Can You Re-Use Main Bearing Cap Bolts?

[tpepmeie]

Howdy gents,

Reading the FSM, it appears that the main cap bolts are Torque to Yield, and are recommended to be replaced after use. Is this, in fact, the case?

If so, where is the best place to get replacement bolts (2-bolt motor)? Are there any upgraded bolts or studs? I know Bill K used to sell the stud kit, but I think it required some machining of the block and loss of the alignment dowels.

Thanks in advance,

Todd

SOLUTION: Yes, you can re-use them if they are in good condition.

[phrogs]

good luck finding some.

I have been searching for a while for my spare motor, try kurt he has some of them but I am missing the washers as well and he doesnt have those I think he might have the main cap bolts.

I don't think they must be replaced

[Polo-1]

Sent you a pm

[flyin ryan]

Sent you a pmThis will be good :cool:

[A26B]

Todd,
I had this very discussion with Graham last year at BG. You were there too, sure wish you had been there for the talk-about.

Summary: Torque to yield doesn't actually mean the bolt exceeded yield strength and suffered permenant deformation which would occur if yield had been exceeded. The differential thermal expansion rates of steel & aluminum would however, place additional longitudinal stress on the bolts, for which no empirical data was ever obtained. It could be calculated but would probably assume "0" deformation under the bolt head or through the thread engagement.

Bottom line: Graham didn't think there would be any adverse results from reusing them. FWIW, this same line of thinking also applied to the head bolts.

He also went on to say that he was opposed to increasing the main bolt dia because of the possibility of encountering casting porosity during the bolt thread enlargement. It would be difficult to determine and would result in potentially catastrophic results.

Having said all of this, I feel confident that Graham was probably thinking along the lines of a stock or mild rebuild. Considering what you are doing, this bit of info probably doesn't have much value to you, except for the larger main bolts/studs.

[flyin ryan]

He also went on to say that he was opposed to increasing the main bolt dia because of the possibility of encountering casting porosity during the bolt thread enlargement. It would be difficult to determine and would result in potentially catastrophic results.

I agree, need to have the meat in the casting first. If the surrounding material isn't there...

[tpepmeie]

Sent you a pm

:jawdrop: Kevin, thanks.

[rkreigh]

Todd,
I had this very discussion with Graham last year at BG. You were there too, sure wish you had been there for the talk-about.

Summary: Torque to yield doesn't actually mean the bolt exceeded yield strength and suffered permenant deformation which would occur if yield had been exceeded. The differential thermal expansion rates of steel & aluminum would however, place additional longitudinal stress on the bolts, for which no empirical data was ever obtained. It could be calculated but would probably assume "0" deformation under the bolt head or through the thread engagement.

Bottom line: Graham didn't think there would be any adverse results from reusing them. FWIW, this same line of thinking also applied to the head bolts.

He also went on to say that he was opposed to increasing the main bolt dia because of the possibility of encountering casting porosity during the bolt thread enlargement. It would be difficult to determine and would result in potentially catastrophic results.

Having said all of this, I feel confident that Graham was probably thinking along the lines of a stock or mild rebuild. Considering what you are doing, this bit of info probably doesn't have much value to you, except for the larger main bolts/studs.



I was there and overheard this discuss at JVDs. graham is the man. he also didn't think studs were all that hot either as the bottom end is plenty beefy.

you can magnaflux the bolts, but I would chase the threads, lube em up and reused them. you should be fine.

[Polo-1]

He also went on to say that he was opposed to increasing the main bolt dia because of the possibility of encountering casting porosity during the bolt thread enlargement. It would be difficult to determine and would result in potentially catastrophic results.


I agree, need to have the meat in the casting first. If the surrounding material isn't there...

Also these are " formed " or " rolled " threads NOT cut threads. The blocks are threaded to the bottom of the holes.

[HAWAIIZR-1]

So how many folks have done a rebuild with old bolts and how many folks with new bolts only? I have never had issues in the past with SBC or BBC rebuilds using the old bolts.

[Polo-1]

SBC BBC are not torque to yield bolts, same as SBF BBF and Mopar. The New Stuff is, and are older LT5.
From what I have heard other builders are doing the reuse on the mains, as you can not buy new. Nothing from ARP either.

[HAWAIIZR-1]

SBC BBC are not torque to yield bolts, same as SBF BBF and Mopar. The New Stuff is, and are older LT5.
From what I have heard other builders are doing the reuse on the mains, as you can not buy new. Nothing from ARP either.

Thanks for explaining, yeah I have to get the correct tools too for torque to yield. I want to save where I can, but not at the expense of doing it correctly. I just took off the oil pan tonight and it looks like 10 bolts if going new, not counting the lower case bolts. Kurt White has them new, but I have not looked yet to see what they cost; I'm scared. If the builders are reusing them then I would do it too. I guess I better invest in a good torque angle meter too.

[Polo-1]

Kurt does not have the larger bolts for the 2 bolt blocks. He does have the smaller bolts for the 4 bolt blocks 93-95.

A torque angle guage is a must.

[bdw18_123]

I just bought a torque angle meter yesterday.

So, it sounds like its ok to reuse the main cap bolts (at least once anyway), how about the rod cap bolts? Can you reuse those too?

[Polo-1]

Not when you could buy new, or better then new bolts.

http://www.zr1specialist.com/HAT%20Web/products/connecting%20rod%20bolts.htm

[HAWAIIZR-1]

Thanks for the info. I ordered con rod and camshaft bolts from Marc H yesterday. Bad news about the main bolts for 2 bolt blocks (4 each), but I think mine has not been gone through since factory assembly so hopefully okay to reuse. It is such a shame that ARP does not make these. Kurt shows stockage of these, Bolt, Crankshaft Bearing Cap M10 - 1.5 - 111 (http://www.whiteracingproducts.com/index.php?main_page=product_info&products_id=102) but maybe his site is not current? I have a bunch of other tools to buy too and have slowly been switching to Snap On as I have been finding that Craftsman is just not cutting it for certain things and it makes a difference with the right, high quality tools.

[HAWAIIZR-1]

On another note, I love watching the Nelson Racing Engines University ZR-1 videos....this guy is awesome and makes it look so easy. :worship:

[Polo-1]

Yes 10mm are the small mains (2,4) 12mm are 1,3,5. No one has the 12mm.

For the later 4 bolt blocks 8mm and 10mm.

I have called and emailed Nelson.... No returns.

[Jeffvette]

I have called and emailed Nelson.... No returns.

Yep, he did the same thing when he ordered a set of bearings.

[HAWAIIZR-1]

Yes 10mm are the small mains (2,4) 12mm are 1,3,5. No one has the 12mm.

For the later 4 bolt blocks 8mm and 10mm.

I have called and emailed Nelson.... No returns.

Okay, thanks I understand now. That really sucks.

[HAWAIIZR-1]

SBC BBC are not torque to yield bolts, same as SBF BBF and Mopar. The New Stuff is, and are older LT5.
From what I have heard other builders are doing the reuse on the mains, as you can not buy new. Nothing from ARP either.

Kevin,

You made me read to try to get smart about torque to yield and thank goodness for the internet there is so much information including video if one is interested. I have also ordered some engine blueprinting/building books. In addition, while looking for a good torque angle meter I think I will get the Torque Wrench, Electronic, TECHANGLE, Flex Ratchet, 12.5 to 250 ft. lbs., 1/2" drive

http://www.torqueinlesstime.com/

This thing is awesome and I think I'll get both the 1/2" and 3/8" drive.

Thanks again!