Hi all,

There is no specific question in this post, it is more of a please read and give me your thoughts & ideas.

I also think it could be quite long as I have a lot to fit in!

Starting with the symptoms which have caused the need to identify.

Earlier this year I had a severely bent pushrod (on 8). This was swapped, along with the lifters on both valves on 8. Had several other issues since so hasn't really run since then. Also had plenty of WD-40 down the valves, and marvel mystery in the oil and fuel.
Once started it bent the pushrod again. This was swapped twice more (hoping the valve may be sticking from standing and it would free up). It bent both of these, a 3rd was put in and run with the valve cover off, and it bent this one too, though the valve was moving. The other pushrod on 8 wasn't even trying to move.
Pulled the cam and that lobe is basically round, rest of the lobes look pretty good, looks like it’s a refinished cam that’s been put in recently.
So hence trying to identify the engine, so I can get the right replacement.
Now I have looked into it some more I am confused about what I actually have, and whether it is ok!!

I was told it is a 390 (VIN says 352).
Measurements:
Bore: 4.05
Stroke 3.5
So this suggests 361 (390 block with 352 crank?)
Heads are C8AE-H (360/390)
Deck clearance figures:
1: 0.2125
2: 0.2075
3: 0.2175
4: 0.2275
5: 0.239
6: 0.2595
7: 0.2665
8: 0.248

Which seems like quite a lot, but if it is a 390 with a 352 crank in it and nothing else changed, the crank throw difference is about 0.14 to start with so that would account for most of this. I imagine this has reduced the compression ratio quite a lot.

There are no casting marks on the block that I can find, but it has the vertical ribs.
Date is 1D21 (with the two dots under the 1) Similar code on the heads.

So as I said, looking for thoughts on what could be causing the bent pushrods, and whether it has been put together with a combination that is any good.

 

1D21 = Block cast April (D) 21, 1971 (1).

360/390 block is the same, the bore is 4.05"

The stroke is different: 3.50" = 360 / 3.78" = 390.

 

Thanks,
So it is a standard 71 360.

Do the deck clearances still seem a little big though? The data I have is suggesting it should be 0.104 so I am almost double. And there is quite a difference between cylinders.

 

Bad gas can bend pushrods. How old is the gas?

What happens is it will start and run alright but once it has been allowed to cool, varnish forms on the valve stem, which can cause them to stick. The pushrod, being the weakest link, bends. The fix, take the heads apart for a thorough cleaning, reassemble and use good, fresh gas.

Nearly 1/4 inch in the hole does seem excessive. In general, it is wise to tighten that up so that it is pretty close to 0.

 

The gas has been in it about 8 months.

The 3 pushrods it bent recently were changed while it was pretty hot, I don't know how much it has to cool for the varnish to form and stick the valves?..

Heads will be cleaned up.
Also, would it be likely to bend the same one four times?
Does it seem a coincidence that both valve related problems are on the same cylinder?

How would I go about tightening it up, is that something needing changing or an adjustment?

 

8 month old gas is questionable. Get some fresh gas to eliminate that as the problem.

I don't know how much it has to cool and it may not be your problem but it is at the top of the list for me when old, questionable gas is involved.

Since we don't know the cause at this point, yes, whatever is causing it may cause the same one to bend 4 times. Anything that is restricting the movement of the valve will cause similar failures until the problem is found and properly addressed. Not coincidence.

Someone more familiar with FE's will need to speak up but here are my thoughts. With nearly 1/4" of deck clearance, you probably have mis-matched parts. To fix that will require swapping rods and/or pistons. Once the proper conrod and pistons are installed, it is a matter of milling the deck surface of the block.

 

A stuck value, is a stuck value. If it's not opening up all the way, it will continue to bend push rods. It may only be opening part way, = bent rod.

Did you find any kind of rust color inside the value compartment area?
Do you live in a high humidity area?
Do you have a big temp or moisture change from day to night time?
Just a thought.

 

Sounds like OP has a 352/360 crank, and short 390 rods with the standard 390 car spec piston Ford used in the 360.

Deck - piston - rod - 1/2 stroke = top of piston to deck.

10.17 - 1.77 - 6.49 - 1.75 = .160. A little less than the OP measures, but enough to take compression into the 7s methinks.

If they were dished pistons, OP may have the dish in there too. And there are variances in the parts themselves, usually a few 1/1000s, but add those up along with some wear and .200 or better is within spitting distance.

Any good? It will probably run for a long time if you can sort out the push rod.

However, with a round cam lobe, you know the oil has been a metallic milkshake for some time.

Tear it down, check the block. If it's sound, make a 445 stroker with aftermarket aluminum heads, EFI and ceramic coated headers, along with roller internals. Serving suggestion, let your wallet be your guide.

 

Will try and answer all questions.

No rust colour in the valve compartments.
Humidy generally varies from about 70% to 90% (currently 94%)
Overnight temperatures can drop about 10 - 15C (about 20F ish)
(This is based on some quick searches for averages, South coast UK if anyone can correct me!)

Piston tops look like this:


And clearance was measured to the top of the flat, with none of the recess measured.

I don't think the wallet is going to guide me that way! More get it up and running nicely and reliably so I can trust the thing with some decent runs! Not looking for huge power, and it only has a 3 speed on it.

 

What we are talking about is hardly about huge power. It's more about getting that engine to produce the power it should produce.

There are long term benefits to getting that clearance tighter. For one, your excessive clearance can actually make the engine more prone to detonation, which is bad. Increasing compression not only helps with power, throughout the entire rpm range, but it also increases efficiency, or in other words, miles per gallon.
With such excess clearance, simply fixing that issue should produce a significant increase in compression and you probably will not have to change the grade of gas you use so you will be paying the same per gallon while getting better mileage, so fuel costs should drop.

85e150six4mtod seems to know what he's talking about and based on what he says, you just need to get a correct set of rods. That's not a very big job at all and you clearly have the engine down that far since you have the piston out, so now is the time to fix that problem. You will be happy in the long term that you did.

 

Or get a 390 crankshaft.

 

If you have hydraulic lifters, then your valve train is not adjustable. The pushrods have to be measured with the lifter collapsed to get the correct length.

 

Didn't mean to confuse anything with the piston pic, that's just an example of the top as I wasn't at home to get a pic of mine.

The block is still in the truck, and (ideally) it would stay there!

But it looks like it will need something changing.


Any idea if it started life as a 390 and now has a 360 crank, or started life as a 360 and has 390 rods in it? I was hoping the pistons may shed some light on it.

I measured the new pushrod set based on the ones that were in it. I think they were 9.62

 

FE pushrods are made in different lengths. Each pushrod has to be measured to get the proper clearance.

 

This is out of a 1971 Ford shop Manual. Read paragraph #5.