How Important Are 4 Bolt Caps

[etriebe]

Well Im Sitting Here And Contimplating Wether Or Not To Put 4 Bolt Caps On My Block. Im In The Middle Of Rebuilding The Engine Again, I Have It All Apart And Bought A 415 Cam And Thinking Of Getting Vortech Heads.; Ive Got An Innovative T66 Pushing 18 Lbs Boost Eagle H Beams. My Stock Main Caps Were Ok For The First 74000 Miles And Last Time I Rebuilt The Engine I Installed Arp Main Studs. Just Wondering If I Should Spend The Extra 450 Bucks To Put 4 Bolt Caps On?

 

[TYTILIDIE]

Re: How Important Are 4 Bolt Caps

I have been told by some very good builders that it can weaken the wall. Or where you mount them, what ever its called. I have also been told it is the best thing you can do for strength. Both ways explained to me have made plenty of sense to me. FWIW, I have never seen a 2 bolt main cap break. But then I dont build engines for a living either. I think its a gamble either way.

 

[JSM]

Re: How Important Are 4 Bolt Caps

The 4 bolt isn't done to prevent caps from breaking, but to keep them from walking around.

Splayed caps are the only way, that way the extra bolts actually get drilled into the side walls. Stock 4 bolts used by gm are not splayed and possible can weaken the ribs over a 2bolt.

It is all an insurance policy and depends how much insurance you want and how hard you plan to push the engine.

 

[Loeryder]

Re: How Important Are 4 Bolt Caps

Cost of 4 bolt < cost of rebuild due to bearing failure.

Splayed 4 bolt mains are a very common mod on motors expected to produce high horses.
I am not sure what RPM or horsepower range they become effective, but it goes back to what Jeff said.
It is insurance and much cheaper than a rebuild especially if the block or crank get ruined.

 

[Robert Lone]

Re: How Important Are 4 Bolt Caps

The 4 bolt isn't done to prevent caps from breaking, but to keep them from walking around.

Splayed caps are the only way, that way the extra bolts actually get drilled into the side walls. Stock 4 bolts used by gm are not splayed and possible can weaken the ribs over a 2bolt.

It is all an insurance policy and depends how much insurance you want and how hard you plan to push the engine.

I agree big time....

 

[Tooky]

Re: How Important Are 4 Bolt Caps

FWIW a small handful of guys have gone at least 11.0's on 2 bolt mains. I will be doing 4 bolts on mine when the time comes.

 

[blk00z28]

Re: How Important Are 4 Bolt Caps

They are charging you $450 to drill and align hone the caps? Wow. My machine shop quoted me (for a v8, he told me to call the owner because he couldn't find the v6 rates on the computer) $350. My buddy who's friends with the place said it will come down to under $300 for a v6, could even be closer to $250.

How much are they charging you to balance the rotating assembly?

 

[etriebe]

Re: How Important Are 4 Bolt Caps

They are charging you $450 to drill and align hone the caps? Wow. My machine shop quoted me (for a v8, he told me to call the owner because he couldn't find the v6 rates on the computer) $350. My buddy who's friends with the place said it will come down to under $300 for a v6, could even be closer to $250.

How much are they charging you to balance the rotating assembly?

I THOUGHT IT WAS KINDA PRICEY MYSELF, BUT IF ITS GOTTA GET DONE ITS GOTTA GET DONE, JUST BE DOWN A LITTLE LONGER I GUESS.
FOR A BALANCE THEY SAID $175.

 

[turbodig]

Re: How Important Are 4 Bolt Caps

I THOUGHT IT WAS KINDA PRICEY MYSELF, BUT IF ITS GOTTA GET DONE ITS GOTTA GET DONE, JUST BE DOWN A LITTLE LONGER I GUESS.
FOR A BALANCE THEY SAID $175.

I wouldn't bother on a < 500 hp build. More than that, go for it.

90%+ of bearing failure is due to deto, not block flex or cap walk or oiling, or any of the other normally blamed cuases.

Spending the $475 on a good tune or tuning equipment will make your motor last much longer than the caps alone will.

 

[turbodig]

Re: How Important Are 4 Bolt Caps

Dig: would you please take a moment to explain the "chain of events" by which detonation causes bearing damage?

I'm assuming the 'banging' on the crank causes 'overload' and momentary metal-to-metal contact. This damage disrupts the bearings' load capacity, and more damage continues to occur?

I ask, because I just recently had to replace all the bearings, and turn the crank in my otherwise stock Ty. I am still at a loss as to what caused this in an otherwise very nice 9,500 mile engine.. There WAS an episode of 30+PSI (waste gate hose came off the turbo nipple) detonation. As I recall, the noises began shortly thereafter.............

Thanks,
Dave

You pretty much nailed the sequence of events. The excessive downward pounding transmits force to the center two mains, (as well as the individual rod bearings) causing
them to "grab" momentarily and spin, or just outright flatten the material.

I see people struggle all the time here with repeat motor builds... they never fix the root cause, the detonation. They put the motor back together with the same tune, and expect different results.

The guys that are fast, and really have stuff dialed in well, also have the best longevity.
No deto = long motor life. People think they can throw many $1000s at motor parts and have it live, ignoring the tune or buying an off-the-shelf chip.

I'll take a stockish build with cheap rods and Hyperutectic pistons and a good tune over a full-tilt build with a crappy tune. The stock motor will live longer.

I think you answered your own question. Read Smokey Yunick's book - he goes on and on about deto and bearings, and this is in the context of carbed/non-ecu motors.