i have a 1977 Ford F250 hiboy 400M, and i have been having headaches with the motor. when i first bought it, it was fine, but now, after replaceing the plugs, wires, cap, and rotor, i am still haveing some sort of problem. after doing a compression test, the motor is anywhere from 6:1 -> 9:1. my problem is that im only 16, and have limited amounts of time and funds. i need to know weither to rebuild or just get a different motor. i haev been told to buy a motor by some and by others to rebuild. i just want something that wont give me alot of problems. if u could, just let me know what u think is my best option. and if u happen to know where i could get either a rebuild kit or new motor for a resonable price, please let me know! any help is appriciated. if u need to contact me in any other way, email me at Scolesy8@aim.com

thanks

 

First off..

No M after 400

the M is after 351 in the 351M engine.

Even though The 2 engines are referred to as the M block engines as they share the same block but have internal difference.

You can find out more in the 335 engine forum....that's where engine topics are best dicussed.

Your mention of compression RATIO as ther result of a test is somewhat confusing.

Compression tests are usually recorded in PSI .....not a ratio.

Maybe do it again and report back.

ie: 130 psi in one cylinder and 80 psi in another.

The lowest should be within 10 %,

again this is more an engine topic rather than a 73-79 Truck topic

without the truck involved you still have an engine topic.



The most inexpensive way out is to rebuild the 400 if it needs it.

count on $2000.00

 

Good lord, he's only 16. Kudo's to him for his interest in his Ford when most other kids are working on Hondas.

 

The engine is in a 77 Ford truck, sounds like he is in the right place to me. Granted he might get more responses in the engine specific forum. I would suggest that you look very carefully that all the right wires are on the right plugs. Have you checked the timing? If the truck ran fine before you did the work then the odds are you have made an error someplace along the tune up. Where are you from? If yer near central MO i would be more then happy to help ya out in person.

 

I would ditch the 400 get some motor mounts from L&L and drop in a 460 or 429 Dad built a 400 and it's a real firebreather, lots of fun in his 66 bronco, but it pings I know they make better heads now, but a 460 is just a better motor and most most of it is bolt up, I run the big radiator now, but I didn't have any trouble with the standard 351m radiator other than leaks, and the distributer is interchangeable, so all the wiring is the same, then get someone to fix our exhaust. a 400 is a good motor but more expensive to make really good.

 

I'd put in a 460 before I dumped 2K into a 400. Otherwise I would put in a good used motor for a couple hundred dollars and call it good.