Home » Public Forums » GMCnet » [GMCnet] Fi Tech - any downwsides
| [GMCnet] Fi Tech - any downwsides [message #299475] |
Fri, 22 April 2016 11:43  |
glwgmc
Messages: 1014
Registered: June 2004
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I’m not John,
But, the answer is yes, the FiTech ignition control is an advance curve programmed into a table without a knock sensor. It needs a locked out standard distributor (not HEI) to work. Most of the FiTech support people with whom I have spoken say they run their own classic/muscle cars using the HEI distributor. When Dick Patterson discussed this with FiTech at a trade show, he found the curve to be about what he programs into his HEI units designed for our GMCs. I had him curve one of his HEI distributors for my FiTech application in the Clasco and it seems to perform well.
The 400hp unit was not available when I purchased my 600 hp unit from FiTech - or at least I was unaware of it at that time if it did exist then. The design of the throttle body is the injectors do not squirt directly into the area of the throttle butterfly plates. Instead they squirt into an annular chamber that runs all around the throttle body. Small holes in the inside of the throttle body direct the pressurized fuel from the injectors into the throttle body all around on top of the throttle butterfly plates which they say delivers better atomization. It is not clear to me whether there is any real world difference between the two sizes of injectors given this delivery mechanism. All I know is the 600 hp unit works very well for me. I had one person off line tell me I should be experiencing bogging issues given the size of the injectors in the 600 hp unit. I am not. The only anomaly I have experienced is on two occasions while trying to reset the manual idle air back to the factory setting (I improperly moved that adjustment during installation) I experienced a bog right off idle when first firing up the engine from a cold state and driving off immediately. I have not experienced that since I think I got the manual idle air back close to where it belongs.
Most of the folks who are using computer based spark control with a knock sensor say they are able to achieve more advance without pre-ignition and so experience perhaps a 1 (some even say 2) mpg gain in fuel mileage. Some say they do not. Using the HEI distributor curve in both the Clasco with the FiTech EFI and the Royale with a Patterson Qjet I can’t readily tell any difference in fuel mileage. There is a lot of difference in throttle response, altitude compensation, immediate starting, etc. Lots of variation in our old beasts, I guess.
Jerry
Jerry Work
The Dovetail Joint
Fine furniture designed and hand crafted in the 1907 former Masonic Temple building in historic Kerby, OR
glwork@mac.com
http://jerrywork.com
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Message: 12
Date: Fri, 22 Apr 2016 09:37:58 -0400
From: Ken Henderson
To: gmclist@list.gmcnet.org
Subject: Re: [GMCnet] Fi Tech - any downwsides
Message-ID:
Content-Type: text/plain; charset=UTF-8
John,
In addition to the restriction to points type distributors, it's my
understanding that the only ignition "control" is that the advance curve is
controlled by software tables. That is, there is no knock detector
providing feedback and real time control of advance.
Is that correct?
Thanks,
Ken H.
On Fri, Apr 22, 2016 at 8:53 AM, jhb1 wrote:
> Hi Gordon
>
> I originally ordered the 400hp unit but kept getting the delivery pushed
> back. I ended up ordering the 600hp unit the differences between the two are
> injector sizes and the 400hp unit does not support ignition control. The
> ignition control only works on points type distributors early models
> non-HEI.
> Hope this helps
> —
=================
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Jerry & Sharon Work
78 Royale
Kerby, OR
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| Re: [GMCnet] Fi Tech - any downwsides [message #299492 is a reply to message #299475] |
Fri, 22 April 2016 13:52  |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
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Thanks, Jerry.
If I weren't already deeply into TBI with EBL, I'd probably be going with
that system also. I don't see the dramatic mileage improvement with CCD
that some claim, but then I don't track MPG much either. I do enjoy
knowing I have full advance without having to worry about not being able to
hear knocking though.
Ken H.
On Fri, Apr 22, 2016 at 12:43 PM, Gerald Work wrote:
> I’m not John,
>
> But, the answer is yes, the FiTech ignition control is an advance curve
> programmed into a table without a knock sensor. It needs a locked out
> standard distributor (not HEI) to work. Most of the FiTech support people
> with whom I have spoken say they run their own classic/muscle cars using
> the HEI distributor. When Dick Patterson discussed this with FiTech at a
> trade show, he found the curve to be about what he programs into his HEI
> units designed for our GMCs. I had him curve one of his HEI distributors
> for my FiTech application in the Clasco and it seems to perform well.
> ...
