Bearing Measurements

[JMofIRW]

Hi,

I would like to post this because answers I get may help a lot of people.

I am currently rebuilding the 7mgte.

On the way out of course I measured everything, Rod bearings all plasti gauged in spec.
My mains clearance measurements were as follows-

1 .051mm (#4 stamped on bearing)
2 .051mm (3)
3 .038mm (3)
4 .051mm (3)
5 .038mm (3)
6 .038mm (3)
7 .051mm (3)

Standard Clearance is .030 - .048 which means I have 4 with too much large of a clearance. I am guessing I would have to get oversized bearings by .010 about to drop the clearance to about .041. I am just in need of advice and help with this.

I would just like a little technical assistance.

Thank you

 

[grimreaper]

Something isnt right with those measurments. The bearing clearance measure .025mm? Tsrm spec is min 0.030-0.048mm. Max is .07mm. If you measured the bearing wall itself thats not right either.
a .25 undersize bearing shows as 2.123-2.133mm per tsrm.

 

[JMofIRW]

Which is why I am posting. everything is in good condition in the block, so when I go home I will post all the numbers, but I am trying to see why 2 bearing clearences may come up as .025mm all the others were .038 i think it is, which as you said is within spec.

 

[grimreaper]

What i meant was something didn't look right with your post and the numbers you gave. Not with the actual measurements. Did you/they measure the actual bearing as well?

 

[JMofIRW]

No I did not, I just measured clearances so far, I am going back home this weekend to record all the number matchmarks on the bearings and the numbers I got for clearances. As soon as i get home I will measure the actual bearings too.

 

[JMofIRW]

Posted the main clearance measurements on first post. please let me know what you all think.

 

[IJ.]

RWHP goals on this engine?

 

[JMofIRW]

Stock basically, I am rebuilding now to keep it stock for 1 year. I am not changing Main Studs, or rod bolts. The engine is clean inside and only needs cleanup hone/cleanup mill no pitting or damage anywhere except my timing cover.

So no more than 300rwhp. 3 inch exhaust, intercooler, and thats really all. Suspension and other things that won't effect power are done as well.

It had a BHG so I just want to do it right, machine work, cometic mhg, arp headstuds.

I only put a w58 for my low power goals as well.

I have had the car nearing 2 years and am excited to finally get to rebuild.

 

[IJ.]

The .051 is going to work but you're going to struggle for Oil pressure at idle unless you mod the rest of the Oiling system and run fairly heavy oil.

Usually only do this over 500rwhp to help the bearings live a bit better with the block/crank deflection.

 

[grimreaper]

IJ: what type of clearances did you run for the cam caps when opening up the bottom end and using thicker oil? I see a few guys follow this path for the higher hp goals but haven't seen any mention anything about the clearances for the cams..

 

[IJ.]

On the high side of the stock spec Grim.

 

[JMofIRW]

I can order the stock toyota bearings then? Struggling for oil pressure at idle, won't that be a problem? What options would I have? Any idea why the clearance would be so high? The motor supposedly has 75k on it, I am fairly sure someone just slapped a MHG on it backwards, so when I bought it it ran, but I knew better...


thanks for the advice, the teardown went well with this being the only thing that worries me, i just want this 7m to be reliable for awhile at this HP.

 

[IJ.]

"Should" be able to juggle select fit Toyota bearings to close it down some.
(theres a chart in the TRSM covering it all)

 

[JMofIRW]

So are you saying, since on the TSRM chart, bearing 5 is the thickest for the ones that measured .051, i "should" be able to get the number 5 stamped bearing for those and close up the gap a little, then i should be OK?

I am figuring this goes for the rod bearings too? Please correct me if I am mistaken.

 

[IJ.]

You need to measure everything then use the chart and see if there are bearings that will close the gaps down to spec.

 

[I6Boost]

I can order the stock toyota bearings then? Struggling for oil pressure at idle, won't that be a problem? What options would I have? Any idea why the clearance would be so high? The motor supposedly has 75k on it, I am fairly sure someone just slapped a MHG on it backwards, so when I bought it it ran, but I knew better...


thanks for the advice, the teardown went well with this being the only thing that worries me, i just want this 7m to be reliable for awhile at this HP.

Possibly, but just to make sure, Shim your oil system.
It will increase your oil pressure a little.

Use the search button here, theres a few threads on how to do it.

-

So your re-using your old bearings?

IMO if your already down there inside the crank you mise well go spend the $187.29
on toyotas select fit main bearings.

Then the Rod bearings are like $15.27 a piece or something.'

But yea like IJ said above, go buy these select fit bearings, install and plastiguage.
It should bring your clearences up a smidge and or just juggle them around ie: if one is too
close of a clearence and one is too large of a clearence, switch them.

I just got done doing all this a week ago and IJ helped me out alot.

 

[IJ.]

Measure first THEN buy bearings
(PPPPPP aka Proper Planning Prevents Piss Poor Performance)

 

[JMofIRW]

I do not plan to reuse bearings. I am reusing main bolts and rod nuts.

I measured the clearances and I'll have my machinist Mic the crank since he has it. I am not buying anything until the measuring is figured out. I waited a long time to even do this, so I do not mind waiting for it to be done properly.