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Mercarb chokes. Functional?

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oxnut85

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2001 Chapparal Signature 28, Just got it, twin 4.3 262 V6's with Mercarb 2 Barrels. is the choke supposed to work? Mine are stuck open because the link goes to a bell crank that is held tight by a screw (no swivel). One is oxidized in place and wont move anyway, (PB Blasted it and it freed up a bit) but the screw on the linkage bell crank is binding the linkage and choke plate open, is this normal or the way its intended to be? The Starb engine took for ever to start, like 3 - 10 second cranks before it sucked enough fuel in. Thats why I was thinkin' choke, and its elect choke heater on there? Didn't know the Mercarbs actually had an Accelerator Pump, so I'm using that as my start enrichment. I release the shifter for just throttle actuation, and start cranking dry then pump the throttle twice after the cranking starts and two turns, fires right up. So, are the chokes actually supposed to be functional? or did the guys before me screw these up?

Greg
 
Having the chokes stuck open isn't the end of the world but the fact that they are messed up would make me nuts. That's just me tho. 20 year old carbs with unknown history need to be renewed or rebuilt. Yes electric choke.
 
oxnut85 said:
2001 Chapparal Signature 28, Just got it, twin 4.3 262 V6's with Mercarb 2 Barrels. is the choke supposed to work? Mine are stuck open because the link goes to a bell crank that is held tight by a screw (no swivel). One is oxidized in place and wont move anyway, (PB Blasted it and it freed up a bit) but the screw on the linkage bell crank is binding the linkage and choke plate open, is this normal or the way its intended to be? The Starb engine took for ever to start, like 3 - 10 second cranks before it sucked enough fuel in. Thats why I was thinkin' choke, and its elect choke heater on there? Didn't know the Mercarbs actually had an Accelerator Pump, so I'm using that as my start enrichment. I release the shifter for just throttle actuation, and start cranking dry then pump the throttle twice after the cranking starts and two turns, fires right up. So, are the chokes actually supposed to be functional? or did the guys before me screw these up?

Greg
Click to expand...

If you are that unfamiliar with the starting procedure for carbed engines, it would be best to find someone who knows this and spend some time understanding that it is not like fuel injection. It takes a certain manual method to properly start a carbed engine.

here is a basic starting procedure,

1. Push/disengage shifting so you have throttle only function of shift control handle.
2. Pump handle several times at least 3/4 of throttle handle movement at least 3-4 times.
3. Return handle to ~ 10:00 position (which will cause engine when it starts to be high rpm) and when engine does start YOU manually control rpm.
4. maintain 1500 rpm for ~ 1 minute, may take longer. Once engine has warmed up enough you then can move throttle to neutral position and engine should idle normally. If not continue to maintain higher idle until it does.


Carbed engines require manual control for starting until engine idles normally.







Chokes must function as designed. If not it will cause hard starting.

As prior comment, best to have refurbished or replaced so you get proper function and get to enjoy your new boat.
 
Thanks for the reply Jack, much appreciated, but you missed my point, my question was specifically if anyone knew Mercarbs and if the chokes were supposed to be functional. (I assumed so, Butt) I am 60 and have rebuilt 1 barrels and 5 or Q-Jets, (one on my 78 T/A 455 .030 over, runs awesome) any way, it just seemed odd that both had the same bound up choke linkage that was prohibiting functionality. I actually prefer to pump the throttle and actuate the accelerator pump into a moving stream of air through the intake instead of letting it drip to the bottom of the intake, but that's just me. TY, I did appreciate your response.

Greg
 
oxnut85 said:
Thanks for the reply Jack, much appreciated, but you missed my point, my question was specifically if anyone knew Mercarbs and if the chokes were supposed to be functional. (I assumed so, Butt) I am 60 and have rebuilt 1 barrels and 5 or Q-Jets, (one on my 78 T/A 455 .030 over, runs awesome) any way, it just seemed odd that both had the same bound up choke linkage that was prohibiting functionality. I actually prefer to pump the throttle and actuate the accelerator pump into a moving stream of air through the intake instead of letting it drip to the bottom of the intake, but that's just me. TY, I did appreciate your response.

Greg
Click to expand...

yes quite obviously they are supposed to be functional. Likely what happened is they stuck closed repeatedly (happened to me) which will kill the engine by fouling plugs. I forced mine open a ran for many years like that just had rough starts on cold wet mornings. Ultimately when you could get a new aftermarket electric choke coil for $30 i fixed it
 
oxnut85 said:
2001 Chapparal Signature 28, Just got it, twin 4.3 262 V6's with Mercarb 2 Barrels. is the choke supposed to work? Mine are stuck open because the link goes to a bell crank that is held tight by a screw (no swivel). One is oxidized in place and wont move anyway, (PB Blasted it and it freed up a bit) but the screw on the linkage bell crank is binding the linkage and choke plate open, is this normal or the way its intended to be? The Starb engine took for ever to start, like 3 - 10 second cranks before it sucked enough fuel in. Thats why I was thinkin' choke, and its elect choke heater on there? Didn't know the Mercarbs actually had an Accelerator Pump, so I'm using that as my start enrichment. I release the shifter for just throttle actuation, and start cranking dry then pump the throttle twice after the cranking starts and two turns, fires right up. So, are the chokes actually supposed to be functional? or did the guys before me screw these up?

Greg
Click to expand...
Merc carbs are a poor design. Copied from Rochester when they went to fuel injection. Not sure why the person who copied the Rochester carb left off the choke pull off. As a result you can't set the choke rich enough when the engine is cold.Got to love engineers!!
 
888mustang said:
Merc carbs are a poor design. Copied from Rochester when they went to fuel injection. Not sure why the person who copied the Rochester carb left off the choke pull off. As a result you can't set the choke rich enough when the engine is cold.Got to love engineers!!
Click to expand...

The mechanical choke pull off is only used with mechanical choke set ups ("choke chimney with by-metal spring) when mounted to the manifold.

When there is a electric choke, the adjustment of the bi-metal spring by rotating the choke disc determines the richness of cold starts.
 
kghost said:
The mechanical choke pull off is only used with mechanical choke set ups ("choke chimney with by-metal spring) when mounted to the manifold.

I'm a auto tech 40 years . Most cars in the 80s had a electric choke and had to have a choke pull off because they were tuned so lean for pollution reasons.
With a choke pull off you can set the choke much richer without choking the engine when cold. If my 3.0 mercruiser had a choke pull off I wouldn't have to warm up
my boat for a few minutes. Never had to warm up 80s cars for more than a few seconds.
Click to expand...
 
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