Hey Everyone,

I'm going to be doing some engine work soon and I wanted to get some advice. First let me tell you what I have. I have a 66 F250 4x4, 4 speed manual with 35x12.50 tires and 4.56 gears. It currently has a 390 with an edlebrock 600 cfm carb, aluminum intake, electric fuel pump and headers, other than that no other work has been done to it. I want to get some more power out of the engine because I will be using the truck for off roading. Most of it will be trail riding, a little bit of mud but nothing too extreme. The truck does well now, but I just wish it was more responsive and powerful, especially when climbing hills. I will often run out of power and have to get a faster running start. This truck was my daily driver about 12 years ago and the engine only has about 30k on it since it was rebuilt then. If I just replaced the cam would I feel a noticable difference or would I need to have more done to the engine? Now that this is my project vehicle, I'm willing to spend more time and money on it. so I'm not really concerned with keeping it cheap. Let me know your thoughts please.

 

I can't imagine a decent 390 not having enough power to wheel 35" tires. If you don't have enough power something is wrong. Wheeling doesn't require a lot of power unless your out to get very stuck in very deep mud or just break stuff including your neck.

 

Your carb may be running out of gas or flooding due to extreme angles. Holley has a carb for just such extreme angle purposes.

 

Good point, carbs and extreme wheeling just don't mix.

FWIW if was building the ultimate off road carb it would be a 4160 holley based carb most likely one from Quick Fuel. Build it with 4 corner idling, manual butterflys opening in parallel, double pumper, jet extensions, and a hose on the bowl vents.

Edelbrock carbs are horrible off road cause of the location of the pump, needle & seats, and the long flat bowls.

 

It's possible the carb could be the issue. I i think the truck is running fine though, I think it comes down to me just wanting more power. I've modded all of my other vehicles in one form or another

 

Lower gears and lockers can also get you up those steep hills.

I'm getting close to having my 390 in a 62 F250 running and couldn't imagine it not having enough power to get me where my 92 4runner with the 3.0L V6 can't. Even with stock gearing and open differentials it goes where I point it to as long as I choose the right line. A few times I had to find another way around the steep hills though. Engine won't keep the wheels going even in 4 low if it's steep enough.

 

The 390 in question--was this a '70s pickup motor? With the stock cam? One of those with your mods is probably worth 250 horse or so, and would peter out about 4500 rpm.

What do you have for compression and cam?

 

You would be surprised what you can get out of an FE by tuning the mechanical and vacuum advance in the stock distributor. If the dizzy has been changed, or the motor is not original, who knows what the dizzy is setup for.

Likewise, the compression has a lot to do with how much power you'll get from them. Without tearing it apart, it's hard to tell, but the head casting numbers would at least tell us what decade it came from

 

like said ,, what C/R and cam ?
bump the C/R up to 9.? and get a good TQ cam

 

I did change out the distributor because I converted it to electronic ignition. I think the engine came from a 70's LTD car. I was told that back then the cars and trucks used the same cam. Is that accurate? On a side note, I do have a Ford 360 engine sitting in a 72 ford I have thats not running. Maybe I should pull that engine and work on it. I'd love to learn how to tear down an engine

 

Hhhmmmm. How many bolts holding the valve covers?

The 390 bowed out of LTD duty at some point with the intro of the 429 and the 400, possibly with the last one in '68 for the LTD.

IF it's a late '60s car 390, it would have 9.5 or 10.5 compression and a modest cam. Car and pu cams may have been the same, with the pu motor getting lower compression.

 

MUCH LOWER COMPRESSION

 

I'll have to check the valve cover bolts when I'm under the hood tomorrow. I'm not sure what the compression ratio or cam is. Here's the story on the truck. My dad had it for years. Back in 1999, it was sitting without an engine. The engine was halfway apart in a shed 9and had been for several years. I was just in high school at this point so my dad finished putting the engine together. He cant recall the compression, but he did say he left the original cam in there. Depending on where money is at in the next couple of months, i might just pull the engine and start from scratch. I may go talk to a machine shop this weekend to get an idea of costs and options