Annular vs. Downleg

[blizzard]

okay... i've pretty much already decided on annular but the other thing i can't make my mind up about is vacuum vs. mechanical... what are your opinions? i know vacuum is more street friendly but i like the idea of the <fun?> that progressive mechanical offers. i've always had vacuum secondaries and used quick change springs to get the "powerband" i like but never actually ran mechanicals on my cars.... any input??

[somethingclever]

mech.

[2001GTTT]

i wish i knew what we were talking about...lol. enlighten me.

[HidalgoGT]

I ran both but, enjoyed mechanical alot more.

[torqueboxer]

whats your setup? If its a big heavy car with shallow gear, low stall, mild motor go vac. Light car, big gear, high rev ,go mech. It depends on what you have.

Ive got a solid roller, 4:10,s, 3.27 first gear, 11-1 comp and a mech secondary carb, street car...not a bog in sight. Fill us in on the combo you are running to better help you out.

[blizzard]

it's a lite and nimble 85GT with 10.2:1 comp 306 with a 218/228dur 472/496lift hyd and fully ported E7TEs with 1.94/1.6 valves... weiand Xcelerator, full-length headers, all that crap... 3.35? first gear and 3.27s out back... i ran a holley 600 with vacuum sec on it and experimented with springs (i think i ended up with the yellow one?) and it worked very well. but after a few years, holleys get old and need rebuilt so i was shopping for a new Demon carb and thought i might enjoy using the mechanical secondaries... as i would have control of the four-barrels at my foot rather than just mashing the pedal and wait for the vacuum... ??

[Troll]

i wish i knew what we were talking about...lol. enlighten me.

it has to do with carburetors. you don't need worry your little head about it.

[2001GTTT]

it has to do with carburetors. you don't need worry your little head about it.

I need some eduMakution troll!

[Rodeheaver's]

is it an auto or a stick?? autos really benifit from vaccum secondary carbs where sticks like the mech carbs, a mech carb on a street car may give you a little bog.. and make sure not to go to big, that is the number one killer in carbs, this is how to figure the cfm out.... you take cubic inches X max rpm divided by 3456.. (example) 306ciX6000rpm=1836000/3456=531cfm, and thats @ 100% volumetric efficiency, most street engine are about 85% VE, so this example engine would run its best on the street with around a 500-520cfm carb...

[blizzard]

thanks for the heads up Tim. that has been taken into account.

it is a 5 speed. granted if it was a big'ol sled with an auto, there would be no question i would want vacuum sec with kickdown an'all... may still choose that route but taking opinions on the mech from the general concensus like would it use a lot more gas and would i be fighting the pedal at cruise? would a progressive rod prevent this as opposed to the 1:1 ??

[Rodeheaver's]

thanks for the heads up Tim. that has been taken into account.

it is a 5 speed. granted if it was a big'ol sled with an auto, there would be no question i would want vacuum sec with kickdown an'all... may still choose that route but taking opinions on the mech from the general concensus like would it use a lot more gas and would i be fighting the pedal at cruise? would a progressive rod prevent this as opposed to the 1:1 ??

just about all holley carbs come with a progressive linkage, you can adjust it slightly by bending it. and i would deff stay progressive for the street.

[blizzard]

right on... thanks for the info