500. Had 1100 more til shift light. Didn't want to go THAT crazy on a public (very safe, for others) road.

It's the local, well known "spot" 3/4 mile, double lane, on-ramp that has now gone damn near unused due to new interstate re vamped 10 years ago or more.

 

[TT5.9mag]

12.7 to 13.2. Nephew says I ran it to 5500. Had 1100 more til shift light. Didn't want to go THAT crazy on a public (very safe, for others) road.

It's the local, well known "spot" 3/4 mile, double lane, on-ramp that has now gone damn near unused due to new interstate re vamped 10 years ago or more.

Very nice. You could probably trim that down a bit (2-3 tenths) but it won’t make much difference power wise. Nice work.