109 Block Specs

[TurboWh1]

Anybody have any info on where to find specs for the block? Specifically I'm looking for cylinder bore and main bore clearances. My mains are out of line .004". The number 3 journal was the worst. I just checked it out on my dads CMM. Needless to say I roasted pretty much all the main bearings in my engine. I've looked on GNttype.org but only seem to be able to find specs for the crankshaft itself....

 

[QUIP'6']

Anybody have any info on where to find specs for the block? Specifically I'm looking for cylinder bore and main bore clearances. My mains are out of line .004". The number 3 journal was the worst. I just checked it out on my dads CMM. Needless to say I roasted pretty much all the main bearings in my engine. I've looked on GNttype.org but only seem to be able to find specs for the crankshaft itself....

DIDNT LOOK HARD ENOUGH!!!:biggrin: Factory Engine Specification

 

[Nick Micale]

DIDNT LOOK HARD ENOUGH!!!:biggrin: Factory Engine Specification

Keep in mind, these "factory" specs apply to a production V-6 which were used with a 2 barrel carb economy engine, not a performance turbo build.

The "Buick Performance Source" would be a more appropiate as a reference when building a turbo engine.

 

[Scott87]

Hope this infor is what your looking for.

 

[TurboDave]

Keep in mind, these "factory" specs apply to a production V-6 which were used with a 2 barrel carb economy engine, not a performance turbo build.

The "Buick Performance Source" would be a more appropiate as a reference when building a turbo engine.

Nick,

The clearance specs I've seen in the sources I've looked at say: .0003 to .0018 for the mains.

I couldn't really find any "specs" listed in the power source, just clearances in "example" builds. And those specs seemed REALLY loose. Over .002 on every build for the mains and rods!

What are your typical build clearances??

I just checked my new bearings to crank clearance, and found the following:
#1 .0017
#2 .0015
#3 .0010
#4 .0013

If you saw these numbers, what would be your next step?

 

[TurboWh1]

Yeah I would like to make sure I have the correct numbers this time. I built the engine 5 years ago and have put about 7000 miles on it. It doesn't see the track a whole bunch but I want to get it right this time. So hopefully I can keep it together. I actually used these specs on my prior build. I was just wondering what numbers you guys were going by on your performance builds.

 

[turbofabricator]

Yeah I would like to make sure I have the correct numbers this time. I built the engine 5 years ago and have put about 7000 miles on it. It doesn't see the track a whole bunch but I want to get it right this time. So hopefully I can keep it together. I actually used these specs on my prior build. I was just wondering what numbers you guys were going by on your performance builds.

Clearance numbers vary from guy to guy. (OK I'm sure there are a few gals that can chime in, too) But, I shoot for .0018"-.002" clearance for both rod and mains. If it makes more than 600hp, then I will open them all the way to .0022" Then there is the ring end gap clearances and that depnds on bore size, but too loose is still OK, but too tight is TROUBLE! Top ring tighter than second ring. (.019"-.026" top and .021"-.028" second depending on bore diameter, i.e 3.8 liter or 4.1 liter) Lifter pre-load I shoot for .020" for street, and .015 for race. Thrust shoot for .005"-.009". Did I miss anything?

 

[Nick Micale]

Nick,

The clearance specs I've seen in the sources I've looked at say: .0003 to .0018 for the mains.

I couldn't really find any "specs" listed in the power source, just clearances in "example" builds. And those specs seemed REALLY loose. Over .002 on every build for the mains and rods!

What are your typical build clearances??

I just checked my new bearings to crank clearance, and found the following:
#1 .0017
#2 .0015
#3 .0010
#4 .0013

If you saw these numbers, what would be your next step?

Why do you say 0.002" is too much for a performance turbo V-6 build?

That is what the BPS specs states in the turbo section.

Most custom and race engine builders usually determine bearing clearance based upon journal diameter and use, the factory specs are used as a guide, or starting point

Your new bearings clearances are way tighter than we ever do, even for a
street build. With 0.0010" total clearance on the crank bearings, that will only give 0.0005" actual clearance when running.

We have built and installed MANY of these builds down into the 8's with both stock-type oil pumps and the Dut style pump, and have never lost an engine bearing because of too loose a clearance.

I have to give credit to Mike at TA, Ken D. and Mike Zimmerman who have years of experience in building race engines, all who have helped "educate" me over the years, starting with the 455 Buick V-8 engines.

You could also check with some of the other known, quality engine builders of turbo V-6 engines to see their view on this subject.

 

[TurboWh1]

I guess I'm a little scared of trusting the machinist to get it correct. There are some good local engine building companies in my area but I'm still a little cautious. I obviously got burned the last time. I like being involved in the rebuilding process. So I would like to assemble the engine myself plus I can actually verify that the specs are correct.

 

[TurboDave]

Why do you say 0.002" is too much for a performance turbo V-6 build?

That is what the BPS specs states in the turbo section.

Most custom and race engine builders usually determine bearing clearance based upon journal diameter and use, the factory specs are used as a guide, or starting point

Your new bearings clearances are way tighter than we ever do, even for a
street build. With 0.0010" total clearance on the crank bearings, that will only give 0.0005" actual clearance when running.

We have built and installed MANY of these builds down into the 8's with both stock-type oil pumps and the Dut style pump, and have never lost an engine bearing because of too loose a clearance.

I have to give credit to Mike at TA, Ken D. and Mike Zimmerman who have years of experience in building race engines, all who have helped "educate" me over the years, starting with the 455 Buick V-8 engines.

You could also check with some of the other known, quality engine builders of turbo V-6 engines to see their view on this subject.

My mistake calling .002 really loose. It was just a perception on my part based on the factory manual. Obviously from my posts, I'm looking for advice from the experts here on what I and others should shoot for. Tuning I can do, but I'm kind of in the dark on setting up the internal clearances. I've got plenty of good tools (micrometers, dial bore gauges, etc). Just gotta get the measurements right.