For a propane conversion, (heat to bottom of manifold) is rather pointless. I was considering putting in a thin sheet of metal above the gasket and disabling the flapper from directing exhaust by it. Is that a viable idea?

What else have people done to decrease heat to the manifold? And no, headers are not really an option, due to price, and unavailability of them for an 81 W150.

Any ideas welcome.

dutra duel duels

I'd love to, but the pocketbook says "no".

I haven't seen many propane conversions, but the ones I have seen seemed to use the original intake/exhaust manifolds. I know of one propane fork lift truck that is at least 35 years old, in perfect working order, looks stock except for propane carb, valves and pipes/hoses. The ones that are dual fuel needs the heater. I have never tried to do the calculations, but does it matter much for power output?

Olaf.

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Aspenized

It's true that propane engines don't need intake manifold heat. Since the manifold heat control valve is thermostatically controlled, I don't think it would cause any problems to leave it in working condition.

If you want to keep the intake manifold cold, putting some sheet metal above the gasket work probably work fine. Alternatively, you could disable the flapper to the closed position by removing the spring and/or brazing the shaft. I suppose some refractory cement over the flapper would further keep the intake manifold cool.

For newer engines, keeping the EGR system operational helps to reduce NOx emissions.

What were you planning to use for your propane system?

A 225 or 300 mixer and a closed loop system for keeping the air fuel ratio close to stoich. I have a super six intake and am looking at using a throttle body that should bolt right to it. I thought a 425 would be too big, with the little six never getting anywhere near the capacity of the carb, and probably having a little harder time getting it to meter well.

I'm talking to the folks at msefi to see if someone can do some coding of some kind to make the MS capable of duty cycle O2 feeback type of control.

The MS also gives me the ability to tailor make timing curves for the engine, as well as using a Ford EDIS ignition, instead of the distributor.

I believe the BT2-11 and at2-11-1 will bolt directly to the super six intake, at least the bolt pattern appears identical, leaving you with some of the larger mixers (200 and up?) to choose from.

As for performance, I'm intending to go serious on the compression ratio (11 or so) and larger valves - and tweaking the cam timing ahead a smidgeon. I need an increase in power over the 1bbl sick engine it has now and what I want is torque, not max horsepower.

A Model 225 or Model 200 would be a good choice in a straight (mono-fuel) application. The Model 300 is a bi-fuel mixer and might have hood clearance issues, depending upon how you mounted it. Adapters are getting hard to find now as many of them are already obsolete.

For the parts required, see Model 200 2BBL Carburetor. You can use an Impco A2-3 air horn adapter to use the OEM air cleaner with a Model 225 mixer. If you were thinking about using the Dual Curve PN 5952 for mixture control, you'll have to find it on eBay. A similar alternative is the LPG/CNG Feedback Fuel Controller.

If you're interested in propane injection, see LPG Injection on a 400m.

I would not run compression ratios over 11:1 with straight propane (see compression guide).