Yes the flat tapped cam will work in any Gen I block. Somewhere I remember something about GM using a small letter designation for various improvements which actually are quite a few it looks something like this.
- The original had no oil filter, mount provisions were on the front facing the radiator, cam had a transfer groove in the bearing for moving oil.
The oil transfer grooves were removed from the cam’s bearing journals to be machined into the block behind the cam bearing shell.
- Then came the mods to put an oil filter on the block, the original was a can with a replaceable element, a few years later that changed to a spin on.
- Then the mounts were moved to the forward side of the block.
- Heads were modified to allow accessory brackets and accessory to be secured to the front of the heads. This, also, drove the long version of the coolant pump.
- The intake and block was modified to remove the oil fill passage and the road tube cast provisions as PCV cam. This also made changes to the valve covers.
- Thin wall casting gets introduced in the early 1970’s.
- The two piece rear seal was changed to a one piece and the accessory drive converted to serpentine belts which includes a modification to the coolant pump for counter clockwise rotation.
- The fuel pump mount area remained but for engines expected to get fuel injection it wasn’t completed, there are exceptions to this. At first only blocks going to passenger cars getting roller cams were cast and finished with the needed provisions. A separation was made for heads going to Tuned Port Injection (TPI) or Throttle Body Injection (TBI) the latter getting Swirl Ports the former did not. Eventually all blocks got roller provisions as castings but blocks headed for trucks were left somewhere between as cast to fully machined. Inside this time frame rods were changed from mild steel forgings to powder metal forging. Pistons became hypereutectic castings, and the spigot length of the cylinder wall extension was shortened as the tighter fit hyper pistons didn’t need as much wall support through the BDC event.
- The 1996 introduces a completely different top end from the heads up and many changes made to support the OBD 2 electronics plus a modified coolant pump to change the bypass locations to fit to and around the new fuel injection, these being the L30, 305 and L31, 350 Vortecs.
These just touching on some of the mods made to the Gen I engines over their life time, there are many smaller tweaks as well not just on the engine but to its manufacturing and casting processes. To emphasize all the above are considered Gen I engines.
Gen I roller blocks can use the earlier Gen I flat tapped cam by simply using the flat tapped cam timing set. Flat tapped blocks can use what is called a retro-fit roller cam with a thrust bumper, you can actually do this to a roller block as well. The factory roller prepped blocks use what is called the OEM roller cam, it uses a bolt on thrust plate and the can has a reduced diameter extended nose to accommodate that which retro-fit cams do NOT have. The bolt circle between flat tapped and retro-roller cams is different from OEM roller cams so the timing sets do not interchange
Gen II introduces the 1990’s LT1 and LT4 engines ( note the original LT-1 of the late 1960’s early 1970’s has a dash between the letters and the number of the designation where the 1990’s version does not.
* Enter the LT1 and LT4; these are designated as Gen II engines. The basic block and head castings are unique and do not interchange even though bolt patterns for the man caps and the heads to block are the same.
- The cooling system is reversed where the pump feeds the block but that is now a passage that immediately reroutes the coolant into the heads first. Coolant then flows down into the block from the heads and returns through new passages in the front of the block to a completely different front assembly that includes a cam driven coolant pump and an optical distributor. None of this interchanges with the Gen I engine.
- What can be interchanged with the Gen I engines is the crankshaft rotating assembly including rods and pistons. The roller cam will interchange with the Gen I roller block castings if they are finished out by the factory or the motor builder. The lifters interchange as do push rods and rockers for use on Gen I heads that use self-guiding rockers, design change that came around 1987 I forgot to include in the above list of Gen I changes. Valves and springs will interchange but the LT4 uses a 2 inch intake where the LT1 retains the familiar 1.94.
Yes the flat tapped cam will work in any Gen I block. Somewhere I remember something about GM using a small letter designation for various improvements which actually are quite a few it looks something like this.
- The original had no oil filter, mount provisions were on the front facing the radiator, cam had a transfer groove in the bearing for moving oil.
The oil transfer grooves were removed from the cam’s bearing journals to be machined into the block behind the cam bearing shell.
- Then came the mods to put an oil filter on the block, the original was a can with a replaceable element, a few years later that changed to a spin on.
- Then the mounts were moved to the forward side of the block.
