LPG question

[73GreenMachine]

I know there are many 250 crossflows out there running on LPG. My question is what form of carby do they use? I have adapted a 34ADM onto my prexflow and want to convert it to LPG and was wondering what I need to do in regards to carbeuration. Is there a LPG only mixer that will bolt on because I will be converting to straight gas so I can ditch the fuel tank and install a nice twin system on the Cortina 8) I want a mixer suitable for a performance application rather then just general commuting. I seem to remember Xtaxi having something interesting on a 350 Holley base. Thanks.
73GreenMachine.

 

[wagon]

An EFI intake (with the injector holes blocked off with welch plugs) with a gas research or similar lpg carby will work well on a crossflow!

 

[aussie7mains]

You did say a precrossflow, and Ill presume a 1v head, so if you look for an IMPCO CA125 single throat mixer it should be able to be bolted on to the carby flange.
Youll need the siuatable convertor etc to complete the job.
Please remember the precrossflows dont have hard exhaust valve seats and you might get seat recesion on LPG.
Otherwise its staightforward.
A7M

 

[73GreenMachine]

IMPCO CA125 mixer hey? I will have to do some research on that one. Do you think it will flow enough? By the way don't worry about the valve seats, I've already got hardened ones in there. The head and motor have been nicely modded but I can't afford to run it these days. So the head is off fixing valve\spring issues and I'm converting to LPG at the same time. If I can hijack my own post...I have a number of issues with the current LPG conversion:
Does anyone know the correct spring pressure for a 282 degree Crow hydraulic cam. I am using the 7820 hi performance springs at the moment, but don't know what pressure to set them to.
Also, what would be a suitable compression ratio to run for LPG? I was thinking 10.5:1?
Has anyone heard of teflon stem seals and are they worth the $$?
What is a standard compressed thickness for an ACL head gasket? I need this to work out final chamber volume for a good compression ratio for LPG.

I know I know too many questions.....but I'm having just as many problems! Thanks anyway,
73GreenMachine.

 

[aussie7mains]

Cant remember the exact data for the CA125, it might be a tad small, but impco have a good range.
Dont go over 9.5 real CR with iron head, more advance is better.
Keep the cam really small that one is probably too much for real street use, the 1v heads doesnt flow too well so dont bother trying to make a racer out of it.
Head gaskect will probably be 1.5mm, dont forget to allow for the deck clearance with your CR calcs, a good exhaust is wise, I like to divide the centre exhaust port and split the exhaust 123 456.
A7M

 

[73GreenMachine]

I was looking through some old posts last night and found that XECUTE was using a CA300 mixer on a holley base. He said something along the lines that there was a high flow version of this mixer that was capable of 200hp or so. So far I have 97.2kw at the wheels before I pulled it apart AGAIN. When I drove it, the cam didnt seem to be a problem on the street. Unfortunately I've already tried to turn the engine into a racer lol. If only I had have waited until I got the 2v. I've bored out the log, reshaped the runners, ported and polished it and made up a custom carby adapter already., Getting 10.5:1 might be a problem after all since the piston dish is 22cc. Why is 10.5:1 a problem with a cast head? Will there be reliability problems?

 

[73GreenMachine]

Things are finally happening!
I am not going to use a holley based mixer anymore, but am making up a pipe coming out off the log intake and bending 90 degrees to face the front of the car like EFI. I have also bought a impco 225 mixer, L series convertor and throttle body to mount on for $120. The pipe is an XB falcon ute fuel filler pipe. For some reason it is 60mm mandrel bent so it works perfectly. I should have some pics in the next couple of weeks.
73GreenMachine.

 

[MRJLB84D]

be interesting to see these pics!

 

[73GreenMachine]

Here is the first pic of my LPG setup. Its only a mockup at this stage,just trying to work out the correct orientation for the intake pipe but thats essentially how it is going to look(aside from the upside down axle stand )
CA225 mixer onto a Nissan 2.4 litre throttle body adapted onto a 90 degree bend of 58mm mandrel bent pipe(from a fuel filler pipe). Going well so far at a cost of only $120 including an Impco L series convertor.

