mopar1rules Posted May 6, 2008 Report Share Posted May 6, 2008 is there an advantage to taper boring carbs versus straight boring? i was thinking with taper boring, you would increase the velocity of the air...right? just like the venturis on the stock carbs. they start big and then taper down to 26mm. shouldn't it speed up the air travel if i taper the bore 2 mm? start at 28mm on the intake side and taper it down to 26mm on the engine side? or should i just bore it to 27.5mm-28mm? looking for a cheap alternative to more power for now, until i can afford the 28mm flatslide tm's. Quote Link to comment Share on other sites More sharing options...
blowit Posted May 6, 2008 Report Share Posted May 6, 2008 is there an advantage to taper boring carbs versus straight boring? i was thinking with taper boring, you would increase the velocity of the air...right? just like the venturis on the stock carbs. they start big and then taper down to 26mm. shouldn't it speed up the air travel if i taper the bore 2 mm? start at 28mm on the intake side and taper it down to 26mm on the engine side? or should i just bore it to 27.5mm-28mm? looking for a cheap alternative to more power for now, until i can afford the 28mm flatslide tm's. We feel the taper bore was a fad and that is about it. The reason mostly for the venturi on the back of the carb is not for velocity, but for pressure drop that allows a low pressure cell over the jets to allow better fuel flow. Brandon Quote Link to comment Share on other sites More sharing options...
Bansh-eman Posted May 6, 2008 Report Share Posted May 6, 2008 We feel the taper bore was a fad and that is about it. The reason mostly for the venturi on the back of the carb is not for velocity, but for pressure drop that allows a low pressure cell over the jets to allow better fuel flow. Brandon Correct me if I'm wrong but wasn't the whole tapered bore more of a 4 stroke thing? Quote Link to comment Share on other sites More sharing options...
blowit Posted May 6, 2008 Report Share Posted May 6, 2008 Correct me if I'm wrong but wasn't the whole tapered bore more of a 4 stroke thing? LRD was doing it with a PWK 28mm tapered to 30mm. They do not perform any better than a 29mm carb. Simply that even with an increase in velocity after the carb, the air charge will still hit a brick wall (the reeds) and null any effects. Brandon Quote Link to comment Share on other sites More sharing options...
mopar1rules Posted May 6, 2008 Author Report Share Posted May 6, 2008 well, this is good to know. the wheels in my head were spinning this morning, and i just thought of posting this, to get all of your guys's thoughts:) Quote Link to comment Share on other sites More sharing options...
Wildcardracing Posted May 7, 2008 Report Share Posted May 7, 2008 Taper bored or not, I wouldn't recommend going any larger than 27.5mm through the venturi...you will cut into the slide bore if you go larger. Quote Link to comment Share on other sites More sharing options...
mopar1rules Posted May 7, 2008 Author Report Share Posted May 7, 2008 OK, THANKS Quote Link to comment Share on other sites More sharing options...
00tbanshee Posted May 7, 2008 Report Share Posted May 7, 2008 Taper bored or not, I wouldn't recommend going any larger than 27.5mm through the venturi...you will cut into the slide bore if you go larger. agree.i had a junk carb laying around and triied to go larger then that.27.5 is the max. to be safe Quote Link to comment Share on other sites More sharing options...
freddy Posted May 8, 2008 Report Share Posted May 8, 2008 agree.i had a junk carb laying around and triied to go larger then that.27.5 is the max. to be safe do you guys know any preffered place where i can get my carbs bored to 27.5 for a decent price? and do i still keep the slides the same or do those go bigger as well? thanks Quote Link to comment Share on other sites More sharing options...
Wildcardracing Posted May 8, 2008 Report Share Posted May 8, 2008 Your slides will stay the same, I recommend Lynn at LCPerformance (www.lcperformance.com) I think he charges @ $50 a set for the straight and $90 a set for the taper bore and shaving the intakes to match. Quote Link to comment Share on other sites More sharing options...
mopar1rules Posted May 8, 2008 Author Report Share Posted May 8, 2008 and shaving the intakes to match. shaving the intakes to match? what do you mean? can you elaborate on this for me please? i never heard of this. Quote Link to comment Share on other sites More sharing options...
Wildcardracing Posted May 9, 2008 Report Share Posted May 9, 2008 shaving the intakes to match? what do you mean? can you elaborate on this for me please? i never heard of this. In your intake manifolds there is a lip that seats against the carb, when you get a taper bore the I.D. of the carb is larger than the I.D. of the intake so he shaves the lip down to match the carb bore. Quote Link to comment Share on other sites More sharing options...
mopar1rules Posted May 9, 2008 Author Report Share Posted May 9, 2008 ahhhh, i see. thanks. Quote Link to comment Share on other sites More sharing options...
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