Carb Rebuild or Buy

[ajexpress]

I need to replace or rebuild the carb on my 454 mag. Can anyone either recommend a place to buy a remanufactured unit, or someone who does excellent work rebuilding them.

Thanks.

 

[ajexpress]

For reference the SN of the motor is D604208

 

[boatman4021]

I have a nice 800 Holley for sale?

 

[SippyRat]

SN of the motor doesn't really help. Anyone could have changed the carb through the years. The carb should have a ID tag under a screw on the top and could possibly be stamped on the base. Cleaning and rebuilding is pretty straight forward. Find the #'s and hit google or call you local marine shop for the kit.

 

[ajexpress]

SN of the motor doesn't really help. Anyone could have changed the carb through the years. The carb should have a ID tag under a screw on the top and could possibly be stamped on the base. Cleaning and rebuilding is pretty straight forward. Find the #'s and hit google or call you local marine shop for the kit.

I got the SN of the engine for reference for a new/reman carb. Like you said who knows what's been put on there, but I suspect it's stock.

 

[SippyRat]

I got the SN of the engine for reference for a new/reman carb. Like you said who knows what's been put on there, but I suspect it's stock.

ajax, my point is this......you already have a carb which you stated in your first post is in need of replacement or a rebuild. this leads me to believe that your engine is not running properly. it also leads me to believe that you are not looking to gain any real performance or deliver more fuel to the engine, you just need it to run better (based on the info I have).

if this is the case then there is no reason to look for a replacement or for someone to rebuild the one you have unless you are not comfortable tackling it yourself. either way rebuilding what you have should be far more cost effective than a replacement carb new or used.

by the way what makes you think you need to replace or rebuild your carb?

 

[ajexpress]

I was skipping past the diagnosis because I've already done some of that on an offshoreonly thread. I'll link the thread when the offshoreonly site isn't down like it has been for the last two days.

Long story short, yes I was having some issues with the engine not running properly. Only when after a long run and then letting it sit for 20-40 minutes, then restarting. It would be rough at idle and stumble when I tried to get on plane. What I found was I could gas my way out of it by keeping the throttle dropped. That lead me to believe the problem was gas related and not electrical. I started a thread on offshoreonly and at the end the conclusion was most likely carb related. So, three options, rebuild it myself, buy a reman, or have it rebuilt by someone else. The largest carb I've rebuilt was a two cylinder motorcycle carb so my initial thought was to buy a bolt on reman and be done with it. If rebuilding the carb I have is straight forward for any half way decent person with a mechanical appititude I'll consider rebuilding it myself.

You are right, with a 454 mag that has 615 hours on it, I'm not looking to upgrade the carb. I'm just looking to replace what is on it.

 

[Jimway]

If the engine starts fine from cold, warms up and then performs properly until being shut down, you may be experiencing 'hot soak' issues on one or more components. If the motor runs fine, post hot soak, after hard acceleration, you might be looking at something else. Resist parts replacing. I guess I'm kind of an 'old school dinosaur' but back in the day, you troubleshot the problem, identified the problem, removed and rebuilt the component, replaced it and returned the motor to tune. Be wary of 'trouble shooting over the phone' and don't overlook the obvious. I can't tell you how many times I've repaired dead marine motors by simply cleaning electrical connections, or merely tuning the thing up( and I'm not talking about spraying carburator cleaner into the motor while reving the **** out of it). I like SippyRat's idea on this one though, if it indeed turns out to be the carb, a rebuild kit is cheep, and you keep your original carb and don't inherit someone elses disaster carberator that some guy or gal in some third world country has cobbled together from three different donor carbs salvaged from the last hurricane aftermath.

 

[ajexpress]

If the engine starts fine from cold, warms up and then performs properly until being shut down, you may be experiencing 'hot soak' issues on one or more components. If the motor runs fine, post hot soak, after hard acceleration, you might be looking at something else. Resist parts replacing. I guess I'm kind of an 'old school dinosaur' but back in the day, you troubleshot the problem, identified the problem, removed and rebuilt the component, replaced it and returned the motor to tune. Be wary of 'trouble shooting over the phone' and don't overlook the obvious. I can't tell you how many times I've repaired dead marine motors by simply cleaning electrical connections, or merely tuning the thing up( and I'm not talking about spraying carburator cleaner into the motor while reving the **** out of it). I like SippyRat's idea on this one though, if it indeed turns out to be the carb, a rebuild kit is cheep, and you keep your original carb and don't inherit someone elses disaster carberator that some guy or gal in some third world country has cobbled together from three different donor carbs salvaged from the last hurricane aftermath.

The engine does not start fine. It usually takes at least two tries, and after started I have to keep the throttle at 1K to keep it running. If I start and bring it to neutral it will barely stay idling...and probably die. After it warms up for a bit, it runs fine.....until the previously mentioned issue happens.

 

[wired]

If its a holley you might just have a blown power valve. $7 part plus a set of bowl gaskets.

 

[atc250r]

My last I/O did that when the fuel got some water in it. Just food for thought.

 

[ajexpress]

My last I/O did that when the fuel got some water in it. Just food for thought.

When I've had gas with water in it, it usually slightly cuts out while running. Having an issue starting, but no issue while running doesn't seem like water in the gas, but I did put some seafoam in the tank before it was winterized.

 

[atc250r]

When mine did it it started out as stalling/running rough at idle then progressed to missing while running too. If it is in fact water in the gas Seafoam won't get rid of it. Ended up pumping out the tank and starting with fresh fuel and water separator. Found crud from it in my carb too and that was just after I rebuilt it.

 

[RNGRDVE]

Did you check the timing? I've seen similar issues on cars.

 

[Gimme Fuel]

Vapor lock issue? He said runs rough/starts hard after long runs. That matches well. Im not a big carb guy though. Powervalves, float bowls, and jets scare me. Fuel injectors, sensors, and computers excite me though....

Only carb I trust myself to rebuild is a Mikuni.

 

[atc250r]

Going with what Dave mentioned about the timing. Don't ASSume the balancer marks are accurate. Had the outer ring slip on two Chevy's. One my boat 305 and one my Nova 454.

 

[Jimway]

"Only when after a long run and letting it sit for 20 to 40 minutes, then restarting." The 'cold start' I am refering to would be a start from an extended shut down such as overnight. What type of carb? What type of choke/cold start enrichment? If you have experienced water in the fuel, you will find yourself closely familiar with all of the components of the fuel system as you clean them all up again, and remove all traces of water, if not done already. Has it been recently tuned, ie, compression test, battery check and cable resistance, oil and filter, spark plugs and ignition check, base and dynamic timing, crankcase ventilation system, fuel filters and running fuel pressure, cold start operation, ignition/ shift timing/ idle speed retarder(if present), Timing chain backlash(617 hours on motor).