Determining Engine Components

[mitsocruiser]

I,m getting ready build my motor and turbo finally .The problem is I,m a victim of second hand tuning . I got the car a few years back and the guy I bought it off of had just put a brand new crate motor in it .Here lies the problem I don,t know what type of crate motor it was I was just getting into DSM so I didn't bother to ask anything else about it . So is there anyway to tell what internals it has besides tearing the motor apart. I don,t want to build the motor if it is already built and I hate to break a great motor open.I know it,s not a stock 420A just from performance and sound after getting into DSM and hanging out with some other 420A guys we all agree she aint stock.So any suggestion would be greatly appreciated!!

 

[totaleclipse_05]

Take the oil pan off and see if you can see upgraded rods/pistons from there. If not, it's probably just a stock engine.

 

[Rob10_99]

Be a little more descriptive in your titles please,
First off, you can pull the plugs and see the pistons, rods you will have to pull the oil pan, or possibly using a scope fish it in there and look for arp bolts and such.
Is the block clean, look like its been machined in the last few years? You should be able to tell from surface rust or built up grease ect.
Not sure on the 420a if you can see the headgasket like on the 4g's, but you should be able to see a tab to figure out what its made from. Plus you can pull the valve cover to see if its cammed. Write everything down.

 

[mitsocruiser]

Thanks for the help ,the motor still looks brand new I have had the car for about 3 or 4 years . I will try to get the time to pull the oil pan and take a look this weekend . I,m also going to do a compression test this weekend as well. If the engine has been modified would that change the compression test # in any way? And again thanks for the help

 

[VelocitàPaola]

Thanks for the help ,the motor still looks brand new I have had the car for about 3 or 4 years . I will try to get the time to pull the oil pan and take a look this weekend . I,m also going to do a compression test this weekend as well. If the engine has been modified would that change the compression test # in any way? And again thanks for the help

Any pistons with a CR different than stock will make for different compression test results. There are, however, a few other variables that can influence a compression test, such as ring wear, ring type, etc., so research the topic a little.

I believe most forged pistons have engraved part numbers and possibly logos on their undersides, whereas cast pistons should the stock part numbers. Aftermarket rods are easy to tell apart from stock rods just by looking at the shape, but they should also have numbers on them.

Do a Google Images search for stock and aftermarket pistons and rods. At the very least, you're going to need to remove the oil pan. Bearings and gaskets/seals will be almost impossible to identify, unless you tear down the whole engine. Even then, there are no guarantees...

 

[mitsocruiser]

Thanks for all the advise guys I think I'll start with the compression test and see where it's at. If good I might just go ahead and throw 6psi of boost on it for now . I don't see any sense of taking a good motor apart untill I have to.

 

[tkelly27]

Pulling off the oil pan is not a big deal and will tell you a lot.

That boost level is safe, but assume you've got a rebuilt stock engine. If you start adding boost and throw a rod, you won't even be able to reuse your block.

 

[mitsocruiser]

I just find a whole motor and tranny I'm picking up . I'll build that motor so my daily driver isn't down . Thanks for all the help though guys

 

[Shadow98]

JE's have have the mark on the bottom of the pistons which you'll be able to see if you remobe the oil pan...