I have used a set on my SV540 and another on a O320. Just recently bought a set for my AV540 but have not yet installed. No leaks so far and I have reused the carb and intake gaskets successfully. I like them, good luck.

asmcpeck@msn.com

Klondike, Understood, that is the basis of my recommendations. If you were to setup for true 500 Hp I'm pretty sure you would need to turn a minimum 6,000 RPM. You can gear and prop for that, but will find your cruise RPM just jumped to 4,500 with a lot of time in the 5,000 range. You would need a b...

The 1 1/2 should meet your need for a 383 spinning 5400-5600 rpm. In a natural aspirated engine a narrow long tube will aid in building torque as the scavenged exhaust gasses develop a flow and help to enhance your usable power. The use of an oversized or wider short tube will aid in making extreme...

I asked the builder of my new engine about them, and he said I didn't need them. He is a certified aircraft mechanic that does not make a living building airboat engines, but putting engines in the air, so I took his word for it. I highly recommend you listen to him, if it ain't obvious yet, I'm ma...

Thanks lariat, I hope this is helpful, I would know you are lying if you said you understood it all, I have spent my whole life trying to understand, design, troubleshoot and improve dynamic systems, it's never simple, this is just a primer. On a system as complex as this, with so many variables (pr...

I am very sorry to hear this news. I never had the chance to meet the man, but I did talk with Mr. Branch one day concerning a possible engine build. We had a great conversation, Buddy was more than helpful and free with information.

Slidin. I hate to sound like the dumb a$$ that I am, but I'm not sure what I'm looking at with your illustration. Could you tell me exactly what it is I am looking at and how it affects our motors? lariat, Making you sound like a dumb a$$ is not the goal, you asked an interesting question, but it's...

I agree that your accelerator pump is the most likely culprit, particularly since ether solves things. I imagine a shot of fuel into the intake would do the same. But, a weak ignition can also cause cold start issues. Just this past weekend I could not get my injected engine to lite off on a cold mo...

I figured out how to take a video screen capture of the software screen to show live (recorded) action. One thing that caught my eye is a harmonic popping up around 196 Hz, which is 4.5 times the engine RPM. So that is a bit interesting, basically something is audibly vibrating every 4.5 times per e...

To further this discussion I downloaded a copy of Sonic Visualizer, it's freeware and does what I am looking for here. https://www.sonicvisualiser.org/ I opened up the video file down below into the software and got the following results. The top graph is the sound signature vs. time. The bottom gra...

6 cylinder direct drive is 3 cylinder pulses per revolution. Assume 2,000 RPM, that's 6000 cylinder pulses per minute. Divide by 60 and it's 100 Hz (Pulse per second). Each one of those pulses creates deflection in every part of the engine, slightly twisting the crankshaft, basically winding up a sp...

:thumbleft: on the NGQ, it's a pushing prop. It won't have the top end like that Razor, but it pushes at all speeds, idle and up. I owned a 72" Q on a SV540 originally. I swapped to the NGQ and found significant improvement at lower speeds and call it even on the top end. My AV540 came with a 72" Wh...

Ted, I just re-read your thread, I had mixed up the 3,200 helicopter rating Kwan posted vs. what I now see is your present 3,000 setting. 3,000 rpm is much more in line with reason for the prop. What pitch has you at 3,000 on the trailer? Jacking up compression with no other mods increases torque bu...

I guess the really question is with the increases in pitch, does that offset the drop in hp to some extent? I believe it was twin ma5 carbs originally. No it does not. But 3,200 RPM is pretty far off the chart for efficiency of the prop and it must be loud. 2,800 should work well, lower rpm will sa...

This was covered pretty well in Fishstickers build thread, starting at the end of page 13. The consensus is go as low as possible. The prop sits lower in my open hull vs. my deck over simply because there’s a deck in the way on the deck over and it would drag in the water off plane. https://southern...

Port or Stbd depends on your torque side and conditions. Torque side is the side that dips on throttle. Direct and belt drive torques to stbd. Your gear drive torques to port. In deep water, turn away from the torque side. In real skinny and dry turn into the torque. You will have to try to understa...

Some relevant posts on mags ,timing etc.

viewtopic.php?f=47&t=72785&p=700226#p700226

viewtopic.php?p=696442#p696442

$75 to help swfwmd deal with a problem? Incentive consideration? Gimmie a break, are we gonna make hog hunting the next BASS tour? Permits, blah blah blah. How about just opening the places up to hog dog hunting year round, then maybe we can keep the population in check. I can't keep a pack of dogs ...

SAE has several different standards for noise emissions: https://www.cpperformance.com/t-state_noise_laws.aspx SAE J34: The most precise measurement available, taken of a boat at a distance of 50 ft. with wide-open throttle (the near maximum noise of the boat). Although great for engineering standar...

Do you normally dry launch or wet launch at a ramp? My tilt trailer is easy unload dry. With the right balance it an easy brake tap to drop it past center to tilt and launch. If you wet launch, no need for a tilt.

Backfire off throttle and stumble on acceleration can both be caused by lean conditions, classic intake leak symptoms. Typically this is resolved by replacing the intake runner gaskets and hoses. Check the tubes themselves too. Get a can of carb cleaner with the mini straw for reach and spray everyt...

Eric, Thanks for the heads up on this issue, I would not have known about it without your original post :thumbleft: Here is the full direct length for all interested: https://parkplanning.nps.gov/document.cfm?parkID=352&projectID=49334&documentID=107460 Here is what the National Park Service has pos...

woodlineO540 wrote: ↑

Mon Nov 23, 2020 6:21 pm

I have been converting 520s to airflow performance fuel Injection

What are the pro’s and con’s?

I run Continental injection on my angle valve Lycoming. Starting is a learned skill but performance has been instant and reliable.

Thanks...had a great first ride. Been many years since I rigged a boat out and it took a lot longer than I thought it would, but I am tickled shitless :D Rick Excellent! You did a great job on the boat, glad to hear she performs :cheers: When you said you would post more last night and then didn't,...

Don't get your A's and W's mixed up Gonna keep runnin aeroshell and keepin my A&W just like it is ........... :toothy7: Let me help you out Kwan, you were looking for this: :cheers: https://southernairboat.com/wp/wp-content/uploads/rtMedia/users/2619/2020/11/AW-Logo.jpg?1605745763 The thing is, the...