Double Pumper or Vacuum Secondaries?
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From: Dickinson (Houston) Texas
Double Pumper or Vacuum Secondaries?
When I build my Big Block, I was planning to get a Holley 850 Double Pumper, but in talking with some friends of mine, they recommended that I should consider getting one with Vacuum Secondaries since my Vette will be mostly a street cruiser.
What are your opinions?
www.bigdogvettes.com
What are your opinions?
www.bigdogvettes.com
Race Director
Joined: Dec 1999
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From: Forked River NJ
Need more info. Cam, heads, trans, rear gears, etc. A mild street motor will be better with vacuum. Something with good heads healthy cam and some gears would be better with a DP carb. I like the DP carbs, you always know when the secondaries are in.
Race Director
Joined: Nov 2000
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From: Waterloo ontario Canada
I am a big fan of the double pumpers. Yes they are richer then a similiar vacuum carb but with a little leaning out they give similiar mileage. I have even used the big double pumper on a small block with good luck.
For a big block I feel a 850 double pumper is ideal
I like them so well I use 2 of them on my 460.
For a big block I feel a 850 double pumper is ideal
I like them so well I use 2 of them on my 460.
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From: Dickinson (Houston) Texas
Originally Posted by Gordonm
Need more info. Cam, heads, trans, rear gears, etc. A mild street motor will be better with vacuum. Something with good heads healthy cam and some gears would be better with a DP carb. I like the DP carbs, you always know when the secondaries are in.
I have had double pumpers and vacuum secondaries, and I really loved the DPs! Really made my Big Block 68 Camaro come alive when they hit.
I am still leaning towards the DPs, but just looking at all of the options.
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From: Dickinson (Houston) Texas
Originally Posted by Gordonm
Go with the DP. Much better response with that setup.
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From: Dickinson (Houston) Texas
Originally Posted by dath
9.5:1 sounds a little low to me if you are going with aluminum heads, no? I would think you could easily go 10.5:1 or 11:1 with a bit of a cam???
-dath
-dath
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From: Dickinson (Houston) Texas
Originally Posted by youwish2bme
I'd go with a Barry Grant over the Holley if it were me.. 850 Mechanical secondary's... JMO... Dave..
The BGs may be worth saving up for however!
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Le Mans Master
Joined: Apr 2000
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From: cincinnati ohio
St. Jude Donor '09
Originally Posted by matchframe
I have been seriuously been considering that, but the price factor has always brought me back to the Holleys.
The BGs may be worth saving up for however!
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The BGs may be worth saving up for however!
www.bigdogvettes.com
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From: Dickinson (Houston) Texas
Originally Posted by yellow 72
Summit is closing out their BG line and have discounts on some models
Thanks!
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Melting Slicks
Joined: Aug 2005
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From: Lincoln CA
Originally Posted by matchframe
I would like to go with the higher compression, but I also want it to be gas pump friendly. I don't really plan to race this Vette, but I would like it to be a real responsive street machine.
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Burning Brakes
Joined: Jul 2000
Posts: 1,162
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From: Beaverton, OR
I agree with RagTop69, though I'm by no means an authority. Weight and compression ratio are the two major reasons I've heard for using aluminum heads. If it weren't for those reasons, I'd stick to iron heads as they have a couple of advantages as well. . . Price, not as many sealing issues, and not as likely to strip bolt holes or plug holes if you get heavy handed. . .
Just my $.02, I'm sure someone who knows better will chime in
-dath
Just my $.02, I'm sure someone who knows better will chime in
-dath
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From: Dickinson (Houston) Texas
The reason I want to use aluminum heads is for the weight issue. I got my 454 out of a 1 ton truck which had a set of peanut port heads. I knew when I bought the truck for the Big Block that I was going to use aluminum heads for the weight difference so getting the engine out of a truck was a good deal for me.
I did not know that aluminum heads made it able to use a higher compression and still be pump friendly!! I will need to check this out further!!! I had rather use as high as compression as I can.
Thanks for that info!
www.bigdogvettes.com
I did not know that aluminum heads made it able to use a higher compression and still be pump friendly!! I will need to check this out further!!! I had rather use as high as compression as I can.
Thanks for that info!
www.bigdogvettes.com