Propane.

[CJim7]

Anybody running propane on their engine?

I've been doing the research for a few years now on this conversion, read multiple articles and write-ups, and spoke with Gotpropane.com a few times through Email. I even bought a complete conversion kit last year...the price was a steal even though I wasn't quite ready for the conversion.

So in speaking with the owner of the shop that did the machine work on my 401, he suggests that I dont do the conversion. Claims heat would be a bad issue on a engine that traditionally runs hot anyways. He also said I would need to run different valves, guides, and seats...

Now this guy is reputable, he has been in the business for years and builds raceing motors so I dont really doubt his knowledge, but Im left scratching my head.

Everything I've heard, read, and seen, says you can slap on a propane conversion and not worry about it.

So does anyone here have experience running the stuff? IS there a heat issue combusting LPG rather then gasoline? I could just call Gotpropane and probably get an answer, but I thought this would be a good subject to discuss here....

 

[Old Dog]

Years ago I ran a duel-fuel set-up on a 350 sbc. I would run gas on the highway and switch to propane for off road.
sbc's don't run that hot though so I never had problems there.
As far as valves everything was stock 77 chevy.

 

[CJim7]

Years ago I ran a duel-fuel set-up on a 350 sbc. I would run gas on the highway and switch to propane for off road.
sbc's don't run that hot though so I never had problems there.
As far as valves everything was stock 77 chevy.

Thanks Old Dog. Im actually less worried about the valvetrain then I am the heat issue. Im turning a much higher compression then stock (10:1) and this motor has ran a little hot from the day I broke it in. I might just have to figure out a way to cool this thing more efficiently if I want to run the propane.

 

[myjeepsbigger]

I ran propane for several years on my SBC XJ buggy. In my experience, the LPG setup actually ran COOLER than the engine did on gasoline. LPG doesn't have the BTU energy that gasoline has, so the higher compression should help you retain some of the 'lost' power when switching over to propane. Propane also loves a lot of timing, and likes it quick in the rpm range. Usually "all in" by 3500 or so. I bought an advance spring/weight kit and ran the heavy weight/light spring kit (think: drag race advance). Made a tremendous difference in the way the engine ran over the stock weights & springs.

There are special cam grinds that you can get for propane also, IIRC, they close the exhaust valve more softly to help save the valve seats.

If you already have the kit, you should at least give it a "chance" before giving up on it. I only had a few complaints about my setup-- a. it's a pain to fill the tanks (we did it right at the bulk propane tank at our farm), b. my supply lines would freeze up near the tank in the winter if I was really running it hard (high fuel usage), c. When we ran in Moab, I couldn't really ever get the thing tuned correctly with the altitude change.

 

[CJim7]

I ran propane for several years on my SBC XJ buggy. In my experience, the LPG setup actually ran COOLER than the engine did on gasoline. LPG doesn't have the BTU energy that gasoline has, so the higher compression should help you retain some of the 'lost' power when switching over to propane. Propane also loves a lot of timing, and likes it quick in the rpm range. Usually "all in" by 3500 or so. I bought an advance spring/weight kit and ran the heavy weight/light spring kit (think: drag race advance). Made a tremendous difference in the way the engine ran over the stock weights & springs.

There are special cam grinds that you can get for propane also, IIRC, they close the exhaust valve more softly to help save the valve seats.

If you already have the kit, you should at least give it a "chance" before giving up on it. I only had a few complaints about my setup-- a. it's a pain to fill the tanks (we did it right at the bulk propane tank at our farm), b. my supply lines would freeze up near the tank in the winter if I was really running it hard (high fuel usage), c. When we ran in Moab, I couldn't really ever get the thing tuned correctly with the altitude change.

Thanks man. Im might just give it a try after all...I really want to make this work, My gastank is in the way of my rear stretch plans...

I guess the worst case, is it runs hotter then I feel comfortable with, and I swap the Qjet back on it.

 

[myjeepsbigger]

Thanks man. Im might just give it a try after all...I really want to make this work, My gastank is in the way of my rear stretch plans...

I guess the worst case, is it runs hotter then I feel comfortable with, and I swap the Qjet back on it.

