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Discussion Starter · #1 ·
Boat runs great up to 3800 RPM and then she falls on her face. I get a “waaaa, waaaa” noise that sounds like the secondaries trying to kick in and occasionally a subtle miss. The carb is the 600 cfm marine on a very mild 454. Talked to Edelbrock and checked a few things but everything looks good. I previously checked the plugs after a few WOT runs and they looked good. However I’ve fixed a few things since then (bad plug wires etc…)

Any thoughts on the carb or other sources. I’ve heard that distributor needs to be recurved for a boat. If so what should have been done? It wouldn't surprise me if the guy that put this engine together just stuffed in an HEI he found someplace.

A couple other tidbits. I’m at 4700 ft and as part of the process I recently replaced the fuel filter and gained 200 RPM before the problem kicks in. The filter was nasty.

Just looking to create a list of things to check so that I’m effective with my time so any help is appreciated.

PS. The “waaaa waaaa” noise sounds much more realistic when I do it with my voice than when I type it…
 

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mo balls than $cents$
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put a fuel pressure gauge up on the carb fuel line and see wtf pressure is doin at wot(should have at least 6psi), bet you're losing fuel pressure, fuel supply system isn't hanging with the carb:)bulb
also check tank vents, when tanks aren't vented well, weird things will happen, motors will melt down:)sphss
 

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Discussion Starter · #3 ·
put a fuel pressure gauge up on the carb fuel line and see wtf pressure is doin at wot(should have at least 6psi), bet you're losing fuel pressure, fuel supply system isn't hanging with the carb:)bulb
also check tank vents, when tanks aren't vented well, weird things will happen, motors will melt down:)sphss
How sure are you of that number? I checked it at WOT and it was 5 psi. The edelbrock tech guy said that was fine but...... Regardless I'll check the vents. It does it with both tanks but it wouldn't suprise me if I don't need to clean the tanks. I'll also check the filter again.

PS... me no like melted motors.
 

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mo balls than $cents$
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How sure are you of that number? I checked it at WOT and it was 5 psi. The edelbrock tech guy said that was fine but...... Regardless I'll check the vents. It does it with both tanks but it wouldn't suprise me if I don't need to clean the tanks. I'll also check the filter again.

PS... me no like melted motors.
that's fine, i just like alil more pressure on a edel carb than most. yeah, check the tank vents well! your fuel pump can actually pull a vaccum on the tank if its not vented well and you'll really notice it when fuel demand is high.

600 is a bit small for any bbc, ain't got a 750 dp holley handy?:Dany idea where the timing is at wot?
 

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Discussion Starter · #5 ·
that's fine, i just like alil more pressure on a edel carb than most. yeah, check the tank vents well! your fuel pump can actually pull a vaccum on the tank if its not vented well and you'll really notice it when fuel demand is high.

600 is a bit small for any bbc, ain't got a 750 dp holley handy?:Dany idea where the timing is at wot?

regarding the 600 cfm... I know. Just looking for reliable for now. Considering a restore then the current motor becomes a paper weight...

Going to check the timing this weekend again. Didn't check the WOT timing last time (I was fighting a low speed overrich condition at the time).

What timing at WOT should I look for in a boat? Obviously just need smooth not max horsepower (see 600 CFM carb above.....) :)
 

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mo balls than $cents$
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34-35 is good and safe if you're runnin decent gas(mid grade or higher)
 

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The Eddy 600 marine is jetted/tuned for a 260-300hp small block.

The Eddy 750 marine is jetted/tuned for a 310-350hp 454.

The wah,wah and misfire is probally a result of your A/F ratios going sky high.

Make sure your fuel system is flowing enough fuel and get that carb tuned for your motor before something inside the motor melts/breaks.
 

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BTW: if you have an enclosed engine compartment you need a USCG approved distributor - along with starter,alternator, fuel pump, and etc.
 

