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.
 

WarWagon

Caustic Cacophony
Joined
Mar 10, 2007
Buick is alive and working great so far in 2021.
Yesterday was a garage fresh four mile shakedown good results. This morning no leaks so I drive it to work, this will be a fifty mile round trip when I get home.
The underside needs a cleaning bad with the oil coatings over the last two years.
 

WarWagon

Caustic Cacophony
Joined
Mar 10, 2007
I only started really paying attention after getting the Impulse and seeing the balancer on it with no damper. As I putting this engine together I grabbed the balancer I've been using: stock '85 HA damper from a 140 block. It has no damper it is just a balancer..
Now I have to look at all of mine, they are all stock. Next up was my stock '84 4.1 balancer it had no damper. Last was my stock '79 turbo balancer it has a damper ring shell over rubber and it's starting to come apart.
I did not know that I thought every stock GM balancer was a damper too.
 

ek02

Well-Known Member
Joined
Jan 31, 2008
The 4.1 balancer has an extra amount of weight on it when you compare it with a 3.8. I guess due to the different piston weight. It can't be used on a 3.8 unless the rotating assembly is rebalanced. BHJ and ATI are the only balancers for the V6 that have a damper on them. I wonder if your 79 turbo balancer is stock? It may be aftermarket.
 

WarWagon

Caustic Cacophony
Joined
Mar 10, 2007
Thanks Ed.
I'll have to look at the 4.1 balancer again for the part number if it has one, it's always been on that engine. I'm certain the '79 balancer I have is original GM, I'll get a pic and see about a part number on it too. I still think it's strange that most of these Buick v6's didn't have a damper then. The only other GM engine I know don't always have a damper was the Corvair flat 6.
 

WarWagon

Caustic Cacophony
Joined
Mar 10, 2007
I've gotten over 100 miles of street driving done on this new engine, it's running great. I gave it a few hits on the street and I have a very slow boost oscillation that is new. I need to check the base ignition timing I believe I have three extra degrees in and go over the MBC. I've never had this issue before so It's either a leak, a dirty part or an adjustment needed on boost controller again.
I broke my left ankle and wrist at work Monday so I do what I can on this and my other projects but that will slow me down.
 

WarWagon

Caustic Cacophony
Joined
Mar 10, 2007
Went back over my notes of the manual boost controller then checked the current settings. This is a TurboXS HP controller, The coarse tuning was good but the fine tuning air bleed was four turns too close to the seat, needs eight full turns on my setup. Easy adjustment there and fixed the slow boost oscillation on my test hits today. Data from my new 45psi boost gauge, it was a guess last year what that boost was went it was running in the 10's now I know. The first street hit was good spike to 38psi settled to 35psi then something popped under the hood and oil smoke everywhere. Still running good so drove 5 miles home and found the grommet and the 90* fitting to my catch can popped out of the intake valley hosed everything with oil. I cleaned it up best I could for now and pulled 1 turn out of the coarse boost adjustment for an constant 30psi on the last street hit. That's plenty power for the street here and I can turn it back up at the track. Perhaps in the future I will use an electronic boost controller
 
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