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970 Holley Vac sec VS 850 BG double Pumper
#536985
11/26/09 02:10 AM
11/26/09 02:10 AM
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Joined: Aug 2005
Posts: 65
Adelaide, SOUTH Australia
REDNICK
OP
member
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OP
member
Joined: Aug 2005
Posts: 65
Adelaide, SOUTH Australia
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Hi, Whats the consensus? Engine is a 512 cube/10.5:1/stealth heads/290s comp cam solid/1.6 crane rockers/wieand "old school" single plane/4speed/3.91 suregrip in a 68 Coronet R/T Current carb is a 870 Street avenger with bigger base plate ( supposedly 970 cfm) "80''s in the primary, #2 power valve, small yellow spring. Its scary fast now... but those in the game reckon if I fit any sort of big DP( especially a BG) it will want to tear me a new one.... a difference of night and day? What do the forum members reckon? Nick 
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Re: 970 Holley Vac sec VS 850 BG double Pumper
[Re: REDNICK]
#536989
11/26/09 06:41 PM
11/26/09 06:41 PM
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Joined: Feb 2005
Posts: 5,221
Branson, Mo.
joedust451
super gas
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super gas
Joined: Feb 2005
Posts: 5,221
Branson, Mo.
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Quote:
Thamks,
Others have said the vac sec carbs work good with a 50cc pump, light springs and rich settings on the secondary jets.
The carb works pretty well now, just wondering if its justified spending big $ on a different carby for not much seat of the pants difference...
If that 870 is doing good & you feel you have it dialed in, i'd just leave it be & keep it, you may get another .1 & 1 mph or so from a different carb, but is it worth the 600.00 or so you'de have to spend, i say no, drop the bottle on it, that'll give you a nice  for about the same price.
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Re: 970 Holley Vac sec VS 850 BG double Pumper
[Re: dodgeboy11]
#536990
11/26/09 06:51 PM
11/26/09 06:51 PM
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Anonymous
Unregistered
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Anonymous
Unregistered
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Quote:
The advantage to the DP is that the secondaries will open by foot, not when the engine needs it. Bigger is still bigger. On the dyno at work a 428 ford made 391 hp with an 850 dp. When I put the 950 vac secondary carb on I eventually coaxed 430 hp out of it. I figure those numbers speak for themselves.
the only thing those #'s speak are that the 428 needed a bigger carb. put a 950HPDP carb on it with a good tune and
add another 10ft-lbs and 15hp to the entire curve. peak should be roughly the same. never ever seen a vac.sec. carb outdo a DP
in my life. unless the DP had a major crappy tune. with that 512 in the OP i'd go 950HPDP.
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