The Stovebolt Site Forums The Shop Area Engine Shop Mystery Intake Manifold....Propane?

Hi, I recently acquired this intake manifold and am just curious what it is. I was told it was used on the 216/235/261 6 cylinders when they were converted to propane for more power, but the ports look a bit too big. Could it possibly be for a GMC or something like that? I have absolutely no clue. It was made by the Johnson Machine Company. Thank you.

http://chuddy117.homestead.com/propane.html

Chad

Two things ..... measure the manifold end to end the GMC is longer
When I went to you link I got two pop-ups on the desktop DON'T DO THAT!!

It is NOT for a pre-63 GM 6-cylinder.If it fits GM, it will be 63 and up when they made the 194-230-250 and 292.I would almost guess it to be a marine manifold,,,,,or off an engine from a generator (large type).
Are you positive it is GM ??

Sure spaced out there! I was thinking marine too as you said Johnson Machine in your post and I was thinking of Johnson outboards. ports don't look right for GM.

I'm gonna guess and say a 1 bbl manifold for a big F*** six.

chip

Nope not for a big F**d. They had individual intake ports.
Dennis

Whoops... Knew the **** fuelies had individual ports, wasn't sure about the carb version. So what is it?

Are the ports too big for a 250?
Was GM the only company that didn't have bolt holes in their intakes?
Any kinda engine come stock in that green color?
Why could it be a propane intake?

chip

This is a photo of a 292 Chevy manifold.Looks pretty much the same, except for the holes in the mounting flanges.
[img]http://pstr-m05.ygpweb.aol.com/data/008/4D/06/D7/34/U5pT2wlUOj0L9j9EG2S6Lse4FqcpRnDc0180.jpg[/img]

Tony,,,,, go see the optometrist!!!!

It does have the same bolt-holes! On the mounting flange to the head anyway.the exhuast manifold to the bottom of the intake has some difference though!

Ok Mechainac, I found my reading glasses.At least I can see it ain't a GMC,FoMoCo,Mopar,AMC,or Honda LOL

The lack of exhaust manifold attached to the bottom of the intake makes me think it is for a marine application.It certainly looks like a GM 230/250/292!

BTW,,,, glad you found your glasses.I was getting a little worried!

Hey, thanks for all the posts guys. Why would this company go to all the trouble of producing an intake that is almost identical to the stock manifold? Is this worth anything or is it a boat anchor? I'm thinking of just throwing it on ebay or something. Thank you.

Chad

That looks an awful lot like my '63 230 intake, especially the drilled 'hump' on the left for the throttle linkage. However the carb mount isn't as built up as it us on mine.
[img]http://www.msnusers.com/acpngi6ubdjpoiv6d045kfo3g6/Documents/Pictures%2F230intake2.jpg[/img]

It probably isn't a propane manifold. Propane engines absolutely require heated manifolds to keep from icing up since propane is compressed to a liquid when stored and when it comes out it cools off by about 50 degrees (kinda like nitrous). It would ice up the manifold on a street engine. The regulators and carbs have to be water heated.

The only heat required in a propane fuel system is in the regulator/convertor. Liquid propane, like LIQUID gasoline will not burn. Propane at normal temperatures is a gas. I cannot remember the temperature that propane becomes a liquid, but it is pretty cold (like -50 or so???)

Anyway, when propane as a liquid becomes a gas, it evaporates which has a cooling effect, hence the need for heat in the convertor/regulator to keep it from icing up. The propane in the tank will not evaporate fast enough on its own to run an engine under full power, so hot water basically boils the liquid propane, so the engine will have enough vapor to run on. Once the propane is a vapor, it has to be pressurized (250-300 psi) or supercooled to become a liquid again. That is where propane has an atvantage over gas. In normal operation conditions, propane is a vapor and will stay suspended in the intake manifold to be burned by the engine. It is a much cleaner fuel to handle and burn because it does not have all the additives and contaminants that gasoline has. It does NOT have the BTU energy that gasoline has, so it will not produce as much power.

I remember some guy around Wichita KS about 25 years ago that built a heat exchanger that vaporized gasoline which he then ran in a propane carburetor. They were interviewing him on TV and the reporter asked him if his pickup (a 66 Chevy pickup) showed any difference in power or economy with this invention. He said he was getting 60 mpg pretty regular. The reporter asked about power again, and the guy got this sly grin on his face. He jumped in the quietly idling pickup and smoked BOTH tires (posi) all the way down the block and most of the way down the next block before he backed out of it. The smoke cleared just enought for the reporter to surmise that power was not a problem and the story ended.

Thanks for the info on the propane! Thats interesting.....so do you think this is a propane manifold or just a marine manifold? I suppose it could be used for either purpose. I'm just wondering what to write when i throw it on Ebay. Thanks!

Chad