- Heads were modified to allow accessory brackets and accessory to be secured to the front of the heads. This, also, drove the long version of the coolant pump.
- The intake and block was modified to remove the oil fill passage and the road tube cast provisions as PCV cam. This also made changes to the valve covers.
- Thin wall casting gets introduced in the early 1970’s.
- The two piece rear seal was changed to a one piece and the accessory drive converted to serpentine belts which includes a modification to the coolant pump for counter clockwise rotation.
- The fuel pump mount area remained but for engines expected to get fuel injection it wasn’t completed, there are exceptions to this. At first only blocks going to passenger cars getting roller cams were cast and finished with the needed provisions. A separation was made for heads going to Tuned Port Injection (TPI) or Throttle Body Injection (TBI) the latter getting Swirl Ports the former did not. Eventually all blocks got roller provisions as castings but blocks headed for trucks were left somewhere between as cast to fully machined. Inside this time frame rods were changed from mild steel forgings to powder metal forging. Pistons became hypereutectic castings, and the spigot length of the cylinder wall extension was shortened as the tighter fit hyper pistons didn’t need as much wall support through the BDC event.
- The 1996 introduces a completely different top end from the heads up and many changes made to support the OBD 2 electronics plus a modified coolant pump to change the bypass locations to fit to and around the new fuel injection, these being the L30, 305 and L31, 350 Vortecs.
These just touching on some of the mods made to the Gen I engines over their life time, there are many smaller tweaks as well not just on the engine but to its manufacturing and casting processes. To emphasize all the above are considered Gen I engines.
Gen I roller blocks can use the earlier Gen I flat tapped cam by simply using the flat tapped cam timing set. Flat tapped blocks can use what is called a retro-fit roller cam with a thrust bumper, you can actually do this to a roller block as well. The factory roller prepped blocks use what is called the OEM roller cam, it uses a bolt on thrust plate and the can has a reduced diameter extended nose to accommodate that which retro-fit cams do NOT have. The bolt circle between flat tapped and retro-roller cams is different from OEM roller cams so the timing sets do not interchange
Gen II introduces the 1990’s LT1 and LT4 engines ( note the original LT-1 of the late 1960’s early 1970’s has a dash between the letters and the number of the designation where the 1990’s version does not.
* Enter the LT1 and LT4; these are designated as Gen II engines a well as a miserable cast iron headed 265 inch version call the L99. The basic block and head castings are unique and do not interchange even though bolt patterns for the man caps and the heads to block are the same.
- The cooling system is reversed where the pump feeds the block but that is now a passage that immediately reroutes the coolant into the heads first. Coolant then flows down into the block from the heads and returns through new passages in the front of the block to a completely different front assembly that includes a cam driven optical distributor under the coolant pump driven with a gear an short jack shaft off the timing set. None of this interchanges with the Gen I engine. The idea was that putting the recently cooled coolant into the head first would allow higher compression ratios than the head in a conventional engine receives coolant previously heated in the block. This is an old idea that rears its head down through industrial age time always with less than conceived results. An example Pontiac tried this on their OHV, V8’s. It lasted from 1955 to 1959 where the inservice failure rate drive a more conventional design, Chevy got about the same life out of theirs from 92 to 96.
- What can be interchanged with the Gen I engines is the crankshaft rotating assembly including rods and pistons. The roller cam will interchange with the Gen I roller block castings if they are finished out by the factory or the motor builder. The lifters interchange as do push rods and rockers for use on Gen I heads that use self-guiding rockers, design change that came around 1987 I forgot to include in the above list of Gen I changes. Valves and springs will interchange but the LT4 uses a 2 inch intake where the LT1 retains the familiar 1.94 inch intake.
OK this is at detail complicated, the simple answer is the Gen II engines consist only of the LT1 and LT4, 350 cast iron block with aluminum heads and the all cast iron L99, 265 made from or rather made from 1992 through 1996, some sources suggest 1997 was the last year. These were replaced by the clean sheet of paper, newly designed Gen III, LS1 which shares nothing with the Gen I or Gen II engines.
Yes the flat tapped cam will work in any Gen I block. Somewhere I remember something about GM using a small letter designation for various improvements which actually are quite a few it looks something like this.
- The original had no oil filter, mount provisions were on the front facing the radiator, cam had a transfer groove in the bearing for moving oil.
