1971 3.0 Liter Carb Question..

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cjray03

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I have acquired a 1971 Hydroswift with the 3.0 Liter Mercruiser in it. I need either to rebuild the carb or replace it. For the life of me I can not find the kit or the carb for it anywhere. Everyone I can find has the 3-1/2 x 2 bolt pattern and mine has the smaller pattern. I think I am only finding ones for mid 80's and up. Does anyone know where I can find the older kit or carb? Thanks in advance for the info.
 
Bondo

Bondo

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Ayuh,.... Posting the motors serial number usually helps,.....
 
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cjray03

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Sorry. Yeah the serial number is very hard to make out, but I believe it is 8792432. Thanks
 
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dubs283

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cjray03 said:
Does anyone know where I can find the older kit or carb?
Click to expand...
Try Mike's Carburetor, Google will help locate the website

Lots of good info and parts available. If you can't find what you need send them an email. They are very helpful and fairly quick to respond
 
Alumarine

Alumarine

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The carb rebuild kits for 1968-1982 2.5 and 3.0 liter should all work if it's the original carb.
Mercury # 823427A-1 Sierra 18-7746 or 18-7070
I just measured the base gasket from my 823427A-1 and the mounting holes in it are 3.28" x 1.91" and the bores are 1.487"
 
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cjray03

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Yeah that's about the right size. I measured the bolts on mine and they were 3.25 x 1.75, but I was measuring with the carb on so I may be a little off. Thanks for the info! I am ordering the carb kit. Kind of disappointing I find the newer kits and they're like $9 and the one I need is $36. I guess that's the price you pay for having an older boat...lol.
 
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cjray03

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Hey. Got the carb kit and did the rebuild. Everything seemed to have went well. I reinstalled the carb and had some issues with the idle. After a while it seemed to work itself out. I had it running smoothly at 7-800 rpms. That's on the muffs obviously. I took the boat out and it fired up, but was running sluggishly. I didn't take any tools with me (stupid mistake) so I couldn't get the idle up. I was able to turn the idle screw all the way in but it didn't help. It died and wouldn't start back up. We were dead in the water. I got it home after a tow and it fired right up and ran smooth at 7-800 rpms on the muffs. Ok for the question after all that...does the idle out of the water need to be higher? It seems to bog down a bit in the water. Sorry for the long post.
 
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dubs283

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Check/set idle timing prior to adjusting the idle speed and air mixture. Once that's all dialed in you can check it again in the water under load at idle speeds

Full rpm range lake test only after the idle issues are resolved
 
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airshot

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Adjusting the carb mixture on a trailer does not work ! Get everything set correctly and go for a ride on the water, dead idle or as slow as you can go then adjust. My 3.0 after a complete tuneup and a head rework ( warped head) it would idle down to 600 rpm and run there for quite some time without loading up.
 
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cjray03

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Thanks for the info. It has new points, condenser, coil, plugs and wires...I haven't had a chance to check the timing. That's what I am going to do today. BTW I have a ? About the vent on the valve cover...the spark arrestor I was able to find...had the have the 2-5/8" opening...it has no connection for the vent. What do I do with it?
 
Scott06

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cjray03 said:
Thanks for the info. It has new points, condenser, coil, plugs and wires...I haven't had a chance to check the timing. That's what I am going to do today. BTW I have a ? About the vent on the valve cover...the spark arrestor I was able to find...had the have the 2-5/8" opening...it has no connection for the vent. What do I do with it?
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SO you didn't set the points when putting them in? Ste timing and dwell then adjust the carb mix and idle speed. I usually set the idle speed about 700-725 on the trailer, do final mixture and speed settings on the water in gear 650 or so. 1.5 turns out is a good starting point for the idle mix.

On a 1971 it probably just had a breather vs the hose directing the blow by to be sucked into the flame arrestor

not 100% sure this is your engine but it is what I recall from similar vintage mecruisers - part 15 is the oil fill cap - looks like they have inventory. Would expect its an old school breather with some type of element or steel wool in there to drop the oil out

 
Scott Danforth

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cjray03 said:
Thanks for the info. It has new points, condenser, coil, plugs and wires...I haven't had a chance to check the timing. That's what I am going to do today. BTW I have a ? About the vent on the valve cover...the spark arrestor I was able to find...had the have the 2-5/8" opening...it has no connection for the vent. What do I do with it?
Click to expand...
file the points with a points file
use a dwell meter to set the dwell (just gapping isnt good enough)
then adjust timing
then adjust the idle speed like mentioned above.
 
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