cleareance's

[gnxtc2]

you might want to think hard about those "factory" specs-------5 tenths on the rods and 3 tenths on the mains is mighty tight-------if you wander close to those clearances you better have absolutely perfect concentricity of journals and bores------and plan on using high viscosity oil--------long ago i tore down two brand new short blocks right out of the crate to check the specs-----tightest bearing in one block was #1 main at 9 tenths--------tightest main in other block was 12 tenths--------no rod was less than 15 tenths-------some were over 20.........RC

Richard

5 tenths (.5) or 5 ten thousandths (.0005)

I am getting confused over the tenths.

.005 = 5 thousandths
.015 = 15 thousandths
.0015 = one and a half thousandths

A human hair (head) is .003.

Billy T.
gnxtc2@aol.com

 

[johnplogii]

5 tenths is .0005

 

[phillyvader]

To simplify the math..here are the limits expressed in thousands.

Rod bearing to crank journal clearance limits: 2,000 of an inch to 65,000 of an inch

Main bearing to crank journal clearance limits: 30,000 of an inch to 45,000 of an inch

 

[phillyvader]

Richard

5 tenths (.5) or 5 ten thousandths (.0005)

I am getting confused over the tenths.

.005 = 5 thousandths
.015 = 15 thousandths
.0015 = one and a half thousandths

A human hair (head) is .003.

Billy T.
gnxtc2@aol.com

.005= 1/200 : one two hundreds= 200 of an inch
.015= 3/200 : three two hundreds= 600 of an inch
.0015= 3/2000 : three two thousands= 6,000 of an inch

 

[phillyvader]

.005= 1/200 : one two hundreds= 200 of an inch
.015= 3/200 : three two hundreds= 600 of an inch
.0015= 3/2000 : three two thousands= 6,000 of an inch[/QUOTE

srry ... was just informed that all my clearances are wrong ummmmm forget the last two post

 

[johnplogii]

Yeah, you are making it WAY more complicated than it is, plus your numbers WAY off.

 

[Blazer406]

IMHO - .0015-.002 is fine on rods and mains.... and if you err... err to the loose side..... 6500 RPM....the looser clearances will allow more volume of oil to flow around and past the bearing...... therfore cooling the bearing off too..... a must have in a high RPM engine. All of this assuming your oiling system is up to snuff......

HTH

 

[JDSfastGN]

So you, an "unknown" internet name, is asking other "unknowns" on the internet for critical information on building an expensive engine about what they recommend?

There are a few people qualified to answer this, IF they had all the proper information, and were willing to share it - very seldom does this happen.

If you are not knowledgeable, experienced or qualified to do this job correctly, it would be best to find someone that has, and use them.

I know many of the "qualified" Buick engine builders around the country, and almost never do they post or respond with details like you want.

Save yourself trouble and expense in the long run, and find an experienced person [with a proven track record] to help you. :smile:

WTH is this crap? A few people are qualified to answer a ? on bearing clearances on a buick V6 engine? Get over yourself

 

[disco stu]

Geeez. This **** ain't rocket surgery. You do have to have a good reputable machine shop that will do what you want, not what they think you want.

A typical street motor only needs to spin up to 6 max in most cases. If you got a big solid roller that needs more RPM then it's probably more of a race deal.

I build them on the tight side of .002 rods and mains. I have also done them at .002 with coated bearing which put clearances at .0017-.0018 and spun it to 6500-6700 for 300 passes and the bearings looked brand new except #2 and #3 main due to a cracked and flexing crank.

Don't use plastiguage. Use a dial bore guage if you have access to one. Your machine shop should be on top of this but if you are like me you don't ever take anyones word, and check it yourself.

I've done it this way with a HV timing cover with the main feed drilled to 1/2" and all turns ported and radiused and matched to the block and have had 20-25 psi hot at idle with no cooler in the TX heat. Also, use TA's coated Durabond bearings and follow the instructions on orientation.

It's not like this sh!t is some sort of proprietary secret. It's pretty much done by anybody that has screwed a few of these together. So, yes. It's good to have a Buick experienced machinist instead of some roundy round dirt track builder. But good machine work is good machine work and it can be done yourself if you pay attention to details.