Need quick answer on bearing clearance.
Thread Starter
Drifting
Joined: Apr 2002
Posts: 1,716
Likes: 4
From: New Baden Illinois
Need quick answer on bearing clearance.
I am finally putting together the short block and I am measuring all of the clearances. The main bearings all measure alright.
I did a search on the forum and found the rod bearing clearance is supposed to be .0025. I have measured twice and got .0015. Is this too tight?
I did a search on the forum and found the rod bearing clearance is supposed to be .0025. I have measured twice and got .0015. Is this too tight?
Le Mans Master
Joined: Apr 2006
Posts: 5,403
Likes: 95
I am finally putting together the short block and I am measuring all of the clearances. The main bearings all measure alright.
I did a search on the forum and found the rod bearing clearance is supposed to be .0025. I have measured twice and got .0015. Is this too tight?
I did a search on the forum and found the rod bearing clearance is supposed to be .0025. I have measured twice and got .0015. Is this too tight?
Thread Starter
Drifting
Joined: Apr 2002
Posts: 1,716
Likes: 4
From: New Baden Illinois
Before I have to send parts back to Ohio Crankshaft again, let me make sure that I am doing this properly.
I put the piston in the hole, with the rod attached and the bearing on the rod. I fit it to the journal, put a piece of plastiguage on the journal, fit the rod cap (w/ bearing) to the rod, and torque it to 45 ft/lbs. Then remove the cap and measure the imprint with the plastiguage scale.
Did I pretty much cover it?
I put the piston in the hole, with the rod attached and the bearing on the rod. I fit it to the journal, put a piece of plastiguage on the journal, fit the rod cap (w/ bearing) to the rod, and torque it to 45 ft/lbs. Then remove the cap and measure the imprint with the plastiguage scale.
Did I pretty much cover it?
Melting Slicks
Joined: Aug 2004
Posts: 2,165
Likes: 950
From: Keizer Oregon
I am finally putting together the short block and I am measuring all of the clearances. The main bearings all measure alright.
I did a search on the forum and found the rod bearing clearance is supposed to be .0025. I have measured twice and got .0015. Is this too tight?
I did a search on the forum and found the rod bearing clearance is supposed to be .0025. I have measured twice and got .0015. Is this too tight?
I have found a big difference in color to color measuring when close to the edge of the tolerance of the plastigauge. Make sure your torque wrench is dialed in right. A difference of a few ft/lbs will change your readings big time.
Good luck...
Thread Starter
Drifting
Joined: Apr 2002
Posts: 1,716
Likes: 4
From: New Baden Illinois
What are you using to measure? Plastigauge? Which color? Red or green?
I have found a big difference in color to color measuring when close to the edge of the tolerance of the plastigauge. Make sure your torque wrench is dialed in right. A difference of a few ft/lbs will change your readings big time.
Good luck...
I have found a big difference in color to color measuring when close to the edge of the tolerance of the plastigauge. Make sure your torque wrench is dialed in right. A difference of a few ft/lbs will change your readings big time.
Good luck...
I am using the green plastiguage. I double-checked the torque wrenched and it is right at 45.
I just miked the journal and it is right at 2.100. The bearings are stamped STD.
What gives?
Advanced
Joined: Feb 2007
Posts: 90
Likes: 0
Measuring clearances
Plastigage is not an accurate tool to measure anything. If you want to be sure about the measurements you should invest in a few of the right tools. With all the tool seller's available it pays to make the small investment.
A simple set of mikes and a couple of inexpensive bore guages will let you check all the clearances accurately on your own. Rods, mains, pin to piston, pin to rod, piston to wall, etc.
If you need more room King has the bearings you need.
Harry P. Hunter
A simple set of mikes and a couple of inexpensive bore guages will let you check all the clearances accurately on your own. Rods, mains, pin to piston, pin to rod, piston to wall, etc.
If you need more room King has the bearings you need.
Harry P. Hunter
Burning Brakes
Joined: Nov 2002
Posts: 952
Likes: 44
From: NC
I am finally putting together the short block and I am measuring all of the clearances. The main bearings all measure alright.
I did a search on the forum and found the rod bearing clearance is supposed to be .0025. I have measured twice and got .0015. Is this too tight?
I did a search on the forum and found the rod bearing clearance is supposed to be .0025. I have measured twice and got .0015. Is this too tight?
James
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Thread Starter
Drifting
Joined: Apr 2002
Posts: 1,716
Likes: 4
From: New Baden Illinois
I just plastiguaged #3 and #4 and it was the exact same. The plastiguage has to be wrong. The journals are miking out exactly and the bearings are all standard.
Burning Brakes
Joined: Nov 2002
Posts: 952
Likes: 44
From: NC
Personaly I think you will be ok. I had a few bearings that were like that And I think it is just an error with the plastigauge. It shows that you do have clearance, it is just tight. I could be completely wrong.
I understand what you are saying now about the oil...I didnt think about it having a lower zinc content.
I understand what you are saying now about the oil...I didnt think about it having a lower zinc content.
Le Mans Master
Joined: Apr 2007
Posts: 7,353
Likes: 72
From: Graceland in a Not Correctly Restored Stingray
As much time, effort and money as you're investing in doing in your own build, I'd advise getting the inside mic's or snap gauges. The relative cost isn't that significant, and you'll sleep better knowing for certain you've gotten this critical spec. correct.
