Smoking Joe Posted May 31 Report Share Posted May 31 (edited) Hello my secondary throttle blade was frozen in the closed position. I have taken the base plate off and gotten the secondary back in smooth operation. Is the secondary operated by engine vacuum thru the bore itself. Or does the actuator it’s attached to open it with vacuum. Or is the actuator some sort of restrictive module that slowed the opening of the throttle blade. If it is an actual vacuum module where on the carb is the vacuum line or port to provide vacuum. I wanting to check it’s operation before reassembling the carb but I can’t fine the vacuum source to make it operate. Thanks in advance you guys are great Edited May 31 by Smoking Joe Add photo Quote Link to comment
datzenmike Posted May 31 Report Share Posted May 31 The vacuum is a combination of the primary venturi and the secondary venturi when it starts working. The combined vacuum hold the secondary open. The vacuum is passed through internal openings, no way to test really. If the throttle shaft or the throttle plates were stuck but are now loosened, then the vacuum secondary should now work. It's hard to hold the throttle wide open long enough to watch it open, the engine revs to the moon. You can hold the primary open to release the secondary interlock and push down on the vertical rod of the round vacuum actuator pictured above. If loose and free to open the secondary throttle shaft it can be assumed to be working. Quote Link to comment
Smoking Joe Posted June 1 Author Report Share Posted June 1 Yes it’s free to move the actuator arm in and out of the actuator body. So maybe it will work. Has anybody had any luck with the Chinese hitachi carbs that are available for about a hundred bucks. In the event this one doesn’t work properly. amazingly prior to the blown head gasket issue I had. This engine and carb ran perfectly as for idle and sensible power for what it is. Now with fresh engine and a hopefully functional secondary it should very satisfactory for a daily driver Quote Link to comment
datzenmike Posted Monday at 01:08 PM Report Share Posted Monday at 01:08 PM The Hitachi is a very complicated and intricate, but the best over all running, carburetor when working properly. I should imagine the Chinese 'knock off' is the same but perhaps with less quality parts in it, like most counterfeit things. I'm sure it will work but I doubt for as long as the original. A hundred bux looks inviting. Usually owners with a poor running Hitachi replace with a Weber 32/36 and get good power and reliability, but up to 4 times what the Chinese carburetor is. If your Hitachi works then I would run it and worry about replacing later. Quote Link to comment
Smoking Joe Posted Monday at 01:53 PM Author Report Share Posted Monday at 01:53 PM Yes I prefer to keep the Hitachi for various reasons. I have considered the Weber cost not withstanding but the issues of modifying the original air cleaner to adapt to the weber and the A/C kicker solenoid etc. I prefer to keep my truck factory appearing as well. Thanks for your responses to all my various questions. And If I may ask Id love to see you change your imogie or what ever you call the little video image attached to your responses. Yes its a religious thing to me. Just a request certainly not a demand. Thanks again Quote Link to comment
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