Old engine conversion to propane

rockcity

rockcity

everyday is a chance to get better
Joined
Apr 10, 2005
Location
Greenville, NC
OK, time to finally :shaking: get the engine in the buggy running. I am looking at a 71 V8 to put in the buggy. Its running and will be a decent engine until I get the 351 rebuild finished.

Is that engine too old to run the propane on? I've heard talk of needing stainless valves and hardened seats. Will I have to do anything to this 71 302 before putting propane on it?
 
I'm bored at work and will take the first stab to get flamed all to hell to get this one going!:flipoff2:

Answer - it will run.

1971 302 lists at 8.5:1 compression. But even the Ford Industrial 4.9's fitted from factory with pane only had 8.5:1. Just not the desired compression for performance. Iron heads are desired to be in the 11-12:1 ratio for maximim performance. Aluminum heads need to be in the 13-14:1 range. There's calculators for octane ratings on the internet that I took that info from. But it's kinda like putting racing fuel in a stock motor. You get stock performance along with the added heat.

1972 was the first year for introduction of hardened seats. Look at your heads for the Ford part number stamp to confirm year. It'll be 4 digits long and starts with a letter. Ford did letter "C" for 60's and "D" for 70's and continuing today. The next number is the year. Your heads are likely "D0" (meaning 1970). You can run without hardened seats but the longitivity of your exhaust valve seats are shorter. What shape were your seats to begin with? Wouldn't hurt to pull a head to check valve seats if it's never been torn into and replace the stock head gaskets to the better ones of today. But doing that always results in persuasion to rebuild the entire motor...

Stainless valves do nothing for propane that I am aware of? Besides being a tad stouter, stainless is used to deflect carbon buildup in which pane produces way less than gasoline to begin with? I hear you can tear down a 100,000 mile pane motor and can only tell with gages and micrometers.

A set of aftermarket heads is always an answer to all the compression and valve seat issues but with mucho dinero and can be retrofitted onto the 351W later on by drilling out the bolt holes (Or vise versa with grade 8 stepped washers). Have you cc'd the heads or looked them up by the part number to confirm the chamber size? 64cc being the lower and 58cc being the higher. I sold a set of 1969 high compression 302 heads about 2 months ago thinning out for the big move - cheap! Cheap iron heads can still be found on ebay to bump compression up or you can always shave the head surface as well.

I say "Go-for-it" with the 302 to just get everything idling and mounted right just for troubleshooting purposes. THEN build the 351.

I don't remember the exact links but I researched using propane onto small block fords extensively. I have a short deck 1969 351W block machined just for this purpose but never got that far. I have 3 different IMPCO 425 kits I scored cheap locally that I was going to mix match and experiment from. Each one is a different setup.

Don't forget a recurve kit for the stock dizzy from Napa. The rest of the system is unaffected by pane.
 
The hardened seats are necessary if you plan on running it very long at all. The reason is the heat that builds up in the chambers will deteriorate the seats, and YES, the valves also. (mainly the exhaust side)You can get by with it for a while. I saw first hand what a valve looks like coming out of an engine that had run pane for a long time without both. The valves sank so far into the head they barely opened, and looked like like cowboy spurs. I didn't need a micrometer to see the damage.

How long will it last? I can't give you a good educated guess on that.

So choices are run it like it is, and hope it will last until you get the other engine done.
or
Get a newer set of heads with hardened seats and slap em on
or
same as the second option and while you have it down put in stainless exhaust valves

I would try it first without the dizzy curve. Mine is a stock dizzy and have had no issues with that part once I advanced the timing.
 
Thanks all. Well, I'm going to use the engine only until I finish the rebuild of the 351W. Hopefully that won't be for too long. I don't have the engine now. Its in a running truck right now, I'm just deciding if it'll be worth getting it and putting it in or if I need to hold out for something newer.

Right now I'm leaning towards just getting it and running it as is and see what happens.
 
Call Carey at gotpropane.com He is great to work with and will answer all your questions straight up. He does this for a living and will tell you yes it will or no it won't, even he doesn't make a sell. He's answered alot of questions for me.
 
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