Good luck with it. It should definitely be an improvement over the Quadrajet....especially it you take it offroad at all. A well-tuned propane setup is very smooth and completely immune to off-camber situations (as I'm sure you're aware)... it's a great alternative to EFI as long as you do your homework.

Keep us updated as you get it put together!

 

[CJim7]

Good luck with it. It should definitely be an improvement over the Quadrajet....especially it you take it offroad at all. A well-tuned propane setup is very smooth and completely immune to off-camber situations (as I'm sure you're aware)... it's a great alternative to EFI as long as you do your homework.

Keep us updated as you get it put together!

Will do thanks!
As a side note, my Qjet turned out to be absolutely awesome as far as carbs go offroad (and I've ran a lot of carbs). It will pretty much run on its side, and nose up/down isn't much of an issue for it... But, in the end, it's still a carb and Im looking forward to trying out the propane as the EFI alternative.

 

[Fifesjeep]

Everybody that I talked to that ran propane said that their rig seemed to run cooler... One guy said that running propane you can run 10:1 CR without issues. Somebody mentioned something about valve seats but I can recall what he said...

 

[robert1973]

My friends runs a duel fuel setup and he runs 10-15 degrees cooler on the propane. He is running a 351windsor. I believe he got his kit from got propane too.

 

[nctom]

I am in the process of putting together a dual fuel setup for my daily driver. Are you planning on using a DOT approved tank or a forklift cylinder? I was good to go until I realized that forklift cylinders would't deal well with a rear impact on the road. Trying to find a DOT tank that would fit has been a real pain. Let me know what you find, eh?

Thanks!

 

[CJim7]

I am in the process of putting together a dual fuel setup for my daily driver. Are you planning on using a DOT approved tank or a forklift cylinder? I was good to go until I realized that forklift cylinders would't deal well with a rear impact on the road. Trying to find a DOT tank that would fit has been a real pain. Let me know what you find, eh?

Thanks!

Im going to use forklift tanks. Originally I got my hands on a set of tandem tanks, 10 gallons each side, that were for a vehicle application but the dang things weigh an absolute ton even empty.

I wouldnt feel comfortable installing my tanks anywhere but inside the roll cage (where the rear seat used to be) I feel whatever I run there will be plenty safe.

 

[fzsk4p]

Jim,
propane runs "drier and cleaner" then gasoline. Meaning that the cushioning effects/lubrication that the additives in gasoline provide valve seats, stems, cylinder walls is reduced with propane.

Remember the old muscle cars of the 60`s ? The tetrela ethly lead (spelled wrong) lead was removed from pump gas. The lead did several (generically speaking) things. Raised octane levels and cushioned valve seats. It also was classified as a carcinogen and a pollution element. Hardened valve seats and reduced compression was the what the manufacturers had to deal with.

Today`s engines with new technology (fast burn for example) cylinder heads and very precise fuel metering is allowing compression to bump up a bit. Plus the addition of knock sensors push the envelope even more.

There was the gray area that folks with "old" style engines running "new" gas did have problems with valves and seats. Pre mature valve jobs, dieseling on shut down to name a few. Also pre-Ignition and detonation were prevalent. Enter the world of off the shelf octane boosters and top end lubes. Snake oils did well.

Propane will run cleaner then gas. And as already mentioned, cooler. If your heads are after the early 70`s (that would have harder seats) I would not worry to much about valve seat pounding. That is if you have a decently wide contact area between the valve and the seat. Not some fancy multi angle valve job that compromises valve /seat life for a few extra CFM of flow. Hardened seats are available for your consideration.

A good motor oil with plenty of anti scuff properties (Lot`s of ZDDP) will help to offset the "cleaning" action the propane has. Important for valve stems and cylinder walls.

Again as mention, the BTU content of propane is less the gasoline. Expect a little less power. If that really matters with a 401 . Some of that power can be retrieved by increase timing. Again as already mentioned. Also expect less mileage then gasoline. Net result will be a little less power. Cooler running temps and reduced emissions.

If you can handle the down sides. Then next to FI, propane is a great choice. The green tree huggers will love you !!

