351 XE on LPG
Join Date: Jul 2003
Location: Perth, Western Australia
Re: Dual Fuel 351C
Forget about running dual fuel ! You cannot tune a motor to suit both fuels, as they both have different burning properties, so a compromise is required and you can never get the best out of either fuel.
Remove the petrol tank, fuel pump and carby and convert to straight LPG. It's the best thing I've done. We've got 3 vehicles at the moment all running straight gas, (XE 351C, XY 302W, 1993 Patrol 3.0). If your motor is built and tuned for gas, it will end up making more power then if you left it on petrol. Your motor will also last longer on gas, but that's another discussion. LPG is not a gutless taxi fuel as ignorant people would have you believe, but the secret to this cheap source of HP is slowly getting out there. It took me a while to research my 351C build and source the right cam profile, etc. That was over 2 years ago, but it sure was worth the effort. I now have heaps of tyre turning torque and an XE Fairmont that I can drive everyday and never have to worry about the cost of fuel. An LSD and 255's work hard to keep traction with a long 2.77 rear end.
For starters - fit an Impco 425 carby on an 850 Holley squarebore base plate. Recurve and advance the distributor to suit gas, fit a set of ICE leads, fit the electronic dissy and ignition system from an XE. When the time comes, fit a set of 302C heads. Depending on who you listen to, this should give you somewhere between 10.5 and 11.4 to 1 compression. LPG just loves compression, but beware - not all LPG is the same. Over here in Perth, I use Kleenheat Autogas which is usually 100% propane. Don't touch BP. It has a lot more butane in it which lowers the octane level. The more propane the better.
Hope this helps you on your way.