PlainwhiteZ28

Ok I am going to build my first engine sometime in the near future.

I have decided to go with a lunati rotating assemply, prolly the 383.

I will be using all ARP bolts and studs for the mains.

My question is, what kind of bearing clearance should i shoot for for a daily driver/occasional strip use?

thanks guys

Scalpel

iTrader: (4)

Do you want an oil burner, yes or no?
That should be your first question as that'll dictate your clearances. The "looser" you go the less friction = more HP but you get oil blowby at a higher rate = lots of oil level monitoring.

PlainwhiteZ28

Well not really,

but 1qt every 3000 miles is acceptable.

I dont wanna have to add everytime i get back from a cruise or the strip.

SeeinRed

1 qt every 3k? I use more than that one my stock ls1 haha...

Mike

PlainwhiteZ28

I just re thought this,

how does bearing clearances affect oil consumption?

PlainwhiteZ28

have you tried a different brand?\\

i used to burn with mobil

switched to GTX no more burn

DaleMX

iTrader: (4)

Well I dont understand how the bearing clearances effect the oil consumpsion either. It would effect oil pressure, that I know.

Scalpel

iTrader: (4)

I asked this also before and these are the responses I got:


A motor that has more clearence can move more freely, thus making more power. There are negative effects to this though, such as oil consumption. Diffrent shops have diffrent method of doing things. I would say you could go a little more loose on a nitrous motor, but would need to be a little tighter on a blower motor due to the boost. Lots of all out motors might be set loose cause they know they will be rebuilt in due time, but street/strip car would be built "tighter", so you don't burn lots of oil and smoke alot.

---Beast96Z

Ditto on what beast said. With looser tolerences there's not as much drag and your motor can rev faster with minimal resistance. The factory has it's reasons for the tighter tolerences, including oil consumtion issues and excessive piston slap. It all depends on what your priorities are.
-- phenyxTA

Country Boy

iTrader: (24)

lol.... oil consumption has nothing to do with bearing clearences

Oil consumption comes from anywhere oil can get into the cylinders... IE. Rings and valves.. Unless the oil is coming out of the motor.

DaleMX

iTrader: (4)

I agree with you Country Boy. I just wanted to hear the logic behind it. You never know. I would think a tighter engine with more oil pressure would atomize more oil and maybe drag it out via the PVC, but that is contrary to what is being said here.

PlainwhiteZ28

Well ok then,,,,,

What am should i shoot for........mainly street.

.005-.015 or .020 or WTF........LOL......back on topic

strokedls1

iTrader: (1)

I don't know where some of this info is coming from but it isn't engine builders. The bearing clearance I used on the mains and rods is .002. The thickness of the rings, material of the rings, the amount of tension on the rings, and how much the rings are gapped will have effect on oil blow by and reving. Thinner rings that are low tension allows the engine to rev quicker and make a bit more power at the cost of some oil control issues. Like has been said oil can only be lost through the valve seals, pcv, or oil ring blow by. Proper bearing clearances just equate to good oil pressure. I have .005 end play on the crank. Ring gapping is usually set fourth by the piston manufactuer. If you want a street only engine get the stock thickness rings with recomended ring gap.

Scalpel

iTrader: (4)

Country, you need to reply to all of my tech posts so I don't get the wrong info

White_Hawk

iTrader: (3)

I know the Buick GN's are a little different, but we used to shoot for 1.5 - 1.8 on the mains and 1.8 - 2.0 on the rods (in thousandths). We went tight to compensate for a poor stock crank design. The pistons were a different story, though. We always went to the loose end of the stock tolerance to give them room to expand (lots of booost!). Just a little extra honing, that's all. I would think that would apply to any motor.

-Geoff

Country Boy

iTrader: (24)

lol... I dont mean anything by it nor is it just you. I surf the board alot and just correct wrong info so people dont get all confused. Its kinda a pet peve

Scalpel

iTrader: (4)

Oh I know, I prefer you do that. I hate to spread the wrong info