Hi! I have a Ford FE 390 with a broken crankshaft and I could get a new 428 crank with bearings. What should I do with the adittional parts: pistons, rods. Which can I use from my 390 FE? I know that I have to have internally balanced the 428 crank. Can I use the 390's rods with new 410 Mercury pistons? Can I just cut some material from the top of the 390's pistons to use with the 428 crankshaft? Thanks!
You can use the 390 rods with the 410 pistons on the 428 crank-that's what Mercury did in '66-'67 to create the 410. The 390-410-427-428 rod sizes are all the same. Not sure if you can safely remove .100 from the 390 pistons, but I would not do it. Bob
The difference in strokes is .200", 3.78 (390/406/427) vs 3.98 (410/428). So halve that is .100, which would have to be removed from the 390 pistons to work with the longer 428 stroke. Not sure about the compression-I'd have to go through my "FE" stuff to answer that accurately. I'm sure someone here can. Bob
It is a very common swap,Ross, and probably others,make pistons.I helped do the swap in a Cobra kit car and a 74 Ford truck,great results. ROY.
Do you mean I can make good pistons from the 390's? Can you tell me how to make that step by step? It would be a great help!
Some people use 390 truck pistons that are .080 down in the hole from the factory to start with. You could use a 410 or 428 front balancer & flywheel too instead of internally balancing it. The mallory metal they use to internally balance the crank is god awful expensive. http://www.network54.com/Forum/74182/ good info here
You can get a set of 391 Truck pistons on E-pay for $60 to $100. You can resell the pins (heavy wall) to some one building a blower motor and recoup your money. Since the 391 was a 7.5:1 motor the pistons sat about 0.080 down in the hole as mentioned above. Next, If you go this route, make sure to mock up the engine, number each piston to its hole, score the pistons to the deck top. Find a machinist with a lath, have them milled to zero deck or 0.004 in the hole for each piston (not all cut the same because blocks are NOT square). Obviously you need to check how much the piston is above deck on your finish decked block. Usually it will be about .020...more or less to a zero deck. If you bore your block, make sure the pistons pretty tight in the bore, cast pistons like about .002/.003 to minimize piston "rock". Some guys like the pistons .010 out-of-the-hole, but if your more cautious, .005 is good. Ten thou out will keep the piston tops nice 'n clean. Also with the pistons this far up, you've GOT TO check your valve-to-piston clearance...it is NOT optional. There are several "advantages" to this set-up in a street 390. Lighter rods and (because they're milled) pistons, the rings slightly higher in the bore, less prone to detonation. Trying to zero deck an FE by decking the block an excessive amount will make an already difficult-to-install intake manifold a REAL nightmare! Be sure to use good file-fit rings and good valve guides in the heads, 'cause if oil gets in the chambers...it'll "rattle". I have heard of guys building this combination and it will run great to 5500 RPM and about 350 +/- honest HP and 475+ FT torque starting at about 1800 RPM! Big power, 14 MPG in a truck with 3.50 gears and an AVS carb. and all for less then you would expect if you do some work yourself.
Hello, I see you have the expertise to take a 390 to a 410 cu. I have a 390 GT 4v motor. I have the 410 crank and flywheel. So besides buying the 410 pistons, is there anything else I need to do with the 390? Thank you
I believe a 390 is zero balance, what about the 428, aren't they externally balanced. Might have to be rebalanced?
Re-balancing is a must. Generally speaking the 390 used lighter rods to achieve the internal (zero) balance. When going to a 410/428 crank with 390 rods, the balance will be off, and require a re-balance.
390 and 410 rods are the same. You need the 410-428 balancer and flywheel. 410-428’s are external balanced and 390’s internal balanced. Some Ford trucks used 410 pistons, but 391’s aren’t the ones, too heavy. The 410 pistons were used in low compression pick ups. Good luck in finding any. Ross and JP make 410 pistons.
Properly built , would a 390 built correctly not give you the same thrill for a lot less money? Sorry just a stupid question. Lippy
FE balancers are neutral balance CJ motors used a front balance weight but is was not the balancer all used a weight on the flywheel. 390 truck used 410 pistons 1.66 compression height. There are 4.250 stroker kits out there in the $1600-$2000 range for not much more than 428 crank new pistons rings and bearings.
The 428 front balancers were also neutral. The 428 SCJ did use a special "hatchet" front spacer because of the heavier LeMans cap screw rods. The 428 flywheels and flex plates had the added external weights.
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