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By 46yblock - 18 Years Ago
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I have wondered about these heads, out of curiosity, for a while. Big valves low compression 82 cc chambers. What was their purpose? Were they a replacement for the EDB-D and E heads used with superchargers, and recycled into '59 vehicles to get used up? How did the trucks and unfortunate Mercurys run with the 471's? Finally, were the chambers open, or was there a quench area? Mike
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By Hoosier Hurricane - 18 Years Ago
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Mike: The 471 heads were truck heads from their inception. Many folks say they are replacement blower heads, but Ford did not ever list them as such. They are not open chamber heads. They were low compression heads for 292 trucks, and probably came on the Merc 312s as a regular fuel engine with 8:1 compression. They are sought after now as blower engine heads due to the impossibility of finding D and E heads nowadays. There was also a B9TE truck head with the big chamber and valves, but the exhaust valves in those heads were sodium filled valves with 7/16 diameter stems. They can be converted to 11/32 stem valves with replacement valve guides. John
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By 46yblock - 18 Years Ago
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The quench area then must have been at least decreased I would think. OK they were low compression heads for trucks, and passed off to Mercurys. What was the performance characteristics that Ford was looking for to combine a quite low compression with big intake valve? Were they engineering a motor to lope along at 1000 rpm without dying, but one that could gulp large quantities of A/F mixture for heavy loads? If so then why would they have been in everything from light duty to heavy duty trucks? This isnt totally academic, because I now have a low compression big valve motor.
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By Ted - 18 Years Ago
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Quench area for the ‘471’ head is marginally smaller as the footprint of the ‘471’ combustion chamber is 9.3% larger than a ‘113’ head and 11.3% larger than a ‘G’ head. Use of the ‘471’ heads was just one way to lower the compression ratio in the trucks as using the shorter 312 length connecting rod and dropping the piston in the 292 bore was another. The ‘471’ head would have been the ideal method to lower compression ratio as quench would be maintained but there were a multitude of truck engines out there with pistons sitting 0.090” or more in the bore and using the smaller chambered heads. To this point in time, I've only seen the 471 heads on truck engines and have yet to see a pair actually factory installed on a Mercury engine.
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By pegleg - 18 Years Ago
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Mike, I don't think that the subject of "Quench" was as widely understood in the 50's as it is now. I'm not sure that the lack of quench area would have been an issue to them. I have a set of 471's on my F code, and have run it without the blower on the street. The car runs very well even with no pressure. I think it's just slightly less than 8 1/2 to 1. You won't have to worry about octane ratings much.
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By 46yblock - 18 Years Ago
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John, Ted, & Frank thanks for the info. It may be an easily understood issue, but not by me. Why is a low compression motor an advantage to a working truck .And, that low compression big valve motor of mine, the one with 312 rods and 292 crank, the one that has a replacement motor ready on the stand: Yesterday totally unexpectedly I picked up what looks like a good 10/20 312 crank  .
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By Hoosier Hurricane - 18 Years Ago
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I'm not sure valve size mattered much to either the engineers or bean counters. All '57 passenger cars had G heads, whether 272, 292, 312. Now what would the old lady school teacher need with big valves in her go to church never over 1800 rpm 272 2 barrel? Ted, I have bought two '59 Merc engines over the years, both pulled from the car at the wrecking yard, and both with 471 heads. The first I bought maybe 30 years ago, wanted the 312. The last I bought about 5 years ago specifically for the heads. John
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By pegleg - 18 Years Ago
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Mike, In a truck one of the main objectives is long life. Lower compression allows them to run regular low octane gas, (cheap) without worrying about pre-ignition. So the motor stayed together forever. Small ports and valves together with a mild cam to make low end torque, to move a loaded truck. Didn't need a lot of horsepower in a truck. Also the 471's are posted, which makes them stronger.
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By Ted - 18 Years Ago
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Thanks John for clarifying that the 471 heads were also installed on car engines. I’ll wager a guess that the engineers had to detune those 312’s quite a bit so as not to embarrass the occaisional 352 it might come up against.
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By 46yblock - 18 Years Ago
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Thanks Frank for putting it together. A workhorse package of longevity.
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By pegleg - 18 Years Ago
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Mike, You're welcome, should also note that the 471's did have pretty much the same ports and valves as the G's. Mummert's flow numbers don't show a lot of difference, even when compared to the infamous "G" head. I've never seen numbers from an EDB-E or blower head, but I gather that a 471 had the same ports. So it's a pretty good piece. At your altitude in Idaho, I'd use that crank, and do a zero deck motor of 9 or 9.5 to one if you can get there. See Mummert for pistons. Bet that'll move your 46.
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By 46yblock - 18 Years Ago
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I am going to take the crank to the machinist within the week, and will have a couple questions on it to post. If it is used on the .080 over motor, CR goes to 9.4 or 9.5 pretty easy. And, assuming the mystery cam in place checks out to be as represented so many years ago (.460 lift 270 duration), it will all work out well. Here in Southern Oregon our elevation is only 1300 feet, unless you are going up through some of the passes. They are fun going going up, but require some care on the downside.
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