EFI project complete, looking for some 'tuning' info.

H

heinz wittenbecher

New member
Mar 1, 1998
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Just finished with rebuilt heads, new Thorley headers and switch from Howell
EFI to the ported EFI from Rance Fuel Injection. It uses the Accel computer
which is fully programable via their Calmap software.

While the user manual tells how to use the software it doesn't provide and
hints/suggestions on how to program the ECU for performance, efficiency,
etc.

Even out of the box, it's running good, ie smooth, lots of power, etc. but
one has to assume that there is a difference between "out of the box" and a
tailormade tune for a specific engine.

Being just a hobby mechanic I don't have a clue as to how to get it to that
"tailormade" tune. I'd appreciate any hints/suggestions someone might have.
Perhaps a pointer to a book, website or sharing of experience could help me
to get started.

Of course I could leave well enough alone... but that just wouldn't seem
right :-)

Next project: macerator, hitch and towbar.

Heinz
'76 Transmode
 
>
> Just finished with rebuilt heads, new Thorley headers and switch from Howell
> EFI to the ported EFI from Rance Fuel Injection. It uses the Accel computer
(SNIP)

Try going to this website http://efi332.eng.ohio-state.edu/diy_efi/ it
is a DIY website for fuel injection. You may want to start with a
program for the Chevy 454 and then make mods.

Why did you switch from Howell and did you look at the one from Leigh
Harrison? This is a project that I would like to do and any suggestions
would be appreciated.

Marcus
 
>
>Try going to this website http://efi332.eng.ohio-state.edu/diy_efi/
>
Thanks Marcus and Scott for the website suggestions. It may be a little too
advanced for me, especially at this point, but usefull information
nevertheless... heavy duty digestion (or indigestion) coming up.

>
>Why did you switch from Howell and did you look at the one from Leigh
>Harrison? .
>
>Marcus

The decision between Rance and Leigh's was easy... I didn't know about
Leigh's efforts until after I had ordered :-) A GMCnetter alerted me to the
fact but a decision had been made.

However, in retrospect I still think the choice would be the same when
cranking parts availability into the equation. Aside from the intake
manifold assembly I think I could scrounge all other components off the
shelf at most parts stores. THIS IS NOT TO SAY THAT IT WOULD NOT BE THE SAME
WITH A LEIGH H. SYTEM. It's just that didn't have the opportunity to check
that part out.

Both gentlemen were/are a pleasure to speak with/deal with. Workmanship on
their products is excellent. I purchased the serpentine belt kit from Leigh
and am 'very' pleased with it. I run a 150amp alternator and it's always
been more difficult to keep belt tension just right.

Of course it'll take a trip or 2 to really confirm my current enthusiasm.
Just my 2cents worth at this point.

Anyone thinking Serpentine... go for it.
Anyone thinking EFI... there are now several option available, check and
compare and pick what's right for you. Thanks to GMCnet we can now at the
very least make other GMCers aware of the little gems we come accross for
our treasure on 6 wheels :-) and exchange views and experiences. Of course
there's nothing wrong with carbs either :-)

Heinz
'76 Transmode
 
Heinz:

What benefits, other than the tension bit you mention, for the
serpentine belt system?

What are the differences and benefits between Leigh's and Rance's EFI
systems. How do the cost's compare?

Paul Bartz

> -----Original Message-----
> The decision between Rance and Leigh's was easy... I didn't know about
> Leigh's efforts until after I had ordered :-) A GMCnetter alerted me
> to the fact but a decision had been made.
>
> However, in retrospect I still think the choice would be the same when
> cranking parts availability into the equation. Aside from the intake
> manifold assembly I think I could scrounge all other components off
> the shelf at most parts stores. THIS IS NOT TO SAY THAT IT WOULD NOT
> BE THE SAME WITH A LEIGH H. SYTEM. It's just that I didn't have the
> opportunity to check that part out.
>
> Both gentlemen were/are a pleasure to speak with/deal with.
> Workmanship on their products is excellent. I purchased the serpentine
> belt kit from Leigh and am 'very' pleased with it. I run a 150amp
> alternator and it's always been more difficult to keep belt tension
> just right.
>
> Anyone thinking Serpentine... go for it.
>
> Anyone thinking EFI... there are now several options available, check
> and compare and pick what's right for you. Thanks to GMCnet we can
> now at the very least make other GMCers aware of the little gems we
> come accross for our treasure on 6 wheels :-) and exchange views and
> experiences. Of course there's nothing wrong with carbs either :-)
>
> Heinz
> '76 Transmode
>
 
>
>What benefits, other than the tension bit you mention, for the
>serpentine belt system?

