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Calling the boat carb masters, lots of fuel still lean.

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Calling the boat carb masters, lots of fuel still lean.

Old 06-22-2021, 05:12 PM
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Originally Posted by resurrected View Post
O2 sensors are easy to install, I made the spacers for mine, and with an extension like the Innovate motorsports one, they should stay dry.
That is what I thought of doing. Guess I need to give you guys the whole story. Here is the deal thought I had it running right the end of last summer. Ran good came out of the hole good but seemed to be laboring mid throttle. Checked the plugs and they were black. PV checked good so I started leaning out the jets and it started getting wierd not acting right and the transom was getting black. Put fresh plugs in it when I stared jetting it. Just never acted right the last time I had it out and end of summer. Took carb off put it on my bench didnt look at it for a couple months. Sat down one night looked at it started checking stuff. After I got the mighty vac out and checked the power valve it was seeping then when I pumped it up more it just blew out. So all the tuning I had done up to that point was out as I put a new power valve in and ot was lean in the mid throttle.....and was worse then it is now which I equate to not knowing how much fuel was seeping through the pv that wasn't fully blown out. This was memorial day weekend .

Talk to guys at quick fuel and set it up the same as there m650, bleeds restrictors everything, I just added two jet sizes to make sure it was rich enough. Took it out last weekend. Cruised mid throttle as it was pretty choppy, had that raspy lean sound to it give it more throttle to get up on top of the chop and go but it still sounds lean. Stop check plugs crispy white, idle around a bit, stop jet up 2 more sizes front and back, give it a 1/4 turn on all 4 screws. Sounds a little better WOT but not great still got the raspy nasty lean sound in the mid plugs still crispy white.
Reason for asking for some Boat Carb Masters help is we go racing this weekend (go team Capco). Want to take it out 4th of July and really don't have the time to mess with spacer and putting the LM2 on it right now, but still get it rich enough that I don't have to worry about burning the valves out of it or stop every 20 min and check plugs put bigger ifrs in it as the base tune on quick fuel m650 definatly not enough for it with or without 4 more jet sizes on each end.

Thats where I am at right now lol sorry for the long post. Thanks for your guess help.
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Old 06-22-2021, 06:07 PM
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Originally Posted by fbc25el View Post
What size are the boosters and angle channels? I am thinking they should be around .140. If they are too small you can throw more jet at it and it won't help.
they are .140s
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Old 06-22-2021, 06:20 PM
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Originally Posted by fbc25el View Post
What size are the boosters and angle channels? I am thinking they should be around .140. If they are too small you can throw more jet at it and it won't help.
they are .140s
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Old 06-22-2021, 06:30 PM
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may have missed it but what exhaust is on this? also need cam specs as was mentioned earlier it may be reverting some.
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Old 06-22-2021, 06:48 PM
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A too lean sound to me while cruising and throttle not moving is on/off hesitation and a lean pop thru intake hear and there.

So you have me lost on this lean exhaust noise thing.

You need to get a hold on your tuning issues. Why was a 650 so damn rich with out of the box jetting ? Was it really just the PCV ? Kind of hard for me to believe that especially with it turning transom black and such. Was fuel psi ever checked ? Some of these marine mechanical pumps can be all over the place but where we want them. Manufacturing has seemed to take a dump with these too.

If you carb doesn't have the same metering blocks, boosters, venturi size, plate size, etc, I don't get why you changed all those other things to same as a M650.
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Old 06-22-2021, 06:56 PM
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Originally Posted by compedgemarine View Post
may have missed it but what exhaust is on this? also need cam specs as was mentioned earlier it may be reverting some.
Glenwood marine manifolds, with Hardin stainless risers pretty short have to measure them, then straight out the back. Wont let me send pics yet get to have 10 posts. Cam is a Comp Cams 08-501-8 xr264hr-12, 212 in dur, 218 ex dur at 50 112 lobe separation.
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Old 06-22-2021, 07:24 PM
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Originally Posted by SB View Post
A too lean sound to me while cruising and throttle not moving is on/off hesitation and a lean pop thru intake hear and there.

So you have me lost on this lean exhaust noise thing.

You need to get a hold on your tuning issues. Why was a 650 so damn rich with out of the box jetting ? Was it really just the PCV ? Kind of hard for me to believe that especially with it turning transom black and such. Was fuel psi ever checked ? Some of these marine mechanical pumps can be all over the place but where we want them. Manufacturing has seemed to take a dump with these too.
650
If you carb doesn't have the same metering blocks, boosters, venturi size, plate size, etc, I don't get why you changed all those other things to same as a M650.
Think I am not getting the lean pop or hesitation when moving the throttle is that I got the acellerator pumps taking care of that.

The lean sound i am talking about is hard to explain.

Don't really have an out of the box jetting as it has a hp650 main body which they recommended 68 and 78s m650 is richer then that just a little diffrent high speed bleed bit not much.

Power Valve leaking was doing the black transom. When they leak don't know from where or how much fuel it is getting coming through vacuum ports and so on.

Fuel pump is a carter electric marine pump 6an line earls 100gph pre filter mercruiser filter separator after. 6.5 psi at carb idle and WOT

Setup is the same as M650 emulsion jets, ifrs, pvcr, .140 down leg boosters, jets, venturi size, throttle blade size, I guess the m650 does have a choke horn but really never seen them make much difference when the chokes off.
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SB (06-22-2021)
Old 06-22-2021, 07:36 PM
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Okay, that cam is not big. It has been used a bunch in mild 350 marine engines. The 218/224 112 even more. And several with the 224/230 112LSA.

Stock exhaust fine with with your cam

It should use very near box stock jetting from any 650 built correctly from the manufacturer.
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Old 06-22-2021, 08:06 PM
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How to install oxygen sensor bungs.
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Old 06-23-2021, 06:36 AM
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It sounds like you need the boosters to come in quicker. I would go with 2 emulsion @1 & 3 at .028 and drop the HSAB to .069.
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