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View Full Version : New Carb. Still rough idle??


SunCoast 83
04-25-2012, 03:35 PM
Hey guys. I just spent some$$$ to put an end to my ongoing carb issues. I just had the Holley Carb, fuel lines, fuel pump all replaced. In addition our dealer dumped the tank and I added fresh 93 octane gas and Stabil treatment

In running it today it's at about 98% great. It is still having a rough idle but faster speeds and hole shot are good. Is it possible that it may need to tweaked? Like the idle??

I am gonna meet someone from the dealer at the ramp next week. I hope this is it. Anyone else have a similar experience?

Jim@BAWS
04-25-2012, 06:46 PM
Is the timing set correctly? Should be 8 deg BDC
What plugs are you running? Champion RV12YC or AUTOLITE 24s
Are you running points and condensor or breakerless?

Are the bowls adjusted correctly for a motor that sits at a 12 deg slant?

These are all things you need to consider

Jim@BAWS

thatsmrmastercraft
04-25-2012, 08:32 PM
Is the timing set correctly? Should be 8 deg BDC
What plugs are you running? Champion RV12YC or AUTOLITE 24s
Are you running points and condensor or breakerless?

Are the bowls adjusted correctly for a motor that sits at a 12 deg slant?

These are all things you need to consider

Jim@BAWS

Especially good point most won't consider.

ALL the basics first. After that, it might need a little mixture screw adjustment.

Jim@BAWS
04-25-2012, 09:23 PM
Especially good point most won't consider.

ALL the basics first. After that, it might need a little mixture screw adjustment.

Moved again naturally

SunCoast 83
04-25-2012, 10:03 PM
I believe points not breakers. It has new plugs and wires too.
Our local dealer is supposed to meet me at the ramp next week.

I did not consider the slant degree of the engine block. I can pass that along too.

Thanks for the feedback so far I really appreciate it

SunCoast 83
04-25-2012, 10:09 PM
Jim,
It has Autolite Plugs in it.

SunCoast 83
04-25-2012, 10:21 PM
When putting in a new Carb, does it take a bit to work the bugs out of it??

Cloaked
04-25-2012, 10:26 PM
When putting in a new Carb, does it take a bit to work the bugs out of it??Not really. It should be plug-and-play for the most part, if it's a new Holley 4160. There is one area for tweaking and that would be verification that the electric choke is set properly, but it should be close if not dead on, from the box. You are talking a new carb, not a rebuilt, correct?

Also you may want to see that the accelerator pump is set to respond upon throttling up. That is a visual to see when the throttle is moved forward that the pump lever is responding and no gap is there to allow a hesitation or skip. Be patient. Also, I presume you have the 1" spacer plate and two new gaskets when you reinstalled the new carb.

Idle set at ~700-800 RPM? + / - a few...

Also the air screws should have come properly set but there is an area to consider. Typically an idle issue is not impacted by the air screws as much as overall accelerating performance, thus I hesitate to mention.


.

SunCoast 83
04-25-2012, 10:34 PM
Yes. It is a brand new 4160

I notice the rough idle only after it has warmed up. Running more than 20 min.

Cloaked
04-25-2012, 10:36 PM
Yes. It is a brand new 4160

I notice the rough idle only after it has warmed up. Running more than 20 min.
Still pondering. The spacer plate is essential.

Does it start OK after 20 minutes? I have seen them stall upon a hot start.

petermegan
04-26-2012, 07:06 AM
Suncoast, I reckon if it is just when it warms up you will find the mixtures need a bit of a tweek. just my .02

east tx skier
04-26-2012, 09:09 AM
When I replaced mine on my old boat, the only thing I ever had to adjust was the idle. It was set at about 480. I brought it up to about 600 and it ran like a top.

Kyle
04-26-2012, 10:33 AM
Run the mixture screws in and count the rotation. Write the amount of turns it takes to seat the mixture screws down. Loosen the mixture screws 2 full turns.

360* turn is 1 rotation 180* is 1/2 rotation.

You may need to go to 2 1/2 rotations but mine did not.