VAC or Mechanical Secondaries? which is best
#1
Drifting
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VAC or Mechanical Secondaries? which is best
I am in the process of building up a 383 which will have about 420-450 HP. Assuming I go with a Dual plane intake what are the recommendation s for carbs, specifically VAC sendary carb or Mechanical secondaries? Which is better , I realize mechanical secs will be slightly less fuel efficient but all I care about is power and performance.
Heads are Canfield 195 aluminum 2.055/1.6 65cc
:flag
Heads are Canfield 195 aluminum 2.055/1.6 65cc
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#2
Re: VAC or Mechanical Secondaries? which is best (Clink69)
i would go machanical. seems like a lot of people have questions about their secondaries opening, so why not avoid all that an just go machanical.
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Re: VAC or Mechanical Secondaries? which is best (Clink69)
I have both on 2 of my cars and I really like the double pumpers. I know when the secondaries open. Alot say that the vacuum secondaries don't overcarb the engine but I have never experience a problem. I have removed a vac, secondary carb from the mustang and installed a double pumper right after and it really felt alot stronger with the double pumper. I have run dual quad setups with vacuum secondaries and ended up putting in mechanical linkage. For me there is no question.
DOUBLE PUMPER
DOUBLE PUMPER
#4
Team Owner
Re: VAC or Mechanical Secondaries? which is best (Clink69)
Any carb properly setup will function fine. O'Dennis who has been a track champion bracket racer uses only vac secondaries. Over carbed is what you want to avoid. 383 and 750 vac or 700 or less mech secs. I only use big mech secs. Because then I make the decision when I want WOT
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Re: VAC or Mechanical Secondaries? which is best (gkull)
I'm out on a limb here but trying to reach 450 from 383 ci means you need all the tricks. I think the double pumper to be what your attempting. I don't think either matter at WOT. At this power level from this engine I would think driveabiltaty is secondary.(he He).
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Re: VAC or Mechanical Secondaries? which is best (Clink69)
Clink, most carb books recommend staying away from the mechanical secondaries unless your "all-out racing". Youv'e left a lot of information out of the equation...what type of tranny and what rear end ratio? A double pumper with an auto tranny, stock stall, and a 3.08 gear will be slower (less torque) off the line with a double pumper than with a tuned vacuum operated secondary. I've run both style of carbs and they both have their place...one suggestion I'd make...it your going to run a race-style carb (double-pumper) get rid of the street-style manifold (dual-plane). Another thing...if your engine builder is installing a mild cam for emissions reasons, why compound your problems with the double pumper? It's definetly not an emissions style carb. You need to look at the "whole package"...Deen
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Re: VAC or Mechanical Secondaries? which is best (Clink69)
If you drive your car alot and are remotely concerned about economy I think vacuum secondaries is the way to go. I have a Q-Jet on a relatively mild setup and it runs very well. Much quicker than most would think and decent mileage to boot.
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Re: VAC or Mechanical Secondaries? which is best (Clink69)
Application is the key. What are you going to be doing with the car? When doing a build-up this is the question one has to be most realistic about. I think most builders would recommend a well-tuned vacuum secondary carb for any car that is primarily street driven. Vacuum secondary carbs (IMHO) are underrated. Remember that an engine is just an air pump (not a gas pump) and at WOT you will hurt performance if over-carbed (that happens more often than you'd think). A vacuum sec. carb can be compared to electronically controlled EFI systems in that gas is added when the engine load demands it. Unless this is going to be an all-out race car, a vacuum sec. carb will probably give better overall performance.
That's just my opinion...........I could be wrong!!! :eek:
Looks like a real nice set of heads! Also, there are a some cool :cool: cars in this thread! I think only Norval has a chance of being UNDER-carbed!! :D
Good luck with your project. :cheers:
[Modified by ODennis, 9:50 AM 12/8/2001]
That's just my opinion...........I could be wrong!!! :eek:
Looks like a real nice set of heads! Also, there are a some cool :cool: cars in this thread! I think only Norval has a chance of being UNDER-carbed!! :D
Good luck with your project. :cheers:
[Modified by ODennis, 9:50 AM 12/8/2001]