LT1-LT4 Modifications 1993-97 Gen II Small Block V8

Lt1 Vs 4.3l

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Old Jan 7, 2008 | 10:18 PM
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Default Lt1 Vs 4.3l

Is there a way to tell the diffrence between a 4.3L and a real LT1? I am looking at a motor but its not in the car so I cant tell and its complete from a B body non wagon so it could be either of the two.
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Old Jan 7, 2008 | 10:31 PM
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look for a 327 marked on either bank of cylinders in the frost plug area i dont remember what side its on usually or look for the entire casting number on the right rear of the engine kind of where the oil pressure sender would go and the last three letters of the casting number is 327
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Old Jan 8, 2008 | 10:42 AM
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count the exhaust ports or spark plugs. the lt1 should have 8. the 4.3 should have 6
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Old Jan 8, 2008 | 10:50 AM
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Originally Posted by TXFORMULA
count the exhaust ports or spark plugs. the lt1 should have 8. the 4.3 should have 6
that would be the most obvious
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Old Jan 8, 2008 | 10:58 AM
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Originally Posted by GreatWhiteZ28
that would be the most obvious
No, the 4.3L in the caprice is a v8 as well. Not the 4.3L v6 from the s-series trucks.

If you have access to the RPO code sheet on the car you can also look at that. The 5.7L will obviously be an LT1 while the 4.3L will be L99.
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Old Jan 8, 2008 | 11:05 AM
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is the car still around? you can also check by the VIN. The W indicates it to be a L99. G is a LT1.
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Old Jan 8, 2008 | 05:51 PM
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Behind the drivers side head it will say 5700 or 4300, I think you can figure it out from there.

The L99 block does have 327 on it in a few places. On the side of the block where it is cast in raised numbers on the LT1 the L99 says 588, but like on the front of the block where 327 is, the L99 says 327 there and the LT1 block has 588 on the front too just on the passenger side front. That all confusing enough?

That is why I point people too the pad behind the drivers side head.
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Old Jan 8, 2008 | 05:58 PM
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Originally Posted by Ntimid8r7
is the car still around? you can also check by the VIN. The W indicates it to be a L99. G is a LT1.

P is LT1.
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Old Jan 8, 2008 | 06:19 PM
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Originally Posted by 96capricemgr
Behind the drivers side head it will say 5700 or 4300, I think you can figure it out from there.

The L99 block does have 327 on it in a few places. On the side of the block where it is cast in raised numbers on the LT1 the L99 says 588, but like on the front of the block where 327 is, the L99 says 327 there and the LT1 block has 588 on the front too just on the passenger side front. That all confusing enough?

That is why I point people too the pad behind the drivers side head.
GM! those goofy bastards!! thanks for the education
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Old Jan 8, 2008 | 06:55 PM
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Originally Posted by buffman
P is LT1.
thats what I meant..... lol
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Old Jan 8, 2008 | 07:19 PM
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Yep found out it is a 4.3L and its definatly a v8 lol. Everybody thought I was crazy for saying that I didnt want the motor because it was a 4.3. They told me to count the sparkplugs until i printed off the paper showing that gm made a 265 lt1 thing.
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Old Jan 8, 2008 | 07:33 PM
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On the b-body there is a TSB allowing for the defeat of the AIR pump.
I had bought my car used a 50K miles, I brought it back to the dealer that sold it new for that TSB work and the service writer swore up and down someone had put a LT1 in the car because the 4.3L was a V6. Didn't help that GM used VIN "W" same as the actual V6s.
Took like 10 minutes and a trip back into the shop too convince the guy it was a 4.3L V8 from GM and like I said this was the dealer that sold it new.
Little over 5 years ago the L99 came out at 110K miles, today the car has like twice at the wheels what the L99 had flywheel, guessing the original owner would not believe the transformation.

The intake on my motor is the original from the L99. If you get L99s cheap enough there is a lot off goodies to use as spare parts. The blocks, heads,cranks,pistons, rods are all less desirable but everything else is the same as LT1s, even got the same cam as the b-body LT1.

The rods are 5.940 from memory and often pawned off on unsuspecting folks at swap meets as 6".
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