tomas_wallin

I just splashed the Pantera after redoing the interior and a bunch of other stuff.

I boost referenced the carbs and installed an AEM wideband lambda and I got 10:1 in a/f ratio from low to 3500-4000rpm... at idle it's at 12:1 but it drops rather quickly to 10:1.

So far I have stayed out of boost and only reved to 3500 and some occasional 4000rpm since I'm doing the brake in of the new Mr Gadgets XR Drive.

How should I jet and PV the carbs to get it right?
Right now it's jetted at 86/96 and single primary 6.5PV that's boost referenced.

I have 10-15mmHg (since it loopes from 800-1200rpm) in vacuum at idle.

What a/f ratio should I jet for through the rpms?

The engine specs:
825HP@5800rpm / 815Ft-lbs@4000rpm
Block: Merlin II 509ci
Crank: Callies
Rods: Manley H-Beam
Pistons: JE blower pistons (757F)
Piston rings: Total seal TNT gapless top
Cam: Marine Kinetics Hyd roller
242º/250º @ .050" / .646"/646" lift valve / 112LSA
Wot RPM: 5800rpm
Heads: GM 188 mildly ported chambers
Head gaskets: FelPro MLS
C/R: 8.3
Valves: 1.88/2.25
Rockers: Jesel Comp Series 1.7
Intake: BDS Blower intake
Intercooler: Superchiller
Blower: BDS 8-71
Boost: 8psi
Carbs: 2x Holley 9022 800cfm
Jetting: 86/96 6.5PV Boost referenced
Ignition: MSD 6
Distributor: MSD 84891 Crab cap
Exhaust: Stainless Marine Gen III with 4.5" dry tails
Fuel: 93octane

Turbojack

At what rpm does the power valve open up? At what rpm do the secondarys start to open and what is the boost or vacuum at that point.

If you do a search on power valves, back in a round 2006 we had a number of discussions on jetting and power valves. If I remember correct a member by the name of Tom (rtech intercoolers) was involved in the threads.

mrhorsepower1

I would run the primary jetting @ 78 jet with the 6.5 PV. and the secondary jets at 89 with no PV. Those carbs out of the box are jetted with 72 pri. with 6.5 PV and 87 sec. The next thing you want to be sure of is you have proper fuel delivery. I would suggest a Aeromotive system with return setup. I run this fuel system on many supercharged engine packages with zero problems. You need to maintain fuel pressure throughout the RPM range, it should not drop under WOT conditions. If it does your fuel system is not capable of supplying the engine. Set the float levels with the bowls off and inverted . With a 3/8 pin gauge or dowel should just slip between the middle of the float and the inner bowl housing. Fuel pressure should be at 8 PSI. If you want to tame the idle down take the idle mixture screws in (clockwise) to lean. I like to see about a 200 rpm surge. I hope this helps.

tomas_wallin

Thanks, I will give the 78/89 a shot!

What a/f ratio would you like to see in this engine?

Should I keep the 6.5PV or should I use a 4.5 instead?

The pickup tube has an id of 5/8", then AN-10 from there to the A-1000 pump and AN-8 to the fuel regulator. AN-8 to the fuel block and hard tubes to the carbs, AN-8 return with fuel cooler to the fuel filter. It should be steady through the rpms. I have it at 7psi but do you think I should up it to 8?

tomas_wallin

You can never get the same conditions on the dyno as in the boat, since every boat is different. You can get a base jetting on the dyno but to get it perfect you need to finetune it in the boat under the correct load.

GoFastSonic

Hey Scott,

Did they Dyno your motor before it blew up?
Sorry buddy could not pass this one up

Velocity Vector

iTrader: (4)

OUCHY

tomas_wallin

How would you know what load you have in the boat at say 3500rpm when you put in on the dyno?

It's one thing to get it 100% correct at wot since that's what you are proping for but not the rest of the rpms.

tomas_wallin

I changed the jets for 78 and 89 and now it's at 10.9-11.1:1 from "high" idle to 4000rpm.

I will try to put in 3.5PV's next time and perhaps the 86's I've got. I must check when the sec's open as well.

GoFastSonic

Oppps It was the Captain and coke talking LOL