Hey all, its been awhile since I have been around, I now come with a question...
I have an '86 F-150 that was converted to propane at Comox Valley Ford with only 26km on it They used an Impco Model E, VFF30, and a 225 mixer. Currently it sits at 371,401km on the original 300 and I assume fuel system as it still has the green braided lines. I bought it in the spring of last year, and just now insured it.
So far, I know the regulator/vaporizer was rebuilt at some point(it doesn't leak) as I have all of the old gaskets here, I don't see much if any wear in the mixer either.
My problem is, I did a full tune up, plugs wires, cap rotor etc following the specs on the ICG tag under the hood, I just ran it through its first tank of fuel and that lasted all of 280km. Any way to lean this thing out? I'm pretty sure it has been messed with.
I'm basing this off of my experience with my big block Dodge though so I could be wrong.
The 225 has an idle fuel adjustment on it and a load adjustment. You can try screwing the idle fuel in a little to lean it. If you have a vacumn gauge adjust it to highest vac at idle. If that does not help you may need to repair or replace the 225 as they do wear out.
Thanks, I'll take another look today. Any ideas on different gas valves for them? I have one AV12-3 and 2 AV12-2s. The on in the truck's mixer has a handwritten "30" on it. I have a second 225 and a 200A that they are in.
AV1-12 is the std air valve with black fluro-silicone diaphragm, AV1-12-2 is the same but with a yellow Silicone diaphragm I would revcommed it as silicone seem to respond better in cold climates. AV1-12-3 has a leaner cone on it. Make sure your vaporiser does not leak with the engine off by removing the hose and and taking soap solution to form a "bubble" across the end of it, If the bubble grows or pops imediately the vaporiser is leaking thru and will need to be rebuilt, You will need to apply vacumn to the VFF 30 to make sure the vaporiser is under pressure though. You might also remove the air valve and inspect the cone seat inside the mixer, if it is cracked OR out of round replace the mixers as is is junk
I pulled the gas valve out of the mixer this evening, there were very noticeable wear marks in the mixer. I swapped it with my other 225, looks to be in much better shape.
Immediately after the swap, it wouldn't start, had to hold the primer button on the Vapourizer so it would fire, then I found that the idle mixture screw had to be in much farther, it is very sensitive and leans out easily. It seems like there is a vac. leak but I can't find anything wrong.
Onto the gas valves, I started with the AV12-3 in the new mixer, seem to drive alright but feels lean in the higher end. I'll try the 12-2 out of the 200A in the evening if I have time.
I will attempt to post pics of the mixer that was on it as well, both of what looks to be fairly bad wear and how filthy it was inside.
According to an old Impco chart I have the 225 is to small for a 300-6
fomula is as follows
engine cid x max rpm,
divided by 1728, divided by 2, times .85 = cfm flow for carb or mixer
I figured 4000 rpm redline works out to 295 cfm
your timing and advance seem to be high 28-32 deg total intial and centrifical 10 deg or so vac advance
I swapped it with a good 225, tried another AV1-12-2 and the 12-3. Not much of a difference in the way it performs, possibly a slight improvement with the latter. There was a huge change in the idle mixture though, I have the screw pretty much seated to make it run decent vs. 5.25 turns out on the old one(its still lean now).
The main mod I am looking at is opening the intake up some to run a larger TB with a 2.5 or 3" bore rather then having the 225 neck down to the stock Carb's base.