Mixing parts with GRA..

Propane, Butane, LPG, GPL, C3H8, C4H10
storm
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Location: NSW, Australia

Re: Mixing parts with GRA..

Post by storm » Wed Jun 29, 2016 1:48 am

The reg should hold the pressure of the fuel when the locks are opened with the ignition switch opening. If the reg isn't holding the pressure there is something wrong somewhere. I'd be starting with the reg itself or the gas hose between the lock off and the reg. Spray soapy water along the hose and seals on the reg and see if you are getting any bubbles.
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Fuel flow requirements calculations viewtopic.php?f=5&t=1638

gottago
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Location: British Columbia Canada

Re: Mixing parts with GRA..

Post by gottago » Wed Jun 29, 2016 2:41 am

I did the soapy water test and that was fine. The reg is the problem. I pulled the cover off the start solenoid attached to the face of the reg. When key is turned the outer diaphragm pressures up and the hissing begins. That diaphragm is new and seals fine. If I pull the entire top cover off and lift on the lever beneath to hold more pressure on the little flap valve, the hissing will stop. But it takes more pressure to do that than any spring I have would do.

storm
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Re: Mixing parts with GRA..

Post by storm » Wed Jun 29, 2016 5:53 am

Ok, you got this kit http://bluelpg.com.au/shop/index.php?ro ... uct_id=387 and fitted it according to the instructions.
Not knowing anything about Century regs all I can do is make suggestions.
What type of cover do Century regs have? is it aluminium or plastic? If its aluminium is it thinner than or as thick as OHGs? If it's plastic get a metal one.
Is it flat on the sealing edge, in other words have you had a straight edge on it? What you need is a good seal and strength to resist pressure. Any warp at all will cause a leak with the higher pressure springs.
Every job is a self-portrait of the person who did it. Autograph your work with excellence.

Fuel flow requirements calculations viewtopic.php?f=5&t=1638

gottago
Posts: 200
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Re: Mixing parts with GRA..

Post by gottago » Wed Jun 29, 2016 11:58 am

Yes that's the kit I got. I've never worked on an m6 before and it does have some peculiarities. This thing that c38h posted about a variable pressure function may be what I am dealing with. It may not function properly with any other pressure spring other than the original. ??
c38h-
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.
It has a metal lid but haven't compared thicknesses. I am going to put the spring kit into an ohg regulator..
thanks for the suggestions, will post results

gottago
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Re: Mixing parts with GRA..

Post by gottago » Wed Jun 29, 2016 9:27 pm

Spring kit for the b2 fits the ohg no problem.. Running one x1 regulator with two gra mixers. Lean right off the bat but no tuning yet. Pulled the century regulator right down. Never saw this before, it has a very small flapper valve right inside the fuel inlet. Very worn.. No idea where to find parts so will tune the ohg..

storm
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Re: Mixing parts with GRA..

Post by storm » Wed Jun 29, 2016 11:56 pm

Do you have the tune guide for the GRAs? http://www.gasresearch.com.au/gratus.pdf http://www.gasresearch.com.au/IN-0002-B.pdf

I prefer to see 2 regs in builds like this, 1 for each TB as shown in the 2nd file.
Every job is a self-portrait of the person who did it. Autograph your work with excellence.

Fuel flow requirements calculations viewtopic.php?f=5&t=1638

gottago
Posts: 200
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Location: British Columbia Canada

Re: Mixing parts with GRA..

Post by gottago » Thu Jun 30, 2016 8:35 pm

Yes, I would prefer two regs as well but, have to order another spring kit so in the meantime I am going to run a single. Thanks for the tuning guide.. I am waay too lean at idle now but I do have the complete jet set. The small brass idle jets have no numbers but they have a noticeable difference in orifice size. How do you install them and how do you figure out which one is appropriate? Trial and error afr gauge?

storm
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Re: Mixing parts with GRA..

Post by storm » Fri Jul 01, 2016 12:30 am

If you have the jet and rod set in the box the jets are in sections that have labels telling you the size. Otherwise a metric drill set like a jewellers set can be used to size the jets.

Installing the jets is simple just stick it in the progression hose, yes it is that simple. I'd prefer they had screw in jets like a carby but they don't.

