352 to 390 swap

[baronsass]

Hello everyone,

The 352 in my '58 has a cracked block. It's been welded, and though it still runs, I've been on the hunt for a replacement for some time now. I found a 390 in a '66 Galaxie. The engine is apparently strong, but I have yet to see/hear it in action. If it's good, I plan to swap it for my old 352. Forgive my ignorance but I have questions to ask of you lords of 'Bird lore:

1. Is the swap direct? Will a 390 simply "bolt in" in place of my 352?
2. Will the 390 mate with the transmission in my '58, or is there some adaptation that must happen?
3. Is there any way - apart from doing the stroke measurement - to confirm it's actually a 390? Some external obvious clue?
4. There are subtle differences between the exhaust manifolds on a 352 and those on a 390. Is there anything I need to do or be aware of when it comes to the exhaust, or is that simply a bolt on proposition as well?

I have more questions, but this will get me started. Fire away gents!

[jopizz]

The 390 block is basically a bored out 352 so it will bolt right in and mate up fine with your transmission. I suggest you use the 390 heads and not the 352 heads. You will have to reuse the 352 exhaust manifolds though. They will bolt up fine to the 390 heads. The only sure way to tell a 390 is measuring the stroke. Most 390 blocks are stamped "352" so markings won't help you. It should be an easy swap assuming the 390 is in good condition. There are many more aftermarket parts available for 390's like aluminum heads which won't fit on a 352. The 390 block will also have the hole drilled for an alternator if you want to upgrade from the generator. I highly recommend it unless you are looking for a completely stock look.

John

[baronsass]

Awesome, John. Thanks. This is reassuring info. Guess I'll be rebuilding my COM then rather than throwing in a C6. Hole for an alternator is good to know. I'm seeing the engine on Saturday - research on the stroke measurement for the 390 - 3.78 inches (as opposed to 3.5 for the 352). Can you confirm?

[jopizz]

Yes, 3.78 is correct. Here are the bore and stroke measurements for the various FE engines.

CI--Bore ------------Stroke
332 4.000 in (101.6 mm) 3.300 in (83.8 mm)
352 4.002 in (101.7 mm) 3.500 in (88.9 mm)
360 4.052 in (102.8 mm) 3.500 in (88.9 mm)
361 4.047 in (102.8 mm) 3.500 in (88.9 mm)
390 4.052 in (102.9 mm) 3.784 in (96.1 mm)
391 4.052 in (102.9 mm) 3.784 in (96.1 mm)
406 4.130 in (104.9 mm) 3.784 in (96.1 mm)
410 4.054 in (103.0 mm) 3.98 in (101.1 mm)
427 4.232 in (107.5 mm) 3.784 in (96.1 mm)
428 4.132 in (105.0 mm) 3.98 in (101.1 mm)


John

[baronsass]

Thanks again - think there's any advantage to running with a C6 as opposed to my old COM? Frankly, I like the COM, and the rebuild is pretty cheap/straight forward.

[jopizz]

If your COM doesn't have any leaks or other issues I would stick with it. The C6 is a good transmission but it is not a direct swap. You will have to modify the linkage and the trans mount.

John

[baronsass]

Then it's COM for the win! Mine doesn't leak but is old and worn. My tranny guy is absolutely adamant that the rebuild will be pretty easy, so I think I'll go that way.

[YellowRose]

I have taken the information regarding "FE" Engine Bore & Stroke Measurements, added comments on how to check to see if you do have a 352, or other engine, and put it in the TRL. Look down in the Engine section in the 352CI Engine information and you will find it there. Or use the Find feature that Dave gave us a long time ago, (Ctrl F (F for Find). Type in 352CI and it should take you right to it. Thanks, John and Dave for the information.

[baronsass]

My 352 - 390 swap is rolling along quite nicely, but I've run into a "small" issue... The coolant bypass tube that runs into the intake manifold. These seem to have been designed kinda poorly by Ford back in the day - by that, I mean they're short. That said, my old 352 ran for years with that short thing providing coolant to my engine. My question is - can they be readily replaced with something longer? Adapted with an insert? Mine seems VERY attached to the intake. Given that fluid is fed into the engine under pressure through this tube, I'd like some thing a bit longer, and hence reassuring to attach my hoses. Let me know what you guys think.

[jopizz]

New ones are readily available. They are just a press fit.

https://www.macsautoparts.com/ford_thunderbird/ford-thunderbird-water-bypass-tube-steel-5-8-od-2-1-2-long-1958-66.html

John

[jopizz]

If yours has the temp sender in the pipe you will need this one.

https://www.macsautoparts.com/ford_t...8-1958-59.html

John

[baronsass]

Awesome - thanks, jopizz. Mine doesn't have the temp sender, so it's just the straight pipe for me. It this somewhat longer than the original? Think I can knock my old one out pretty readily, or should I tread very carefully? I don't want to damage the manifold.

[jopizz]

The new one should be plenty long enough. You want at least 1/4-1/2" gap between the intake pipe and the water pump pipe. As long as you can get the full width of the clamp on it without being on the flare you are fine. I would split the old one using a chisel and use a vise grip to tear it out. Some WD-40 or Liquid Wrench usually helps. Normally it's rusted to the point where it comes out pretty easily. Clean the opening with some fine sandpaper after you get it out. You don't want any rust or burrs causing a leak. If you have trouble pressing the new one in try putting it in the freezer first. That may shrink it enough to make it go in easier. I usually put some Permatex sealer around it.

John

[baronsass]

Awesome. This is great info. Thanks jopizz. You da best.

[jopizz]

Are you reusing the original '58 intake manifold or using a later 352/390 intake. The original '58 intake had the sender in the pipe and was 7/8". Newer 352/390 intakes used the straight 5/8" pipe.

John