Mixing parts with GRA..

[gottago]

Have a little more time now that its winter over here. Just checking to make sure that I am able to run twin ohg vaporizers through twin gra mixers without any issues? Orange springs in vaporizers? vff30 lockoffs ok to use with that? Posted a picture of the setup awhile back.
viewtopic.php?f=5&t=1461&start=15#p12300

[storm]

GRA uses the Aussie B2 convertor regulator which is a knock off of the OHG convertor. They use a different spring to OHG and Impco because of the different vacuum signal given by a GRA compared to an Impco. I had a pages bookmarked that had the relevant information but it is no longer available. MY suggestion to you is to send GRA an email and ask them what spring they recommend.

[C3H8]

I'm not familiar with the GRA mixers. In the pictures I see they appear to be venturri mixers. Depending on the vacuum signal at crank and idle most venturri mixers will not work with negative pressure regs unless the secondary spring is very weak. They work fine above idle with the lower spec spring but starting is usually compromised. Techno Carb used model E's but they initially had a manual screw adjustment in place of the primer button, This screw allowed them to force the secondary open for starting and idle mix. They devised a system that kept the coil working after the key was shut off to burn off the left over fuel in the regulator since the secondary never closeed. Shortly after that they developed an electric solenoid that would open the secondary as soon as the key was turned on and it would close the secondary when the key was shut off. Later they used a stepper motor on computerized systems. One on the reg controlled the idle mixtures and another in the vapour supply line controlled the cruise and wot mixtures.

[gottago]

Thanks, GRA isn't being very helpful. Apparently gra never got approval for use here in Canada so don't respond to me. I have a lot of old parts for everything kicking around including an m6 century vaporizer with twin feeds. Haven't had much to do with those and don't know much about them but perhaps it is compatible? I'll have to check the spring color.

[storm]

Can't promise anything but I'll see what I can find out.

[C3H8]

The Century M6 was a really good regulator in its day. It is very similar to the model E but does have some unique differences. It was originally designed as a 1/2" negative pressure regulator as far as I remember. I don't believe they ever had other secondary springs for the M6. The primary pressure was unique in that it reduced tank pressure to 1.5 PSI, however as demand increased the primary pressure would increase to as high as 7 PSI. It did this with a balance or sensing tube inside the secondary area that had its opening very close to the secondary valve seat. I believe if the secondary pressure began to drop the balance tube would cause the primary pressure to increase compensating for the reduced flow from the secondary opening. I saw this regulator used many times on early feedback systems where the 425 was used. Instead of a richer gas valve they just substituted the model E with the M6. The lower negative pressure gave the richer mixtures desired to incorporate a feedback system. The M6 was largely used with the Imperial 300A mixer. This mixer became very popular with the M6, IMPCO model E, J, L and other similar products as it worked with all of them. IMPCO adopted or bought (not sure which) the design and made additional models designated the 20 series, 50 series and 70 series. A touchy mixer but it really worked well. Considered a little ugly by many but still a great functioning unit requiring minimal maintenance.

[gottago]

Interesting, I may have to give it a try. On the body of the m6 it says made in Canada but there is also a metal tag affixed on one side that says made in usa. So not really sure what I have but it appears to be in really good condition.

I had assumed that if I matched the working pressures of any vapourizer with the pressure requirements of any mixer that it would balance out in the end and work fairly close to the original configuration.

There are still some propane users around here who swear by the ohg x1 with a blue spring installed but coupled with a new impco 425 mixer. The spring just alters the vap pressure which is why I was considering the x1 with the orange spring to run the gra. Seemed the pressures would match up..

[C3H8]

They were manufactured in the USA. The metal tag was the old way of stating the approvals were good in Canada also. I had a look at those GRA mixers on the GRA website. Very interesting looking stuff. I didn't see secondary pressure listed anywhere on the B2 reg, only a primary of 5 PSI. The mixers appear to have some similarities to the old Century throttle body mixers. The M6 might just work with these but it would really depend on the secondary values. Strom, do you or some else know what the outlet pressure is on a B2?

[storm]

GRA haven't got back to me, pity, so I can't help with a definitive answer just yet.I don't remember the numbers of the top of my head and don't want to give the wrong advice.
B2s sold/used by GRA aren't the same pressures as a B2 sold by LG motorgas.
LG motorgas may have the specs for GRA B2s so I will contact them and find out.

[storm]

Sorry for taking so long to reply. Not one of the manufacturers I contacted got back to me so I have been searching for information.
The difference between a regular B2 and a GRA modified B2 is the primary pressure. Regular B2s run 1.5" primary pressure. (3" is also optional) GRA systems run a twin spring setup to make 5" primary pressure. All other parts are the same. The change from 1.5-3" to 5" primary pressure enables the GRA throttle body signal to work on the converter so it can draw fuel.

[gottago]

Thanks for the info and for making the attempt. I never received any answers either so just looking for a workaround solution now.. The primary pressure spring seems to be the key difference. According the research you supplied I just need to modify that and should be good to go? All else is the same? Hopefully the secondary pressure will just fall into line for what the GRA requires. .. Still not sure what pressure that is but may try just changing to the 5 psi primary spring and see what happens..
Found listed on ebay...
http://www.ebay.ca/itm/LG-Aussie-B2-LPG ... 35d6ea9cee

[storm]

According the research you supplied I just need to modify that and should be good to go? All else is the same?

As far as I am aware. All the informative links I had to GRA stuff, apart from GRA themselves, are no longer available (404 not found) and I can't find anything in the wayback machine. My own car isn't running atm so I can't even give you pressures of that. I'm not happy with the "customer service", this is the type of thing that makes me look for different parts and suppliers. It's no good having great parts if you can't get help with them.

Found listed on ebay...
http://www.ebay.ca/itm/LG-Aussie-B2-LPG ... 35d6ea9cee

Yep that's it. I buy stuff from BlueLPG and they are pretty good. Just contact them first and see if they will post to you though.

[gottago]

Finally managed to get the spring kit from blue lpg. I've installed the dual mixer setup with the twin gra mixers. Found a propane tech guy who was familiar with the century m6 vaporizer and he thought they were similar enough to the b2 that the spring kit may work in that. Sooo, installed it and running but.. vaporizer hisses and sends fuel to mixers even when not cranking engine. Wasn't noticeable with vacuum lockoff but went to an electric lockoff and discovered this. Key on... vaporizer sends fuel without any cranking. All parts look good, diaphragm etc... Back to wondering if I can run either impco or ohg vapourizers with gra. Haven't got a b2 and not so common to find one around here.

Otherwise, it runs quite nicely and would like to get it sorted out.
pictures.. viewtopic.php?f=5&t=1461&start=15#p12300

[storm]

The B2 is an OHG copy, everything is the same, the GRA spring kit simply changes the gas pressure. If you put the spring kit into the OHG reg it will work as long as the OHG reg is in good condition. The same should apply with Impco reg but I can't personally confirm that. Are you sure the Century is in good condition?

[gottago]

thanks, I might have to try the ohg with the spring kit next. The century appears to be in quite good condition, all the diaphrams are real good and it actually runs quite well. Havent' even tuned it in yet. If I hadn't changed the lockoff to an electric one, I probably wouldn't have even noticed the gas hissing through. Starts and idles fine..