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www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: [GMCnet] Fi Tech - any downwsides [message #299494 is a reply to message #299492] |
Fri, 22 April 2016 14:17 |
James Hupy
Messages: 6806
Registered: May 2010
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Lots of engineering went into both the frequency of and amptitude of, as
well as the placement of knock sensors. GM spent a huge bundle on it, and
the other manufacturers did also. If you consider firing order of the
various engines involved, as well as construction materials, engine mounts,
exhaust manifolds, rpm, loads, etc. You get the idea. Fi Tec probably does
not quite have the engineering department that the big 3 have. Might have
more than a little bit to do with the product that they produce.
Their fuel module with internal submerged electric pump is as bright an
idea as I have seen in recent years, and should be adaptable to the Howell
system. I am going to try one as soon as the opportunity presents itself.
We need all the help that we can get to combat fuel vapor lock, especially
with blended fuels with low Reid pressure points. The problem will persist
as long as there is alcohol blended into gasoline, and I suspect that will
be a very long time.
Just what it is. We need to adapt to it.
Jim Hupy
Salem, Or
78 GMC ROYALE 403
On Apr 22, 2016 11:53 AM, "Ken Henderson" wrote:
> Thanks, Jerry.
>
> If I weren't already deeply into TBI with EBL, I'd probably be going with
> that system also. I don't see the dramatic mileage improvement with CCD
> that some claim, but then I don't track MPG much either. I do enjoy
> knowing I have full advance without having to worry about not being able to
> hear knocking though.
>
> Ken H.
>
> On Fri, Apr 22, 2016 at 12:43 PM, Gerald Work wrote:
>
>> I’m not John,
>>
>> But, the answer is yes, the FiTech ignition control is an advance curve
>> programmed into a table without a knock sensor. It needs a locked out
>> standard distributor (not HEI) to work. Most of the FiTech support
> people
>> with whom I have spoken say they run their own classic/muscle cars using
>> the HEI distributor. When Dick Patterson discussed this with FiTech at a
>> trade show, he found the curve to be about what he programs into his HEI
>> units designed for our GMCs. I had him curve one of his HEI distributors
>> for my FiTech application in the Clasco and it seems to perform well.
>> ...
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
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| Re: [GMCnet] Fi Tech - any downwsides [message #299540 is a reply to message #299539] |
Sat, 23 April 2016 11:08 |
James Hupy
Messages: 6806
Registered: May 2010
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Normally, altitude compensation is done by decreasing pulse width in the
fuel injection along with an increase in spark advance. If the distributor
is locked or fixed, then a timing module is incorporated to accomplish the
same effect. All attenuated by barometric pressure changes. (altitude
compensation). Lacking more sophisticated sensors, then the ECU takes over
more control. Lacking that, I suppose nothing gets done but fuel
management. Without more technical information, this is just educated
guesswork on my part.
Jim Hupy
On Apr 23, 2016 8:52 AM, "Billy Massey" wrote:
> Jerry said in February that he didn't used "spark is via an HEI Dick
> Patterson curved for this EfI". So, the schematic on page 11 would be
> correct. Still don't see any means of altitude compensation which would be
> one of my main objectives. I suppose the air / fuel mixture would be
> compensated for with the oxygen sensor.
>
> http://fitechefi.com/virtualoffice_files/30001.30002%20Instructionsm%2012.9.15.pdf#page=11
>
> bdub ... EFI Dummy
>
>
> On Sat, Apr 23, 2016 at 10:22 AM, Armand Minnie wrote:
>
>> go to
>>
> http://fitechefi.com/virtualoffice_files/30001.30002%20Instructionsm%2012.9.15.pdf
>> for a PDF of the instructions for the FiTech unit. The last
>> page has a diagram of what all the connections are.
>>
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| Re: [GMCnet] Fi Tech - any downwsides [message #299606 is a reply to message #299546] |
Sun, 24 April 2016 09:53 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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For about the last five years, I have had an MSD adjustable timing unit in my coach, courtesy of Steve Ferguson. It allows me to adjust the timing from the dash. This makes it possible for me to retard the timing under heavy towing loads and/or at low elevations, or advance the timing under light loads and at high elevations.
This sounds like it would work well with the FiTech system, the only down side being that you would need to manually adjust the timing. After five years of using the MSD spark control, it has become automatic for me anyway.
