Blowthrough build repeat.

Nigel

Well-Known Member
Joined
Jun 16, 2001
I have a lot of good parts to keep on with a 109 3.8L and that is the plan.
But..
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!
 

WarWagon

Caustic Cacophony
Joined
Mar 10, 2007
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.
 

WarWagon

Caustic Cacophony
Joined
Mar 10, 2007
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.
 

WarWagon

Caustic Cacophony
Joined
Mar 10, 2007
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.
 

WarWagon

Caustic Cacophony
Joined
Mar 10, 2007
Slow going but getting done bit by bit. Have to wait on new main and rod bearings to be made so in the down time I installed all my old .001 main bearings in the new block. Cleaned the crank and installed, checking with green plasti gauge #1 was worn the most showing .002 oil clearance #2 was .0018 the rest were .001
I have a few different main caps to swap around yet as #3 was a bit loose in the register for my liking.
The rest of this build will go quick once I get the items I've been waiting on.
 

WarWagon

Caustic Cacophony
Joined
Mar 10, 2007
Tough to keep on this job but progress made.
Self clearanced my steel main caps and a rear main cap to fit this block just tight enough. Using new std size bearings this time after my work I get these oil clearances for crankshaft:
1=.003
2=.0015
3=.002
4=.002
This will be running 20w50 oil when racing and 10w40 with Lucas on the street.
I'm satisfied with my work so far and I'm ready to clean up the block and get it together.
 

WarWagon

Caustic Cacophony
Joined
Mar 10, 2007
The crankshaft spun easy on the std size bearings with just oil and the caps torqued to 100ftlbs
 

WarWagon

Caustic Cacophony
Joined
Mar 10, 2007
Almost had a short block built lastnight. I found one piston slightly tweaked in the 2nd ring land area the ring was tough to remove and the slot too tight to fit the new ring. Swap it out with a spare and keep on building.
 

Nigel

Well-Known Member
Joined
Jun 16, 2001
Almost had a short block built lastnight. I found one piston slightly tweaked in the 2nd ring land area the ring was tough to remove and the slot too tight to fit the new ring. Swap it out with a spare and keep on building.
Looking forward to Research Mule results!
 

WarWagon

Caustic Cacophony
Joined
Mar 10, 2007
Hardest and slowest part over for the build, won't be much longer now. I noticed I have one odd ball piston in this engine, now after selecting the best parts. All of these are older TRW/speedpro before the skirt coatings with oil holes/ drains under the pin bore and the one odd one had these in the ring land. No pics everyone knows what this stock junk looks like, I'll get one towads the end.
I'm a bit excited on this version over the rest, I've never had such a fresh block to start with.
 
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