which carb to upgrade/replace too

bigtoe

Seaman
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Apr 21, 2009
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69
Hi my carb has now passed its end of life. A good boat mechanic has now told me. we cannot get it to maintain a constant . They stripped it down and rebuilt it but they say the jets are now proved to be worn.
So my thinking is what to replace it with , it's a holly 082500 on a 3.0L Volvo Penta block. Blocks been replace but the carb is existing 1998/1999 manufacturer .
Any thoughts guys or any one replaced there's with something better and cheaper ( I can only hope)
many thanks
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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It's a Holley 500 CFM 2300.

There are only 6 moving parts

Get a new mechanic. Seriously, get a new mechanic

Only once have I ever had a Holley that could not be simply rebuilt. And that is because it was acid dipped

Jets are replaceable, and only $2 each

Bowls gaskets are about $2, so are metering plate gaskets

The issue is most mechanics working today do not know how to work on carburetors
 
Last edited:

bigtoe

Seaman
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Apr 21, 2009
Messages
69
It's a Holley 500 CFM 2300.

There are only 6 moving parts

Get a new mechanic. Seriously, get a new mechanic

Only once have I ever had a Holley that could not be simply rebuilt. And that is because it was acid dipped

Jets are replaceable, and only $2 each

Bowls gaskets are about $2, so are metering plate gaskets

The issue is most mechanics working today do not know how to work on carburetors
Well he really did get it running sweet as , I’d never heard it start and sound so smooth . Then when we opened up it kept dying.
He came out on the boat with some gauges and re set it up , sounded again really sweet. Went for a run or two and all was great, dropped him back at the quay and then a run or two later , same issue , then it would not hold idle so I had to speed it up . Just seemed to dance all over the place with problems .
I’m in the uk and I know the refurb kit we get here do not include jets . It’s a Volvo dealership and like I said he did seem to know what he was talking about
 

Scott Danforth

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What is your compression?
What is the fuel pressure?
What is the timing set to?

Dying on WOT is most likely fuel delivery, not the carb

Doubt the carb need replacement. Been wrenching on Holley carbs for over 50 years

Summit racing can get you jets in 3 days from the states. Can even get you in touch with real gear heads in the UK.

Most you need to rebuild the 2300 is 3 gaskets, a needle and seat cartridge, a new PV, and a new acceleration pump kit
 

bigtoe

Seaman
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Messages
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Thanks Scott the guys at the Volvo Penta work shop adjusted the timing again whilst out on the boat, im unsure what they adjusted it to , compression is good it’s only a few years old now and sounded superb when first started up and runs superb , but not as consistent as id like.
When I say it dies at WOT what I should be saying is if I gun it from idle to WOT it can die ( choke it seems) . If I tickle it through the intial stumble then slowly increase to WOT. It goes great. If we are planning and I go straight to WOT it does not miss a beat it just pulls .
So my main concern is at idle/ pooling along for 20 mins at 4knotts to get to open water it seems to start to be not consistent .
Hense why they say the carb is worn and they cannot get it to behave consistently .
Does that ring true or are they missing something in your opinion ?
Thanks
 

Scott Danforth

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When I say it dies at WOT what I should be saying is if I gun it from idle to WOT it can die ( choke it seems) . If I tickle it through the intial stumble then slowly increase to WOT. It goes great. If we are planning and I go straight to WOT it does not miss a beat it just pulls .
the part changer at the dealer (can not call them a mechanic) did not clean out the accelerator pump passage. on a holley, that is on the bottom of the fuel bowl and first to plug.

you are describing a failed accelerator pump circuit. again, your carb is fine, just needs $10 worth of cleaner and gasket. this is something you could even do.

you are not getting fuel thru the squirter.

stop going to that mechanic.

get a bowl gasket and a metering block gasket. if you do not know what you need. go here https://forums.iboats.com/threads/searchable-holley-carb-list.771381/
and download the spreadsheet I put together. look for the list number you have and get the appropriate bowl and metering block gasket.

if the ones you have are blue, they are reusable

disconnect the fuel line

pull the 4 bolts on the face of the bowl, these are #12 screws and you will have either a hex or a slotted screw head

use the handle of the screw driver and tap the bowl on the side to crack teh gasket loose. to not pry

same goes for the metering plate

now at the bottom of the bowl where it meets the metering plate is a small passage. that is plugged and needs to be mechanically and chemically cleared

the ONLY way to clean that is with solvent and manual probing. they need to run a fine piece of copper wire or fishing line thru it to ensure it is clear.

and no, you can not simply spray carb cleaner from a can and hope it works.
 

Scott Danforth

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1770113725149.png
here is a side view of the carb. the newer ones have hex screws, the earlier ones have slotted scrws.

the whole kit is holley part number 703-036, however you only need the two blue gaskets.
1770113838291.png

you can buy a two pack from Summit and with shipping, etc. have it to you in the UK by Friday.

there are about 40000 youtube videos on rebuilding a holley 2300 or 4150.
 

