main bolt to stud, line hone?

[Keith Morganstein]

A couple of questions for the folks like me that have spent their lives building thousands of engines. (and also rebuilt / freshened a fair amount of them again after service)

1) How many stock main cap fasteners have you seen fail?

2) Have you observed any difference in the amount of main cap fretting from stock fasteners to ARP (or other ) main studs?

Please note if you've seen a difference between two bolt and four bolt (or cross bolt) blocks. (Also the applications)

This is not a loaded question. Just interested in what other very experienced engine people have seen.

[rocks409]

Don't know if my 409 stuff counts or not.Main bolt size of 1/2 ''. Everything gets line honed. 4 '' stroke, lots of weight getting spun around. I see more fretting with studs than bolts. Most customers want studs, so studs they get. Really not a big deal.

[falcongeorge]

Man, this site is always a good read. I would not have expected to read this thread and find most builders recommend using standard fasteners, I apparently bought into the whole "studs are better" propaganda. I have always studded and line honed.

Here is a newby question, what are you reffering to when you say "cap fretting"?

Bob

You have seen it, just didnt hear the fancy name. Remember the main caps on the 427 just before you unloaded it? the metal transfer on the cap mating surfaces and the loosened register? The metal transfer is fretting.

To this day, I STRONGLY suspect that most of the fretting, loss of cap register, and funny bearing wear we saw in that motor was due to the rear crank throw being .013 short. Maybe I should start a thread on this, see what others think?

[swatson454]

This is a really informative thread. I too drank the cool aid and was taught that a 500 hp SBC with 2-bolt mains needed studs and a 600+, 4-bolt needed studs. I was also lead to believe that align-honing was really never needed and caused more problems than it fixed because of it now being closer to the camshaft.

I would enjoy some discussion on these points as I'm hopefully not the only one to have been made to believe these things.

Shawn

[falcongeorge]

I too was always under the belief that studs were the way to go, sorry if I helped corrupt you Bob. This thread has given me cause for pause, but if you read closely, its far from universally accepted, there is disagreement even on this thread, I would like to hear more. Maybe some of the studs that are being used dont fit the bolt holes in the caps as tightly as the shanks of the factory bolts? Thoughts?

[mathis]

Whats wrong with checking alingment of the main bores using a precision straight edge and feeler gauges?

[Wolfplace]

In endurance engines, especially 400's with 2 bolt mains the only way we can keep the caps from fretting as bad is to use studs & these are not hi RPM nor do they make much power but they do run for quite a while & are a reasonable example
Splayed caps with studs or bolts problem solved

A 496 with 2 bolts about 750HP maybe 800 & ±7500
Caps looked like shit
Same setup with studs & line hone better but still not "fixed"
Studs with 4 bolt center caps no more issues
Now I did not try bolts but may have had the same results??

Anyway,
The studs appeared to help in all cases
The studs were torqued to 85lbs (small block), 120-125 BB
I would have to assume that the stretch on the stud would be more with the fine thread at the same torque?
More preload assuming the cap is up for it should equate to more clamping force??

Just my experiences but I haven't experienced any downside to using studs in the mains as long as the stud can be preloaded properly

If you use a stud or bolt that is stronger & torque it to the same thing as a stock bolt assuming the stock one is actually weaker,,
I can see the cap moving more not less as you may end up with less fastener preload??

As many questions as answers,,,,,

[CNC BLOCKS]

This is a really informative thread. I too drank the cool aid and was taught that a 500 hp SBC with 2-bolt mains needed studs and a 600+, 4-bolt needed studs. I was also lead to believe that align-honing was really never needed and caused more problems than it fixed because of it now being closer to the camshaft.

I would enjoy some discussion on these points as I'm hopefully not the only one to have been made to believe these things.

Shawn

Shawn

Have you ever line hone a block?? I have 2 line set ups one at each shop and we cut the caps appox.003 line hone and in a perfect world you are only moving the center line .0015.

And have you ever checked the center to center distance on OEM blocks as they are all over the place the worst one we have seen was off .016. Remember GM line bores the cam tunnel with the cam bearings installed, Try to buy a replacement block as they all come with cam bearings!!

I was also lead to believe that align-honing was really never needed and caused more problems than it fixed because of it now being closer to the camshaft.

Interesting don't beleive all your told

[Wolfplace]

This is a really informative thread. I too drank the cool aid and was taught that a 500 hp SBC with 2-bolt mains needed studs and a 600+, 4-bolt needed studs. I was also lead to believe that align-honing was really never needed and caused more problems than it fixed because of it now being closer to the camshaft.

