Building Chevy LT1 engines
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GM Powertrain accomplished all of this by reverse cooling the engine so they could bump the compression ratio up to 10.5 to 1, tweaking the airflow in and out of the engine, and using sophisticated electronic controls for both fuel and ignition. This combination gave the LT1 300 hp in 1992 and ultimately led to the 1996 LT4 that used better heads, more cam timing, roller rockers and sequential fuel injection to make 330 hp.<br><br> | GM Powertrain accomplished all of this by reverse cooling the engine so they could bump the compression ratio up to 10.5 to 1, tweaking the airflow in and out of the engine, and using sophisticated electronic controls for both fuel and ignition. This combination gave the LT1 300 hp in 1992 and ultimately led to the 1996 LT4 that used better heads, more cam timing, roller rockers and sequential fuel injection to make 330 hp.<br><br> | ||
Although the LT1 was only around for five years, there were two-bolt and four-bolt blocks, aluminum and cast iron heads, regular and H.O. cams that came with long and short dowels, and three different front covers. There was also the "Baby LT1," the 265 cid version that was the standard engine in the Caprice from 1994-‘96. With all that in mind, let’s take a look at this family of engines and see what goes where.<br><br> | Although the LT1 was only around for five years, there were two-bolt and four-bolt blocks, aluminum and cast iron heads, regular and H.O. cams that came with long and short dowels, and three different front covers. There was also the "Baby LT1," the 265 cid version that was the standard engine in the Caprice from 1994-‘96. With all that in mind, let’s take a look at this family of engines and see what goes where.<br><br> | ||
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'''BLOCKS'''<br> | '''BLOCKS'''<br> | ||
| + | [[File:Lt1 block.gif|right]] | ||
'''350''' – There are two blocks, one with two-bolt mains and one with four-bolt mains. They both have the same 10125327 casting number, so there’s no sure way to know which one you have until you get the pan off. However, if it came out of a Corvette, it should be a four-bolt block, and if it came out of anything else, it was supposed to be a two-bolt. GM used the two-bolt block for everything but the Corvette because it had plenty of strength and it weighed a little bit less.<br><br> | '''350''' – There are two blocks, one with two-bolt mains and one with four-bolt mains. They both have the same 10125327 casting number, so there’s no sure way to know which one you have until you get the pan off. However, if it came out of a Corvette, it should be a four-bolt block, and if it came out of anything else, it was supposed to be a two-bolt. GM used the two-bolt block for everything but the Corvette because it had plenty of strength and it weighed a little bit less.<br><br> | ||
'''265''' – There was only one block used for the 265 cid version of the LT1. It’s a 10168588 casting that had the numbers "4.3" cast on the side, too. It’s real easy to spot if the heads are off because of the small 3.74" bore.<br><br> | '''265''' – There was only one block used for the 265 cid version of the LT1. It’s a 10168588 casting that had the numbers "4.3" cast on the side, too. It’s real easy to spot if the heads are off because of the small 3.74" bore.<br><br> | ||
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Be sure to check the seal surface on the geared shaft that drives the water pump. If it’s grooved, it will leak and it will be your fault. See the photo. New ones are available from GM (p/n 10219554) for around $40. That’s cheap insurance when you consider that the timing cover, chain and gears have to come off to replace it.<br><br> | Be sure to check the seal surface on the geared shaft that drives the water pump. If it’s grooved, it will leak and it will be your fault. See the photo. New ones are available from GM (p/n 10219554) for around $40. That’s cheap insurance when you consider that the timing cover, chain and gears have to come off to replace it.<br><br> | ||
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| + | [[File:Lt1 oil drive.gif|right]] | ||
'''OIL PUMP'''<br> | '''OIL PUMP'''<br> | ||
| − | The LT1 powerplant uses the late model 350 oil pump with the 3/4" pickup tube. This should be fairly easy to identify.<br><br> | + | The LT1 powerplant uses the late model 350 oil pump with the 3/4" pickup tube. This should be fairly easy to identify. The oil pump is driven by a stub shaft that is located where the distributor would be on a Gen 1 SBC, photo right.<br><br> |
'''HUB AND BALANCER'''<br> | '''HUB AND BALANCER'''<br> | ||
[[File:Balancer hub.gif|right]] | [[File:Balancer hub.gif|right]] | ||
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