 

[Glass84CJ]

There's a lot of them in Key West, FL. They pull "Train Cars" around the streets for the tourists to ride in. Some are specialized vehicles that look like trains, some are Jeeps. The Company that does it was "Conch Tour Train". Their number is 888-916-8687. I'm sure someone can give you answers there. I'd ask for someone in their vehicle repair shop.

 

[CJim7]

Jim,
propane runs "drier and cleaner" then gasoline. Meaning that the cushioning effects/lubrication that the additives in gasoline provide valve seats, stems, cylinder walls is reduced with propane.

Remember the old muscle cars of the 60`s ? The tetrela ethly lead (spelled wrong) lead was removed from pump gas. The lead did several (generically speaking) things. Raised octane levels and cushioned valve seats. It also was classified as a carcinogen and a pollution element. Hardened valve seats and reduced compression was the what the manufacturers had to deal with.

Today`s engines with new technology (fast burn for example) cylinder heads and very precise fuel metering is allowing compression to bump up a bit. Plus the addition of knock sensors push the envelope even more.

There was the gray area that folks with "old" style engines running "new" gas did have problems with valves and seats. Pre mature valve jobs, dieseling on shut down to name a few. Also pre-Ignition and detonation were prevalent. Enter the world of off the shelf octane boosters and top end lubes. Snake oils did well.

Propane will run cleaner then gas. And as already mentioned, cooler. If your heads are after the early 70`s (that would have harder seats) I would not worry to much about valve seat pounding. That is if you have a decently wide contact area between the valve and the seat. Not some fancy multi angle valve job that compromises valve /seat life for a few extra CFM of flow. Hardened seats are available for your consideration.

A good motor oil with plenty of anti scuff properties (Lot`s of ZDDP) will help to offset the "cleaning" action the propane has. Important for valve stems and cylinder walls.

Again as mention, the BTU content of propane is less the gasoline. Expect a little less power. If that really matters with a 401 . Some of that power can be retrieved by increase timing. Again as already mentioned. Also expect less mileage then gasoline. Net result will be a little less power. Cooler running temps and reduced emissions.

If you can handle the down sides. Then next to FI, propane is a great choice. The green tree huggers will love you !!

Ok, that's informative. I remember having to run an octane boost in my '74 Stingray because leaded gas was out of the picture.

My 401 is a '77 and I've had the head worked recently with a basic valve grind...nothing special there.

The system Im using came off a 383 stroker running 500hp, the previous owner said he got pretty much everything the motor had to offer running the LPG, we'll see how it does on mine. I can live with a slight decrease in power, Im at 430hp anyways running unleaded and that's an awful lot to begin with. But it will be interesting to see if I actually gain power, sometimes carburetors hide an inefficiency. We'll see.

Im going to consider running the Joe Gibbs oil full time....$7.00/qt, but might just be worth it to not have to break into this engine again in the too near future. Thanks for all the info.

 

[fzsk4p]

Your 401 will like Joe Gibbs.

Brad Penn around here is running about 5 bucks/qt. BradPenn.com will list suppliers.

Betcha it`ll like the `pane also.

 

[CJim7]

Brad Penn around here is running about 5 bucks/qt. BradPenn.com will list suppliers.

Heck, that's not much more then the cost of a regular qt of Valvoline around here lately

 

[CJim7]

Quick question for those who may know...

I've searched all over the net (short of calling Gotpropane.com) but haven't found the answer Im looking for.

The propane regulator needs a coolant line going to and from it to create gas expansion and to also keep things from freezing up. Im assuming most people just plumb their heater hoses. Question is, would it be better to splice the ingoing line to the heater core or the return side.

I see an argument for both. 1...the water would potentially be warmer heading to the heater core. 2...the outboard side would ensure that my heater temperature isn't compromised. I suspect that splicing the input side would rob heat that I would need to warm up my cab.

Any thoughts? and thanks in advance

 

[nctom]

I would grab the output line. Propane doesn't need that much temperature to vaporize and prevent freeze up. Might as well use what you have left after warming your tootsies in the cab.

 

[CJim7]

I would grab the output line. Propane doesn't need that much temperature to vaporize and prevent freeze up. Might as well use what you have left after warming your tootsies in the cab.

Thanks nctom. Makes plenty of sense