I pulled my 26 engine to install a new cam and thought i would check the rod clearance,i plastigaged them and get a .0025 clearance is this OK or do i need to pull a shim,they haven't been checked since the engine was rebuilt in 2003,it does not knock or have any problem,just thought i would check,i have about 7000 miles.
That is too much. 0.0015 is ideal. It will begin to knock at 0.003. Why in 7000 miles did the clearance go to 0.0025? What did you start with? Was the crankshaft ground? Are the journals round? You should get many more miles than 7000 before shims need to be adjusted.
Jack, it may have more miles i am guessing,the engine was rebuilt by Ron Miller,what should the torque value be on the rod cap bolts?.
I assume you have checked the rods. Please also check the mains, especially the centre main.
35 LBS for the rods
Rick, pulling a shim from each side will be to much as the shims are in 2thou incroments, it may take several checks with the plasti to find which side you can remove just 1 shim.
Rick -- You can make shims from aluminum foil which will be from 1 to 1.5 thou, depending upon the type. Those will often make things "just right" in your quest for the ideal .0015" of clearance. Jack P. is correct (of course), that's the number you should shoot for. The rods won't usually talk to you at .0025", but they are getting close to being too loose.
I would not trust aluminum for shims. Several people I know have tried it and had the aluminum work out leaving the cap able to move a bit which could lead to serious trouble.
Just my penny and a half worth.
Drive carefully, and enjoy, W2
I'm no expert, so take this with a grain of salt. If you are too loose, but removing just one shim makes you too tight, you could probably remove that shim and use a little Time Saver and have the proper clearance in just a few minutes. No gallon of grey sludge will be created. I promise.
By removing one shim the guys above do not mean the whole pack only one leaf. One leaf will not make the rod too tight. after you tighten the rod back down see if you can slide it back and forth along the crankshaft.
If you have .0025 clearance and you remove a .002 shim from each side, leaving you .0005 clearance you'll still be in good shape. Take the recommended .0015 as a maximum. If the bearing "likes" to have a little more clearance it will create it itself.
I understand they are not removing the entire stack. I got the impression that they had run into the problem that they were too loose, but by removing one .002" 'leaf', they were then too tight. I've seen some people say that you should always remove an equal number of shims from each side. I personally don't agree with that. I feel that it is safe enough to remove a single shim from one side, but you wouldn' want to continue to remove single shims from the same side each time you take them up. But, for those that would rather keep equal numbers on both sides and each shim is .002 thick, perhaps Time Saver will give them an acceptable alternative to being either .0025 or .0005.
You could also go the old fashioned route of hand scraping.
OR, simply leave the shims alone and file the cap slightly since all you want is to reduce the clearance by .001.
Well since Jerry brought it up, what do you do when you have no shims left? On an otherwise good running engine, how many of us would tear it down and rebabbitt and how many of us would file the caps? And for that matter, how many of us would SAY we would tear it down, but would really just file the caps when we were REALLY faced with the situation?
You may be able to get away with removing .001 by filing, but I would never personally recommend it to anyone other than a skilled machinist who has a surface plate and indicator gage available.
Myself, I'd never do that when I have a pack of shims available on a near-new engine. Removal of one .002" shim from one side and then as Dave said, be sure the rod will still move on the crank when gently tapped with a hammer per "the bible".
I've filed with success on an old "clanky" engine that had no shims at all, and had about .005 clearance (blocked oil line was it's undoing)...actually over-filed so that I could get a shim pack installed, then had to scrape to regain the 'thou or two that I lost in bearing parallelism on the caps.
Also, I understand the value of Timesaver and similar products, but don't think it's really needed for this (Rick's) circumstance.
If every time an engine needed tightening, one were to file the cap, eventually you will have steel to steel and both the rods and the crankshaft will be worn out. Many years ago, it was likely OK to file the cap a little, but over the years you will wear it out. I, personally will have the bearings re-poured when I run out of shims. You should also look at the upper side of the rod bearing. Most of the wear is on the upper side, and it can become cracked or worn out, and need to be repoured. I don't think that is the case here, because the clearance is so small and the engine was recently rebuilt, but it is a general rule to check the upper half of the rod bearing, not just the cap.
I think we are going overboard here. .0025 on the rods is acceptable. After 7000 miles the clearances have opened up to what is comfortable for those rods and that crank.
Now if you had the engine out for another reason, you might be tempted to get them a bit closer, but absent that, I wouldn't do a thing.
I thought I had to replace the pan in my 10 so I had to pull the engine. Since it was out of the car I checked and adjusted the mains and rods. All the mains had opened to .003 and one or two rods as well. I took out one leaf of shim on the cam shaft side of the offending bearings and did a valve job. But remember I had the engine out for other reasons. After the adjustments I drove it carefully for the first one hundred miles or so to break in the new clearances. I admit it does run better but I suspect that is due to the valve job. Neither the mains nor rods made noise. In fact in ran darn good before I pulled the engine.
Thanks to everyone who gave suggestions,all are good,I had a friend come over and he told me i was using the wrong plastigage,i had the red so i ordered the green and rechecked the clearance and it is showing about .016/.017, so live and learn, again thanks
Do you mean .0016/.0017?
OOps, something wrong with your measurements there, Rick!
Yes, .0016 etc. I blame everything on old age.