Scott Danforth

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I will add, if you choose to rebuild the carb yourself, we will walk you thru it.

but there are many capable carburetor shops in the UK

1770119366879.png
 

bigtoe

Seaman
Joined
Apr 21, 2009
Messages
69
the part changer at the dealer (can not call them a mechanic) did not clean out the accelerator pump passage. on a holley, that is on the bottom of the fuel bowl and first to plug.

you are describing a failed accelerator pump circuit. again, your carb is fine, just needs $10 worth of cleaner and gasket. this is something you could even do.

you are not getting fuel thru the squirter.

stop going to that mechanic.

get a bowl gasket and a metering block gasket. if you do not know what you need. go here https://forums.iboats.com/threads/searchable-holley-carb-list.771381/
and download the spreadsheet I put together. look for the list number you have and get the appropriate bowl and metering block gasket.

if the ones you have are blue, they are reusable

disconnect the fuel line

pull the 4 bolts on the face of the bowl, these are #12 screws and you will have either a hex or a slotted screw head

use the handle of the screw driver and tap the bowl on the side to crack teh gasket loose. to not pry

same goes for the metering plate

now at the bottom of the bowl where it meets the metering plate is a small passage. that is plugged and needs to be mechanically and chemically cleared

the ONLY way to clean that is with solvent and manual probing. they need to run a fine piece of copper wire or fishing line thru it to ensure it is clear.

and no, you can not simply spray carb cleaner from a can and hope it works.
Yes that helps, they used an ultrasonic ( I think that’s correct terminology ) to clean it .
I have stripped it in the past and cleaned it ( years ago over Xmas and cut up cardboard for the gaskets from a Kellogg packet , I was really wanting it back on the water 🤣.
Really appreciate your time and help .
I’ll have a go at it, do you think it’s worth me getting new jets?
 

bigtoe

Seaman
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Messages
69
Thanks for those images and links as well .
I’m a plumber by trade and am allways trying to fix rather than buy new, so I am very grateful for the help 🤙🏽🤙🏽
 

Scott Danforth

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Yes that helps, they used an ultrasonic ( I think that’s correct terminology ) to clean it .
that did not mechanically clean the passage
I have stripped it in the past and cleaned it ( years ago over Xmas and cut up cardboard for the gaskets from a Kellogg packet , I was really wanting it back on the water 🤣.
you are lucky you did not blow up. cardboard is not fuel proof

I’ll have a go at it, do you think it’s worth me getting new jets?
only if the parts changer at the dealer boogered up the jets. not much to them. its a brass screw with a hole in it.
 

Scott Danforth

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Thanks for those images and links as well .
I’m a plumber by trade and am allways trying to fix rather than buy new, so I am very grateful for the help 🤙🏽🤙🏽
I apprenticed under my grandfathers Heating and Plumbing business from the time I was 12 to about 18. he was looking for help, I managed to get a lot of experience. I can re-plumb a house and service the HVAC.... Dad got me into turning wrenches on cars at the early age of 3. learned how to rebuild holley carbs from an old grey bearded hot rod shop owner back in about 1973 or 1974
 

Scott Danforth

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FYI, you should not need to pull the carb or strip it, only remove the bowl and metering plate to clear the accelerator pump circuit.

this will help you. https://www.carburetor-parts.com/assets/manuals/holley-2300-4160-manual.pdf

1770121111401.png


clean out this passage. you will need to carefully remove the accelerator pump cover and diaphragm. you will have either the rubber mushroom check or a real check ball check for the primary check

1770121241938.png


the secondary check is in the discharge nozzle, make sure that is removed and cleaned too. with the throttle blades closed, choke blades held open, use a #3 Phillips screw driver, and remove the screw holding the discharge nozzle, there is a round crush washer under the nozzle, and in the nozzle is a weighted ball check or a fuel needle used as a check. simply make sure the check moves freely.
 

bigtoe

Seaman
Joined
Apr 21, 2009
Messages
69
I apprenticed under my grandfathers Heating and Plumbing business from the time I was 12 to about 18. he was looking for help, I managed to get a lot of experience. I can re-plumb a house and service the HVAC.... Dad got me into turning wrenches on cars at the early age of 3. learned how to rebuild holley carbs from an old grey bearded hot rod shop owner back in about 1973 or 1974
Love that , I’ll get the carb off and have a look at that hole 🤙🏽🤙🏽
 

bigtoe

Seaman
Joined
Apr 21, 2009
Messages
69
Great I’ll get the bowl off , I can’t behave I used Kellogg cardboard and got away with it, was on there at least two years🤣, I’m sure they are hex nuts not straight screw slots
 

Lpgc

Petty Officer 1st Class
Joined
Jun 17, 2023
Messages
399
Bought a Holley carb rebuild kit for mine when I rebuilt the engine a couple of years ago, haven't done it yet because the carb seems fine. The only thing is it likes a little throttle to start it cold or hot.
 
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