By list number that is a 850 cfm and jets are 88/96.
I think carb bigger than needed but think there is another problem also.

Is this a 330hp454 or 365hp 454 ?

What part # Eddy intake ? Got a pic of it on the boat ? What I’m getting to on intake questions, if a spread bore intake, it needs a thin adapter/sealing plate between squarebore carb and spreadbore intake for carb baseplate gasket to seal.

Edelbrock 2732


https://cimg1.ibsrv.net/gimg/www.off...30e8e67a6.jpeg

Post #47, with the pic of your spark plug, has me wondering if that is fuel or oil fouled. Oil fouled will be shiny. Fuel fouled will be shiny too until the fuel evaporates, then it turns to a dull black. Curious if the old plugs still look shiny or not.

Also, what does the exhaust look like? If you running rich enough to foul the plugs, the exhaust should be a black color. If oil is burning, it will be a blueish color..

I'm not sure which 454 it is. It's a 1993 with a bravo 1.
https://cimg9.ibsrv.net/gimg/www.off...0fdde521e7.jpg
https://cimg8.ibsrv.net/gimg/www.off...5e8e9c2296.jpg

I was able to regulate fuel pressure down to 5-6psi and there was no change. Still no idle. I'll also add that I can get a pretty consistent backfire through the carb on a restart with to much throttle, and if I try to save it after it wants to stall. It let's out a backfire through the carb, and then will pick itself back up and run

Have more questions before statement :) . This is your pic from post #14. Where does that black vacuum line from carb go to ?


https://cimg8.ibsrv.net/gimg/www.off...49ed86c79.jpeg

It is capped off

Transom is getting black from the exhaust, Ill get a picture of the old plugs tonight but they are definitely a dull black now.

Black soot is rich. As Smitty said, all things being good, likely a power valve. They do not like backfiring-- at all. You might squeeze 1 or 2 by it, but it sounds like it's been pounded. PV is ported to the manifold and takes a direct hit. It's in the metering block, unscrews, has a number stamped on the face representing vacuum to open. It's kind of odd. Idle vacuum divided by 2 gives the number of PV you need. If you don't know the idle vacuum, a 6.5 is a safe bet. Try it, might be the fix. It ​​​​​​​

I have already replaced the power valve with no change. I was able to briefly measure vacuum a while back at 1000 rpms and it was sitting right at about 12. The power valve that was in it before was a 6.5 and I replaced it with a new 6.5

did this have an answer ?

No sorry,
I was able to check at 1000 rpms and got 10-11 degrees so I figured seeing that timing wasnt an issue.

If timing is good, I'd go ahead and kit it! Also check the floats to see if they are leaking(brass) or saturated (composite) and make sure the check balls are present and loose under the accelerator pump and squirter nozzle. I have taken apart 'rebuilt' carbs that these check balls were missing or stuck. Nothing too complicated makes a Holley flood

Floats are brand new on this carb and it does not have the check balls under the accelerator pump, it has the silicone check valves and those are also new.

Did it ever run right or did you buy it and find out this was the case? Do you have someone else that has a carb to borrow? Doesn't have to be the 'right' carb for the engine, just something that fits and works. Sounds like you've hit all the obvious stuff on this carb. If a different carb works, great, we know are on the right track. If a totally different carb does basically the same thing, then we need to get to the 'not-so-obvious' level. Distributor issue, cam timing off, slipped balancer (moves the timing marks). Wish I was there to help, I'm much smarter sitting over the engine drinking a beer! :drink:

I have another Holley that is working perfectly fine on a SBC I can try but at the time I didnt want to go through the effort of taking it out of the other boat and putting it on this one, I now wish I did this way earlier. Im 99% sure its a carb issue because the motor is pretty clearly getting flooded.

Unfortunately though up here in Michigan we had a 25 degree night earlier this week and I made the call to winterize the boat that night. Im going to take the carb off 1 more time and go through it to see if I can find anything but this motor will not be started back up again until spring time.

Great question.

Answer ?

I was told it ran fine before the carb was rebuilt earlier this summer. Supposedly whoever rebuilt the carb screwed it up.

