interested to find out if it's arrestors that held you back, or volume getting in / going thru the compartment

I'm going to clean the flame arrestor tomorrow morning, I'll post if I get close to the 79 mph mark with the HP 500 arrestors. I wish I had the Gafrigs so I could do a back to back test of the two

Don't the XR tops cause a smidge loss of speed as well?

So they say. But I don't have the props I originally ran to hit 80. Right now, I'm within 1 mph or so and that was with the hatch cover on and cracked vs 100% off. However, most will say running with no flame arrestor at all will also cause a bit of a loss in power.

updates? volume or arrestors?

Time for 8-71's with bird catchers sticking thru the hatch to ensure plenty of clean air! :angry-smiley-038:

I've got the new Gaffrig 10x5's and I'll be running them this weekend. I did run the HP 500's after I cleaned them and I only gained 2 MPH. I'm my opinion they are a big restriction. They really need to be gutted if you want to get the max power out of your engine. When I was cleaning them, I took the air compressor to blow out the carb cleaner, and it was crazy how little air pressure came though the wire mesh. I'd be willing to claim it was only 20% of the force compared to no arrestor. Either way, I'll soon report if a bigger arrestor in stock form makes any difference.

I bought the 10 X 5 for my 598. I do have ram air though.

sub'd

few years ago built a 489, with a 177 blower, Tom from weiand helped with setup, had a new eddie marine H/P flame arrester, 1st time out made 0 boost, was checking everything, found nothing. Called Tom, told me to remove arrester, popped right to 6psi ! so just because they look cool and say H/P does not mean crap ! Articfriends did a bunch of dyno test using EFI arresters and the results were very interesting.
I had some fairly large K&N ones I've had since 88 and now on my gibson, stuck one of those on and still had a tad over 5psi, many say they are junk but ???? so lots to be gained with just these...good luck keep us posted

Agreed! The K&N 14" by 3" tall lost 1 horsepower on the dyno compared to the dyno hat.

What I like about the Gaffrig vs just about all the others is you can easily take them apart and remove the screens. Using my air compressor and hand method I used on the HP's, these flow better. A lot more air comes through, however that is a pretty rude way to test, this weekend will be the real test.

It's actually a horrible test. LOL.

i've used the shampoo and hand method !
how and when does the air compressor come in to play?

Almost afraid to ask, but what is the shampoo and hand method?

:party-smiley-004:

Ha- I'm also curious what the shampoo and hand test is. Anyway, This project is beginning to get old. Okay, it got old a long time ago. The new flame arrestors are too tall to close the hatch all the way. I'm sure if I use a shorter carb spacer they will be fine, but I forgot the Gaffrig arrestors are around 3/4" higher than advertised due to their base. I also have a fuel issue with one of the engines. I thought maybe it was a fuel filter, but nothing changed when I put a new one on. Basically the boat runs fine until 3/4 throttle, then one engine runs out of fuel. You can feel the engine dragging the boat down, It feels like something is in the secondary needle and seat and is restricting fuel flow. I had friends up all weekend again, so I couldn't dig into it. I may or may not get to it this year. At this point the next time I go up to Michigan I need to pull docks and boat lifts. If we have a nice fall, I see what is going on. I'm starting to feel like Full Force with the issues he was having this summer!

if you still have anti-siphoning valves at tank ck there, very restrictive and get get clogged easily

Those are long gone. When I bought my boat it sat unused for well over a decade. The fuel inside the tank created rock like sediment in it, and created all sorts of havoc the first year I owned it. Eventually I cleaned the tank. I'm pretty sure the issue is in the carb, but you never know for sure until it's been ruled out.

[QUOTE=endeavour32;4479294]Those are long gone. When I bought my boat it sat unused for well over a decade. The fuel inside the tank created rock like sediment in it, and created all sorts of havoc the first year I owned it. Eventually I cleaned the tank. I'm pretty sure the issue is in the carb, but you never know for sure until it's been ruled out.[/QUOTE

Hey mike what's the difference in rpm btwn engines. Before pull boat at least swap carbs and ck for WFO throttle blade position. Air / overflow vent clear on the one side? Mud bees love getting their janky azzes all up inside those. You'll get figured out. Like you said short trip with lots to do doesn't help matters any though.

Float levels good at idle?

So long as October is good, I'm going to dedicate as many weekends as I need to so I can get everything ironed out for next year. Maybe by then the course will slow down and you can hop on the boat for a few rides!

Everything is great at idle, it will idle like a 330 at 600 RPM's. The boat ran great the first few trips and then it slowly kept going slower and slower. This past weekend, it was chine walking and felt like crap anything past 4500 RPM's. Getting it over 5k was a real chore, I was able to hit 5200 with your stock 26 Bravo's now I can't hit that with BBlades labbed 26's. The starboard engine is really dragging and causing all sorts of issues.

