Hi folks!

This is my first post, so please be kind!

I am interested in rebuilding the 351W in my trusty 1990 F-250 HD 4wd. She's getting a little tired after 198,000 miles of absolutely reliable service, so I feel that she deserves a freshen up. I've owned this truck since new (in fact, it was the first new vehicle I've ever owned). It has the ZF 5 speed, 10.25" full floating rear, with 3:55s in it. It truly is the best vehicle I have ever owned. Never a minute of trouble (except for paint and AC issues).

I'm not looking for a strip terror, but would like to increase the low-midrange torque a bit, so I am thinking of doing a 393. Coming from the Pontiac world, I am amazed at how inexpensive quality parts are for the Ford, BTW.

The truck is used for Home Depot runs, yard work as well as pulling the boat and car trailer.

I would like to keep the EFI and utilize as much of the original accessories as I can.

In addition to the standard machine work, my plan so far is to buy a cast Eagle 3.85" stroke crank, 302 pistons, rebuild my stock 351 rods with ARP bolts, have the rotating assembly balanced, clean up the ports in the heads, have a good 3 angle valve job with new springs to match whatever cam I decide on. I will also set it up for an adjustable valve train with roller rockers......

I will be doing all of the teardown/assembly work myself (can't be that much different than a Pontiac!)......

Does anybody know what my CR will be with cleaned up stock heads (I don't know the CC volume of these heads, but it has pinged on 87 since day one!), .030" overbore and the 3.85" crank? I do not want to have to run premium gas.

Will I run into any issues with the EEC IV with the stroker and cam change?

Any recommendations for cams? I am running a hydraulic roller in my Pontiac 455, and I absolutely love it's torque band and nicely mannered idle. I'd definitely consider one for this engine, but it's not a necessity.


Thanks in advance for any help/advice you folks can supply!

She's a beater for sure, but I love her! She'll get painted after the mechanical stuff is done!

 

Hi, and welcome to FTE! Please take a moment to check out the guidelines, they contain important info you'll need when posting here:

https://www.ford-trucks.com/guidelines.html

I know it's a lot to wade through, but our moderator Mustang GT221 has done a 393, and has chonicled his experiences over the past year here:

https://www.ford-trucks.com/forums/s...d.php?t=272689

There's a lot of good info in that thread but be prepared fo a long one! I don't think there's anything I could add that hasn't already been said in there.

 

Thanks TigerDan! I am about 8 pages into that link...... LOTS of info to decipher. I had no idea that these Fords were so complicated..... Too many options! With Pontiacs, you open your wallet and choose between stock or basically stock......

I am definitely doing a 393 for my truck....... Now I just have to figure out the particulars and start ordering parts!

 

I have spent the last 2 hours scouring the board for answers, but I still have a few questions.

Justin took a different approach to his build than I want to, and while a lot of the info was helpful, I need some more specific ideas.

I am starting with a bone stock EFI 351. I mainly just want a torquey driver for pulling the boat/car trailer, and I am not too concerned with big HP #s, just want a nice flat low/midrange torque curve. The stock setup stopped dead @ around 4-4500 rpm, and that was fine by me.

Do the 3.85" Eagle cranks have any issues? The Eagles for the Pontiacs almost always need touch up on the finish machine work, even though they are advertised as drop in. Even if they do, the low $$$$ for them might make it worth it. Any other ideas on cranks?

What CR can I expect with .030" over 302 flattops and the 3.85" crank? I am assuming that my head CCs are somewhere in the realm of 64cc, as they are bone stock and have never been of the engine since new. Are dished 302 pistons easy/economical to come by? I do not want to run race gas in this thing....... Any idea what castings came stock on the 1990 351W? The engine is still in the truck, and there doesn't seem to be any way of IDing them externally.

At what performance point will I have problems with the speed density EEC IV setup with the stroker. Any known cams that are computer friendly? I would like to keep the stock EFI, but I am not ruling out a carbed setup, which I am much more familiar and comfortable with, and with my backround, is much easier for me to tailor to my mods.

Thanks!

 

If you can run a carb...run it....

If not, go MAF EFI. I don't think you'll do well with the SD.

I would not advise the stock heads, or close to stock heads on a 393.