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what springs, jets and metering rods do you have in the carb? and ditto on above esp regarding marinized parts. you could be playing with fire - literally. 6psi is pushing it on an edelbrock carb, 5 is better. they push gas past the needles pretty easily. a cheap fuel pressure gauge connected (temporarily) right in front of the carb can be a wise investment
 

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Discussion Starter · #11 ·
BTW: if you have an enclosed engine compartment you need a USCG approved distributor - along with starter,alternator, fuel pump, and etc.
Fuel pump is. Not sure how to tell on the rest of the components. What should I look for?
 

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Discussion Starter · #12 ·
what springs, jets and metering rods do you have in the carb? and ditto on above esp regarding marinized parts. you could be playing with fire - literally. 6psi is pushing it on an edelbrock carb, 5 is better. they push gas past the needles pretty easily. a cheap fuel pressure gauge connected (temporarily) right in front of the carb can be a wise investment
I'm in MN for the week and my notes are on my desk in CO.... I have made changes in the original setup. I recently riched up the secondaries but that had no effect. A couple of notes. I had an overrich conditon that I had been hunting for a while. Turned out to be bad "new" sparkplug wires..... Since fixing that it runs well at low speed and just a tidge rich when idling/crusing at low speed. Also when I not spending any time at any speed especially where I get the "waaa waaa" sound... I really don't like the idea of melted anything other than cheeses... and I do have a fuel pressure gage installed running a max of 5.5 psi.

I'll send in the notes once I'm home unless I can get a buddy to send them sooner...

thanks.
 

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Discussion Starter · #13 ·
what springs, jets and metering rods do you have in the carb? and ditto on above esp regarding marinized parts. you could be playing with fire - literally. 6psi is pushing it on an edelbrock carb, 5 is better. they push gas past the needles pretty easily. a cheap fuel pressure gauge connected (temporarily) right in front of the carb can be a wise investment
Primary jets = .113
Secondary jets = . 107
rods = .068/.047
spring = orange

Gonna check the screen in the needle seat assy for crude and recheck the plugs and timing on sat morning.

Any other thoughts?
 

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Primary jets = .113
Secondary jets = . 107
rods = .068/.047
spring = orange

Gonna check the screen in the needle seat assy for crude and recheck the plugs and timing on sat morning.

Any other thoughts?
the inards you have in that 600 are for the 750 cfm. They might be putting too much fuel for the air available.
Here's a link for all Edelbrock carbs, page 9 has the specs for all Edelbrock carbs- http://www.edelbrock.com/automotive_new/mc/carbs_acc/pdf/carb_owners_manual.pdf

I'd put it back to the stock specs to get a baseline and go from there. Also, fuel pressure shouldn't exceed 6lbs at idle or go below about 2lbs at WOT.
 

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Float drop

Every Edlebrock carb I've ever seen had low float level from the factory, and, the float drop was less than desired. Also, what size fuel line, from the tanks to the pump, to the carb. Sounds like a "volume" issue, rather than pressure........Ray
 

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Discussion Starter · #16 ·
Every Edlebrock carb I've ever seen had low float level from the factory, and, the float drop was less than desired. Also, what size fuel line, from the tanks to the pump, to the carb. Sounds like a "volume" issue, rather than pressure........Ray
Floats measured to spec. Not sure bout the fuel line size but it was the same as the banjo fitting so no restriction down stream of the pump and I maintain 5 psi at WOT.

Good thoughts though.
 

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Discussion Starter · #17 ·
the inards you have in that 600 are for the 750 cfm. They might be putting too much fuel for the air available.
Here's a link for all Edelbrock carbs, page 9 has the specs for all Edelbrock carbs- http://www.edelbrock.com/automotive_new/mc/carbs_acc/pdf/carb_owners_manual.pdf

I'd put it back to the stock specs to get a baseline and go from there. Also, fuel pressure shouldn't exceed 6lbs at idle or go below about 2lbs at WOT.

Went back to factory specs once already. Going to read the plugs again this weekend with new spark plugs before I adjust again.

Fuel pressure is 5.5 max, 5 at WOT.
 

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ever see where the timing was at during wot?
 

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Drop

Floats measured to spec. Not sure bout the fuel line size but it was the same as the banjo fitting so no restriction down stream of the pump and I maintain 5 psi at WOT.

Good thoughts though.
Is the float drop also to spec? ......Ray
 
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