Deciding on the engine is the easy part. Making it fit into a 1986 Pontiac Grand Prix is where the knuckles get busted. Whether you go Big Block or LS, there are specific “deal-breaker” parts you need to have on hand before you start swinging the hoist.
Here is the survival list I wish I had when I started.
1. The LS Swap Essentials
If you chose the modern route, the G-body chassis fights you in two places: the crossmember and the motor mounts.
Transmission Crossmember Double-Hump https://amzn.to/3ZAbgHC
• The Oil Pan (MANDATORY): 302-20 81577 Rear Sump Low Profile Oil Pan Kit https://amzn.to/4qywy3q
You cannot use the stock truck oil pan from a 6.0L; it hangs too low and will smash into the ground. You need a “302-2” style pan. This one is specifically designed to clear the G-body crossmember and steering linkage.
Low Profile LS Swap Oil Pan
This aluminum pan gives you maximum clearance and comes with the pickup tube and hardware you need. It’s the difference between a clean install and a cracked oil pan on your first speed bump.
• The Motor Mounts:
Don’t try to fabricate these yourself unless you love geometry headaches. maXpeedingrods makes a specific set for the 1978-88 G-Body that adapts the LS block to your factory frame holes.
maXpeedingrods LS Engine Swap Mount Adapter Kit with Hardware for G-Body https://amzn.to/405HLO3
These allow you to slide the engine forward or back to clear your headers and firewall. Best money you’ll spend on the swap.
2. The Big Block Essentials
• Cooling is Key: That iron giant generates massive heat. Do not try to reuse your stock small-block radiator. You need a 3-row or 4-row aluminum radiator with dual electric fans. 4 Row Aluminum Radiator https://amzn.to/3MIsWxT
