Dies when put in gear
 

I have stock 454's with holly carbs and thunderbolt ignition. The port motor sounds as if its not firing on all cylinders but runs fine above idol. However when you put it in gear the RPMs drop quick so you have to give it a little throttle to kept it going. It runs great after that with no problems. I have changed the plugs, wires, cap, coil, and rotor and nothing has worked!!!!

Any ideas???

Is the carb flooding?

I dont believe so but I can check. What is the best way to do so?? Is that a problem that can just start? It has been fine until I did about a 45 mile harbor hop and the problem started the next day

You might have a piece of debris stuck in one of your idle circuit air or fuel bleeds.

Drain the bowl of the carb into a cup and check for water in the fuel. When the boat sits the water lays on the bottom of the bowl if there are any and makes it hard to start and hard to keep idleing in gear.

What is the best way to clean that out?

Check the front float. Make sure bowl has gas to the sight screw.

Pull off the bowls and metering blocks. Spray carb cleaner through all the holes in the metering blocks and then compressed air.

It could be that, but I would also verify that the timing has not moved first.

Also, does it seem like its running rich at idle???? It could be blown powervalve.

I doubt its water in the fuel. It would run like crap all the time, not just at idle.

you might try tweaking your idle mixture setting before digging in too deep. try turning them in or out a bit

[QUOyou might try tweaking your idle mixture setting before digging in too deep. try turning them in or out a bit TE][/QUOTE]yes try that first

I'll be at LOTO for a week from June 12-19th and could probably take a listen and try and make some carb adjustments.

Can the carb make the engine sounds off??? And just to clearify it does idol just fine but sounds off its when you pop it in gear at idol it tries to die right away

Griff thanks for the good advice as usual. I will mess with the carb this weekend and see what we can come up with. If I cant seem to get anything fixed I will be more than happy for you to come look at it when you are down. So I can get this right before the poker run.

It could just need an adjustment and adjusting the air bleeds may help some at least.
The problem started all of a sudden so I would suspect some small debris in the fuel got into the carb.

My port engine does the same thing. it idles fine in neutral, but the minute i put it in gear, the rpms begin to drop & it will eventually die. i throw it in neutral, start start it up & idles fine. throw in gear, same thing. if i give it a touch more throttle it does fine while in gear.

You may have the throttle blades to far into the transfer slot. Pull the carb and measure as is currently adjusted...target .020-.025"

If the other engine behaves well, try swapping carbs.

BT :cool:

have you pressure checked your exhaust manifolds recently? I had the same problem last year and found out one of my exhuast manifolds were leaking water into one of my cylinders. No major damage just annoying. I found out after I pulled the motors to do some work on them noticed rust in the exhaust port. my.02 good luck I hope you figure it out.:evilb:

Is your shift interrupter switch sticky? It should only cut dist power for a split second. If its taking too long to resume power to the dist, it could cause the problem you're having.

He does not have a shift interupt.

I may try swapping carbs this weekend and if thats not it I may give griff a stab at it when he gets down to the lake in a few weeks.

Have you looked at the plugs when you pull them? Try idling it for a while under the condition where it sounds bad. Then pull the plugs and see what they look like. You'll be able to tell if it's one cylinder, one bank, all lean, or all rich. That will give you a better idea what to look for.

You can also try swaping carbs and/or ignition if one engine is running good. See if it follows one particular component.

I'm gonna go in an opposite direction here. It sounds lean to me... Pull the flame arrestor off and look down the venturi's to verify proper operation. I've found that shift stalls are usually from being lean on holley's. If the carb is dumping you'll know it at idle. I'd try backing out the mixture screws little by little and see how it effects the idle/shift. Lots of other things to check but I'd probably start with that.

Also, do a visual inspection to be sure all the rubber vacuum plugs are in place and not rotted/cracked, that will also do it.