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hey all i just got a caprice 94. the vin number and everything shows it's a 4.3L .. but the previous owner said the previous owner before him did a 5.7L swap. where can i find the vin or block serial or anything to tell if that's a 5.7L engine?
 

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Easy to tell do you have 6 spark plugs (4.3 L) or 8 spark plugs (5.7).
 

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Actually, the LT1 and L99 engines are both 8 cylinders so counting spark plugs is not going to help.

I have never owned a L99 engine. From what I have read, the LT1 and L99 look the same from the outside so I have no clue how you could tell the difference by just looking at the engine.

L99 cars came with single exhaust. If the car still has a single exhaust, I'd start questioning whether you have an LT1. Seems unlikely someone would go to the trouble of doing the engine swap but stick with the single exhaust.
 

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Got my factory service manual out. It says the engine is "stamped" with an engine identification number. It is 8 digits long. Will start with a letter (identifies assembly plant). Last three digits are the engine code. Unfortunately, the book doesn't say where the number is located on the block. Internet rumor has it that the code will be here: "There is a machined pad on the passenger side deck surface that is not covered by the head. However, it is obscured by the alternator."

FSM also says: "Stick-on-labels attached to the engine indicate the engine unit number and code. These labels also contain bar codes for in-plant identification." Unfortunately, no mention where to look for these labels.

As to whether you have the engine that came with the car, that can be figured out. All engines and trannys are stamped with a VIN derivative number. The number is 9 digits long. The VIN derivative is the 3rd digit of the VIN plus the last 8 digits of the VIN. It will be in one of two spots. Primary spot is above the oil filter. Can be seen here (I couldn't post actual link since this site won't let newbies like me post links):
shbox.com/1/block_vin.jpg

If not there, it is supposed to be stamped horizontally on the block above the oil pan, centered above the deep part of the pan.

The way I read the FSM, the VIN derivative will be in one of these spots, not both.
 

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let me solve this riddle.
1. get in your car.
2. turn it on
3. get on a long straight road and mash it.

if your head hits the seat you have an lt1. they have 80 more hp and over 100 more fp of torque.


seriously, if its fast, its an lt1. if its slow, its an l99.
lt1-260hp
l99-180hp
 

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Look on the back of the motor where it bolts to the tranny, on the driver side, on top, you will either see 57 (5.7L) or 43 (4.3L).

There's a lot involved with a swap from a 4.3 to a 5.7.
 

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let me solve this riddle.
1. get in your car.
2. turn it on
3. get on a long straight road and mash it.

if your head hits the seat you have an lt1. they have 80 more hp and over 100 more fp of torque.


seriously, if its fast, its an lt1. if its slow, its an l99.
lt1-260hp
l99-180hp
L-99 4.3 V8 is rated at 200 hp.
 

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I see that I stand corrected to my above post. When I saw the 4.3 engine in the thread all I knew of was the Chevrolet V-6. So that is why I said check the spark plug count. I was not aware until tonight that the L99 engine was the 4.3L or 262 cid V-8. Well I am never to old to learn, thanks for the information.
 

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when i blew the first motor i remember worrying about this....there is 327 stamped on the block right below the cylinder head i forget what side i think PASS.

i forget the # for the L99 block

so it ain't too hard to figure out, but the dude that said if you have single exhaust is right for the dead give away if i recall...:confused:

-ALF out....
 

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when i blew the first motor i remember worrying about this....there is 327 stamped on the block right below the cylinder head i forget what side i think PASS.

i forget the # for the L99 block

so it ain't too hard to figure out, but the dude that said if you have single exhaust is right for the dead give away if i recall...:confused:

-ALF out....
That's a 350 ci block.
 

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Yes it is.

However, the number 327 is cast into all 5.7 liter LT1's.

It has nothing to do with the displacement.

It is the definitive way to tell an LT1 from an L99.

Fatvet is absolutely correct on this.

Stewart
Yes indeed it is. I was just agreeing with fatvet's post. L99's have "588" cast on the side of the block.
 

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One way could pop out a spark plug, insert wire and press on top of piston, when at tdc, then slowly turn over enine until the piston comes back up. measure the stroke, if it's any thing but 3.48" or 3.66" ('89-'95, "LT5", in "ZR1" Corvette 32-valve DOHC, 5.74" rod) you don't have a 350. on the front of the block there should be a flat plate like looking are with numbers stamped in. record these numbers and go to www.mortec.com
 

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If you look in just the right place the 327/588 can tell you BUT the L99 does have 327 cast into some places on i as well.

Really the markings behind the driver's side head are the most foolproof way of telling.

No rumor or I heard it somewhere or any of that, my car came with an L99 and has an LT1 at this time.
 

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Hi guys!

I am stipping my block appart right now cause im restoring it... well i*am 18 years old and im not done my mechanic class yet so im doing the best i can for now. There is a lot of things you wrote i dont understand. First to make the difference between a L99 and LT1 is simple is the car have the original VIN: 8th digit: P=5.7L 350LT1 W=4.3L That means if you pop the hood of a b body that have a 350 and the digit is a W, well you got screwed... if you wanted an original LT1.

Then the casted 327 in the block... what does it means exactly... thank god i have a 327 casted on each sides on the block between the oil pan and the heads... But like someone said, it is really casted in the block upper right over the flywheel GM 5.7 so that takes all my doughts away! There were a sticker too on the trans but with the years and the dirt, i couldn't read the code... probably the production number of the trans...

Another thing... CAN WE ONCE FOR ALL KNOW WHO SAYS RIGHT...! It is listed somewhere on the internet that the only LT1s with 4 Main Bolt (The Bolts that holds the caps of the crank) are the Corvette, Impala SS are 2 Main Bolts... Mines got 2 Main Bolt... so it makes sense... only MANY people said Impalas are 4 main bolts like corvette 'cause it's simply the same block exept its got more torque because of the weight

Thanks!
 

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Get over your attitude problems with the different packages or the folks who can help you wont waste their time on you.
You are getting caught up in the "magicl" of the Impala and that is where are lot of the bad info confusing you is coming from.

You paid a lot of extra money for a Caprice with base roadmaster seats and almost non-functional rear brakes. That is what made it an "Impala":rolleyes:

The Vette 4-bolt is not worthwhile, by the time the 2 bolt setup needs any help you should go to aftermarket maincaps anyway. It is the same exact block casting, just additional machining.

In all likelyhood by messing with the stock motor you will make it LESSER quality than original. It is not cheap to duplicate much less improve upon the stock shortblock.
 

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Hey everyone I bought a 95 caprice 9c1 with flowmaster dual exhaust the vin has a w in it I was trying to find out if the engine was swapped for a 5.7 the battery is a high performance one as well I can't see any numbers to tell if it's a 4.3 or. 5.7 can I take it to a shop and ask them to do it ??
 
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