well, My machine shop used clevites and 4k later spun bearing in number four. I have a feeling it was oil starvation but the bearing was flattened like a pancake and ended up smashing my piston against my cylinder head until my piston broke into pieces.

anyway the clearances were on the loose side which I thought was good becasue everything grows with heat and revs. Everyone has a opinion on what kind of clearances they like for different reasons, but I would like to here how you like your clearances and why. What kind of applications,etc.

 

For longevity, tighter is better. Looser frees up power, at the cost of longevity. In the past, I set all of my bearing clearances at the tight end of the spec-and had zero problems 9.5-10k rpm, at the cost of a few hp. Running more towards the middle of the specs on my latest motor. All of my engines have been N/A.

 

all depends what oil your gona run

 

to loose YOU know it
to tight EVERYONE knows it.

 

after my build my machine shop said to run rotella 15-40. Give me some examples of your talking about. maybe thicker oil for higher pressure, when running loose clearances????

 

Do you have a oil press. guage?and what were you getting before it spun?

 

Tiiite, like my women.

 

no guage, but I missed a shift and number 4 is farthest away from the pump and when I checked the clearances on the oil pump gear they were barely in spec. So I guess I deserved it. But the motor had major issues after the build even before the spun bearing.

 

were you detonating?

 

actually the machine shop overhoned the block and number 4 burned a ton of oil and rings never seated. yes there was detonation. so much I had to back off the timing and run stupid rich at low rpm.

vtecvoodoo, we all like our women tight and I dont think that needs any explaining but why do you like your bearings tight?? what kind of driving? autox? drag? daily everything?

 

pounded bearing means detonation.

-edit-
they overbored the cylinder walls and put standard bore pistons in? I wouldn't be too concerned about the bearing clearances, infact, I'm suprized it ran. make sure you use a competent machine shop next time. I'd ask for my money back at least, and possibly go after them for some of the charges to rebuild my motor.
The crazy things you hear on HT.

 

the detonation most likely did the damage,not the clearances.You should get a oil press guage FIRST that will tell you a lot about the motors condition.And the excess fuel washed the cyl.walls and took away the oils viscosity also.none of these things are good.

 

stock clearances usually put .05 mm between the piston and wall (or there abouts), does anyone else think .35 mm clearance could be a problem when it is supose to be .05 mm?

 

yep, it took 2 sets of rings to find out that it was overhoned. Number 4 compression number and leak down always sucked ***. When I ask about bearing clearances I am asking what you guys prefer. not so much what happened to my motor because there were a few factors that probably helped blow it up. After I went back to the machine shop about the problem it almost seamed likethey new right away and offered to do all machine work for free. That just leaves me buying new pistons and a rod. I new there was a reason that all of a sudden they didnt want to assemble it after all machine work was done. Shady indead, but I learned my lesson and will be double checking everything myself for now on.

Any way, back on topic, I just want to know your philosophy on bearing clearances and why you feel that way. Some like loose clearances and some like tight. WHY???

thanks john

 

Tight for a daily driver... Play it safe with your investment...

 

I believe it comes from the past when bearing and oil technology wasn't up to par and you had to run extremely large clearences w/at least 50w oil.they have caught up though now look at the factory specs for thr ITR(dont know exactly but relatively tight).Honda doesn't want to warranty an engine,and it revs to the sky.Sometimes it's tough to teach that old dogs new tricks.