Identifying a stroked motor externally...
- Thread starter Cuda416
- Start date
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Icetech
Well-Known Member
pull the plugs and turn the motor to tdc.. mark a rod in the spark plug hole, turn the motor to bottom dead and slide the rod to the bottom and mark it.. measure, should let you know if it's stock or not. Stock i think is 3.331, stroked should be 4" even with margin of error you will see if it is. I would also take a $25 amazon bore scope and check the cyls. Could also pull the oil pan drain plug run the scope up and see the rods/crank..
Cuda416
Well-Known Member
That's kind of what I was thinking but I'm still curious if there's some other ways. Honestly I probably over thought this and you're exactly spot on.
Icetech
Well-Known Member
yeah.. if the piston goes down more than 3.31" then it's stroked
if you get a scope get the one with side cameras on it also..
Dartswinger70
Well-Known Member
Borescope? They have a 40 some dollar one at Lowes hooks into your phone...but you'd have to have an eye for how many inches down the piston is etc. Id imagine.
No reason not to buy a bore scope (seen them for $15/20
on Amazon) if you ever are going to buy a used engine or try
to diagnose a engine issue.
on Amazon) if you ever are going to buy a used engine or try
to diagnose a engine issue.
Dartswinger70
Well-Known Member
Yup wife's 6 cyl mustang is burning oil in one cylinder I think I'm going to tear it down but want to go in knowing if its a valve guide seal or head gasket etc. I'll bore scope it first 
You can use the rod method, but just know it won't be accurate since the spark plug is at an angle. All you'll be able to tell is if the stroke is greater than 3.31" as previously mentioned.
Cuda416
Well-Known Member
That's a valid point and still satisfies most of the question of "Is it a stroked motor". I supposed the bore scope might reveal a piston part number as well which would be the best indicator I think. Wouldn't be much of a chore to put a rod through the spark plug hole of an unmounted head and get a "general" idea how far down the hole the rod tip ends up opposite the spark plug hole. Add that to the actual measurement and that's about as close as you might get.
Icetech
Well-Known Member
no.. a scope would reveal a cracked piston.. or burned valves... unless you have heard it run?
Cuda416
Well-Known Member
I understand that but the question is about identifying a stroked engine . Some pistons have a part number on top which would indicate the actual stroke in addition to the other benefits of using a scope
I wouldn't trust any seller that couldn't verify it. An assembled motor is what the block says it is until the seller proves it.
Cuda416
Well-Known Member
Absolutely agree.
I'm not looking at purchasing this car, it just got thinking about the topic so this is just a minor academic question.
mopowers
Well-Known Member
A lot of times you can tell a stroker piston from a stock stroke piston. If it's a street motor, they should have a distinctly shaped dish and look completely different from a stock-style piston.
Yup. I'd be worried if there was no part number.
mopowers
Well-Known Member
Do some stroker pistons have part numbers stamped on top? I know the autotecs, icons, and KBs I've used didn't. They sure looked different than a stocker though.
Then he should fall back on the rod measurement.
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