1976 F250 390 4 bbl in my '60 Tbird

[cbnsingram]

Responses to my "can I use a 351?" thread have provided me with some great advice about engine choice and some general used engine gotchas like possible timing chain slop. I've started this new thread because I bought a '76 F250 with a running 390 to use in the TBird. The Bird already has a locked up 390 (will keep and build later) so I assume that any fitment issues have already been addressed. I am curious if there are any changes recommended so a truck motor makes the bird drive like it should.

I am looking for only stock performance at this time as it will be a driver for my 16 year old daughter. We'll goose it a couple years down the road. The "new" engine has an Edelbrock 1407 4 bbl and what I think is the original 390 intake manifold (old engine has a stock 2 bbl and intake.). The "new" engine runs well without leaks or smoke, so I don't plan to tear it down unless necessary to prevent it from being a dog.

Have ordered the two engine books repeatedly recommended on this and FE forums, but in general:

1. Should I be considering a specific cam and why? and is it likely to be in the truck block? I assume only a tear down would confirm which cam it has.

2. I've already been told I might want a lower cfm carb - still not sure why though. Anyone?

3. What is the appropriate header style to shoot for, so I can determine if I have it between the two setups? Not afraid to upgrade here.

4. Anything else to consider when dropping in a truck engine?

[simplyconnected]

...I am curious if there are any changes recommended so a truck motor makes the bird drive like it should.

I am looking for only stock performance at this time as it will be a driver for my 16 year old daughter...

Those FEs were built for leaded gas and oil with zinc and phosphorous (ZDDP). That was the standard back then. Standards have changed drastically in the past 40 years. It's not only an issue between truck vs car. Both of those engines ran just fine back in the day.

Have you seen the result of an old 390 that ran unleaded gasohol? My purpose in showing these pictures is to educate folks, not to scare anyone:





These are the heads I removed from the '73 F-100 390 TE. Notice the outboard exhaust valves and how deep they have sunk into the seat pockets. This erosion happens from hot spots; the valve or seat gets a white-hot spot (because iron is a poor conductor of heat), then the valve welds itself shut. Next time it opens, that metal removes from the seat... over and over. After time, the spring cannot completely close the valve. Then, starting becomes an issue...

Rather than pouring a lot of money into machining new hardened valve seats, bronze guides, machining guide towers for viton seals and buying stainless steel valves and new springs, and decking the whole thing, I scrapped these iron heads and bought new aluminum Edelbrock Performer RPM heads. They are bolt-on ready off the shelf, all the parts are matched for today's liquids, they transfer heat a whole lot better, and they retain their value even as 'used' heads. Completely rebuilt and machined iron heads are not worth more than $200 'used', but proper machining/parts costs are nearly as high as the new Edelbrock heads. Two years ago I went through this with my Y-block because aluminum heads were not available at any cost. Heads are a major part of your engine. Please don't try to 'save money' by skimping, here.

I think your question can best be answered with another question: "What do modern engines use (and why do they last 250k miles)?"

They use aluminum heads and intake manifolds and roller timing chain sets. That allows much higher operating temps with no danger of preignition or run-on, and it allows the kind of compression ratio your car came with using today's fuel. New engines run at 190*F, and 19-lbs of pressure. To a machine, it's a very comfy home to live in, it burns fuel more efficiently, and elevated temp actually reduces wear. The most wear happens when any engine is cold.

Another feature of new engines; they have roller cams, not flat tappets. To retain your flat tappet cam, these engines need an oil supplement.

I hope this info helps. It is very difficult to know the true status of a used engine. Yeah, compression tests help but tearing it down is the only way to reveal the truth. I buy used engines with the intention of overhauling it right away. - Dave

[Astrowing]

That's pretty interesting Dave. I thought that the inner cylinders ran hotter and therefore you'd see more valve wear there, but this engine shows the opposite. As you said, I would expect less bearing and block wear on the inner cylinders since they are usually hotter but didn't think that would apply to the valves since they aren't using a film of oil.

[simplyconnected]

Jim, the theory is that 'outside' cylinders run leaner and that more liquid (unvaporized) gasoline quickly runs into the cylinders closest to the carb.

I never saw this engine run. The owner volunteered that it did when it was pulled from the truck. I just kinda smiled and said, 'ok'. My intention was to tear it down ASAP. Good thing I did, too. You saw the timing sprocket with half the nylon teeth missing.

Looking at the residue in the heads, there was clearly no head gasket leak. None of the chambers were oily. But the valves really disturbed me. There was nothing in those heads I cared to salvage. - Dave

EDIT: Jim, after thinking of your post, I know what you are refering to... Y-blocks have two exhaust valves next to each other smack in the middle of each head. No, this is an FE. Notice that it has two intake valves next to each other in the middle and NO exhaust valves are next to each other.

'Adjacent exhaust valves' is why the gasket manufacturers suggest drilling the two holes in your Y-block deck and heads, for steam to pass through. Ford quickly got rid of that I-E-I-E-E-I-E-I configuration when they went to the FE. Funny though... Chevy 283 valves are configured just like the Y.

[Astrowing]

So when adjusting a carb, you're better off to err on the rich side, than lean, as the lean is what causes long term damage. It could be that some of the damage to this engine could be caused by one of the idle jets being lean. That would in of itself affect every other cylinder and not just the end cylinders. 1467 or 5238. Atomization of the fuel is going to be a function of temperature to some degree, and it is different between inner and outer cylinders with the short and long manifold runs.

[simplyconnected]

So when adjusting a carb, you're better off to err on the rich side, than lean, as the lean is what causes long term damage...

And herein lies the problem. We are ever searching for a fuel/air mixture of 14.7:1.

That's nearly impossible using a carburetor. Using injectors is quite a different story. Computer monitoring the exhaust with oxygen sensors nails it. There are restrictions. NEVER mix injectors. Always buy them in sets with the same lot number. If the set is a little over or under in size, the computer will compensate for that. But if one (or a few) are different from the rest, your computer reads the oxygen sensors and then it adjusts the injectors for an 'average' exhaust value. Injectors atomize fuel far better than carburetors because injector fuel is under high pressure. The computer 'dithers' the injectors using Pulse Width Modulation (PWM); a fancy way of turning the injectors on and off at precise time intervals.

One very common engine was the Jeep 4.0L. With a carb, it was a gas-guzzling dog. The moment they put injectors on this old horse, it came roaring to new-found life (almost too much for the Jeep). More ponies, less consumption, etc... 14.7:1 in every cylinder on every day of the year. - Dave

[cbnsingram]

Update - Carburetor for 390

Thanks again for the dialog folks.

I did some more research and now understand what is meant by "too much carb". Horrible mileage and possibility of not passing emissions. I'm selling the Edelbrock 1407 (750cfm with manual choke) that came on the truck engine.

I'm looking for an Edelbrock 1406 (600cfm with elec. choke) and Performer intake. If I can't find a good deal on the intake I will use the stock intake (it is indeed a 4 bbl rather than an adapted 2 bbl.)

I also discovered another reason why the motor feels like mud off the line - the previous owner had used a small screw to force both sides of the four barrel carb to open together, rather than letting the second stage (correct term?) being opened by vacuum. Not sure why he did this unless it had to do with the fact he was pulling large trailers.