Sroker ? does the block need milling??

[JBrobeck]

I Spun a bearing in my '89 4.0 this week and it trashed a crank journal and a rod, I Just need to know ASAP if when doing the stroker conversion (low buck) do you need to mill the block to keep the squish in spec. I will be using the 4.2crank, The 4.2 rods, and stock 4.0 pistons I want to try and stay below 10:1 CR and If I can get away without milling the block it would be a huge help as that is the ONLY machining that would get done if it needs it.

Thanks Huge in advance I really wanna get her back on the road, Its not quite motorcycle season here yet so I have no other transportation!!!

Josh

BTW, I will be posting this at JU also, so don't gimme no crap! :gee:

[Eagle]

You are caught in a conundrum -- the 4.0L engine is already not quench-compliant, and switching to the 4.2L crank and rods makes it worse by increasing the compression. You need to deck the block slightly to improve quench, but doing that also raises the compression. One solution is to run a slightly wilder cam to bleed off some cylinder compression. The calculated compression ratio remains high, but the effective compression ratio get reduced.

Hop over to the Street/Performance forum, look for any post by "Dr. Dyno," and drop him a PM. He has a personal web site with info on several "recipes" for building a budget stroker.