[Gmecm] SBC TBI intake to 86 and earlier ???

[Beau Blankenship]

Another option (that would look good and perform better) would be an
aftermarket manifold from Edel, or Hly. You would have to have the intake
off to drill the holes anyway, so why not just stick a new intake on there
that was designed to fit right. Is it worth the extra cash? How much is your
time worth when you have to chase a vacuum leak or change the intake gaskets
because your "modified" intake is giving you problems. 

As for the heads, I would try to get some of the EFI heads from 87&up. 80-86
was a big "smog control era". The smog heads weren't good for much. I use
mine for mock-ups. The castings were too thin in the bowl areas for any
porting (as if that would help any), and on the "deck" for re-surfacing.
Most performance engine builders will warn you away from those "smog"
castings. The EFI heads were good for drivability, and can be lightly ported
to improve flow a little bit. For high RPM power, look to the older stuff.
Muscle car heads. Double-humps, etc. There is a great book by David Vizard
about selecting and modifying SBC heads. It's one of the PowerPro Series
books. Pick up a copy of that, a die-grinder, some burr-bits, and some
polishing stones, and make a weekend of it. Best to do this with some heads
that already need a rebuild, since they will when you get done.

Beau


-----Original Message-----
From: gmecm-bounces at diy-efi.org [mailto:gmecm-bounces at diy-efi.org] On Behalf
Of jryan at caminofx.org
Sent: Wednesday, January 10, 2007 7:36 AM
To: gmecm at diy-efi.org
Subject: Re: [Gmecm] SBC TBI intake to 86 and earlier ???

Redrilling the holes works, but it's ugly.  Without making special  
washers, you can't get much clamping force on the four center bolts  
(next to the carburetor/TBI mounting pad).  I drilled a TBI manifold  
to fit an '84 305, but I wouldn't do it again.  When I got a 350, I  
got an '87-later-style block and a new TBI manifold and bolted it on.

The bolt angle was changed to make it easier to put a wrench on those  
bolt heads.  It makes a huge difference.

TBI high-swirl heads are meant for high fuel economy and low-end  
torque.  I have them, and I am getting 20 mpg from a 350 in a 3500-lb.  
car that is not very streamlined.  Mine is a daily driver, though, so  
low-end torque and fuel economy are more important to me than top-end  
performance.

For what it's worth, I get the same gas mileage from a 350 with TBI  
high-swirl heads and 9.2:1 static compression as I did from a worn out  
305 with 8.6:1 compression.  Same car, same transmission and rear  
axle, same ECM, only the engine and PROM changed.

Quoting Mike <sonoma at shaw.ca>:

> Hi
>
>
>
> When I installed a throttle body on my friends old Chevy 350 we used  
>  an adapter.
>
> I didn't like the look of the adapter so I was going to use the TBI   
> intake and modify the center bolt holes for my pre-87 engine.
>
>
>
> After reading some of the messages here it sounds like there has   
> been some problems using the TBI intake on the earlier engines.
>
>
>
> What is your experience using this intake on an older small block chevy??
>
> Also I was curious which heads are better 80-86 or 87-91 truck heads  
>  or are they about the same??
>
>
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