TBI Manifold Preference...???

[The Punisher]

Doug:
I have a setup very similar to what you describe. Its in an S-10 pickup so 
weight will be similar to youre vette.
the engine is a 406 small block with 11:1 comp. I used world products dart2 
sportsman2 heads. I think the sportsman's flow a bit more air, but the TFS 
wedge's got a much better chamber(and possibly more detonation resistant).
I applied thermal barrier coating on the piston tops,combustion chambers, 
valve's, and exhaust ports. I air-brushed it on after SAND-blasting(NOT 
glassbead), then cured it in the oven.
I use crane 1.6 rockers and have a hydraulic cam just slightly bigger than 
yours.
I have a torker2 manifold with a custom made 1.5" spacer and a 670CFM holley 
2 barrel injector. I made my own spacer to center the TBI over the center of 
the plenum and ported it to a very smooth transition. The TBI is wider than 
the 4150 type opening and I did not want to disrupt flow with a sharp angled 
adaptor like the holley one.
I still dont have a proper computer on it, I have been using an old analog 
Pro-Jection unit for control. It would be much better with a 747. BUT it 
does run better with the crappy pro-jection box than it does with a 600 
holley vaccum secondary or an edelbrock(weber)600. Not quite as good as the 
800 double pumper I had though.
The guy at holley said that a TBI would be fine on a single plane because 
you are not trying to get a stronger signal to a venturi like on a carb.
I cant realy think of a low rise manifold that would be much better than a 
torker2 for a 406.seems like there is a low rise single plane WEIAND but I'm 
not sure. Certianly a victor jr. would run alot better, but there goes youre 
hood clearence.
If you run a medium/high rise single plane made for a dominator carb, you 
can use a short adaptor plate with no airflow problem. I have seen a few of 
these manifolds(torker4500 ?).
Also you might consider a medium/high rise manifold made with a spreadbore 
flange. then you could use a short spacer. But I dont know how much having 
the TBI at the back of the plenum instaed of centered will hurt mixture 
distribution. Thats why I used an old torker2.

Good luck
The Punisher


>From: Doug Dayson <djdayson at home.com>
>Reply-To: diy_efi at diy-efi.org
>To: diy_efi at diy-efi.org
>Subject: TBI Manifold Preference...???
>Date: Tue, 22 May 2001 12:21:37 -0700
>
>Hi All...
>
>I'm looking into possibly converting my 71 Vette 406/400 to TBI (from a
>well-dialed Q-Jet).
>
>Engine specs...
>
>406ci, TFS Twisted Wedge heads, 1 5/8" X 3" Headers, 218 @ .050 110 LSA hyd
>flat tappet cam with .485 lift with 1.6 Rockers, medium-rise dual plane
>and 750
>Q-Jet. Current powr peak is at 5200 rpm, torque peak at 4000 rpm (a 
>reasonably
>mild and streetable 406).
>
>Old Vettes suffer from low hood lines so high-rise manifolds won't fit. 
>This
>leaves my options at low-rise single plane (Torker II) and medium-rise dual
>plane (Performer etc).
>
>Now I know that the Performer manifold is killing the power over 5000
>rpm so
>I'm considering the Torker II for use with a TBI.
>
>To my undersatanding, since the TBI doesn't require manifold vaccuum to
>properly meter and atomize fuel will the single- plane/TBI combo deliver
>similar low rpm performance as the current dual-plane/Q-Jet?
>
>If yes, then I should be able to see increased performance from around the
>torque peak up past the power peak with the single-plane/TBI, as well as
>comparable low-end to the current dual-plane/carb, yes?
>
>What do Ya'll think?
>
>TIA...
>
>Doug
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