Vacuum vs Mechanical Secondary’s?
Race Director
Joined: Jan 2000
Posts: 13,018
Likes: 2,262
From: Corsicana, Tx
2020 C2 of the Year - Modified Winner
2020 Corvette of the Year (performance mods)
C2 of Year Winner (performance mods) 2019
2017 C2 of Year Finalist
Or splurge and get a 750 Street HP....but either way... double pumper all the way!
JIM
Safety Car
Joined: Mar 2017
Posts: 3,651
Likes: 274
I am a fan of mechanical secondaries / spread bore flange. They seem to like to drink lots of gas though. IS the car a stick? I have had much better luck with mechanical secondaries on my 4 speed cars. Carburetors can be picky if old gas sticks around in them, or not setup correctly.
Thread Starter
Pro
Joined: Feb 2006
Posts: 649
Likes: 10
From: Shelby Twp MI
I probably should have mentioned it’s an auto w/3:73 rear end. So Its looking like the mechanical secondary’s is the way to go and go with a 750DP. I’m assuming I should plan for 6500/7000RPM.
I’m not to a point where I can get into the fine tuning of the 770, but at least I know there is an option.
I’d like to stick with electric choke too. Any issues?
I’m not to a point where I can get into the fine tuning of the 770, but at least I know there is an option.
I’d like to stick with electric choke too. Any issues?
Le Mans Master
Joined: May 2006
Posts: 9,993
Likes: 1,136
From: League City Tx
You have to understand the history on this topic to know that TBTR and I went at it many times over this. He said that double pumpers were for race engines only that ran high RPMs only, and were totally unsuited for street use. AJ knows very well that I agree with him and pretty much everybody else here except TBTR. That's why I put the wink after my post to AJ. It's all good.
Y'all should read what TBTR wrote in the comments on my youtube channel on one of my 71 vette vids(racing a blown 5.0)..... He went on an EPIC rant for 2-3 posts. At first, I didn't know who it was, but after reading it a few times, I figured out who it was, and he admitted he got banned from here. LOL That guy in mental.
Le Mans Master
Joined: May 2006
Posts: 9,993
Likes: 1,136
From: League City Tx
I probably should have mentioned it’s an auto w/3:73 rear end. So Its looking like the mechanical secondary’s is the way to go and go with a 750DP. I’m assuming I should plan for 6500/7000RPM.
I’m not to a point where I can get into the fine tuning of the 770, but at least I know there is an option.
I’d like to stick with electric choke too. Any issues?
I’m not to a point where I can get into the fine tuning of the 770, but at least I know there is an option.
I’d like to stick with electric choke too. Any issues?
Just throw a #4779 on there, it will run great out of the box Set the idle mixture and idle speed screws and that's it. I'd bet the jetting is pretty damn close for your combo. The 750HP series probably make a bit more power, but for some reason they run terribly rich around town....You'll be messing air bleeds and stuff...lots more tuning.
#4779 is just good out of the box....(or they used to be anyway, Holley quality has definitely been suffering the last 5 years)
Race Director
Joined: Dec 2004
Posts: 10,332
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From: PARADISE
St. Jude Donor '09-'11-'12-'13-'14
Y'all should read what TBTR wrote in the comments on my youtube channel on one of my 71 vette vids(racing a blown 5.0)..... He went on an EPIC rant for 2-3 posts. At first, I didn't know who it was, but after reading it a few times, I figured out who it was, and he admitted he got banned from here. LOL That guy in mental.
Glad he's gone(again), but I have a hunch he'll sneak back in. The only problem is his writing style is unmistakeable. Maybe with a ghost writer?
Race Director
Joined: Dec 1999
Posts: 11,096
Likes: 990
From: Sierra Foothills CA
Y'all should read what TBTR wrote in the comments on my youtube channel on one of my 71 vette vids(racing a blown 5.0)..... He went on an EPIC rant for 2-3 posts. At first, I didn't know who it was, but after reading it a few times, I figured out who it was, and he admitted he got banned from here. LOL That guy in mental.
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Verdad Gallardo
Race Director
Joined: Dec 1999
Posts: 11,096
Likes: 990
From: Sierra Foothills CA
Drifting
Joined: Aug 2009
Posts: 1,346
Likes: 160
From: new iberia la
I have run QUICKFUEL SS 750 DP on my 383/525HP Stroker.. for 9 years.. no issues, doesn t need constant adjustment. .. has 4 corner idle system.. which helps with my big cam . We dyno'd with Holley 750 first.. Quickfuel picked up additional 12 HP .
Le Mans Master
Joined: Mar 2001
Posts: 5,738
Likes: 644
From: Lincoln, CA
I use the 830 Quick Fuel DP and once dialed in it's been flawless.
Safety Car
Joined: Apr 2015
Posts: 4,888
Likes: 202
From: Jackson MS
Double pumper is the way to go.
All this double pumper talk is going to cause TBTR to come down with a nervous twitch.
By the way - I found ajrothm's YouTube channel and read TBTR's un-hinged comments.
All this double pumper talk is going to cause TBTR to come down with a nervous twitch.
By the way - I found ajrothm's YouTube channel and read TBTR's un-hinged comments.
Race Director
Joined: Dec 1999
Posts: 11,096
Likes: 990
From: Sierra Foothills CA
Safety Car
Joined: Apr 2015
Posts: 4,888
Likes: 202
From: Jackson MS
His posting style is hard to miss, and is easily baited with any mention of long tube headers.