I'd shy away from the flattop pistons. My 393 has 15cc dished pistons. You can play with this compression ratio calculator...http://www.turbofast.com.au/Tfcomp.html

I don't think you'll get the compression down enough with flattops.

Your heads are typical E7's, the better stock heads than previously but still not very good either way ya look at it.

 

Thanks for the reply!

My first thought with this truck was to convert it over to carb. I am not concerned with the emissions stuff. I'm gonna do some more research before deciding on this issue. After reading about your travails with efi, I am definitely leaning towards a carb! Your experience is exactly what I expect, btw.....

The CR does concern me, so dished pistons are easily available? I am looking for cast or hypers, I do not need or want to deal with forged on this engine. It lasted almost 200K with cast, and this will be a mild, relatively low rpm build.

You think the heads will be a problem for a mild build? My perspective my be a little skewed, but a 393 is pretty small compared to what I am familiar with (4.15" bore x 4.21" stroke = 462 ci...... would make a great truck motor with approx. 600 ft lbs of torque!), and some of the flow numbers I've seen indicate that the intakes should be adequate, and the exhausts could use a little cleanup.

Again, I am more concerned with low/midrange torque than overall HP on the truck. I've got other cars that go fast! With what little research I've done on aftermarket heads, it seems that the port volume on most is such that I will lose a lot of low rpm intake velocity, which is exactly what I don't want. Besides, I really don't want to spring for aftermarket heads for a beater truck.......

The one thing this truck has always been lacking is low end torque, hence the idea of stroking it....

 

Well, don't be totally convinced just based on my situation. I havn't really had any major problems with the EFI itself. The o2 sensor was a little tricky to work out, but I got it pretty easily. I really feel as though I got a bad apple on this particular project...there have been a lot of things that have gone wrong but there are valid reasons for some of the things that have occured. I was in a rush, not very able to spend a lot of time trying to figure it out. When you're in a rush, you'll make mistakes, esp when it's the first time doing it.

But I havn't had any real trouble with the EFI itself. I had to buy a bigger MAF meter, but I got it off ebay for $75 I think. The computer is just a mustang computer and I'm using the original wiring harness with the FMS conv kit. I got it for $400 used from another FTE'r and so far it's fine. She needs a little tuning but thats sorta to be expected with a 393. The dyno guy was great, I need to go back and have it adjusted again but he didn't see a problem when he had it, understandably why. Now that I have the idle working and the o2 sensor working, it's a little more obvious that idle tuning needs to be adjusted. I'm sure he won't charge me much and it'll be pretty painless.

So, just don't let my difficulties make you shy away from it...

You can get dished hyper pistons I believe. I can't think of why that would be a problem, I'd assume they're certainly desired from engine builders so they'd make them. I've never looked for any, CHP put them in. Only difference with mine is they're forged.

The hypers sound right for your engine.

If you feel the 351 doesn't have much low end torque, than drive the 302

I don't think the heads would be a problem per say, but it might be choking the engine a little much. Those E7s don't flow very well "out of the box". Unless you can open them up with bigger valves and a lot of porting, I'd say switch to another head. I am no professional engine builder by no means, but that is what I've come to feel is a good move based on the recent info I've picked up/studied.

I got guys saying to me that the GT-40Ys are way too small.

Aluminum heads will also help keep detonation down, and lighten about 50 lbs off the front of the rig. At 10-10.5:1 compression you'd probably need 93 octane. I'd probably back that down to 9-9.5:1 (don't go with the thicker gaskets unless you are able to keep the right quench area). Use the dish of the piston to bring the compression down or have a shop open up the chamber size, most likely an option. Play with that little compression calculator.

I duno everything but to me you aughta get some decent alumium heads and get a little more air going through that engine. You'll pick up more hp and torque, a 393 will give you pleanty of it. My motor stinks right now but I got 330rwft-lbs at 2300 rpm. I'll see that tq shoot up to about 430-450rw when I swap the heads to AFR185s and bigger intake and cam.

 

Thanks for the response!

The advantage I have (I think!) is that I am starting with a complete and operating OEM EFI setup instead of cobbling one together after the fact. I'm still leaning towards a carb, but if I can get the EFI working with the 393, then I'm gonna use it. My mind was spinning reading page after page of the problems you're having with yours, which is exactly what I imagine my experiences will be.

