Calling all FE gurus...
 

Ok ..new project beginning asap. I am building a 390. I need to get as much torque as possible . What machine work or mods can I do or parts can I add to achieve maximum torque from this engine? It will go in a half ton truck that is used for hauling wood,construction equipment, and recreational vehicles as well as trail driving. I believe the r/p gear ratio is 3.50 and it has a manual np435 transmission. The heads are stock D2's Thanks all.

Not much machine work needed....just a cam and intake and carb suited for the purpose.

If you are building from scratch, I have a set of Ford 390 heads that can be had for a deal. Also have steel 390 crank but the snout has been turned down for use in a 427. Also have Melling oil pump, steel flywheel and a few other items if interested.

Zimmy, do you mean 'steel 391 crank'?

Perry:

No. Actually it is a steel crank (Ford #3U) which is from a 1973-1976 390 Truck

It has 3.784" stroke.

Mr. Bassn:

What you are looking for is extreme low end torque. The truck engines in the FE line were superb heavy haulers in all forms. the biggest of them, the 391 has to be among the strongest engines evr put in a truck.

Torque in your engine is only usable at low rpms, say, from 1500 to 4000. The parts you put in that engine should be singularly chosen with the highest possible air velocity in the rpm range that you will use it. So, do not install drag racing parts in this engine, whatever anybody says. Stay with small valves and ports. The truck engines camw with valves in the small range: 1.95 intake and 1.55 exhaust. They guarantee that you can pull away with a heavy load in high gear from 20mph and 1500rpms without backfiring or hickups.

Use a long runner dual plane intake, such as the Edelbrock RPM, Weiand or Offy. The old GT-390 intake can be found at reasonable prices on E-bay as well as the 428CJ iron intake. Use a brand new small CFM Holley or Edelbrock. The Carter 625 is an outstanding carb as well. Stay away from double pumpers or carbs with a progressive secondary function.

Use a very conservative cam, no more than 210 to 218 at ,050 lift and with a lift no more than ,500" Stay with the stock valves and heads, they are a perfect match for your trucks´weight. If you can and want to go to the longer stroke of the 391 that is good too, but make sure you have the correct rods and pistons with it.

Install a set of RV headers with primary tube diameter of no more than 1 7/8 and a matching tube length for the weight.

If you are going to install new pistons, stay on the conservative side with compression, no more than 9 to 1 with a max of under 10.

Buy roller tip rockers if you can afford them. Use the best ignition that your money will buy.

You will be happy with that formula.

It's not been mentioned, but I always clean up and match the oil galleys/passages. It's cheap insurance.

Putting a 410 or 428 crank with it's 3.98" stroke in your 390 would be a big step up in the torque department. This would provide you with a 416 cubic inch combination if only bored 0.030" over. Also adding an older Edelbrock SP-2P intake manifold with its very small runners will also be step increase in the low end torque department. This manifold starts laying over at 4500 rpm so it would be perfect for your combination. I still see these manifolds floating around at various swap meets and are usually priced reasonable to cheap due to its limited rpm capability.

I've already ran this combination in a '65 3/4 ton pickup that was used for pulling a trailer and can attest to its low end grunt. The fuel mileage was also surprisingly much better than the 352 it replaced. The 3.98" stroke crank also likes less gearing with the above combination. Your 3.50 gears would work nicely. My effective rear ratio with gear splitter activated was 3.19:1 with the 4.10's in the back being very effective for takeoffs with heavy loads.

Your small valve, small port heads are already suited for your intended use and the ports match the SP-2P intake in their stock form.

If money was no object, then I'd really consider the SCAT 4.25" stroke crank in the 390 which would net you 445 cubes with the same 0.030" overbore. Then the stock intake manifolds could be used for the same effective runner volume as the SP-2P on the smaller engine with the still monstrous increase in low end torque. I still like aluminum intakes over any cast iron version though for all the obvious back breaking reasons.

Punch it over, stroke it out, Balance and blueprint the engine.

These engines were designed for trucks. Putting one in a car was an afterthought.

These guys are right. I just added the balance, makes a huge difference.

Thanks guys,I do not have much money ..so aftermarket is out . I have a stock 4bbl intake and I am lacking the crank and rods. I need to find one cheap. Scat is definitely out. I am running all the original equipment as far as the heads,exhaust manifolds,4bbl intake. I added a pertronix unit and blaster coil.I am using a Holley 670 cfm carb. I have a melling hv oil pump and cloyes true double rolller timing chain.And I have the crane 901 cam. All I need is a crank and rods.crank and rods

Zimmy, the 3U crank is cast iron. It's pretty much the same as the 2U also. Look and see if there is a parting line running down the crank. If you see it......it's cast iron. All in all a very good crank.

Mr. B

Don't be in the least bit afraid of the cast iron crank. Surprisingly, many super stock drag racers use the cast crank, because is is lighter than the steel version.

You should be able to pick up a reground crank and a set of stock 390 rods at any reliable engine rebuilder for a pretty reasonable price.

Keep in mind, you do not need hot rod parts at all.

The things you need to do relate to reliability. Oiling and engine balance being the two top priorities, with cooling system a very close third. For cooling, go to your local radiator shop and specify the Ford-made "Super Cooler" radiator for your year of truck. They're a little spendy, but well worth it when you're going slow and putting a big load on the engine. I did it with my '71 Ford F250 4x4 and never regretted it.

Be aware too, a half ton truck is not meant for super heavy loads. You'll eventually eat wheel bearings even if the rest of the rear end lasts. The brakes are also not meant for heavy weight loads.

Al

FFR428:

You are right - my mistake it is cast iron. Was a very good crank.

Mr. B: The crank is available for a fair price (probably pretty cheap -actually) bu again, the snout was turned for a 427. I also have the4 Ford C6AE-C rods for it. They are 6.488" long. Very good condition. The pistons are 4.26" bore sdo they would be too large for you. Let me know if you are interested in either thte crank or the rods.

zimmy, thanks but I better stick with the 390 crank and rods. I am not hauling too heavy of loads. Normal stuff like my camping trailer 16ft. and my utility trailer with about 1 cord of wood on it...stuff like that. I already got larger rear brakes and all new bearings all the way around,new ujoints and just about everything in the drivetrain has been replaced. I had the transmission and tcase gone thru so the engine is the last thing. I found a 4 row radiator for it. It bolte right in. The only harsh drives are the ones up the grades in the mountains .Thanks all you guys for your help.

Bore it .075" over and call it a 406, and stroke it.20"call it a 428. pick parts that all have the same sweet spot at or near the same RPM,Cam ,Intake, heads, and carb..Miss match and it won't be all that at any RPM.