97 posts and we have our answer......:party-smiley-004:

Sorry, this information was purely a starting point for me and that's all I wanted to use it as. I have no proof or information on what work was done before I got my hands on it other than I was told what I stated above. I have learned over the years to not trust what people "tell" you so I want to make sure all my bases are covered.

Okay. Thanks.

Next question: than why was it rebuilt ?Not running right ?

We are not being pain in the azz, we just aren’t getting all the info.

12” vac at 1k is low for a basic oval port motor.

its all good, lots of smart carb guys on here

I do not know why the carb was supposedly rebuilt. The 12" of vac I read was from the PCV port on the carb so it may be a touch low from actual intake measurements

That’s full intake vacuum source. Great spot to check vac. Need a big adapter for the gauge though. :)

Are the transition slots set on the secondaries?

They were initially set with no slot exposed. I opened them up to match the primaries. About .030" showing.

If I recall, there is no direct correlation to matching the transition slots - they’re independent. Set the secondaries to show a near perfect Square, then the primaries will fall wherever the engine likes once you dial in the idle mixture and speed screws.

Recap of everything I did to the motor:

Ignition Related:
-timing at 10 degrees at 1000 rpms
-new AC delco mr43T plugs
-cap and rotor inspected and cleaned
-wires checked for correct order

Carb related
-New gaskets
-cleaned and inspected bowls and metering blocks
-new needle and seats
-cleaned and inspected accelerator pumps, replaced check valves.
-new 6.5 power valves
-cleaned accelerator pump nozzles
-adjusted secondary transfer slots from showing zero slot to about .030" of slot exposed
-regulated fuel pressure from 8 down to 6psi
-adjusted idle air screws to 1.5 turns out
-adjusted accelerator pumps
-adjusted idle throttle blade screw 1 turn in from all the way disengaged
-adjusted floats to the bottom of the sight hole
-adjusted choke

I think that's everything and none of it made any change to the way the motor ran, or started. Couple others things to note:

-I re used the accelerator pumps and I dont know what size they are. The springs on the primary and secondary were different.
-attached are pictures of the accelerator pump nozzles, it looks like they may have been attempted to be drilled out? https://cimg6.ibsrv.net/gimg/www.off...f6cda782e7.jpg
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https://cimg5.ibsrv.net/gimg/www.off...0bcf6bf22d.jpg

Did you ever pull number 1 plug. And make sure dizzy was dropped right? Have you ever actually seen this motor run right? If not I’d go all the way back to square 1 and start over. You shouldn’t be on accelerators for idle. Do you know if it’s the stock cam?

I would disconnect your throttle linkage, remove carb, set secondary transition slot to a square, reinstall the carb, loosen Idle screw all the way out. Leave the throttle disconnected and start the engine. If there is no change, I would think it is timing related and would loosen the distributor and rotate it to retard the timing. Something isn’t adding up here.

If I understand him, it’s not that the engine won’t slow down, like a linkage issue, when he slows it down it dies. I would think way rich or way lean. The fact that it will idle slower cold than hot makes me think it’s flooding.

OP- can you get a complete carb from someone just to test? If that doesn’t cure it you have serious problem somewhere.

Per my remark #53 on page 6 of this thread. I think it's the simplest thing to do and if it 'works' it would save lot of ghost chasing . No matter how weird it may be.

maybe this will get you fixed up.its not mine,I just happen to see this.

https://boston.craigslist.org/gbs/pt...231585404.html

Just to point out that the listed ad, is NOT a marine carb.

OP posted a pic of his on post #14......

rubber hose betw. the j tubes w/ a cut out in the rubber at the top.:D

That's what we did on our rockcrawling rigs before EFI! I love old school!

Yes, you are correct. It dies when trying to slow it down. Yes I have another holley I can test and I wish one of the first things I did was try this carb. The boat is now winterized though so that test is going to happen in the spring.

Yea, I have said a couple times in this thread that I have another carb I can test on this motor that I know is working. At the time I thought I could pinpoint what was wrong with the problem carb quicker than I could take the working carb off the other boat and install on this one. Obviously I was wrong.

I am unsure if the cam is stock or not. I will check tonight to see if TDC on the #1 cylinder lines up with the balancer.