I think it's quieter, smoother. One spare to carry. Easy to change belt.

>
>What are the differences and benefits between Leigh's and Rance's EFI
>systems. How do the cost's compare?

That one I'll have to leave for someone else as it was too late for me to
compare so I didn't dwell on it at the time I found out about Leigh's. You
know, kinda chicken that I might've made the wrong choice I guess :-)

The approach is quite different, Leigh's being a much more ambitious
undertaking, I believe, at least with reference to leading edge technology.
In the computer racket we refer to it as 'bleeding edge' :-) I have to keep
my wounds at a controllable level so have to be alert to that by leaning
towards tried and true, at least initially.
>
> Paul Bartz



Heinz
 
Heinz:

You say you run a 150 alternator.

What kind of a load do you have that requires that size alternator? Did
you upgrade any of the original wiring to carry the increased load?
I've heard various people question the wisdom of not doing so.

Paul Bartz
> -----Original Message-----
> From: Heinz Wittenbecher [SMTP:heinz]
> Sent: Friday, April 17, 1998 12:21 PM
> To: gmcmotorhome
> Subject: Re: GMC: EFI project complete, looking for some 'tuning'
> info.
>
> Try going to this website http://efi332.eng.ohio-state.edu/diy_efi/
>
>
> I run a 150amp alternator and it's always been more difficult to keep
> belt tension just right.
>
>
 
Paul,
When I first got my rig (10+) years ago with a 70amp ( I think ) installed I
had a few alternator failures in a relatively short time. In retrospect it
might've been workmanship :-) of the alternators themselves. That was before
I knew anything about GMC's or the community. ( I had always wanted one, the
opportunity arose, and I still have it :-)

On a trip to Buskirks early on (for sway bars, etc) it so happened that they
had a used 150 and I bought it. We changed the output wire to #4 ( I
think ), i.e. large.

Whether I need it or would do it again? who knows :-)
I've replaced/rebuilt it a few times but overall it's not been giving any
hassles other than being very picky about belt tension. Hopefully that's now
solved as I have the serpentine installed.

Load: originally I figured I'd be running the fridge on 12V while underway,
but it broke and got replaced a long time ago so now run on propane. I do
'cycle' my batteries lots. Computers (full size and laptop), cellphone(s),
used to have a satellite system for comunications before cell phones came
around, etc.

With 20/20 hindsight the only reason for change would be psycological, I
think. I.e. a 150 amp would work less, last longer... equals less downtime
(in one's mind :-)

With reference to the diode/battery splitter gadget ( the proper name
escapes me at the moment :-), after a couple of failures I changed it to a
relay connected 'ignition on' so that the relay is closed and feeds the rear
house battery when engine is running.

Heinz
'76 Transmode

>Heinz:
>
>You say you run a 150 alternator.
>
>What kind of a load do you have that requires that size alternator? Did
>you upgrade any of the original wiring to carry the increased load?
>I've heard various people question the wisdom of not doing so.
>
> Paul Bartz
>> -----Original Message-----
>> From: Heinz Wittenbecher [SMTP:heinz]
>> Sent: Friday, April 17, 1998 12:21 PM
>> To: gmcmotorhome
>> Subject: Re: GMC: EFI project complete, looking for some 'tuning'
>> info.
>>
>> Try going to this website http://efi332.eng.ohio-state.edu/diy_efi/
>>
>>
>> I run a 150amp alternator and it's always been more difficult to keep
>> belt tension just right.
>>
>>
 
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