Blowthrough build repeat.


Well-Known Member
I have a lot of good parts to keep on with a 109 3.8L and that is the plan.
When I want to change it I have a very nice engine build I have been collecting parts and info for.
Just post it here.
Fully forged 10:1cr 4.1L for future power using:
T6P stock stroke steel crank
Molnar 6"rods
Racetec pistons
Will still be iron headed though.
Should be a beast!


Caustic Cacophony
On the way to 2021 build now,
A few parts to order and clean up the new 109 block.
Three things I want to check on this upcoming tear down: the wear on my first bronze distributor gear, Iwis timing chain stretch if any on the JP timing set and the wear on King main/rod bearings. All those parts were brand new when I put this together in 2019.


Caustic Cacophony
Tear down complete and here are the results after 2 years of abuse:
The wear on the bronze alloy distributor gear is acceptable, looks like 30-35% gone.

The Iwis timing chain from JP performance is a bit loose but the least worn out of all I've had.
The bearings I used were .001 undersized King rod and mains. They all looked great except for #1 main had a bit of trash go through it and get passed to #1 rod too. Just looks like discoloration on the bearing can't feel anything.
Rear two mains in block then front two:
These are the #1 rod bearings the cylinder that was getting coolant in it
Then the oddest find was the weird verticle crack in #2 piston between the first ring land and oil ring lands, no damage on the piston crown:
The bearings look great in #2, actually all the rest of the rod bearings besides #1 looked this good:
Lastly the cap side bearing with the thrust facing the rear almost no wear.
This engine was in great condition IMO and didn't deserve to get a cracked or pinholed cylinder or have a odd crack in the piston.
Doesn't matter this was the end of that block and now onto the new foundation.


Caustic Cacophony
Wasn't sure and couldn't remember so I looked hard tonight, the Comp roller cam has an oil passage from the thrust face through to the gear side. Bonus find.
The piston crack was the source of the latest blowby increase issue as well as the block crack too.