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88 Cadillac Brougham 307ci

Posted: Fri Oct 28, 2011 11:04 am
by kuchen
Hi,

I've owned this boat for 10 years now, and its gas milage is not to bad, but the ever growing gas prices in europe finally triggered the idea to convert it to LPG, even though it's not used as a daily driver anymore.
All other vehicles used by our family (VW PAssat, Saab 900 Turbo) were already DIY converted to LPG by using the Polish AC STAG sequential system, but as this computer controlled Olds 307 with a Quadrajet Carburetor (CCC)is definitely not suitable for that kind of stuff, I had to go the Impco way.

Most people throw out all the emission related stuff incl. the O2 feedback control when they convert to propane , but as this system has given me a decent milage in the past, I decided to keep it this way. The problem was to make the stock ECU control the mixture the same way it was initially designed for: My means of variing the dwell on a solenoid valve. The stock valve controls the flow of fuel in the carb, this was replaced by a Pierburg vacuum valve which controls the pressure of the balance line to the Impco Type E.
gesamt.JPG
Basically, it works like the Impco commander, but using the stock ECU for controlls.

Summary:

Mixer CA300 with rich feedback valve
Type E regualtor with feedback on the balance line
Vacuum Dashpots from a scraped Saab 900 to lift and seat the mixer valve instead of a bowden wire
DIY silencer between the Air Divert Valve & the Impco Airfilter

I fine tuned the system with a wideband O2 sensor and a FESTO variable restrictor. The stock ECU is able to control the LPG mixture properly and is not throwing any error-codes.

Sorry, I can't attach my wrap up PDF document.



Ingo

Re: 88 Cadillac Brougham 307ci

Posted: Fri Oct 28, 2011 11:24 am
by Frank
Hello Ingo and welcome to the forum! Thanks for write-up and photo.

Regarding the inclusion of your PDF document, it is possible that I have the maximum file size limit set too low. Is your file larger than 256 kB?

Re: 88 Cadillac Brougham 307ci

Posted: Fri Oct 28, 2011 3:09 pm
by kuchen
Hi Frank,

the size of the PDF document is about 600kb

Re: 88 Cadillac Brougham 307ci

Posted: Fri Oct 28, 2011 3:51 pm
by Frank
Try it now.

Re: 88 Cadillac Brougham 307ci

Posted: Sat Oct 29, 2011 9:47 am
by kuchen
Details 1:

The tank is a polish Stako with a italian Tomasetto Multivalve and Airtight housing
Tank.JPG
The filling point is a Tomasetto compact unit behind the stock fuel filler flapdoor
Filler.JPG
The vacuum dashpots instead of the Impco bowden wire:
Vacuum_lift.JPG

Re: 88 Cadillac Brougham 307ci

Posted: Sat Oct 29, 2011 9:53 am
by kuchen
Details2:

a chrome plated switch that fits the interior at least a little
switch.JPG
The silencer between air pump and open element air filter (noisy WOT without it !)
silencer.JPG
Vacuum hose routing incl. Festo restrictor
VacValves1.JPG

Re: 88 Cadillac Brougham 307ci

Posted: Sat Oct 29, 2011 9:59 am
by kuchen
Details3:

The wrap-up PDF.
wrap-up.pdf.zip
(519.74 KiB) Downloaded 243 times