Okay, so I've come to the conclusion that it's time to just rebuild my engine. She's a 390 FE, probably from the same MY as the truck ('75), but possibly earlier (C6ME). Won't know for sure which until she's torn most of the way down.

I started out thinking that it was all a timing problem (see this thread), but finally decided that rebuilding is the best option.

A local shop has agreed to let me do as much of the work as I want at their place. Probably, I'll just let them do most of it and be as involved as I can afford the time for. I decided not to have a reman engine shipped, mostly cuz I want to learn and turn a wrench or two along the way.

The way I want to use the truck is as follows:

1. Probably 15-25,000 city miles a year.
2. Some hauling and pulling.
3. A couple weekends a year, I'll drive her a couple hundred miles north for trail driving on woodsy "two tracks" (bird hunting). I'd be nice to be able to over-top a (small) tree fall or get through some smaller mud-pits.

Much of #2 & 3 will have to await a front axle rebuild, but I don't want to focus on that until next year. Between now and whenever that happens, it'll be strictly RWD.

She does presently sit on 36" tires with stock HiBoy lift (4").

So, the cheapest option is just to do a stock rebuild. Parts (gasket set, OE cam, valves, pistons, valve seats, NO rocker kit, NO crank, etc) come in around $550 or so. I'm pulling the rockers off later this week to have it looked at to see if that will NEED to be replaced. Labor is labor.

I've already got a Pertronix ignition system and new timing set. Purchased an ARP bolt set for the outside stuff. The truck came to me with an Edelbrock 1406 (600cfm) carb. I have a new set of Hedman headers and header gaskets waiting for the rebuild.

On Orich's recommendation, I've decided to have the existing heads reconditioned (lasted more than 3 decades the first time, and I'm not planning on doing any racing or super-hot, high-RPM stuff).

So, my question is: On which parts of the rebuild should I consider spending extra money? Put another way, how much would component X put me out, and what would I get for it?

Crankshaft
Camshaft
Rocker set

seem to be the big ones. I plan to leave the intake manifold and carb alone for another couple years, as well.

How about motor mounts? (I haven't gotten back around to sticking my head under there to see how that works since the compression results came in last weekend.) Great (anti-cancer) engine paint suggestions?

 

Get a cam and deck the block to raise thee compression up to 9-9.5, you can still run pump gas no problem at all and get better milage and more efficient power, since its driven alot I would lean twards a split duration cam, this will give a smooth(er) idle and plenty off vaccum.

 

What does "deck the block" mean? (I'm a newb.) Guessing here: Is it adding an wider head gasket to increase the volume of the compression chamber?

And what's the FE engine rebuild book that everyone always recommends?

 

Deck the block = machine the block to lower deck height to raise compression. It also possibly = new pushrods.

When you buy pistons, use a mid '60s car 390 2v regular fuel pistons, 9.5 CR as OEM. Or a truck 360 piston, somewhere in the low 9s with the 390 set up, depend on the heads, and any milling or decking.

RV cam also, lots of bang for the buck.

serving suggestion, ymmv

 

I converted my 360 to 390 and had to have some machine work done in the process. The machinist has about 40 years experience and a butload with FMC products. I was going to use the 360 truck pistons but he said the cr would be in the 10.25 to 10.5 range and i would have detonation problems out the wazzoo with todays gas. I went with the 390 2v auto pistons as he said the cr would be 9.25 to 9.5 which should be OK with todays premium. I took his word for it and did not go through all the calculations

 

You can run 10.5+ on pump gas but you need a good builder and a great tune. Most of detonation can be corrected with timing, both cam and distributor.

 

It has been discussed here, using a 390 crank and rods and 360 pistons and NOT decking the block, and getting some respectable compression.

 

Krewat, can you point me in the right direction to one or more threads discussing this? I still have the 360 pistons as the 360 was a rebuild long block my dad had installed back in late 90's. He was unable to drive shortly after that so the rebuild had very few miles on it
Pistons are in great shape and reusable. i haven't started the 390 to date as the resto is at the frame, suspension, running gear etc now and no fuel tank, electrical nor coolant so i have no idea how it's going to run but wanted to keep the 360 pistons "just in case" Any info would be appreciated!

 

66 Crawler....if timing is retarded to eliminate detonation in a 10.25 cr engine is there a trade off with keeping advanced timing with a 9.25 cr engine and no detonation? seems like the retarded timing would negate somewhat the benefits of the extra point in cr.

 

rattler12, here's a thread that goes VERY indepth in spots, but basically says the 360 truck pistons from the 70's are the same pin-height as a 390 car piston.

https://www.ford-trucks.com/forums/8...-question.html

 

This would be where you'd have to do careful measuring and calculating with regards to cc size, deck height, head milling etc.

RSR Static Compression Ratio Calculator

Engine Compression Ratio (CR) Calculator

 

Not really rattler, even a 9.25 motor runs a retarded ignition timing, sure you would have to run 91 octane fuel, people dont want to pay for 91 but if you do the math its not that bad. If your filling up 20 gallons and lets say 91 is $.20 more per gallon than 87 on average than the difference is only $4. There is no reason a 10.5 :1 motor should have problems on 91, hell ive seen 12.5 motors run great on pump but you can also run higher octane and feed it some more timing and make more power. You would have too get a 10:1 dyno tuned in my mind, that way you know exactly what its doing and how to tune it your self if you need to make any changes. With any motor that burns regular gas is a give and take situation, the more compression, the bigger the cam, the more timing the higher octane or less octane less timing. I hear what your saying about the timing but a 10.5 with less timing will make more power than a 9.25 with less timing in the same motor but with different cams. Figure out what compression you want to run and order your camshaft accordingly.

 

Don't forget that compression, spark timing, and other things all center around CAM timing too. You can have 10.5:1 and the right cam and still run 87 octane. Maybe

 

Hold on, hold on!

Let's boil this down a bit for the newb: raising compression ratio means more power, but increases the importance for good timing calibration. So 9.0 should be easier to tune than 10.5, yes?

Assuming I spend a couple hundred on a reasonable cam, I might just end up backing off my timing (from the advance that comes with the cam) to control for detonation in a high CR engine?

 

It's all interrelated in reality. You can't go too far in compression with a mild cam, but you HAVE to go to higher compression with a wilder cam. So if you want big power, you basically HAVE to go higher compression because you're going to be using a more radical cam. The compression does help power even without a cam change, but again, you can only go so far.

If you look at any of the cams available aftermarket, they all have a recommendation for compression ratio.

With higher compression, you need to retard the timing to keep it from pinging, without changing anything else. If you go to a wilder cam, you can start to up the timing again, at least at low RPM.