The oil transfer grooves were removed from the cam’s bearing journals to be machined into the block behind the cam bearing shell.
- Then came the mods to put an oil filter on the block, the original was a can with a replaceable element, a few years later that changed to a spin on.
- Then the mounts were moved to the forward side of the block.
- Heads were modified to allow accessory brackets and accessory to be secured to the front of the heads. This, also, drove the long version of the coolant pump.
- The intake and block was modified to remove the oil fill passage and the road tube cast provisions as PCV cam. This also made changes to the valve covers.
- Thin wall casting gets introduced in the early 1970’s.
- The two piece rear seal was changed to a one piece and the accessory drive converted to serpentine belts which includes a modification to the coolant pump for counter clockwise rotation.
- The fuel pump mount area remained but for engines expected to get fuel injection it wasn’t completed, there are exceptions to this. At first only blocks going to passenger cars getting roller cams were cast and finished with the needed provisions. A separation was made for heads going to Tuned Port Injection (TPI) or Throttle Body Injection (TBI) the latter getting Swirl Ports the former did not. Eventually all blocks got roller provisions as castings but blocks headed for trucks were left somewhere between as cast to fully machined. Inside this time frame rods were changed from mild steel forgings to powder metal forging. Pistons became hypereutectic castings, and the spigot length of the cylinder wall extension was shortened as the tighter fit hyper pistons didn’t need as much wall support through the BDC event.
- The 1996 introduces a completely different top end from the heads up and many changes made to support the OBD 2 electronics plus a modified coolant pump to change the bypass locations to fit to and around the new fuel injection, these being the L30, 305 and L31, 350 Vortecs.
These just touching on some of the mods made to the Gen I engines over their life time, there are many smaller tweaks as well not just on the engine but to its manufacturing and casting processes. To emphasize all the above are considered Gen I engines.
Gen I roller blocks can use the earlier Gen I flat tapped cam by simply using the flat tapped cam timing set. Flat tapped blocks can use what is called a retro-fit roller cam with a thrust bumper, you can actually do this to a roller block as well. The factory roller prepped blocks use what is called the OEM roller cam, it uses a bolt on thrust plate and the can has a reduced diameter extended nose to accommodate that which retro-fit cams do NOT have. The bolt circle between flat tapped and retro-roller cams is different from OEM roller cams so the timing sets do not interchange
Gen II introduces the 1990’s LT1 and LT4 engines ( note the original LT-1 of the late 1960’s early 1970’s has a dash between the letters and the number of the designation where the 1990’s version does not.
* Enter the LT1 and LT4; these are designated as Gen II engines a well as a miserable cast iron headed 265 inch version call the L99. The basic block and head castings are unique and do not interchange even though bolt patterns for the man caps and the heads to block are the same.
- The cooling system is reversed where the pump feeds the block but that is now a passage that immediately reroutes the coolant into the heads first. Coolant then flows down into the block from the heads and returns through new passages in the front of the block to a completely different front assembly that includes a cam driven optical distributor under the coolant pump driven with a gear an short jack shaft off the timing set. None of this interchanges with the Gen I engine. The idea was that putting the recently cooled coolant into the head first would allow higher compression ratios than the head in a conventional engine receives coolant previously heated in the block. This is an old idea that rears its head down through industrial age time always with less than conceived results. An example Pontiac tried this on their OHV, V8’s. It lasted from 1955 to 1959 where the inservice failure rate drive a more conventional design, Chevy got about the same life out of theirs from 92 to 96.
- What can be interchanged with the Gen I engines is the crankshaft rotating assembly including rods and pistons. The roller cam will interchange with the Gen I roller block castings if they are finished out by the factory or the motor builder. The lifters interchange as do push rods and rockers for use on Gen I heads that use self-guiding rockers, design change that came around 1987 I forgot to include in the above list of Gen I changes. Valves and springs will interchange but the LT4 uses a 2 inch intake where the LT1 retains the familiar 1.94 inch intake.
OK this is at detail complicated, the simple answer is the Gen II engines consist only of the LT1 and LT4, 350 cast iron block with aluminum heads and the all cast iron L99, 265 made from 1992 through 1996, some sources suggest 1997 was the last year. These were replaced by the clean sheet of paper, newly designed Gen III, LS1 which shares nothing with the Gen I or Gen II engines.
Bogie
