HELLO to all, hope you can help; Ive got a 390 punched 30 over, the cyl,s are in good shape can still see crosshatching. Id like to clean it up & stroke it. my question is with everything being the same except stroke&compression hight between a 410-390 can a 428 crank be used to stroke the 390 to 410 ..390 comp. ht. is 1.775. the 410&428 are 1.674 can the 390 piston stand having 0.101 taken off the top and work ? I under stand the flywheel & damper must be used from 428 for balance reasons would the whole assy. need a rebalance?

 

You don't have to take that much off as long as you dont mind more C/R You only have to take .085 off the top of those pistons.Another option is bore it to 4.13 and get 428/410 pistons.That is if you have a 73-76 block or have a good block to go that far.Its only .080 from factory 4.05"

 

The harmonic balancers on FE engines are interchangeable as far as balance. They are zero balance.

 

Well it seems ive opened a large can of worms,gonna have to do some serious measurements to figure CR & deck clearence. Dont know about cyl. thickness no #s anywhere on the block, might be a service block or thin wall casting; be afraid to punch it to far... The top end is a mystery also casting #s C4AE-6090-G THE PORTS ARE HUGE & INTAKE MATCHES THEM DEAD ON.single quad. THANKS FOR YOUR HELP GUYS! OH YEAH according to Steve Christ 410-428 cranks are externally balanced....

 

You are absolutely correct. 410 and 428 engines are externally balanced but, don't use the dampener at the front of the engine to achieve balance. They use the flexplate or flywheel with the extra weight on them to achieve the external balance.

 

Richard, of course you should ! the 410/428 cranks offer a nice increase in torque- between 80-100 lbs-ft of it. Do you have a 3.98 stroke crank now ? Aftermarket cranks are available with up to a 4.250 stroke, so more is there if you want it. It all depends on how much you can spend to get the results you want. Yes, the 410/428 cranks are extenal balance from the factor. No, you DO NOT need the 410/428 flywheel. It would be better to have the whole rotating assembly rebalanced. You machinist will have no trouble using a standard 390 wheel. Yeah, you can cut .101 off from the tops of many pistons. I cut my L2291s and added deeper valve notchs to build my 421 ( 390, 060 over, 410 crank ). But flattops with the longer stroke gave my combination over 11 to compression. Not to good for regular fuel. There are plenty of piston choices that are already 1.66 or so high.....need a suggestion ? DF

 

What is the cost of having a 410 or 428 balanced without using the correct flywheel verses using the correct one? Just curious since it would appear to be more work for the machine shop to perform balance work using the incorrect parts.

 

unless one is using all stock replacement parts from the ford dealer, the new parts might weigh in heavier or lighter and be 'not correct' parts. To balance a wheel for the 410/428, ford cast an extra lump of iron on part of the rim of the flywheel. To duplicate this effect it takes you all of 30 seconds with a drill press to remove some weight on the rim of a neutral balance wheel. You have to spin the flywheel in a balance machine to know where to drill, however. If you're having the rotating assembly balanced ( as you should with any non-stock assembly ) the shop is going to do this anyway, so there is no more cost than any other balance job. If you are using an auto tranny, you can weld the needed counter weight onto a normal 390 flexplate. thats how ford makes 'em. DF

 

Didn't we all used to talk about how you had to buy a 428 flywheel DF? Your solution is such a basic fix I can't believe somebody didn't think of it a long time ago. Makes me feel kinda dumb. Its making a 428 crank look much sweeter for my next build!

 

Whoa-Whoa the ole brains gonna need a balance done. Is the bolt patern on 390&428 flywheel &crank the same ??? Also whats the limit on the over bore ??? I dont mind spending some hard earned $$$ but i do want it to last longer than it takes to hand it over... I really appreciate all the responses and see its gonna take a little bit longer & more $$$ than anticipated guess its part of the territory ... THANKS!!!!

 

Richard, yes the bolt pattern on the end of the crank is the same on all of the FEs, and the FTs as well. For pistons for a 410 clone, you might try silvolite 1139s, or fedmogul 381Ps both of whigh are 1.66 tall, and will fit nicely with 6.488 (normal 390 ) rods and a 3.98 crank ( from a 410 or 428 ). DF

 

dinosaurfan, thanks for the piston #s & flywheel info. Now to figure out which block ive got , after scrapeing every machined pad i could find i came up with 2 different groups of #s first was OE11J , the other was 17521 . Do these make any sense ? im still trying to figure out how far i can go on the bore & still have a safe wall thickness..

 

Well depends on the block,The 73-76 block are supposed to be the replacement blocks for the the 428 CJ. Due to the fact they had to offer a over the counter block to service them for 10yrs.(I.E. 1980) But in any case it is a good idea to have them sonic checked at your local machine shop,just to make sure there is enough material left to handle things.