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Connecting rod side clearances

Started by Mrbill426, May 30, 2021, 09:21:38 PM

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Mrbill426

@TGGodfrey  I have a whole bottle of the ARP fastener lube and have been using it in the threads and under the nut faces.  I will (try to) check to see if the rod bearings are contacting the sides of the crank weights but I don't think so, they sort of set back from the edge of the rods; they are Clevite 77 bearings in Mopar Performance boxes... well six of them are and two are Mahle but have identical part numbers on the back of the bearings.  Maybe Clevite is now Mahle?
I am trying to get past this step but don't want things locking up on me when I run it.  It does turn over smooth but with some good effort with a breaker bar; I suppose that is normal.



Quote from: TGGodfrey on May 31, 2021, 10:16:49 PM
Rod bolts on and off..... yes you can do that as long as you have moly or oil on the threads.  IF you torque them dry, you will gall the threads and snap on one off. Then you will have to go through weight matching a new bolt to the old one.

Calipers are not the best way to measure this.  there is a lot of room for error with them.  Stick with feeler gauge between the two installed rods. 

Something to take notice of..... as mentioned earlier, when a crank is ground, the machinest may leave a fillet at the end of the grind (corner of the rod pin to the weight).  If the bearing makes contact with the fillet, the bearing needs to be clearanced.  There is a specific tool for that.  This is also why many bearing manufacturers do not take the bearing material all the way to the edge of the rod.  Other bearing manufacturers will chamfer the rod bearings.

The rod set with the .005 clearance, check it with a feeler gauge, see if .006 will fit.  if it will, you are fine, factory spec is .006-.014 as mentioned.  I have built larger clearances in both race motors and restoration though.   

EDIT:  Did all these rods go back in the same location they came out of?  The .010 makes me wonder if a couple rods got moved between those two rod pins.
Terry

Mrbill426

@TGGodfrey I marked all the rods and caps 1-8 before they went to the machine shop.



Quote from: TGGodfrey on May 31, 2021, 10:16:49 PM


EDIT:  Did all these rods go back in the same location they came out of?  The .010 makes me wonder if a couple rods got moved between those two rod pins.
Terry

TGGodfrey

Turnover is normal.  Those pistons use a heavy high friction ring set.  Thats normal to use a bar or ratchet.  Liek I said, usea  feeler gauge.  I bet you get .006 or better.  Your fine at that point.

Terry


Mrbill426

@TGGodfrey isn't going to happen with a ratchet; not for me anyway.  I used Speed Pro file fit plasma rings and hopefully got the gaps right at around .017" top ring and .020" on second ring.  I will get busy with the feeler gauges today.  Looking through my manuals I am finding a variety of different spec ranges though ranging from .006" to .017"; my machinist called me back that he had found a spec going as tight as .003".  I suppose I have been forgetting that the oil in there will be under pressure and will be forcing its way between those rapid moving parts even when tightly packed.


Quote from: TGGodfrey on June 01, 2021, 12:06:54 AM
Turnover is normal.  Those pistons use a heavy high friction ring set.  Thats normal to use a bar or ratchet.  Liek I said, usea  feeler gauge.  I bet you get .006 or better.  Your fine at that point.

Terry

TGGodfrey

@Mrbill426 the factory spec is .006-017 so like i said, you should be fine.

As far as your ring set, the Speed pro rings require .004 per inch of bore on the top ring and .005 on the second ring. 

If you are standard bore 4.010 then
4.010 x .004 = .01604.   .017 is acceptable
4.010 x .005 = .02005.   .020 is acceptable

If you are .030 over
4.040 x .004 = .01616.  .017 is acceptable
4.040 x .005 = .0202.    .020 is still acceptable.

You have no reason to worry unless this is more than just a street motor.

As far as the ratchet, depends on the ratchet you are using.  Little 8" craftsman, yeah prolly not but a 12-14" 3/8 Ratchet, you should be able to rotate the shortblock.
T

1 Wild R/T


Mrbill426



1 Wild R/T

That piston & your intended usage I'd shoot for .017 on the top ring & .020 on the second ring... Tight is bad, a couple thou loose won't make a measurable difference but try for .017... And the second ring should be a little wider, trapping pressure between the rings causes ring flutter....

Break-away torque should be around 30-35 Ft/Lb & rotating torque should be 15-20 Ft/Lb

Mrbill426

Yes that is right about where the rings are, no smaller.  It's bored to 4.060 (+.020).
The side clearance I think is good to go too.


Quote from: TGGodfrey on June 02, 2021, 11:43:58 AM
@Mrbill426 the factory spec is .006-017 so like i said, you should be fine.

As far as your ring set, the Speed pro rings require .004 per inch of bore on the top ring and .005 on the second ring. 

If you are standard bore 4.010 then
4.010 x .004 = .01604.   .017 is acceptable
4.010 x .005 = .02005.   .020 is acceptable

If you are .030 over
4.040 x .004 = .01616.  .017 is acceptable
4.040 x .005 = .0202.    .020 is still acceptable.

You have no reason to worry unless this is more than just a street motor.

As far as the ratchet, depends on the ratchet you are using.  Little 8" craftsman, yeah prolly not but a 12-14" 3/8 Ratchet, you should be able to rotate the shortblock.
T