i need to know if an 85 LG4 would have the dished, or the flat top pistons

and if flat top then whats stopping it from having the compression ratio of an L69 if it has the same pistons and 14014416 heads ?

https://www.thirdgen.org/forums/tech...4-pistons.html


thanks

 

Officially in a 3rd gen F-body 1985 was the first year for the higher compression LG4 (9.5:1, same as the L69 HO motor). Using the same flattop pistons in the LG4 as were used in the L69 is how they achieved this.

The other thing that started at the same time as this increase in compression is that the factory started using a knock sensor in the LG4. Prior years of the low compression LG4 did not use a knock sensor.

 

my 85 Z28 has an LG4 and the pistons are dished, i rebuilt it 3 years ago. i can tell ya though those LG4`s are a really good engine i re used the stock bottem end and spun it too 6500 rpm`s many times and even 7000 a few times and she never let go, i was surprized.

 

My L69 has dished pistons. Dident come out of a 3rd gen tho.