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
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| Re: [GMCnet] Fi Tech - any downwsides [message #299607 is a reply to message #299606] |
Sun, 24 April 2016 10:03 |
A Hamilto
Messages: 4508
Registered: April 2011
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Carl S. wrote on Sun, 24 April 2016 09:53...I have...adjustable timing...from the dash. ... My dad had a gizmo in a pickup truck that he tried to use to get max power going over the continental divide. Burned a valve. Spark advance can't be done manually with any expectation of success. It needs a knock sensor coupled with the electronic ignition, or mechanical/vacuum advance that is not too aggressive.
[Updated on: Sun, 24 April 2016 10:04] Report message to a moderator |
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| Re: [GMCnet] Fi Tech - any downwsides [message #299626 is a reply to message #299607] |
Sun, 24 April 2016 17:16 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
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A Hamilto wrote on Sun, 24 April 2016 08:03Carl S. wrote on Sun, 24 April 2016 09:53...I have...adjustable timing...from the dash. ... My dad had a gizmo in a pickup truck that he tried to use to get max power going over the continental divide. Burned a valve. Spark advance can't be done manually with any expectation of success. It needs a knock sensor coupled with the electronic ignition, or mechanical/vacuum advance that is not too aggressive.
I stand corrected. I'm not sure how one burns a valve by retarding the timing six or eight degrees to eliminate detonation on a hard climb, but I always defer to the experts
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
[Updated on: Sun, 24 April 2016 22:23] Report message to a moderator |
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| Re: [GMCnet] Fi Tech - any downwsides [message #299628 is a reply to message #299627] |
Sun, 24 April 2016 17:32 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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A Hamilto wrote on Sun, 24 April 2016 15:30Carl S. wrote on Sun, 24 April 2016 17:16A Hamilto wrote on Sun, 24 April 2016 08:03Carl S. wrote on Sun, 24 April 2016 09:53...I have...adjustable timing...from the dash. ... My dad had a gizmo in a pickup truck that he tried to use to get max power going over the continental divide. Burned a valve. Spark advance can't be done manually with any expectation of success. It needs a knock sensor coupled with the electronic ignition, or mechanical/vacuum advance that is not too aggressive. I stand corrected. I'm not sure how one burns a valve by retarding the timing six or eight degrees to eliminate detonation on a hard climb, but I always defer to the Not retarding. He was advancing it for power and trying to back off when it knocked. It didn't work. Manual control can't do enough fast enough.
His mistake.
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
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| Re: [GMCnet] Fi Tech - any downwsides [message #299629 is a reply to message #299475] |
Sun, 24 April 2016 17:32 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
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Retarding the timing means the mixture lights later and burns later. Leaning from altitude makes the mixture burn slower. Combine the two and you can be blowing fire past the valve when it opens.
--johnny
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: [GMCnet] Fi Tech - any downwsides [message #299630 is a reply to message #299629] |
Sun, 24 April 2016 17:55 |
James Hupy
Messages: 6806
Registered: May 2010
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Hmmmm? Let me see if I got this. Intake opens, piston travels down and
atmospheric pressure forces air/fuel mix into cylinder as long as there is
a difference in pressure between the two areas. Intake valve closes, piston
travels up compresses the mix, 8 or 10 degrees before tdc at idle speed,
plug fires, mixture expands and shoves the piston down. Few degrees before
bottom, exhaust valve starts to open. By this time, no Ox left to oxidize
the valve seat or valve face. Inert gasses are not the cause of oxidation.
Valves can run red hot without burning and do a lot of the time under heavy
loads. Thermodynamics teaches us that as long as heat is exchanged to the
exhaust and cooling systems at a greater rate than combustion heats them
up, the valves and seats can survive in that environment, AS LONG AS NO
OXYGEN IS PRESENT.
Jim Hupy
Salem, Or
78 GMC ROYALE 403
On Apr 24, 2016 3:33 PM, "Johnny Bridges via Gmclist" <
gmclist@list.gmcnet.org> wrote:
> Retarding the timing means the mixture lights later and burns later.
> Leaning from altitude makes the mixture burn slower. Combine the two and
> you
> can be blowing fire past the valve when it opens.
>
> --johnny
> --
> '76 23' transmode Norris upfit
> Braselton, Ga.
>
> "Sometimes I wonder what tomorrow's gonna bring when I think about my
> dirty life and times" --Warren Zevon
>
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| Re: [GMCnet] Fi Tech - any downwsides [message #299632 is a reply to message #299475] |
Sun, 24 April 2016 19:07 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
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That's the way it was 'splained to me. And supported by the fact that retarded idle spark using ported vacuum makes the engine run way hotter. particularly exhaust valves and downstream components.
Maybe one of the engineering types will take this further.
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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