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Nathan 01-17-2008 07:04 PM

Buying/Installing a Dual Fuel Propane Kit?
Hi guys,

I've done a bit of digging around online, trying to read up about propane conversion kits. Anybody out there done this? I've got an '85 350 V8, and am thinking of running dual fuel. The idea of having the option to run either gas or propane sounds attractive, with propane being a cheaper alternative.

I don't really want to get into the whole California DMV/smog/propane issue, at the moment. But, if anyone has tips regarding that, I'd sure like to hear them. As far as I can tell, it's semi-impossible to have a personal street legal propane-run, smogged vehicle in the state of California. However, I am wondering if with the dual fuel, you could smog it on gas, and then run it on propane after that? Of course, you'd have to find gas station attendants to fill your bus up for you.

In the near future, I may be moving back to Oregon, where there really isn't much in the way of smog issues, so this whole smog deal might be avoided in a bit.

Okay, I am rambling again. First things first. If anybody has any tips or recommendations of kits or companies to check out, I'd greatly appreciate it!


the_experience03 01-17-2008 09:02 PM

Re: Buying/Installing a Dual Fuel Propane Kit?
From what I've read you are correct on the California thing. It used to be a credit to do it and now it is impossible I guess. I'm not sure...I don't live there.

Here's a couple resources for you.

A word of advice on Pirate...join up and use the search function, but if you're going to post a question do so in the newbie forum. Those guys aren't always the nicest to noobs and get sick of answering the same questions over and over again.

Nathan 01-17-2008 09:40 PM

Re: Buying/Installing a Dual Fuel Propane Kit?
Hey, thanks for the tips. I was actually cruising around some of those sites today. I am nowhere near read up enough on the subject to ask them questions, but will try to make sure I don't ask the same basic questions everyone always posts.

Yeah, the smog/emissions rules have always confused me, too. They used to give you credit for it, now you can't do it. Meanwhile, many government vehicles run on dual gas/propane setups.

It seems to me that emissions test should just simply check your emissions. If you pass, you pass. It shouldn't really matter what your engine runs on, how it runs, what parts you have in it, etc. If you build an engine that drives you down the road safely, and doesn't pollute the environment more than whatever the standard is, then you're fine. :)

A slightly on-topic rant, I had a Chevy Tahoe I brought down from Oregon a few years back. I installed a K&N air filter on it, along with the little "CARB/smog legal" sticker for California. When I went to smog it, to register it as a California car, the smog guy said he couldn't even test it because it had an "altered air intake system" and was illegal. He said I had to put the factory intake back on the car to be legal, even with my little legal sticker.

Okay, enough ranting about things that I really don't have much knowledge about. :) There's probably a good reason for all the rules and hooplah, I just don't see it.

the_experience03 01-17-2008 11:14 PM

Re: Buying/Installing a Dual Fuel Propane Kit?
I hear ya. I agree too. Put the sniffer in the pipe...if it passes it passes. I've actually heard some people saying that more recently that is what is happening with them. They just get sniffed. There is no visual because if it passes then there really is no reason to dig deeper. I'm sure it's just all about where you live and who you know.

Pirate is probably going to have the most information for you. I believe you would be looking for an Impco 300A mixer. That might help you in your searching.

KevinCoughlin 02-25-2008 01:46 PM

Re: Buying/Installing a Dual Fuel Propane Kit?
The big issue with dual fuel is the timing differences. Propane has a higher octane (but less BTU per gallon) and needs to be more advanced timing. One way to dual fuel is to use an electronic advance unit - I have one for dual fuel setup I could sell you, except it is for a 6 cylinder motor. Ooops.... I bought the wrong one on ebay.

Most of the time a dual system is a compromise. Propane would work much better at higher compression than your gas engine. Super or turbo charging is good, or have the head shaved a bit to up the compression if you were running only propane....

I don't have direct experience with a dual system - my bus is propane only. Poor mileage/performance compared to gas versions (I doubt it was modified for higher compression) but I did see an increase in pep once I pushed the distributor timing up to where it should be (it was set like a gas engine when I got it) and added a hotter sparking ignition system.

As for legal - in Washington state they don't even sniff a propane only rig.... they just charge you extra to license it because propane is not "road taxed". Being based on weight - it runs me almost $250 a year more for the privilege of not polluting. I'm thinking of dropping a gas carb on the rig, changing the title to gasoline powered, and then yanking it again once I get home. In my county (country rednecks) they don't have emission inspection requirements yet, so it does not matter....

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