I know what you mean about the 302..... It's a great engine in a lighter vehicle, but it's lack of low end torque is the reason that I had a 300 I6 in the F-150 I had before this truck! If I had something else to drive on a daily basis when I bought this truck, I would have gotten a 460 for it's prodigous torque curve.... I just didn't want to feed it the 99% of the time I wasn't towing. This F-250 was my daily driver for 12 years. If it wasn't such a PIA to swap a big block into this truck, now that it's a part timer, that's exactly the engine I'd be putting in, but the different bellhousing pattern makes it just enough of a pain to prevent me from even considering it. The trans is fine on the truck and I don't want to get that far into it. The 351 is fine for just driving around, but really lacks low end grunt with a heavy trailer on it. Fortunately, I have the granny 1st gear to get it going.

I am way too familiar with the evils of high CR on the street, which is why I am concerned about it for this truck. I went for cubic inches and pump gas friendly 9.5:1 on my GTO engine, and I am very pleased with the results. It was easy on that engine, as mid '70s, low CR 400 heads (96cc after cleanup) were perfect on the .030" over, 0 decked 455. No detonation issues, and the car is an animal on 93 octane.

I'd like to keep it right around or even a little less than 9:1, and I agree completely about maintaining quench. IMHO, I am far better off with a little more CR than I am moving the piston down the hole or go with a thick gasket. A buddy of mine is learning this the hard way, after cutting a few thousandths off the top of his pistons to reduce the CR from over 12:1 on his 462. That's why I asked about the dished pistons. I'll have to run the setup through the compression calculator and figure out what size dish to get.

As for the heads, I agree that in some cases, more is better, but for a 5300 lb truck, I harbor no illusions of 6000 rpm shift points. Low-mid rpm flow is more important to me as the main reason I want a stroker is for trailer pulling. A torque peak right about 2500-3000 is perfect, as that puts me right at highway speeds.

Aftermarket heads are not out of the question, but unless I can't get acceptable performance or CR out of the stockers, I am probably not going to get into them. If I can't get the CR to an acceptable level, I might just rebuild it as a 351, lack of torque notwithstanding.


I am still open to suggestions......

 

Well, you'll have to do more research on what those heads are going to do for ya with 393 cubic inches to feed.

Just because the engine would spin to 5500-6000 rpms, doesn't mean it's effective power is that high. A 351 make's its torque peak around 3000-3500 if I remember correctly. On a 393 with the same heads, that peak would be moved down...which may sound like what you want...but consider the whole scheme of things.

Smaller ports and such dont always optimize torque. These 393's are capable of a very wide powerband, where most of your RPMs have 400+ tq...say at 1800-5000 you're above 380tq, but it peaks at 430tq around 4000 rpm. That'll be ok...you'll have PLEANTY of torque down low, even if your peak isn't that low in RPM. It's usually a very flat torque curve, so the peak isn't so important. See what I mean?

Think about that a little bit, but I think thats about as much advice as I'm able to give about what heads you should use.

 

Thanks for the advice, I've got a lot to digest.........

 

Well, here's some more to think about:

https://www.ford-trucks.com/forums/s...d.php?t=318691

I've been thinking about this for the last several hours, due to your concerns about high compression. I finally had to go looking for this thread that I remembered reading some time ago.

 

Thanks Tiger Dan......... My brain hurts......

 

Mine does that...that's why I don't use it anymore!

 

http://cgi.ebay.com/ebaymotors/SB-Ford-Aluminum-Heads-289-302-347-351-Racing-Complete_W0QQcmdZViewItemQQcategoryZ33617QQitemZ80 02676899QQrdZ1

Any comments on these ones? The price seems right, and would work great with the 28cc KBs......... I had budgeted around $500 to rebuild and port the stock heads.

They should flow pretty well too!


Oh, and I am considering going with a 408........ Not a heck of a lot more $$, for a few more cubes and better rod/stroke ratio...... If I am going to blow the budget, why not go all out? You guys are as bad as the Pontiac guys! My wife is gonna hate you guys too!

 

Still doesn't work...... Item number is: 8002676899

I am considering this rotating assembly:

http://www.cnc-motorsports.com/product.asp?ProdID=9309&CtgID=9052