Shell Rotella T Oil Results - 120,000 miles / 5 years / 4000 mile change interval...

[turbokinetic]

Quick question, was the LG3 100% compatible with a GN or did you have to modify or fabricate any parts?

Hi, the LG3 has a few differences. Its block is constructed similar to the 86-87 Turbo Regal '109' block. It is heavier than the early model TR blocks, has counterbored head bolt holes, and 86-87 oilpan bolt pattern. Some major differences are:
- Roller lifter guide mount points in block valley.
- Bellhousing - uses the same bellhousing as the 2.8 Chevy 60°V6 and the other front wheel drive engines.
- Crankshaft - flywheel flange different from RWD.
- Heads. LG3 has pedestal-mount rockers / RWD engine has shaft-mount. Heads will accept same intake manifold, however I am not sure about the exhaust. It seems the LG3 heads have a different angle to the surface where the exhaust manifold mates up with the head. LG3 takes center-bolt valvecovers which are attached by 3 extended rocker pedestal studs / nuts.

As far as adapting the 1970's Turbo Buick parts to the engine; all external parts were direct bolt-on except for the following:
-Oilpan. Required modification. Used oilpan from LG3, but had to modify the front part to work with distributor-style (or cam sensor-style) timing cover.

-Camshaft. Aftermarket hydraulic roller cam required. LG3 cam has no distributor drive hear whatsoever. RWD stock cam not usable with roller lifters.

-Timing set. Use tensioner for LG3. Use lower timing gear for RWD 3.8 engine. Upper timing gear and chain are same for both.

-Oil return. Had to drill this into block.

That's what I can remember off-hand. Here is a video where I build a hybrid Turbo Buick / LG3 engine:

 

[MCH86GN]

Hi, the LG3 has a few differences. Its block is constructed similar to the 86-87 Turbo Regal '109' block. It is heavier than the early model TR blocks, has counterbored head bolt holes, and 86-87 oilpan bolt pattern. Some major differences are:
- Roller lifter guide mount points in block valley.
- Bellhousing - uses the same bellhousing as the 2.8 Chevy 60°V6 and the other front wheel drive engines.
- Crankshaft - flywheel flange different from RWD.
- Heads. LG3 has pedestal-mount rockers / RWD engine has shaft-mount. Heads will accept same intake manifold, however I am not sure about the exhaust. It seems the LG3 heads have a different angle to the surface where the exhaust manifold mates up with the head. LG3 takes center-bolt valvecovers which are attached by 3 extended rocker pedestal studs / nuts.

As far as adapting the 1970's Turbo Buick parts to the engine; all external parts were direct bolt-on except for the following:
-Oilpan. Required modification. Used oilpan from LG3, but had to modify the front part to work with distributor-style (or cam sensor-style) timing cover.

-Camshaft. Aftermarket hydraulic roller cam required. LG3 cam has no distributor drive hear whatsoever. RWD stock cam not usable with roller lifters.

-Timing set. Use tensioner for LG3. Use lower timing gear for RWD 3.8 engine. Upper timing gear and chain are same for both.

-Oil return. Had to drill this into block.

That's what I can remember off-hand. Here is a video where I build a hybrid Turbo Buick / LG3 engine:

Thank you that is a terrific synopsis. Definitely check out the video.

 

[turbokinetic]

Thank you that is a terrific synopsis. Definitely check out the video.

You're welcome. Hope it helps!