Tuning is trial and error, once you have done a few you get to know what to select before you start then it's just fine tuning from there. Yes use an AFR-Lambda gauge. I prefer setting up by Lambda cause I don't have to adjust things from 1 fuel to the next, but that's just me.

In my experience on EFI cars they are quite difficult to set idle because the mixture screw doesn't have much effect. To me the idle mixture setup is all wrong, they let air in to mix with the LPG but I think they need to let LPG in to mix with the incoming air. The jet in the progression tube has a big effect though so you may have to play around with various sizes. If your progression jet is wrong you will end up with a stumble-dead spot on tip in so be careful. I have also found the metering rods are very generic and to get a proper tune you will need to resize one in a lathe. Swap different rods in and out for different speeds, cruise, power and get the best sizes for each one and then machine the rod blank (I got a rod blank in my jet-rod set) to suit the measurements you have found to suit your setup the best.
Every job is a self-portrait of the person who did it. Autograph your work with excellence.

Fuel flow requirements calculations viewtopic.php?f=5&t=1638

gottago
Posts: 200
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Re: Mixing parts with GRA..

Post by gottago » Fri Jul 01, 2016 10:43 am

hmm jet in the hose ... whoda thunk.. Anyway as long as it works.. I'm so lean right now that I need a big change. I have the rods too, wondered what that blank one was for. Ok, thanks probably get some more time this weekend to finish it off.

gottago
Posts: 200
Joined: Thu May 24, 2012 7:39 pm
Location: British Columbia Canada

Re: Mixing parts with GRA..

Post by gottago » Fri Jul 01, 2016 9:24 pm

Well that didn't do any good, still super lean no matter which jet since the spring change. too rich before with ohg springs. .. New springs are quite a bit longer and stiffer than the ohg.. They are much closer length wise to the impco vaporizer spring length than the ohg.

storm
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Re: Mixing parts with GRA..

Post by storm » Fri Jul 01, 2016 10:14 pm

How is it without any jet? I don't have a jet in my Ecotec V6.
Every job is a self-portrait of the person who did it. Autograph your work with excellence.

Fuel flow requirements calculations viewtopic.php?f=5&t=1638

gottago
Posts: 200
Joined: Thu May 24, 2012 7:39 pm
Location: British Columbia Canada

Re: Mixing parts with GRA..

Post by gottago » Sat Jul 02, 2016 2:28 am

No difference either way.. too lean right across the board. The spring length really seemed too long for the spring saddles. I don't think they will work in the OHG. I am wondering about the impco E though. Spring length is much more compatible. Meanwhile back to looking for a rebuild kit that includes that little flapper valve for the fuel inlet on the century m6. I could glue a small round rubber disk on to the flapper mechanism but concerned about raw propane reaction to the adhesive and rubber material.

storm
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Joined: Wed Jan 10, 2007 10:10 pm
Location: NSW, Australia

Re: Mixing parts with GRA..

Post by storm » Sun Jul 03, 2016 3:33 am

Have you got a picture of this on the vehicle?
Are you tuning 1 or both TBs at idle?
Every job is a self-portrait of the person who did it. Autograph your work with excellence.

Fuel flow requirements calculations viewtopic.php?f=5&t=1638

gottago
Posts: 200
Joined: Thu May 24, 2012 7:39 pm
Location: British Columbia Canada

Re: Mixing parts with GRA..

Post by gottago » Sun Jul 03, 2016 10:29 am

Pictures don't show much, fairly tight in the engine compartment. Really just seeing the top of the plenum now. Tried tuning one at a time then both..

C3H8
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Re: Mixing parts with GRA..

Post by C3H8 » Sun Jul 03, 2016 7:57 pm

Your previous statements on the M6 installation puzzled me. The M6 is a negative pressure regulator. It should take .5" WC of vacuum to open the secondary. With the addition of your stronger springs it should even take more. If there is fuel coming though the secondary seat with just key on there is a primary seat problem. I'm trying to remember the construction on this reg for the primary seat, however I have to assume the flapper inside the reg inlet you mentioned is the primary seat and it must be leaking which increases the primary pressure to the point that the secondary is force open. Proquip in Calgary might be able to get a repair kit for you. 1-866-692-8132. I sent them a text and waiting for an answer.

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