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Discussion Starter #1
So I finally got my never ending oil leak solved, was rear main seal. My mechanic told me something interesting yesterday when I picked it up. He thinks I have a 428 block, not a 390.

Ok, I know the blocks look the same on the outside, but he had to use a rear main seal for a 428 and mains for a 428, the 390 parts he ordered didn't fit.

So, hmm I bought the engine 90% built by someone else. Is there any way to really know if it's a 428 or 390? I have pics of all sides of the block, all the numbers etc...

Thanks fellas.
1964 Galaxie with a 390 er maybe a 428 ?
 

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It their a weight on the flex-plate/flywheel 428's are externally balanced so the flywheel will have a balance counterweight on it. 390 and 352 are internally balanced
And I believe that the crank journals are the same dia so the seal and mains would be the same for 390 and 428
 

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Crank numbers (IU,IUB,IUA), or measuring the stroke (3.98), and bore size (4.13) is the only way to determine if ya have a 428.
 

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Crank numbers (IU,IUB,IUA), or measuring the stroke (3.98), and bore size (4.13) is the only way to determine if ya have a 428.
True on a non running motor pulled out. But the 428 was the only externally balanced FE so on an engine that is running and installed if it dose not have has a counter weight on the flex plate or flywheel its 99% sure it not a 428
 

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Bearings and seal are definately the same for 390 or 428. And most all other FE's for that matter. Someone was mixed up on what their parts were.
 

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Water jacket on passenger side if you knock it out it will have raised letters inside that says (428). That block came out of a 7 liter car and heads would be 6090-G. 390 will not have that. There are 6 different blocks or more for a 428 and all are easy to id.
 

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COUNTERWEIGHT :) Screw the block plug removal or dropping the trans to look at the back of the block, just check the Flyweel or flex plate or measure the stroke.
That can be said to see the difer between a 390 and a 428, however that cannot be judged to see the difer between what kind of 428 one has.
 

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Discussion Starter #9
I don't think the flexplate has counterweight. It look normal to me with noting special on it. I've only seen "normal" flexplates in my experience. What would the counterweight look like?

And I got a wood dowel to measure the stroke today.
Thanks guys.
 

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If a peek is avail this is a copy and paste from a different site that confirms the Id no.'s above: 352, 360, 390, 427 are internally balanced, 410, 428 are externally balanced.

The SCJ engine had heavy LeMans rods that required extra weight to be added at the front and back of the crankshaft. This crankshaft is stamped 1UA.

410, 428, 428CJ cranks are stamped 1U

390's are stamped 2F
Also if the heads are stock oem to YOUR block, the no. for CJ428 heads are C8OE-N Between the 2 center spark plugs, Also from a post elsewhere on this site is:


To identify a 410 or 428 Fe, you can look for the external balance weight on the flywheel. With the TDC on the damper at the six o'clock position, then the weight on the flywheel should be at the bottom of the flywheel or also at the six o'clock position. The only hitch to this is if the engine has been balanced internally
 

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Reason for my response, "The only hitch to this is if the engine has been balanced internally". Happens a lot more these days.
And get a different mechanic for any more major repairs/upgrades. Preferably one with more FE experience.
 

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Reason for my response, "The only hitch to this is if the engine has been balanced internally". Happens a lot more these days.
And get a different mechanic for any more major repairs/upgrades. Preferably one with more FE experience.
THESE DAY'S.....

His motor is ageless to us so far... Not knowing when it was built maybe it' snot a these day's motor. I still think the dowel test is the best thing.

I totally agree that he needs a mechanic with a higher knowledge of the FE series.

The 410 Casting info is also the same but Generally a 410 owner will Retain the Mercury Valve Covers rather than go with the Ford style, and the 410 was only made in 66 and 67 so any C8 or C5 castings cannot be a 410 engine...

Stroke Stroke Stroke....
 

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428's used more than one configuration of externally balanced flex plates. Early TBird 428's used one that did not use the small weight as shown above? They used one that had a thicker (about 1/4") flex plate with large 1" balance holes drilled in them.

Scott...
 
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