brnagn

iTrader: (3)

I know there are a lot of different opinions on this subject and I have read through most of the posts related to it. However, I would like to hear from engine builders who consistently build street engines.

I am building an iron block 402 (LQ4 block). I am using King Engine bearings on both the rods and mains. I am measuring the clearances with a 2-3" micrometer and a bore gauge with .0001" resolution. There is at least a couple of tenths of inaccuracy in my setup, but I am confident that I am in the ball park.

Mains:
Using standard bearings on the mains I get clearances of .0018"-.0021"
Using one standard shell and one standard+.001" I get .0025"-.0027"

Rods:
Using standard-.001" bearings on the rods, I get clearances of .0018"-.0022"
Using one standard-.001" shells and one standard I get clearances of .0024"-.0026"

Based on real world experience, what clearances would you run? Am I over-thinking this and either set would likely hold up fine on the street? Thanks in advance!

chrisfrost

iTrader: (8)

I would say first off You need to be more clear about exactly what You're saying . Standard means .000 or the same as when factory new , no over or undersize . So when You say 1 standard bearing You have .0018-.0022 . This is what You want all the rod clearances to be ,,,,,,in that range unless You're engine will be considerably more powerful than stock then go with .0023"-.0027" but You don't want to mix-n-match bearing halves . You have to use 2 bearing halves that are the same (.001,,,,or .002 ,,,,, or standard) for each rod to achieve You're clearances . Even if You're not using ARP or Katech rod bolts ,,,,,with any mileage at all the rod big ends are going to be a little out of round so really they need to be honed and Federal Mogule makes LS rod bearings that are .002 oversized to the outer diameter of the bearing in standard and all of the undersizes that are different sizes on the inner diameter of the bearing .

brnagn

iTrader: (3)

I apologize for not being clear:

Standard: Standard Bearing Size
Standard-.001": Undersize by .001" for cranks that have been ground.
Standard+001": Oversize by .001" for additional clearance.

Mixing bearing halves to achieve optimal clearance seems to be an accepted practice and I even have documentation from King engine bearings stating that this is acceptable.

As far as the rods, they have been checked by a local shop and are within spec in terms of roundness. The crank I am using has also been balanced, checked for straightness and the journals have been ground.

mark21742

I'd shoot for .0025-.0028" on rods and mains since its an iron block, and I have seen lots of builders mix and match halves, but you went to keep your differences from each side to a very minimum

KCS

iTrader: (20)

It's ok to mix and match shells to a certain degree. Std/X is ok as well as Std/.001", mixing an X and a .001" is too much of a difference and is quite honestly retarded.

Bearing clearance is influenced by several factors including oil type, power level, intended use, etc. Street engines are typically just fine at about .001" per 1" of shaft diameter as a general rule of thumb. So a 2.55" main will run forever with about .0025" clearance.

Of course, you can go a little tighter, but do so at you're own risk. I built my 376ci iron block with .0022" on the mains and .0019" on the rods.

brnagn

iTrader: (3)

Agreed! If someone is doing that, then a set of standard (upper and lower shells) should work for them. Hopefully, I did not suggest I was doing that. I am only mixing 1 size up or down.

brnagn

iTrader: (3)

BTW, how many miles are on your engine, what hp, and how is it holding up?

Sales2@Texas-speed

iTrader: (5)

Based on your measurements and being the iron block, I'd likely opt for the .0025-.0027" on the mains and .0024-.0026" on the rods. On an aluminum engine, I would have gone with the tighter clearances however.

RezinTexas

Here is a list of sources I compiled on the subject:

Mains (iron block):

0.0024 - 0.0027": ex-HKE engine builder
0.0024 - 0.0027": Tony Mamo (https://ls1tech.com/forums/generatio...clearance.html)
0.0019 - 0.0026": Clevite catalog "reasonable starting point for most engines"
0.0031": Clevite catalog "high performance engines"
0.0020 - 0.0030": Joseph Potak Book, p. 40

Rods:

0.0016 - 0.0021": Clevite catalog "reasonable starting point for most engines"
0.0026": Clevite catalog "high performance engines"
0.0020" - 0.0025": Joseph Potak Book, p. 40

KCS

iTrader: (20)

It's got about 5k miles on it since April and oil pressure is perfect. The LS6 clutch isn't too happy with the new engine, so I haven't gotten a good measure but based on the torque numbers so far, it'll make an easy 470-480whp. Eventually I'll put in a new clutch combo and do the drill mod and get a solid dyno run in. At the present it won't hold more than 430ft-lbs or 5000 RPM.



More details HERE.

iroczracer07

iTrader: (1)

I'm gonna be rebuilding my aluminum LS1 Matt, so your mention of bearing clearances grabbed my attention. I'm new to LS1 motors, and plan to make around 450-500 at the flywheel. Nothing too awesome for this motor. Of course, that's provided that I can keep the power bug away, lol. Anywho, what bearing clearances would you recommend?

Sales2@Texas-speed

iTrader: (5)

The aluminum engines need a bit tighter clearances setup because at full operating temperature they will expand close to .001"! If you start looser than .0025" main bearing clearance or so on aluminum engine, be ready for some oil pressure woes. We like to be closer to .019-.023" or so on the main on the average aluminum build (and of course there are more variables than can come into play here!!)

k_cash1432

iTrader: (9)

IM in the process of building a forged aluminum LS1 and my machinest said hes gonna turn my crank ten/ten What kind of tollerances should i run on my mains and rods since all the journals will be turned?

Sales2@Texas-speed

iTrader: (5)

Turning the crank doesn't mean you want different clearance, you just have to use different bearings to get to the same clearance as you would have with an unturned crank!

brnagn

iTrader: (3)

Thank you everyone for your replies. I really appreciate the advice and I feel more comfortable moving forward with my build.

k_cash1432

iTrader: (9)

previous owner had a lifter turn in the bore so it chewed it up and send some filings through the motor and chewed up the mains so im having my machine shop turn the crank down. Im curious as to what you would recoment to have my bearings since you say the aluminum engines have a tendancy to expand when heat cycled. Im going to be running Eagle H beam rods and wesco forged pistons with intentions of spraying and then going turbo. Do you guys at TSP offer bearing packages?

PlymouthBarracuda

Dear all, could you please be so kind and listen to my engine. The knock is not so loud, so phone's camera couldn't catch it well. But anyway, in the headphones you could advise me something... Is it rod knock, lifters ticking or my own glitch ??


Video made up from the several fragments:
-210F, idle, 20 psi oil pressure;
-1200 - 1500 RPM;
-The same idle from behind the left wheel;
-Gauges readings after fully heat-up (OIL TEMP UBNORMAL HIGH??);
-250F, idle, 14 psi oil pressure.

While driving from 30 mph and up oil pressure is 30+ psi.
Oil filter (ACDELCO UPF48R) was cutted and found no metal signs.

G Atsma

I'm not hearing anything that could be called rod knock. Mostly just the valvetrain noise that LS1's are known for.
20 psi IS a little low for idle oil pressure, but not unusual for an engine that might on the tired side of things.

PlymouthBarracuda

Thank you so much sir! You saved my nervous))
I have one more problem that could be from the crank bearings side. When oil temp is 220F and higher I from time to time can't start the engine. Starter makes 1-2-3 turns and stops. I ordered heat shield blanket and still waiting.. I put additional ground to the starter (from transmission to starter) but this didn't help.

G Atsma

Starter might be getting tired, but just a guess. Make sure ALL connections are solid.