390 Engine Advice

[travellew]

Ok.. First. I'm not looking to build an engine for the most horsepower. I know you can port this, deck that, cam this, holley that and get a 400+ HP tire burner. Not the point of this post.

I have begun the rebuild of the 390 in my 66. Its not an original engine and was swapped in at some point. I believe to actually be a 390 FT block from a 1970 "F" series truck (guessing an F-150 due to the 2bbl carb). I have found a nice 4bbl stock intake I will be using ($28 at the local wrecker.... SCORE).

I'm still digging into things to try and determine how far I need to go. I found some light vertical scratches on 2 cylinders. It may hone out and then 0.003 oversized rings, but probably not and I will need to go 0.030 over. We will see.

Anyway... My point.. I'm looking for some suggestions on a CAM and springs. I have been told that the a nice mild CAM can really improve this motor, but I have no idea what to look for. I absolutely want to keep the budget (so nothing super expensive), but would like to wake it up a bit. Suggestions?

P.S. Yes yes.. I'm looking into an ignition system and possible TB fuel injection. I really want FI, but it may turn out to just be too much (fuel line runs, electric pump wiring, tank outlet welding, ect ect). In that case, I will just go to the tried and true Holley.

[jtschug]

First, An F-150 from 1970 would have an FE motor. FT engines were used on bigger commercial trucks, and it would be a problem because the crank snout is bigger and it wouldn't fit the belt driven stuff. A lot of F150s had 360 engines, so you may want to double check the bore and stroke to confirm it is a 390. Standard bore for a 390 is 4.05", standard stroke is 3.78" (A 360 will have a 3.5" stroke)

With regard to the cam, a common upgrade is the "RV" grind which provides a bit more low end torque (presumably to motivate a big heavy recreational vehicle). I don't know the manufacturers, but buy one from a reputable manufacturer and from a solid vendor.

You need to know that motor oil has been reformulated to remove ZDDP commonly called "zinc". ZDDP is very important to flat tappet camshafts. Also it seems that some manufacturers have forgotten how important tight tolerances and good surface harness is for these old flat tappet systems. The internet has been filled with many tales of woe about cam and lifter failures in the first 200 miles after rebuilding an engine. When this happens the engine must be removed and disassembled again to clean out all the metal flakes. People have had this happen multiple times on the same engine, it would have been very unusual back 15 or 20 years ago, but it seems to happen all the time now. When you build your engine: 1) make sure to prelube the cam very well 2) use a ZDDP additive to the engine oil 3) follow you cam manufacturer's break in procedure.

There are roller lifters which will work in an FE engine, but given that you are on a budget, it may not be worth the extra cost.

[travellew]

Although this is my first Ford, its not my first rodeo with flat tappet engines. Rotella T4 for ALL my older engines since I only run them in the summer anyway. Even then, for the initial 2-3 oil changes I will throw in a zinc additive.

Its definitely a 390 based on the stroke (heads are off, easy to measure). That is the only thing I'm certain about. The cast numbers on the block seem to be upside down and read 49DII or 49D11. Of course it has the standard 352 with a 65 above on the front. I have attached an image of the casting number, maybe someone will know something.

As to the CAM, maybe its best to just ring up a company like Comp Cams or similar and see what they suggest.

[jtschug]

The casting numbers don't tell you much. It looks to me like 49 DIF. DIF stands for Dearborn Iron Foundry where all the blocks were cast. I'm pretty sure my block cast in 1974 has exactly the same marking.

[travellew]

The casting numbers don't tell you much. It looks to me like 49 DIF. DIF stands for Dearborn Iron Foundry where all the blocks were cast. I'm pretty sure my block cast in 1974 has exactly the same marking.

Oh that makes complete sense. Thanks a bunch..

I did find what looks like an ID tag under the oil filter adapter (which is a %90 adapter pointing the filter straight down). Unfortunately I can't read it. I will be flipping the engine over later today and should be able to clean it up and get better light on it. Even if I just get a date of the casting, it will give me a better idea of what it came from.

Anyway.. Thanks for the responses everyone!

[jtschug]

Yes, the casting date is on that marking below the oil filter adapter.

Here is the decoder:
https://www.fordification.com/tech/datecodes.htm

You will need to use other clues to figure out which decade it is from, but it isn't that hard to tell the 1950's from the 1960's from the 1970's

[travellew]

Sigh.. unfortunately the engine history doesn't matter. Turns out the block is junk. It was previously bored 0.40 over and currently has been scratching in 3 holes. Machine shop recommended I scrap it as 0.60 is considered max for a 390 and this one may need more.

