Fixed Vs. Adjustable High Speed V4

yorab

yorab

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1963 75hp Starflite. My original carb had a stripped screw hole in the choke butterfly shaft and I had a few other things wrong, so I bought a used 2 bbl carb from an early model V4 to scavenge parts from. The newly purchased carb is identical to mine except that it has adjustable high speed whereas my original had fixed high speed. I'm wondering which is better. Can they be interchanged on the same motor? Advantages? Disadvantages? I see that OMC offered an "accessory adjustable high-speed needle valve kit", part #379189 for the '63 75hp. Was this considered an "upgrade" to the "base" fixed high speed? If the adjustable is a better system and will work on my motor, I may change it over. Thanks.
 
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F_R

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Re: Fixed Vs. Adjustable High Speed V4

yorab said:
1963 75hp Starflite. My original carb had a stripped screw hole in the choke butterfly shaft and I had a few other things wrong, so I bought a used 2 bbl carb from an early model V4 to scavenge parts from. The newly purchased carb is identical to mine except that it has adjustable high speed whereas my original had fixed high speed. I'm wondering which is better. Can they be interchanged on the same motor? Advantages? Disadvantages? I see that OMC offered an "accessory adjustable high-speed needle valve kit", part #379189 for the '63 75hp. Was this considered an "upgrade" to the "base" fixed high speed? If the adjustable is a better system and will work on my motor, I may change it over. Thanks.
Click to expand...

Well some people just figure they should be able to fiddle with the needles and couldn't stand it when they were gone. So they were offered a kit to get them back.

If everything is right with the motor and the carburetor is clean, I defy you to set the adjustable needles more accurately than the fixed jets. The usual procedure was to open them 1/2 turn + two clicks and let it go at that. Let the gas flow.....
 
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blk98gt

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Re: Fixed Vs. Adjustable High Speed V4

I think this is covered in the repair manual. I don't have it in front of me right now. Do you have a manual?
 
yorab

yorab

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Re: Fixed Vs. Adjustable High Speed V4

FR, I'm rebuilding the motor and carb, so I'm starting fresh. I have the option of going either way, I just wanted to get some opinions on which is better, the fixed or adjustable. Are you saying that you prefer the fixed?

I have the '64 Starflite repair manual and it makes no mention of the adjustable high speed.
 
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a70eliminator

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Re: Fixed Vs. Adjustable High Speed V4

I have two identical carbs both off 60's V4' engines, identical on the outside but with different size jets and emulsion tubes, I would prefer the fixed jet provided it's the correct size for the HP.
Just for say, one carb came off a 60HP and the other off an 80HP identical except for the jetting.
 
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F_R

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Re: Fixed Vs. Adjustable High Speed V4

yorab said:
FR, I'm rebuilding the motor and carb, so I'm starting fresh. I have the option of going either way, I just wanted to get some opinions on which is better, the fixed or adjustable. Are you saying that you prefer the fixed?

I have the '64 Starflite repair manual and it makes no mention of the adjustable high speed.
Click to expand...

As the guy in the repair shop where the rubber met the road, yes I totally prefer the fixed jets. I liked it even more when fixed idle jets came along. Yea!!
 
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R.Johnson

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Re: Fixed Vs. Adjustable High Speed V4

Fixed jet's are great if we all lived at the same altitude, but we don't. An adjustable needle make's calibration much easier as we go up in altitude. My LaPorte City, Ia. engine does'nt want to run so great for my son in Denver, Co. You change the jet's, or adjust the needle. Go to a dealer, and buy the jet's you need over the counter. You will get a blank stare, and a suggestion to change the prop.
 
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F_R

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Re: Fixed Vs. Adjustable High Speed V4

R.Johnson said:
Fixed jet's are great if we all lived at the same altitude, but we don't. An adjustable needle make's calibration much easier as we go up in altitude. My LaPorte City, Ia. engine does'nt want to run so great for my son in Denver, Co. You change the jet's, or adjust the needle. Go to a dealer, and buy the jet's you need over the counter. You will get a blank stare, and a suggestion to change the prop.
Click to expand...

Yeah, I forget that the highest spot in this state is about two feet above sea level. Well-----maybe a wee bit more. And not many of us snap our boat on the hitch and go to Colorado.
 
yorab

yorab

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Re: Fixed Vs. Adjustable High Speed V4

Well, I'll mostly be using this motor in Pennsylvania, not too high in elevation. So based on responses, I'll stick to the fixed high-speed. Thanks.
 
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