I recently purchased a 71 F100 that was advertised as a recent rebuild on the 390. Long story short, low oil pressure and a sever leak in the rear main lead to removing the pan, which lead to new main and rod bearings and the discovery of lots of silicon and gasket particles in the pickup screen. I had only driven the truck 1300 +/- miles, and the original owner claimed roughly 500-600 miles after the rebuild. Got the bottom end back together, no leaks, but still have relatively low oil pressure. Mechanic is concerned that there is more upper end wear (cam bearings, rockers) that is probably causing further loss of oil pressure. The pressure before the new seals and bearings was 20psi cruising, 2-5psi idle hot, after the new seals and bearings 25-30psi cruising, 10 psi idle hot. There are no signs of any knocking or ticking in the engine, none before the new seals and bearings actually.

My mechanic has a 390 recently removed with 60k on it that he thinks I should swap. He has offered to roll the charge for the bottom end work into the swap to help me out. I don't have a lot of money, and while I hate to lose the offer to roll the money I've already spent into the new motor, I really don't want to invest more now.

Question is, I have done a lot of research and believe while my engine probably does have upper end wear, with a little care it could run for some time.

Here's a picture of the bearings:

http://home.indy.net/~jsdailey/bearings.jpg

So, what would you guys suggest?

ps. this is my first post and I do appreciate your input!

 

Those sure as hell aren't new parts, think you got the shaft. I doubt the mechanic wants your engine, and with siliycone in the pickup neither would I.

Swap the engine start saving your coins and properly rebuild your current engine.




John

 

Ya what John said. It will most likely dollar ya to death and leave ya walking. Make the trade. Than with yer spare change and time let us help ya put the bad one back together and have an engine that will be right. Main thing for now is a dependable engine to get the kid to school.

 

Do not believe one single word a seller claims. Private sellers can lie just like used car dealers and lawyers.

People make all sorts of claims in ads about rebuilt this, rebuilt that, new this, new that.

Ask to see the receipts for all the work done. Even if they did the work themselves, there will be receipts for all the parts they bought.

No receipts? PASS!

On sale day, 360 engines magically become 390's.

Is it a 390...or not? Measure the stroke: 360 = 3.50" / 390 = 3.78"

The 360/390 use the same block, the bore is the same: 4.05" / The difference between a 360 vs a 390 is the crankshaft, rods and pistons.

The 4th digit of the VIN is the engine code. While not an absolute considering engine swaps...

1968/72 F100/350: A = 240 1V 1-6 // B = 300 1V I-6 // G = 302 2V (1969/72 F100) // H = 390 2V // Y = 360 2V.

 

While it's going to hurt financially, I guess the swap is my best bet. Will let you know how this comes out. I contacted the seller to see if he would help me pay for the repairs and he referred me to his lawyer!

 

It's a damn shame people just can't be honest. Good luck with the truck, I hope you can work something out.

 

His lawyer is probably just as slimy as he is. Don't bother. I hate to hear about stuff like this.

The other guys are right. Do the swap and take your engine and do a proper rebuild on it. If it is a 360 IMHO change it to a 390 when you are doing the build. You won't regret it. Far better performance IMO.

If you have the ways and means ( desire & tools ) I recommend taking it apart yourself ( label everything according to bank ) ( L/R ), cylinder #, etc. ( unless your going to get all new ) and even where each bolt goes. I'm talking about the top end. You want to label the bolts, piston rods, w/ cylinder # for the lower end too. I'm not sure how crucial this is but the guys at the engine shop told me to do it so I did.

When I rebuilt the 390 I had in my 65 F100 I kept the lifters, push rods, valve springs as they all checked out spec wise so that helped me keep the cost down ( I'm sure some guys on here are cringing ). I had everything that needed to be done to the block, crank and cylinders done at a welll referred machine/ engine shop. They also helped me to get the correct bearings, pistons and rings.

I bought the bearings, pistons, cam, etc. and put it back together. It was one of the most rewarding things I have ever done vehicle wise.

If you can do this it will save you quite a bit of change and if you have ever built models it isn't much different. You just need to follow directions and pay attention to your torque specs and sequences.

Special tools are minimal. You need to find out if there is a place(s) where you can rent them.

The only thing I couldn't do was press the harmonic balancer on the crank so I had that done at the engine shop. Other than that, I can't think / remember of anything else I couldn't do by myself.

Another thing I did was to take pictures during the disassembly process using a unsharpened pencil as a gauge for bolt size in case something got mixed up, ( didn't happen, but I have an intimate relationship with Murphy ). labeled the individual bolts by what they were and where they were and placed them in plastic zip lock bags. and labeled the bag by what the bolts were for. Kind of redundant but I had never put an engine together before. Again, refer to Murphy.

It was funny when I got the block and heads back. I just kind of marveled at how clean it was for about an hour. Didn't want to put it together right away! You'd understand if you saw the gunk ball I had bought.

That 390 replaced an I6 300 that was the original engine. That engine ( 390 ) purred, well, growled so nice and it was probably the best engine I ever had except for the 283 and 396 I had in My 67 Elcamino and 66 Chevelle but I didn't bring those to life!

Lord, how I miss that truck. I'll never forgive my ex for that.

 

The seller wasn't being dishonest....It was recently rebuilt. It just wasn't rebuilt well.

A minor note: Another common cause of low oil pressure in an old engine is the pressure relief spring in the oil pump. They can corrode and go soft with age, which will cause low pressure regardless of the bearing clearances, etc. Also, the oil pump may be worn and have too much clearance. When you had it apart, did you replace or check the oil pump?

Engine rebuilding is like any other form of craftsmanship. The final result depends on the amount of time and care you put into it. If you want an engine that will run strong and reliably for many years, then you need to either spend the money to have it done right by a good engine shop, or take the time and do it yourself, carefully and patiently. There's lots of good info out there on how to rebuild an engine; it's not a mysterious art. The main thing is to take your time with it.

Like the other guys have said, swap another engine in there to keep the truck driveable, and rebuild the original yourself. That's what I plan to do someday soon on my '67's 352.