351m/400 on propane????

[fordsharleys]

I have a Ford 351m that I am going to build and put into a 1955 F100 pick up. I am going to use 400 heads and a 400 crank. Trying to get 10:1 or 10.5:1 compression ratio. Trying to get 400 hp or so. Has anyone done this or have any pointers.

[fordsharleys]

I forgot to say that this truck will be run on propane. First time doing this.

[gottago]

A guy here in my town did one of those a couple of years back. He used the 2v cleveland heads put hardened seats in it but just used the 400m lower end. At least 10.:1 compression, he's very happy with it.

[storm]

I have a Ford 351m that I am going to build and put into a 1955 F100 pick up. I am going to use 400 heads and a 400 crank. Trying to get 10:1 or 10.5:1 compression ratio. Trying to get 400 hp or so. Has anyone done this or have any pointers.

You will need at least 2 IMPCO 425 (or OHG equivalents if you can find any) mixers if running naturally aspirated if you want 400HP. I agree with sticking with the 2V heads but use a dual 4 barrel manifold. 2V heads will give you more low rev torque and a better street usable rev range.

[Imperial73]

A technocarb-setup with single mixer will also work fine.

It also depends on how the truck will be used. If most is normal driving, and budget is limited, then you will get more satisfying results with a single Impco 425 mixer (or OGH X-450 if you can still find one). If you really anticipate on using all 400 horses very often (maybe a lot of hish-speed highway driving?) then a wilder setup is required.

Some details will also depend on local regulations.

Also, on any propane-engine, it pays off to invest in a good ignition system.

[fordsharleys]

Thanks to everyone for the feedback. I plan on driving this truck on weekends and going to car shows. Of course the foot will be in the carburator on occasion. The budget for the complete motor is going to be around $4000.00. I am starting from scratch and putting a good ignition system in the truck. I did some looking on the internet and found someone who had 20 OGH X-450's but that was from 2 years ago. Still have to do some checking. What is the advantage of the X-450 over the 425?

[C3H8]

The X450 has a slightly higher flow rate then the 425. The other difference in the mixer included a more radical design that could be prone to problems. Early versions worked very well but later versions were prone to quality control issues. The company changed hands a few years ago and the quality improved. At this time I am not sure if they are still manufacturing the X450 however they are easily accessed as a used or excess inventory item. The X450 has a large piston with an O ring instead of a diaphragm, 3 metering rods, a vacuum controlled power circuit and does not include a power valve to meter the maximum fuel at full throttle. The X450 works with a regulator pressure of -.5" WC differential.

The 425 is about 60 years in production. The only issue was in the early 80's when IMPCO decided to use a composite sleeve in the vapour bore that could work its way loose. They returned to the original design and have been virtually trouble free since. The 425 has a diaphragm controlled gas valve and a separate idle circuit. Newer models have tamper resistant adjustments on both the idle and power circuit.. The 425 will flow 460 CFM at 1.5" mercury or 533 CFM at 2.0" mercury according to the IMPCO charts. The mixer can handle anywhere from 287 HP to about 300 continuously, however it can likely do more then that for a short burst. It operates with a regulator pressure of -1.5" WC.

The 425 is easily refitted for various conditions. There are 4 or 5 gas valve designs to allow customization of the fuel mixtures. It is still manufactured as a common item today and parts are available virtually around the world.

[fordsharleys]

Thanks C3H8,
That is great info to know. My computer was down for over a week so I am just getting back on. As long as I am asking questions, where is a good place to buy tanks/ whether they are used or new, it doesn't matter. I am looking for 2 of them. About 10 gallons each to fit on the frame of the truck.

[C3H8]

Most common tanks used in NA are made by Manchester Tanks. Check out their website at http://mantank.com/.
Manchester is a US manufacturer and can provide a local distributor.

Or Sleegers tanks. site is http://sleegers.ca/. Sleegers is a Canadian manufacturer but I am sure they have distributors in the US also. There may be others that have entered the market recently but I don't know them very well.