tassie55 Posted December 27, 2014 Report Share Posted December 27, 2014 hi just chasing the difference between 3,4 and 5k carbies as I'm chasing a new unit to put on a junior sedan and as far I I can tell are all the same in fitment but am unsure wether the jets are any bigger on the 5k ones?? and at around $250 delivered to my door may be a good place to start seeing as all is brand new any help would be appreciated thanks Darren Quote Link to comment Share on other sites More sharing options...
Super Jamie Posted December 27, 2014 Report Share Posted December 27, 2014 (edited) I don't have any throat/jet measurements, but the carbs differed greatly from 3K to 4K in their emissions gear. The late model 4K KE70 carbs have a spaghetti of hoses on them to apparently be more environmentally friendly and probably suck all the power out. Also keep in mind a 5K carb is from a van, they were probably intended for all low-down power, I'd be surprised if they breathe well up high. I know 3K carbs have manual secondaries, I'm not sure if any come with vacuum secondaries. Others probably know. As you're running off the street and you're probably building a lot yourself, my recommendation would be to get the cheapest carb you can, tear off all the emissions crap and plug up any holes, rebuild it with a $50 kit off eBay, and see how it goes. If you need more air, lathe out the throats a tiny bit at a time, and drill the jets if required. I have a 3K carb I did this to and managed to get it almost perfect, very responsive at all throttle positions. It'd run out of air at 8500rpm on a worked 060 over 4K. The only emissions gear I ran was a hot idle valve but you probably don't even need that. Edited December 27, 2014 by Super Jamie Quote Link to comment Share on other sites More sharing options...
tassie55 Posted December 27, 2014 Author Report Share Posted December 27, 2014 thanks Jamie wasn't sure wether it would work so i'll grab either a new 4k or 3k one pollution gear will go straight away as will choke butterfly I think I read a post here earlier saying 4k carb was better on a 3k so I might do a bit more research an forget the 5k Quote Link to comment Share on other sites More sharing options...
Super Jamie Posted December 28, 2014 Report Share Posted December 28, 2014 Yeah I take the choke butterflies out too, just run rich idle. Quote Link to comment Share on other sites More sharing options...
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