There is a 390 block at the local wrecker I will be taking out of the truck tomorrow. Fingers crossed that this block will be usable. Sigh, classic cars.

[jtschug]

While 0.060 is the Ford limit, a sonic check will tell you the wall thickness. At 0.080 over, 428 pistons will fit.

[bbogue]

When I had the engine rebuilt in my 61, I found that toying with the options available at the Comp Cams website was helpful in making a selection, which I then confirmed with my engine rebuilder. I tried to select something with good torque at low rpm’s, similar to what’s been called an RV grind. It doesn’t appear that Comp offers my camshaft now but SKU 33-234-4 appears similar. Best of luck.

Bill

[travellew]

While 0.060 is the Ford limit, a sonic check will tell you the wall thickness. At 0.080 over, 428 pistons will fit.

Ya... The local machine shop said they would definitely take my money but recommended I look at other options. While it could be done, it would be the least "preferred" option.

So off to the wrecker I went.... and guess what, the 390 I planned to remove was a 0.060 overbore and had a cylinder that was completely blown out. I would never have believed it if I hadn't seen it with my own eyes when I removed the head. A chunk of the cylinder wall had blow right into the water passage. Crazy.

However, fate was with me and they just received another truck with a 390. A 1974 2V version. So I now have that in my garage and I'm super happy. The truck had 157K KM on it and the engine is completely original with no overbore. The bores look excellent so I will be sending it for magfluxing and cleaning and then building this one. Of course its a standard truck version of the 390 with modified pistons for low compression (research tells me they actually moved the wristpin location to reduce compression to like 8.6:1). No worries I will be replacing the pistons and all the accoutrements to build it like an original 390 from a 66 bird.

When I had the engine rebuilt in my 61, I found that toying with the options available at the Comp Cams website was helpful in making a selection, which I then confirmed with my engine rebuilder. I tried to select something with good torque at low rpm’s, similar to what’s been called an RV grind. It doesn’t appear that Comp offers my camshaft now but SKU 33-234-4 appears similar. Best of luck.

Bill

Bill.. Thanks a bunch. I will call comp cams and give them this number. I'm sure they will set me up. I haven't hear a bad things about them.

[travellew]

Welp after some measurements, is a 360, not a 390... Gotta love wreckers...

Anyway, it doesn't matter as I have a 390 crank (will get machined), 390 rods and I will be buying new pistons and rings. So we will make it back to a 390.. I just thought I would post for future people who might be in the same position. A 360 is really a 390 except for the rotating components (crank, rods, pistons, cam).

Still.. The block is immaculate, so I'm pretty happy!

[Alan H. Tast]

Why can't you get the bores resleeved?

[jtschug]

Why can't you get the bores resleeved?

Depending on the shop, once you get past two sleeves, it is probably cheaper to start with a different block. If it is something rare, like a 427, or if it is a numbers matching 428 cobra jet Mustang, then it is certainly worth it to do multiple sleeves. This one doesn't sound like either of those situations, particularly since he doesn't even want to spend the money on a sonic check.

[travellew]

Why can't you get the bores resleeved?

Depending on the shop, once you get past two sleeves, it is probably cheaper to start with a different block. If it is something rare, like a 427, or if it is a numbers matching 428 cobra jet Mustang, then it is certainly worth it to do multiple sleeves. This one doesn't sound like either of those situations, particularly since he doesn't even want to spend the money on a sonic check.

It just comes down to money.

By the time I pay for cleaning, mag fluxing and a sonic test I'm over the $500 mark and the shop gave it a 50-50 based on previous experience with 390s. Then if it passes the sonic tests, the costs for boring sleeving are north of $1200.

Instead, a complete engine from a wrecker is $350 and I was able to inspect it before taking it. I now have a much better block that I'm confident in rebuilding as it has never been rebored. Of course I will still need to clean and mag flux it so that cost is the same (if cracks are found, the wrecker will take it back and give me my money back).

And yes, since the engine in the car was swapped in the 80s (from a 428 to a 390) the numbers don't match. So there is no reason to try and save an "iffy" block.

[bbogue]

Besides the camshaft, another good way to increase power in the 390 engine is to replace the log exhaust manifolds with headers. My engine rebuilder estimated at least 20hp increase. The details of the cam I used indicated that they “liked” headers. I think FPA makes them for your car. They may be a snug fit, however. For my 61, 1/4” spacer plates between the motor mounts and frame were required. Hood clearance was minimal. Maybe someone who’s used them on your model year will comment. My headers were $700+ almost 10 years ago, pricey.

A search in this forum may be helpful.

Good luck.

Bill