Thinner oil isn't the right solution. Crutches are Bubba's way out.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
Remove the cap and bearing halves from the piston rod in question. Feel along all of the bearing mating surfaces with your finger tips...on the inside of the rod journal, bearing cap and outside of the bearing pieces. See if there are any "high spots" that could give you a false reading. Sounds like the others are OK...I'm surprised that this one is different. If you find high spots, dress them down with mild Scotch-Brite on the outside of the bearing halves [don't do anything to the inner surfaces], and fine stone, etc. on steel parts. Clean everything again and reassemble to check it again. You might check the plastigage a couple of times in different areas around the journal. If you get at least .0015" wherever you check it, you should be OK.
Le Mans Master
Joined: Apr 2007
Posts: 7,353
Likes: 72
From: Graceland in a Not Correctly Restored Stingray
0.0015" may work OK, but it will most definitely cost horsepower vs. 0.0025". Example: two identical 455 Buicks personally blueprinted with 0.0005" difference in bearing clearance. The looser one was 0.7 quicker in the 1/4 mile.
Last edited by TheSkunkWorks; May 21, 2007 at 01:52 AM.
Thread Starter
Drifting
Joined: Apr 2002
Posts: 1,716
Likes: 4
From: New Baden Illinois
I know a guy that owns the local automotive repair shop in town. I will see if he has a set of inside mics or snap guages I can borrow. Or, I can just take one of the rods and bearings to him to mic.
Racer
Joined: Apr 2004
Posts: 401
Likes: 0
From: IL
Who's rod bearings are you using?
Your crank's rod journals are right at spec of 2.099"-2.100" and your .0015" is at the "tight" end of spec. Most guys use .0025" as a mark to decrease the effects of friction and create more hp. Stock is .0015"-.002".
We use to measure each rod bearing halves and match them as a pair. Using a ball mic adapter on a 0-1" mic place the ball on inside of curve and measure thickness of halves. Place them on paper with each measurement written below, then once their all done match based on one thick and one thinner. Because of the top coating on bearings this thickness varies, that's why your matching halves, so one rod isn't "tighter" than the other. Shops typically have more bearings in stock and will measure more then one set and use all thinner or thicker depending on need. But in your case all you can do is match thin/thick to average out each rod. Example, let's say each half is .062" thick but if measured with ball adapter you'll see range of .0621" - .0629". If you put to "9's" together you'd be over .001" thicker on that one set/rod compared to others with .0621" halves.
Note, if your using FM perf bearings this is not required as there is no top coating and bearings are typically withing .0001" of each other.
Hope this helps,
Later.
Your crank's rod journals are right at spec of 2.099"-2.100" and your .0015" is at the "tight" end of spec. Most guys use .0025" as a mark to decrease the effects of friction and create more hp. Stock is .0015"-.002".
We use to measure each rod bearing halves and match them as a pair. Using a ball mic adapter on a 0-1" mic place the ball on inside of curve and measure thickness of halves. Place them on paper with each measurement written below, then once their all done match based on one thick and one thinner. Because of the top coating on bearings this thickness varies, that's why your matching halves, so one rod isn't "tighter" than the other. Shops typically have more bearings in stock and will measure more then one set and use all thinner or thicker depending on need. But in your case all you can do is match thin/thick to average out each rod. Example, let's say each half is .062" thick but if measured with ball adapter you'll see range of .0621" - .0629". If you put to "9's" together you'd be over .001" thicker on that one set/rod compared to others with .0621" halves.
Note, if your using FM perf bearings this is not required as there is no top coating and bearings are typically withing .0001" of each other.
Hope this helps,
Later.
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
I am finally putting together the short block and I am measuring all of the clearances. The main bearings all measure alright.
I did a search on the forum and found the rod bearing clearance is supposed to be .0025. I have measured twice and got .0015. Is this too tight?
I did a search on the forum and found the rod bearing clearance is supposed to be .0025. I have measured twice and got .0015. Is this too tight?
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CB-663P 0.0012"-0.0037"
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CB-663H 0.0009"-0.0030"
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-edit-
If you run hi-volume oil pump and/or real thick oil ... Set it toward loose end of scale.
Last edited by jackson; May 21, 2007 at 12:20 PM.
Thread Starter
Drifting
Joined: Apr 2002
Posts: 1,716
Likes: 4
From: New Baden Illinois
The bearings are Clemex bearings.
One other thing. When I used the plastiguage, it pretty much stuck to the crank and bearing and I had to get the plastic off of the inside of the bearing with my fingernail. Is the bearing still alright to use? I assume that it is because there is no other way to use the plastigauge.
One other thing. When I used the plastiguage, it pretty much stuck to the crank and bearing and I had to get the plastic off of the inside of the bearing with my fingernail. Is the bearing still alright to use? I assume that it is because there is no other way to use the plastigauge.
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
The bearings are Clemex bearings.
One other thing. When I used the plastiguage, it pretty much stuck to the crank and bearing and I had to get the plastic off of the inside of the bearing with my fingernail. Is the bearing still alright to use? I assume that it is because there is no other way to use the plastigauge.
One other thing. When I used the plastiguage, it pretty much stuck to the crank and bearing and I had to get the plastic off of the inside of the bearing with my fingernail. Is the bearing still alright to use? I assume that it is because there is no other way to use the plastigauge.