 

[Danielson]

Hi There GreenMachine What's happened to your log ? It looks odd as in the pics !! Nice idea though ditching the carb and going straight gas, would it be feasible to feed the gas into each end of the log (via removal the welsh plugs) as well as the centre port ????
Cheers Dan

 

[73GreenMachine]

What's happened to your log ? It looks odd as in the pics !! Surprised

Umm yeah forgot to mention that. This is one of the practice heads that I have played around with. It was the head I first practised port polishing on as well as hacking off the intake manifold. I was hoping to make an adaptor to go between the sawn off log and a 250 2V manifold but Ford slightly changed the port spacings so my idea no longer worked. Another plan was to braise in 1.5" mandrel bent mild steel pipe to each runner and build my own intake manifold for carby, or bring it into an EFI style "Super Log" and bolt on a huge butterfly and Impco 425 LPG mixer. I could have also used three separate mini butterflies and for LPG and set up a triple side draught style gas system . Soooo many options For now though, this LPG system should support around 150-170kw(if the log can handle it) hopefully without freezing the convertor and has cost me less then 1/3 of the cost of the 425 mixer on its own.

would it be feasible to feed the gas into each end of the log (via removal the welsh plugs) as well as the centre port ????

Yeah I have though about that aswell. I might run some balancer pipes from in between the (1 and 2) and (5 and 6) cylinders to equalise the flow . I wonder how much power potential a setup like this would have as compared to an Offy setup on petrol?

 

[addo]

What Ford did with the port spacings is a little sneaky. The flange of the 2V head is about 16mm thick, and in that distance, they curve around back to regular "log" configuration. It's really only the the centre four; 'specially the middle pair. If you look at a 2V fanimold, you can just see the transition curves starting.

So - it's possible to adapt but you need to fix a thick plate to the head with undersize holes - then open/align.

Starting to think hard about LPG for the truck. It's a thirsty mongrel!

 

[TCSTEVE]

Didn't the government just anounce a GAS insentive program. I heard you get $2000 back on all cars fitted with new gas systems that are 3 years or older........
If its true half the bloody worked cars around the country will start smelling really bad soon

 

[73GreenMachine]

Yeah I head about that little incentive scheme, but I doubt theyll give me a $2000 grant because I've only spent $300 so far converting it and probably will only spend $6-700 all up, depending on what they charge for connecting the lines and slapping on the appropriate sticker(doing the hard stuff like tank mounting, underbonnet and electrical work myself). Oh well we will see, but I predict the price of LPG and the appropriate converison rising in the near future because of it. Good news is the adaptor is pretty much done and the head should be finished by now. Its been in the shop for four weeks so he had better have completed it (warranty job). Then it goes off to another machine shop for some more work.
A question too, are Mike's (Classic Inlines) dual outlet headers made by Pacemaker??
Who else made this style of header?

 

[73GreenMachine]

I was having a look at a Bosch catalog at work today and for the XE electronic dizzy it says to use an electronic coil. I have been using a GT40 which is for points. Could this have something to do with my ignition problems? Is there a hotter coil than the stock Bosch item?

 

[addo]

You could try the HEC 716. Worked like a charm for me.

 

[73GreenMachine]

You could try the HEC 716. Worked like a charm for me. Wink

That number rang a bell! Had a look through an old post of mine and found you told me that like....many months ago. Oops I didnt pick it up at the time but it now makes sense. P100 mentioned something similar aswell. Update on the Cortina, unfortunately this guy has taken 7 weeks to fix my head and still hasn't finished yet Thats warranty work for you. Once he finishes give it a couple of weeks and I might have a car again!

 

[73GreenMachine]

Are there any differences between HEC716 and MEC717 apart from having a male and female type lead attachment respectively? Or should I just modify my coil lead?

 

[addo]

You've got me there! Perhaps an email to Bosch (just asking differences)would be in order.

 

[Vaughano]

Are there any differences between HEC716 and MEC717 apart from having a male and female type lead attachment respectively? Or should I just modify my coil lead?

I reckon you're right. The XE and early (leaded) XF were the same ignition but the XF had male terminals on the cap and coil. To mix caps and coil you'll need a male to female coil lead.