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engine guys, #3 bearing cap won't seat ? **update**
#461809
09/07/09 01:36 PM
09/07/09 01:36 PM
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Joined: Jan 2003
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Frostbitefalls MN (Rocky&Bullw...
gregsdart
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While measuring main bearings, # 3 came out with serious differences between the front side of the bearing and the back side. All measurments done at 12 oclock/six oclock, 90 degrees to the parting line. Front side, .0025. Back side, .004! Pulled the cap off, looked it over for obvious things like debris under the cap, a nick on the cap or block. I took the studs out and ran a stone over the mating surfaces lightly to see if anything showed up. Nothing. There is no material from cap walk affecting it, looks good. I tried another bearing, same readings. I pulled the cap off, and reset the dial bore gauge to that diameter, and got the same thing, back side over .001 too big. Checking the main bore, it is as if the cap is cocked in the block, the measurements taper perfectly from one side to the other. It actually measured .0017 difference. I am stumped. All readings done with studs torqued to spec. Any ideas?
Last edited by gregsdart; 09/15/09 09:12 AM.
8..603 156 mph best, 2905 lbs 549, indy 572-13, alky
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Re: engine guys, #3 bearing cap won't seat properly?
[Re: dvw]
#461811
09/07/09 01:55 PM
09/07/09 01:55 PM
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Joined: Jan 2004
Posts: 27,347
Today? Who Knows?
1_WILD_RT
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Quote:
Could the holes in the cap be so tight that the studs are causing the cap to lean over? I would try a stock set of bolts. If the stud to hole clearance was close and the hole bores were not machined square it could force the cap out of position.
Doug
I agree, with studs sometimes you need to clearance the bolt holes to get the caps to seat properly & with #3 being the thrust bearing it's more critical...
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Re: engine guys, #3 bearing cap won't seat properly?
[Re: 1_WILD_RT]
#461812
09/07/09 01:58 PM
09/07/09 01:58 PM
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Joined: Jan 2003
Posts: 1,633
Jacksonville, NC
RonP
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Quote:
Quote:
Could the holes in the cap be so tight that the studs are causing the cap to lean over? I would try a stock set of bolts. If the stud to hole clearance was close and the hole bores were not machined square it could force the cap out of position.
Doug
I agree, with studs sometimes you need to clearance the bolt holes to get the caps to seat properly & with #3 being the thrust bearing it's more critical...
Had to do exactly that on mine. Been 3 years of beating since. Chuck at Best (his caps) had me open the holes in the cap some and all was well.
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Re: engine guys, #3 bearing cap won't seat properly?
[Re: gregsdart]
#461816
09/07/09 02:27 PM
09/07/09 02:27 PM
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Joined: Nov 2004
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Syracuse,NY
CompWedgeEngines
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Greg,
The best way is to use an adjustable blade reamer. Done many this way. Very common problem. Surprised you didnt have thrust issues with the cap like that. You CAN drill it, especially if you have a good solid Bridgeport or drill press, but I have done both and I prefer the "dial in" ability of the reamer. Technichally the bolts dont do anything but provide the clamping force, and shouldnt even touch the cap, but you dont want to over bore the holes.The cap register provides the right fit. Good luck, hope it works out ok.
RIP Monte Smith
Your work is a reflection of yourself, autograph it with quality.
WD for Diamond Pistons,Sidewinder cylinder heads, Wiseco, K1 rods and cranks,BAM lifters, Morel lifters, Molnar Technologies, Harland Sharp, Pro Gear, Cometic, King Engine Bearings and many others.
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Re: engine guys, #3 bearing cap won't seat properly?
[Re: CompWedgeEngines]
#461817
09/07/09 03:29 PM
09/07/09 03:29 PM
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Joined: Jan 2003
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Frostbitefalls MN (Rocky&Bullw...
gregsdart
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Went out and measured the studs, and cap holes. Studs, .497.
Caps, .530 . Plenty of room in all directions, no binding. I looked at # 1 with the dial bore gauge and came up with results that are similar but not as bad. Also the minimum diameter of the # 1 bearing bore is .0005 looser than #3. I wire brushed the cap to clean off the cap walk gunk but it is still out of tolerance in my mind. Think it is time to have this block line honed. What do you guys think? I don't want to spin a bearing.
8..603 156 mph best, 2905 lbs 549, indy 572-13, alky
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Re: engine guys, #3 bearing cap won't seat properly?
[Re: gregsdart]
#461818
09/07/09 04:00 PM
09/07/09 04:00 PM
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Joined: Aug 2003
Posts: 43,176
Bend,OR USA
Cab_Burge
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Quote:
Went out and measured the studs, and cap holes. Studs, .497.
Caps, .530 . Plenty of room in all directions, no binding. I looked at # 1 with the dial bore gauge and came up with results that are similar but not as bad. Also the minimum diameter of the # 1 bearing bore is .0005 looser than #3. I wire brushed the cap to clean off the cap walk gunk but it is still out of tolerance in my mind. Think it is time to have this block line honed. What do you guys think? I don't want to spin a bearing.
you have plenty of bearing to crank clearences and(if) it has been running okay so far so  it is uo to you, do what you thank is best 
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: engine guys, #3 bearing cap won't seat properly?