Make a difference hot or cold. Just wondering if it's possible lifter failure. Kinda doubt it but...

Nope- same hot or cold. Also lifters are not making any noise, after a hard run there is no ticking, nice an quiet. Tinkerer did a good job building these engines!

Are you running the carbs I had on them? Are you still messing with jetting? Have you checked your exhaust for reversion? Any chance you are taking on water weight somewhere? an engine not running properly wouldn't cause chine walking. Something has changed in the boat. Any chance you blew a power valve? i have had that happen before.

He's dry all the way back. Boat stored on lift. I think the chine walking is an over trim thing to get rpm up I'd guess anyway. No blown pw.

I had an issue once few years back, where my port engine simply laid down over 4500rpm. Turned out I had a slightly loose fitting on the suction side of my fuel pump, must have been sucking air. It wasn't leaking fuel though. Anyhow, tightened fitting up, went back out for a ride, 5500RPM again.

It really could be something that simple. The past two weekends I've been up to the boat, I've had a boat load of people on it. So I've had no time to dig into anything. It's been driving me nuts, because I hate it when the boat isn't running as it should and I'm not going to run it hard when it's like this.

Tinkerer- I had a similar issue a few years ago where one engine was falling on its face around 4500 rpms. The other would make power to 5200 and pull the other with it, but the boat was a hand full to drive until the issue was fixed. This feels similar but the engine will surge, as if it gets the correct fuel for a second and then fall on its face again. At 70+ mph this surging is causing the boat to "feel" like its chine walking. Prior to this issue, at 80 mph the boat was rock solid. Nothing has changed other than this new issue. I'm pretty sure it's going to be a dirty needle and seat in the secondary, but until I clean it, it's only a guess. As far as the trim is concerned, I'm only at 5-6 typically at WOT, anything more and I gain nothing.

Yes I'm still running the carbs that came on the motors. The boat ran great the first time out, I'm just chasing things now to get it to run like it did that first day on the water. Once I get it to run consistently, I'll start fine tuning it.

Now that I think about it, I did change the toe in on my drives. I went form 1/8" toe in to 0" toe in. It is possible this is causing the steering/tracking issue . I'll have to change it back and see what happens.

I know too well!!! do you run a wideband?

things to look at... trust me I been there... and if you do not have wideband you are doing even more guessing and it sucks.....

really need to rule out if its fuel or spark related....you have 2 engines take a couple hours and swap things one at a time and try....

Swap to different props? a heavier load can cause this... ask me how I know??
swap carbs....
swap coils (had one not pull rpm like this)
swap fuel pumps..
swap ignition modules...
swap distributors...
swap fuel lines at tank in case one pickup is cracked.
remove screens on pickup if you have them..
verify no air leaks in fuel lines to pumps.


A wideband will tell you ALOT about whats going on... you can get a exhaust pipe clamp on style if needed also for testing, but without that or egt its going to be a parts swapping game...

good luck bud, took me 1.5 seasons to figure out I needed ALOT less jetting on one engine, I pulled my hair out forever... that's even after dynoeing engines!!

Thanks for all the advise. Once I get all of the docks and lifts out, I'm going to spend the rest of the season working on this. Over the winter I'm going to have bungs installed so I can check everything with a wideband. Till then, I want to check all of these other issues.

Just saying the wide and may be better sooner then later, or your chasing unknowns all the time

To much partying and entertaining is the real culprit here. :ernaehrung004::party-smiley-048::drool1::drool1::picard1::picard1:

Ha- more like sick of screwing around with the boat. The next upgrade is a new boat already done! Turn the key and go is sounding really good right now!

Getrdunn - I was thinking a possible cracked / leaking header or riser gasket. Been there DUNN that.:)

So are you saying that a cracked or leaking header would cause issues at WOT? The boat runs perfect until 1/3 of the way into the secondary. Any other speed, everything is perfect. Just FYI, I'm running Gil exhaust with thru-transom pipes that are dry to the tip. It is possible that I have a cracked manifold, but I'm not sure why I would only have an issue when at WOT. Also never an issue starting. It would seem that if I had a crack in the manifold it would leak into a cylinder and hydrolock when the engine is not running. I've never had a leaking manifold, so I honestly have no idea what the symptoms would be other than the obvious.

Wide and or just run it...... Chasing issues forever .

We'll get his bungs welded in.

That's the problem for using wideband this year. By the time i pull the exhaust, take it somewhere to have bungs installed, its going to be November. I'm not tuning the boat in 40 degree November weather. The boat will be ready for proper jetting come spring, but not till then.