[Gmecm] Project underway...

[Garrett Herning]

Hi David,

I think the injectors would be about the right size. Unless you are trying 
to push some large horsepower out of that flathead with a hugh compression 
increase and a turbo or blower...

I put a TBI from a 4.3L on a 78 pickup I have with a 5.7L. Since its for the 
most part a stock engine (8:1 compression or whatever 1978's best was), and 
its not a real hp monster I thought they would work ok. It runs fine and I 
haven't had any trouble with it bogging down. I used a MegaSquirt, and if I 
crank up the high throttle end of the fuel table, it moves pretty good 
(along with the gas gage..lol).

I think the biggest decision would be how to orient the TBI. The stock 
manifold seperate each bore to feed 1/2 of the cylinders... a V8 would feed 
4 with one and the other 4 with the other, 2 on each side. Since you have a 
totaly different manifold you'll have to see the best way to feed them. On 
my 78, I made an adpater for a normal Qjet type manifold and so there was a 
plenum area under the TBI where they could mix. The only thing I see on your 
pic is it appears that the runners go down toward the front and back, so 
having it sit 90 deg from normal might work better on that manifold... maybe 
even some kind of divider that helps direct the flow of air and fuel from 
each bore down to the front or back.... just a thought... I'd not an expert 
of intake design though.

Good luck, looks like a cool project!

Garrett


>From: "David Allen" <davida1 at hiwaay.net>
>Reply-To: gmecm at diy-efi.org
>To: "GM-ECM" <gmecm at diy-efi.org>, <diy_efi at diy-efi.org>
>Subject: [Gmecm] Project underway...
>Date: Sat, 1 Sep 2007 12:45:15 -0500
>
>  I'm working on a project with a friend, converting a 1940's Ford 255CID 
>flathead V8 from carb and points to a TBI/ 1227747 setup.  The electronics 
>hardware side is done.  The engine has an afermarket distributor with a 
>conventional VR pickup coil.  This is connected to a standard HEI module 
>that is firing an MSD box. In the pictures the advance weights are still 
>present, but they have been removed and the advance bolted so the ECM can 
>control the timing.
>  Here's where I want you guys' thoughts.  The intake manifold has a huge 
>plenum, look at pictures linked at bottom. We're using a 4.3V6 throttle 
>body and injectors.  Do you think the injectors flow enough for accel 
>enrich to keep from bogging when you open it?  It is a very mismatched 
>setup on the engine/ cam/ manifold but this is what we have to work with.
>  We'll be using Cats RT Tuner and a wideband to adjust the VE tables.  
>This has been a fun project so far, but the real fun will be making it run 
>correctly. It will be an open-loop calibration, tuned for drivability 
>first, power second.  Any thoughts?
>Thanks in advance,
>David
>
>
>
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