[Re: emarine01]
#461820
09/07/09 04:20 PM
09/07/09 04:20 PM
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Joined: Jan 2003
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Frostbitefalls MN (Rocky&Bullw...
gregsdart
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At this time I have more time than money, so I will do my best to get accurate data on where the bearing crush is, and decide from there. If that is in range or reachable I may try a back yard fix. Any input on that is appreciated!
8..603 156 mph best, 2905 lbs 549, indy 572-13, alky
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Re: engine guys, #3 bearing cap won't seat properly?
[Re: gregsdart]
#461821
09/07/09 04:38 PM
09/07/09 04:38 PM
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USA
Ron Silva
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The problem is not the actual clearance measured by the hole diameter vs stud diameter. The hole in the cap may not be consistent and it could be because the stud is not straight after seating in the block. It is very common to have problems when using studs. A bolt will not seat in the hole like a stud will. Think about it. The whole area in the block is threads and will come STRAIGHT out. A stud will not. My Machinist reamed out the holes in my main cap using a reamer. Makes a smoother hole but a drill would be fine. You have nothing to lost by drilling the hole one size larger. I bet that fixes it.
OR you can try intalling the cap temporarily with a BOLT and see what that does (re measure). If that fixes it then drilling the cap hole larger will almost for sure do it.
SRT DEMON ONE SEAT
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Re: engine guys, #3 bearing cap won't seat properly?
[Re: Ron Silva]
#461822
09/07/09 04:42 PM
09/07/09 04:42 PM
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Michigan
Hemiroid
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Quote:
The problem is not the actual clearance measured by the hole diameter vs stud diameter. The hole in the cap may not be consistent and it could be because the stud is not straight after seating in the block. It is very common to have problems when using studs. A bolt will not seat in the hole like a stud will. Think about it. The whole area in the block is threads and will come STRAIGHT out. A stud will not. My Machinist reamed out the holes in my main cap using a reamer. Makes a smoother hole but a drill would be fine. You have nothing to lost by drilling the hole one size larger. I bet that fixes it.
OR you can try intalling the cap temporarily with a BOLT and see what that does (re measure). If that fixes it then drilling the cap hole larger will almost for sure do it.
 Had problems lots of times with studs. I would approach it this way if it were me. No sense driving yourself crazy and spending money if you don't have to 
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Re: engine guys, #3 bearing cap won't seat properly?
[Re: B G Racing]
#461824
09/07/09 05:17 PM
09/07/09 05:17 PM
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Frostbitefalls MN (Rocky&Bullw...
gregsdart
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I tried different bearings, swapping halves to see if it were a bearing issue. It is definitely not the bearings, as the measurements came out differing the same when I measured the bores minus bearings. The back side was still .0015 larger. Plenty of room around the studs, checked for that and found the holes all consistantly .530, studs .497. The studs are perfectly centered, allowing cap placement way forward or backward to get proper bearing alignment of the #3. Plenty of room side to side as well.
Any one have the specs for max minimum bearing bore diameter for proper bearing crush? Standard rb bearings.
8..603 156 mph best, 2905 lbs 549, indy 572-13, alky
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Re: engine guys, #3 bearing cap won't seat properly?
[Re: gregsdart]
#461825
09/07/09 07:51 PM
09/07/09 07:51 PM
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communist bloc of new jersey
jamesc
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Greg you make no mention of what block this is (one you've been running?), mega, stocker? as others have mentioned studs can cause issues even if they're loose in the cap. 25 years ago i had a 340 that wouldn't even turn with studs. not knowing what to do or having the $$$ to hone it i put the bolts back in it. engine ran 11teens and is still together and running this day. just because the engine was correct before and ran OK doesn't mean things can't or won't move some. if you've measured the bores without bearings and are getting bad readings might be time to hone it. also remember even if the numbers are good doesn't mean the bores are in a straight line. the stock FM "book" spec for the bores is 2.9425-2.9430
Last edited by jamesc; 09/07/09 09:43 PM.
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Re: engine guys, #3 bearing cap won't seat properly?
[Re: jamesc]
#461827
09/07/09 08:26 PM
09/07/09 08:26 PM
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Frostbitefalls MN (Rocky&Bullw...
gregsdart
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Jim the block is a megablock, the original block for this motor. Guess you are right, it may have shifted with use, especially with all the flex this thing has had. My biggest concern is I have fairly tight piston to head clearance as it is, and don't want to risk moving the crank up too much. I am at .046 with 6.965 steel h beams and about .001 oversize on piston to bore clearance with 4.500 pistons. I will have to call the shop tomorrow and see what they say. On the bearing bores, I was referring to the diameter without bearings installed. Looks to be about 2.940?
8..603 156 mph best, 2905 lbs 549, indy 572-13, alky
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Re: engine guys, #3 bearing cap won't seat properly?
[Re: gregsdart]
#461828
09/07/09 09:00 PM
09/07/09 09:00 PM
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Joined: Apr 2005
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USA
Ron Silva
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Please stick a couple bolts in there and torque to specs and remeasure. Then report back what you find.
SRT DEMON ONE SEAT
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We found a similar problem at #3 thrust and it was actually cause by #5 cap that the bearing was riding on the radius and creating the issue,that's why I suggest you check all mains. 