I would enjoy some discussion on these points as I'm hopefully not the only one to have been made to believe these things.

Shawn

Usually spoken by someone that does not have a way to align hone or from experiences with someone that does not know how to use it
I have seen some absolutely horrible align hone jobs, just finished up a 460 Ford done by what was supposed to be a reputable shop that was an example of why some people should not own a tool box let alone machining equipment,,,,
I have no idea how it is possible to get a block this far off with a hone but they did,,,,,

But yes there are many blocks that would probably be just fine without align honing & many engines assembled without doing it
It still amazes me what these things will tolerate & still run,,, makes one wonder why we "chase tenths"

[CNC BLOCKS]

A couple of questions for the folks like me that have spent their lives building thousands of engines. (and also rebuilt / freshened a fair amount of them again after service)

1) How many stock main cap fasteners have you seen fail?

2) Have you observed any difference in the amount of main cap fretting from stock fasteners to ARP (or other ) main studs?

Please note if you've seen a difference between two bolt and four bolt (or cross bolt) blocks. (Also the applications)

This is not a loaded question. Just interested in what other very experienced engine people have seen.

I have taken old OEM blocks apart to find the head of a main bolt in the pan but the the engine was high milage and the ones I have seen didn't seem to cause a problem and one was on the rear main cap and it ran fine but was using oil.

I don't use GM fasteners as the ARP fasteners work fine for me.

We don't use 2 bolt blocks for our build unless splayed caps are added!!

Since Dart has come out with the SHP blocks that seems to be the common block we machine at our shop.

[rocks409]

I would never argue that bolts are better than studs. Everything we know about clamping force screams studs are better. Keith asked for observations and I have observed more fretting with studs than bolts. Apples to apples, my stuff is 2 bolt mains and only 6,500 rpms.

[Keith Morganstein]

This is a really informative thread. I too drank the cool aid and was taught that a 500 hp SBC with 2-bolt mains needed studs and a 600+, 4-bolt needed studs. I was also lead to believe that align-honing was really never needed and caused more problems than it fixed because of it now being closer to the camshaft.

I would enjoy some discussion on these points as I'm hopefully not the only one to have been made to believe these things.

Shawn

Shawn

Have you ever line hone a block?? I have 2 line set ups one at each shop and we cut the caps appox.003 line hone and in a perfect world you are only moving the center line .0015.

And have you ever checked the center to center distance on OEM blocks as they are all over the place the worst one we have seen was off .016. Remember GM line bores the cam tunnel with the cam bearings installed, Try to buy a replacement block as they all come with cam bearings!!

I was also lead to believe that align-honing was really never needed and caused more problems than it fixed because of it now being closer to the camshaft.

Interesting don't believe all your told

Carl, I think you misunderstood Shawn's post. My take on Shawn's post is that he was told not to align hone, but now realizes it's a basic part of engine machining/rebuilding.

Align honing is important. Not only does it ensure that the mainline is correct, It's the first step in blueprinting after the block is cleaned. The ironic part is align honing is a fairly inexpensive and straightforward machining operation. So many want to skip that step, but will spend thousands on other parts.

[swatson454]

Shawn

Have you ever line hone a block?? I have 2 line set ups one at each shop and we cut the caps appox.003 line hone and in a perfect world you are only moving the center line .0015.

And have you ever checked the center to center distance on OEM blocks as they are all over the place the worst one we have seen was off .016. Remember GM line bores the cam tunnel with the cam bearings installed, Try to buy a replacement block as they all come with cam bearings!!

I was also lead to believe that align-honing was really never needed and caused more problems than it fixed because of it now being closer to the camshaft.

Interesting don't beleive all your told

I'm not a machinist so I'm stuck learning what I can through books and topics like we see here. It makes it difficult to know what to believe if you don't have the equipment to check things yourself. Then you have to be able to trust a machine shop.

[JBV-HEADS]

I've seen more movement on studs than bolts. I just kind of written it off to the fact that bolts have the shoulder near the top by the head. However there is a good possibility that more high HP and RPM engines use studs because of the increase in steady force. In any case studs have been the higher number of instances. Why is a good question though. I also can't really blame a main fastener for a failure. The block is what gives, or the cap on iron caps break.

Joe

[falcongeorge]

I am just a backyard dumbass, but I would think that caps that are moving around are far more likely to break. Again, what I would really be curious about is why are some guys seeing more cap movement with studs than with bolts? Again, not trying to start the fur flying, just trying to learn something here. I am thinking something along the lines of Joe, with his comment about the shoulder on the bolt. Right away, I started to ask myself if the bolts are doing a better job of locating the cap more positively than some studs.