[Gmecm] Project underway...

Tue Sep 4 03:59:29 UTC 2007

  Thanks for the comments!  My friend is doing the fab work on the TB 
adapter.  He's got a really cool looking "bug catcher" scoop that was 
hand-made by a friend of his.  The TB will sit as you suggest, with the 
bores front to back.  It'll feed the front and rear groups of cylinders 
better that way, plus the scoop will fit over it better. Will have pictures 
as soon as it is done. We're lacking fuel lines and completion of the TBI 
adapter plate/scoop holder before starting the engine.  The rest of the car 
is lacking some of the last electrical details (gauges, exterior lights, 
etc), cooling fan, and seats.  It'll be a while before it is ready to drive 
and be real-time tuned; but the engine may run in a few days or so.
  I'm using the ECM that came with the TBI, I have a 5.0 V8 calibration to 
start with.  The flahead engine was 80 to 90 HP stock, with a tiny 
carburetor.  The bottom end is not designed for high RPM use, it only has 3 
main bearings.  It will not see over 5000 RPM; if that. The top end injector 
flow should not be a problem, but filling that cavernous manifold plenum 
with a proper A/F mixture when the throttle is bumped open, scares me!
  I have heard nothing but good success stories with Megasquirt EFI, but 
I've never used it.  For some reason I like the GM computers.  The fully 
mappable ignition timing and fuel tables; and low cost were my deciding 
factor. I've got 4 GM engines of my own (plus several outside projects) and 
the same tuning hardware works on all.
  How much tunability is in the Megasquirt ECU? How is the ignition mapped?
  Later,
David

----- Original Message ----- 
From: "Garrett Herning" <herningg at hotmail.com>
To: <gmecm at diy-efi.org>
Sent: Monday, September 03, 2007 6:02 PM
Subject: RE: [Gmecm] Project underway...

> 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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