Ford Mercury Truck Engine

RalphG

RalphG

Well-known member
Finally got around to checking my Ford Fast Moving Parts catalogue this morning. They list two horsepower ratings for the Ford and Mercury trucks. Specifically the M68 Mercury one ton had the 100 hp engine in 1949. The Ford version of the truck, F68 only shows 97 hp. So, two different engines maybe?
Mercury cars were rated at 110 hp the same year.
 

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The horse power of most engines is determined by the advertising dept of the manufacture, not the engineering and production depts.
 
Ron's right. Also check the rpm that hp is rated at. Could be the same engine, if rpm's quoted are different.
Again, ref the marketing dept.
jmo
 
On the 48-53 trucks, they list the HP @ RPM on a Ratings Plate in the glovebox or on the firewall. It is almost random the HP and RPM's they put on the V8's, I've seen everything from 93 to 97 HP and at 3200 to 3600 RPM.
 

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Ross F-1 said:
On the 48-53 trucks, they list the HP @ RPM on a Ratings Plate in the glovebox or on the firewall. It is almost random the HP and RPM's they put on the V8's, I've seen everything from 93 to 97 HP and at 3200 to 3600 RPM.
Click to expand...

This M68 has both. The firewall plate with serial number and then another plate on the inside glove box door. I don't recall seeing horsepower ratings on either but will take another look. I just found it curious that Ford would list two different horsepower ratings for the same truck in the photo I posted. Only difference was 3 more horsepower in the Mercury. Funny, some of the bigger trucks were rated even as low as 88 hp.
 
Since the claim is that that is "certified net HP", the big trucks with the 6-blade fans may well be down on power just due to the fan, also larger generators.
 
If it was dyno'd with a fan! Most engines were tested on a test fixture with no assesaries attached. Engine hp ratings were always somewhat of a pipe dream, mainly for advertising. There were even cases in later years (60s) of them under rating the hp rates of some high performance engines.
 
This is for a 59-series engine, but it shows pretty clearly the effect of the accessories and exhaust system. Top curve is the bare engine, middle is with fan, lower is fan + exhaust.
 

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I guess my question is this. Some have stated that Ford and Mercury one ton trucks and pickups came with the same engine (239). So why was Ford rated 97 hp and Mercury 100 hp? I'd assume if they were tested it would have been under the same conditions. Was there only 3 hp difference between the 239 and 255 engines?
I guess the only way I will find out for sure is to tear the engine apart and check if it has the four inch stroke. I'm not ready to do that just yet.
And I checked both i.d. plates and there is no mention of engine size or horsepower.
 

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Ross F-1 said:
This is for a 59-series engine, but it shows pretty clearly the effect of the accessories and exhaust system. Top curve is the bare engine, middle is with fan, lower is fan + exhaust.
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What is interesting about those dyno charts is no one seems to be able to match them in independent test. Interesting.
 
Excellent thread on decoding Canadian Mercs: http://www.ford-trucks.com/forums/1337738-the-canadian-vin-info-thread.html

From that:
ENGINE NUMBER

The first digit of this number indicates the model year the engine was originally built, “6” indicates “1946”. The letter in the engine number indicates the piston displacement of the engine, and the type of transmission as follows:

“E” indicates 239 cu. in. piston displacement with 3 speed transmission
“EE” indicates 239 cu. in. piston displacement with heavy duty 3 speed transmission
“J” indicates 239 cu. in. piston displacement with 4 speed transmission
“P” indicates 239 cu. in. piston displacement with 4 speed transmission, passenger camshaft
“G” indicates 239 cu. in. piston displacement with 4 speed transmission, truck camshaft
“Q” indicates 337 cu. in. piston displacement with 5 speed transmission


Your truck's engine code is 9J, so it's a '49 239 ci with 4-sp crashbox trans.

To be clear, NO Ford trucks ever used a Merc engine from the factory (in the flathead era).
 
Ross, The J, P and G engine codes all show 239 ci and the 4-speed transmission. I wonder what makes the J different from the others? Do the P and G engines have the T98 4-speed and the J a T9?
Mark
 
I can only guess they may indicate extras like a governor, different fans (4 vs 6-blades, HD cooling), also possible they indicate the full-flow oil filter setup. It's possible it relates to the trans, T98 vs T9, PTO, etc. As that thread shows, there is nothing simple about the Merc coding system!
 
The 239 engines were all near 100 HP. The Mercury engines were 110 HP. Camshaft, carburetion, and the 4-inch stroke were the only differences and the Mercury had larger clearance volume to keep the compression ratio about the same. Not much difference in horse power but torque was a bit higher on the chart. Trucks generally had more clearance volume with the 8RT heads when they in the mix. This kept the compression a bit lower to keep the ping away. The big F7 & F8 trucks had the Lincoln 337 engine to give them more soup.

The Mercury engine was available for special applications but I haven't heard of them being standard in anything but the Mercury big car and the Ford Monarch car.
 
rotorwrench said:
The 239 engines were all near 100 HP. The Mercury engines were 110 HP.

The Mercury engine was available for special applications but I haven't heard of them being standard in anything but the Mercury big car and the Ford Monarch car.
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And also the Canadian Meteor Customline had the Mercury 255 engine.
 
If you don't have JWL's book, you're unaware of the fact that you can't get a100 HP from a 239 engine no matter what you bolt on it. (excluding a blower). In fact it only produces aprox 80 HP with out a fan or gen/alt. However, It sure sounds good.
 
I saw the results in JWL's book and was confused. All the official Ford curves show substantially more torque and HP for a stock engine. The ones I looked at were from the FORD engineering dept, not the sales or marketing division.

Perhaps there is a difference in the DYNO characteristics? or maybe different correction facts were used in the FORD test?

It would be nice to understand the reasons for the difference. Any old FORD engineers on board?
 
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