Good mornin' fellow A-4 opperators and mechanics. I have been working on fuel consumption on my A-4 and have deciced to take a different tack. I am changing the main jet rather than using an adjustable one. I feel that if it is running right it is right. I have played around by changing the orifice diameters since I have access to a machine shop and a vast array of reamers. I have filled the jets and re-reamed to a smaller diameter with a good deal of success. I finally reached a point where I was loosing throttle responce and a few RPM (@.038") by going leaner (4 steps). I decided to contact Zenith and see about ordering foctory jets of a smaller diameter which they stock for the late model carb. I ordered the next two sizes down and the stock jet (#'s 21, 20 & 19). I now have the time to play with them during the holidays as my shop is closed. When I recieved the parts and the jets numbers were the same however the jet was a little shorter in length about an 3/16 of an inch, the actual metering orifice is inside the threaded area not the extended nose. My question is has anyone out there used the shorter jets or did I get the wrong ones? The threads are the same and I don't see any reason that they would not feed the emulsion well passage any differently.
By the way my A-4 was frozen tight when I bought the boat 22 years ago. I pulled the head cleaned the water passages and did a valve job as one had a rusted groove in it. I used a "dead blow" hammer and a soft piece of pinewood to knock the pistons loose and have been running ever since as a raw water cooled boat in southern California. When I got the motor running the compression was 55 to 70 psi and last year checked at 90 - 100 psi. Truely a durable motor!!!!!!!!!
Thanx Dave Neptune
Volador 1970 E35-MkII
By the way my A-4 was frozen tight when I bought the boat 22 years ago. I pulled the head cleaned the water passages and did a valve job as one had a rusted groove in it. I used a "dead blow" hammer and a soft piece of pinewood to knock the pistons loose and have been running ever since as a raw water cooled boat in southern California. When I got the motor running the compression was 55 to 70 psi and last year checked at 90 - 100 psi. Truely a durable motor!!!!!!!!!
Thanx Dave Neptune
Volador 1970 E35-MkII
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