Ignore the opening comment - the PV was always on and I was just interpreting the data thinking the circuit was working.

I’m not against trying it with jets only, but with this being NA, I think the PV is needed for a cleaner cruise. Right?

Back to the way it came with exception of the fuel curve change in the metering blocks. Should be minor and only help.


We shall see!

I’m going to replace the base plates - only thing original will be the main body and bowls. The PV kits that I installed left too little of a margin between the throttle bore and the casting. The main body orifices line up perfectly with a Quick Fuel/Holley base plate and gasket so should be fine (maybe an upgrade even).

Getting closer to water testing.

I replaced the base plates with parts from Quick Fuel. They were comparable to the Demon parts but with exception of visible quality control improvements over those from BG/Demon. I added alignment pins to the base plates - made a big difference in the alignment of the throttle bores and venturii.

Initial startup last weekend was good but eye-bleeding rich. That was quickly fixed and and I got both engines to run well on the hose. Wednesday, I dragged the boat to the ramp and started working on in-gear idle on the trailer. Out of gear both are running about 12.6 with vacuum at 18 inches, but as soon as she's in gear she drops to about 8-9 but a/f climbs 13.3-13.5. Blipping the throttle in-gear (from 700 to 2000 rpm), a/f rises but quickly recovers - very crisp. Idle is about 850 out of gear, 650-700 in gear. Trying to raise the in-gear idle makes for excessive out of gear idle so it appears that this is where both engines want to be.

I was thinking more idle would be good to combat reversion, but with the long tail pipes of the TRS set-up and squat of the 311, I don't think there's much of a concern. These were Rookie's old 454 cams and he didn't have reversion issues with his TRS set-up so I think I'm good.

Time to yank the engine hatch off and get some seat time to work on the jetting. I'm pretty sure they're going to be pretty rich. I did a whole lot of math to get the primary and secondary sides close to one another so I'm sure both will need to come down. Have to start somewhere though.

Thanks Dan. Based on the what I found with the orifices not being drilled, anything that I mentioned about PVs opening at a given RPM aren't accurate - they were always open and I guess I may have been seeing the handover of the idle circuit to the mains. It'll be interesting to see with the reconfigure.

I have thought about going that route, but with an NA set-up, I felt the cruise economy would really suffer. That's the whole point of the power enrichment routine - allow the engine to cruise on the mains, and then use the PVCRs to add another 25-40 percent more fuel when giving it the beans.

Maybe the boat is less affected with it's constant load - possibly. Did you (or anyone reading) run a similar set-up without blowers?

Tom,

I'll never understand carbs. Little vacuum "computers" doing shizzit because voodoo. They amaze me.

I fought and fought and fought and fought and fought the carb on the 454 in our Rinker. For the life of me, I could not get it to run between 3600 and 4200 RPM. As soon as the secondaries would want to open, they'd open. as soon as they want to close, they'd close. And that was it. It was either under or over or transitioning between the two. Never just.... running. It would hum along at 3100 all day long, purring like a kitten, and it would just sing at 5100 WOT until it ran out of fuel. But 4K? Not a shot. I took it to a local carb shop numerous times and he would "fix" it on his shop engine (He refused to work on it in the boat. Probably a liability thing), it would do the same thing, and I'd farq it up again trying to make it work right. Never did figure it out. Sold the boat to a buddy. Still does it. He doesn't care.

Glad SoMeBoDy understands how they work.

Thanks. Brad.

Took her out yesterday and did a lot of stepped rpm testing. It was a cold but fun day messing them. We were out there for a good four hours running back and forth.

At the end of the day, both carburetors are pretty consistent to one another (within a couple tenths) but they’re both still running lean.

A/f ratio getting above 4500 is in the upper fourteens with the following setup:

Primaries: 88
Secondaries: 98
pvcr: .063
pv: 8.5 - primary only

We tested with the secondaries disconnected and held closed was able to run up to about 4500 rpm but a/f was high 14s wide open. Hooked the secondaries back up and a/f didn’t change. The flame arrestors were off and I could see that the secondaries weren’t starting to draw fuel until around 4300. Decided to bump jetting on primaries and secondaries from 86/95 to the 88/98 listed above. Ran to about 70-71 and a/f was mid 14s on both.

Trying now to figure out what the next step should be. Seems that the idle circuit is running until about 2k rpm than the mains starting coming along with the power valve. Thinking that maybe we need to go up to 92 on the primary and maybe increase the pvcr to .067-.070. From there test and see if I can safely get to wot.

Also, the distributors were a little loose and had backed down to the indentations on the body resulting in 30 degrees. I bumped them back to 35 and the engines seemed to really love that.

Any thoughts?