Reuse main cap bolts or replace?

[Tim_K]

I'm building an '89 common block, and just got it back from the machine shop. The machinist, who has built a lot of racing engines and some 2.2's, says I can reuse the stock main cap bolts.

Are they the stretch type like the head bolts? What kind of torque value do they get when installed?

I'll buy new bolts if needed, but want to know about this anyway.

[GLHS0658]

You can reuse them. If you buy new bolts (ARP), you should have the mains align honed. The new stronger bolts will have better clamping force.

[Tim_K]

I'm not reusing these bolts now. I had them all sitting at 30 ft-lbs., and went to give them their 1/4 turn as specified in a Haynes manual. The first cap bolt clicked the torque wrench which was set at 100 ft-lbs. just before it got a 1/4 turn on it. The second bolt went PAST a 1/4 turn and still hadn't clicked! So I quickly backed them both off to 30 again. New bolts on the mains!

Any idea of an actual torque number instead of this 1/4 turn BS?

[Tim_K]

I think these bolts will be okay now. I talked to the machinist about them who has rebuilt lots of these kinds of engines, and he says you really can't go by a set torque number. Don't really know if that's true or not. I'm used to REAL bolts on 1970's chrysler engines, so all this is new to me.

I went back and set the torque wrench to 80 ft lbs. I figure 80 pounds is plenty of torque for an engine like this. All 10 bolts clicked the wrench after about 1/8 of a turn, then they still received their full 1/4 turn after 30 ft lbs. So I think it's okay now.

And the prices for these junk bolts are insane! Auto parts stores here can't get them, and dealers wanted $120-$150 a set! I could get ARP main studs for $85!

[glhsken]

LOL Junk bolts.... Hmmm Stock motors go 200K often yep Junk...

Why the heck does everything need questioned. 30 ft lbs and a 1/4 turn... self explanatory. That's right. these aren't REAL MOPAR engines from the 70's (you know.. the v-8's making 150 hp)

[GLHS0658]

I know this subject has been beat to death
but Ken, explain it !!! Some people just do NOT know the difference.

Regular bolts clamp down with a certain torque amount to hold....
whatever

torque to yield bolts were designed to clamp better! yes better!
The TTY bolts get torqued to just before they coke bottle themselves. Then you have maximum clamping force.
Also there are other variables such as resistance in the threads, the head of the bolt bottoming out against the surface, etc.
Torque to yield bolts have more tolerance to these variables since you are not going to a torque number. You torque to a lower number then turn 90 degrees. And you should use a torque angle meter....Lisle tools makes a decent one, easy to use/find.

Having said all that...you still need to clean/chase the threads in the block. AND you should use a light weight oil or graphite on the threads AND under the bolt head to minimize resistance.
This gives a better (accurate) torque reading.

This is also why you are not supposed to reuse them. The previous person may have over torqued them and exceeded their
limit. Although factory installed bolts are torqued correctly, I would still replace them due to their age when a rebuild occurs.

[glhsken]

Quote:

Originally posted by GLHS0658 I know this subject has been beat to death but Ken, explain it !!! Some people just do NOT know the difference.

You are right... my apologies... I just did not appreciate the attitude displayed in virtually every post regarding the cars. If you don't like them.. don't build them.