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  #1  
Old 08-14-2000, 04:08 PM
tim tim is offline
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Hello, a freind says hell give me a 750 holley double pumper with mechanical secondaries. Car is a 340 with 727 column shift. Is vacum secondaries the way to go or mechanical secondaries ? Thanks tim

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  #2  
Old 08-14-2000, 08:34 PM
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tsteiner61 tsteiner61 is offline
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The only difference between the two, someone correct me if I'm wrong, is that a mechanical secondary is triggered by throttle position whereas a vacuum secondary is triggered by manifold vacuum (airflow through primary barrels). Most guys I know with all kinds of cars prefer the mechanical for performance, vacuum if you are looking for slightly better gas mileage. Other than that they are pretty much the same and it sounds like the price is right. Take it.
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  #3  
Old 08-14-2000, 09:33 PM
ChristianCuda ChristianCuda is offline
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Hey tim go for it will cost you if you need to put a kit in it but worth it.

And if you dont need it send it to me. I will pay your shipping

LOL

Christian

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[This message has been edited by ChristianCuda (edited August 14, 2000).]
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  #4  
Old 08-15-2000, 06:49 AM
DartGT66 DartGT66 is offline
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Usually the vacuum model is a more forgiving carb, it doesn't have to be adjusted up to par to work pretty well. The double pumper has to be dead on. It's also more sensitive to correct carb size; too big and it will not work in the street. I think the 750 is on the big side for a street 340. Numerically low gear ratio makes things worse with the DP. I think a vacuum carb is the choice for a streeter, they can be made to perform very close to the DP's with minor tuning and tend to have better driveability and traction control.
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  #5  
Old 08-15-2000, 04:12 PM
tim tim is offline
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Right on guys, I,m gonna give it a try.and yes dartgt66 the car is for the street. Currently using eddlebrock 750, rpm 1500 to 6500 eddlbrock manifold, bored out ..30 over, 71 j heads with mild porting, shaved heads and block (compression is 10.2), balanced crank, speedpro cam with 480 lift and dynomax headers. Car runs really well but always looking for more. Thanks tim

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  #6  
Old 08-15-2000, 04:15 PM
tim tim is offline
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oh yeah forgot to tell ya, am running a set of 3.55,s right now and am considering on putting in 3.91,s as a freind also gave them to me.

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  #7  
Old 08-15-2000, 11:26 PM
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You've got some nice friends! Buy them a bump for helping you out. Oh yeah, vacuum.
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  #8  
Old 08-16-2000, 07:47 AM
tim tim is offline
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lol, yup good friends, small logging town lots of parts sheds. Only two older dodges in town, but everyone used to own one.

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  #9  
Old 08-17-2000, 04:37 AM
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pishta pishta is offline
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I'de go vacuum for the carb of choice. You can run 100 more CFM with a vacuum than a mech, and not lose any performance, ie. they will match up pretty close in most categories. You can really dial in a vacuum with a 6 buck spring set, as opposed to a steady throttle foot with a mechanical. Vacuum's way more forgiving in the long run, cheaper to rebuild also.

3.55's are nice, but the 3.91's will get you there quicker, and with a bigger carb, you'll like the response from a higher RPM motor.
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