hello, i have a '67 f-100 with the 352/3 speed manual trans.i recently replaced the enigne with a "m" vin 390 factory 4 bbl from a 74 f-250.i know that an "h" vin 390 factory 2 bbl. from a '68-'72 was rated at 255 hp. i am wanting to know the hp & tourqe for the "m" vin that i have & if the heads are the same.thanks

 

Let me try to answer some of this for you. The truck 390 heads from 1970 to 1976 have the exact same size valves, same size springs, guides, and seals. Whether or not there are different casting numbers or not, I don't know. From this info above, you can figure that the heads are probably the same and I know you can interchange them, (in pairs). Whether or not there is any difference in chamber size, I can't answer that but someone will come along that can.

Regarding the 1974 Truck 390, you will find Ford made NO mention in their advertising as to what the compression ratio, what the horsepower rating, or what the torque rating was. The 1973 did show the following: Horsepower = 195@4400, with 319@2400 ft.lbs. of torque, and a compression ratio of 8.2 to 1. I personally know the 1974 dropped compression to 8.0 to 1, but I have no other specs I have found for the 1974. I know there was both a Horsepower and a Torque drop again in 1974. This was the year of the "Boat Anchor Motors."

The 1967 through 1971 390 Truck V-8's all had 255 hp. In 1972, they were all de-tuned and it lost 54 horsepower to 201, then 195 hp in 1973, and Ford must have been extremely embarassed in 1974 because they no longer divulged this information. You will find the 1974-76 390 to be a "real dog" for pulling power in its stock configuration.

It would be a "Cardinal Sin" to replace any of the 1967 to 1971 390 V-8 engines with a 1972 or later one. I wouldn't be a bit surprised if your old 352 would easily outpull and generally outperform the 74 with the 4 barrel. One thing for sure, the 74 will use a lot more gas if it even tries to perform. It will make all the right noises, but as far as pulling, I'm sure you will be disappointed, that is, unless you have modified it to be able to run again. Hope this helps a little...... Oh, by the way, one of the older 360's were 215 hp with 327 ft.lbs. of torque which was more than the 72 and later 390's by a long ways!!!!

 

if the heads were the same as the other 390's, wait was done to cause the power loss.also what could be done to make power like the 71 & earlier 390's? thanks for the other info as well.

 

The compression ratio changes, (dropping the ratio lower), was responsible for about half of the power loss on these engines. Also, lower compression increased the need for more gasoline to attempt to obtain more power. The other half of the power loss was attributable to the fact they retarded the camshaft timing, (6 to 8 degrees according to the arguments), and the grind of the cams were changed. They advertised these engines to be less polluting. However, I have never been able to understand how burning more gas would make for less pollution. It did, however, make for much more sluggish performance.

Use new pistons with higher compression and a new camshaft with a modern grind and new timing gear/chain set to advance the timing to "straight up" and the power returns. Then a 4 barrel carb becomes of use to you and careful driving can even increase fuel economy and power. Good Luck!

 

what is the difference between the heads and valves on my 67 352 and my 74 390 truck enigne.by just looking every thing looks the same? any other info or perfrmance tips on the 74 390 will also be very helpful. thanks

 

Google the casting numbers and see what the difference is

 

The main reason for the big drop in hp numbers from 71 to 72 was a change in the rating system from gross hp the SAE net hp, there may have been a little change but not the massive drop the hp figures show. Trucks were didn't have the same emissions standards as passenger cars to they held onto their power a little longer.
-Johnboy

 

Thank you for posting actual facts,rather than just opinions!
If and when NumberDummy sees this thread,im fairly certain he will mention something about there not being any 390 4bbl carbs in trucks from the factory before 1976 or so.....