I am relatively new to carbeureted third gens and know a bunch about the EFI ones. I am currently thinking of purchasing an 86 sport coupe with an LG4.

From what I am reading there are only a few differences between the LG4 and L69 motor. Those being the exhaust and camshaft. (both of which I will change on this car)

About the cam; the only roller cam LG4 is the 87 model year correct? What are the differences in roller and non-roller cam? Is it beneficial to have one over the other?

Thanks for all the help.

 

there are a lot of differences between the lg4 and l69


-Carb secondary rods and hanger.
-electric fan
-more aggressive timing curve (computer tuning)
-L69 cars came with 3.73 rear ends.
-cam
-entire exhaust including manifolds
-Dual snorkel air cleaner
-slightly different a/c routing
-Pistons were different in early years. I think 86 they may have been the same.

 

There are a lot of differences, but the major power-limiting differences are the cam, exhaust, and air cleaner. After addressing those, the remaining differences are handled by tuning.

Between the flat tappet and roller LG4 cams, there isn't much difference. There certainly isn't enough difference performance-wise to justify changing the '86 over to roller lifters.

There's a thread in the FAQ forum about this stuff.

 

Thanks for all the help guys.