At what point are these needed? I always thought there was no need to upgrade the mains unless you are going 600+ hp. I've read a few threads lately of people using them with only a max of 400 hp in mind. I plan on making about 400 - 450 at the wheels ... doesn't seem like these are necessary are they??

necessary? no

will it hurt to have them? no (considering you install tehm right, ive heard stories of aligning them wrong or something of such)

I'd do them for piece of mind, plus your old main bolts have probably been streched.

If your going to use them you HAVE to get your block line-honed and I can't find anyone in my area that can do this to my satisfaction and I'm told it's a wide-spread problem. So use caution unless if you really know how to find a competent shop. I'd say if your going to go this far than you might as well dowel your mains as well. But for 400-500 hp that's probably overkill. For that hp range I would chase the threads and buy some factory bolts and procede to loose sleep over other issues.

Andy

Using ARP's is worth it as soon as you start building a strong bottom end. Since you should replace the stock bolts and Align Hone the mains anyway why not go with better fasteners.
But then again you might have the mains in specs with the "old" stock bolts so you might decide to "stay stock". It's just that I don't know how confident that you have a strong enough bottom end you will be when you decide to go for more HP levels since I hope you know that you will never be satisfied with what you have.
For more info read This

Boost Addict said:

I'd do them for piece of mind, plus your old main bolts have probably been streched.

Click to expand...

Definitely. It's much better to be safe than sorry.

main studs are good to 550ish WHP,

almost evreyone stays with stock main studs

If you're taking them out, change them. If not, just leave the old ones alone. You're much more likely to break something else other than a main stud.

TargeT said:

main studs are good to 550ish WHP,

almost evreyone stays with stock main studs

Click to expand...

cool I just reused them .. hopefully they won't give me problems. Only had 60k before the rebuild and never boosted over 18 psi.

one of those things, you know if your going to do tje whole engine might as well, but it doesnt have to be done

I did the mains in my car with ARP's, however two of the bolts stayed stock as the ARP's on one end would not clear the oil pan due to the nut sticking up to much. On my seven bolt rebuild I had to beat the hell out of the pan from teh inside to get the nuts to clear. The stock ones seem to be just as good as the ARP's. I would stay with the stock if I had to do it all over again.

if you on a budget leave em out. If not then go for it.

What exactly are you guys trying to be “safe” from? Can you list a single example of failed main bolts? I am not saying that it never happened, but I just never heard of it (and I have been around for a while . However, I have seen people making 700+ whp on factory bolts.

As several people already mentioned, you MUST line bore your block when you install ARP studs, why give machine shop another potential place to mess up?

I prefer to use new factory bolts in my motors…

Leon
RR

yeah but we all know some wierd things happen to dsms. And new things are still apearing. Arp studs just ease a persons mind i guess.

in fact more problems can arise when you use arp mains. You should get the crco dowel kit to get them aligned, and you have to get your block align honed. Just because ARP head studs are always a good idea doesnt mean you should buy every single ARP product just because its ARP. How many people have you seen lose an engine due to main bolt failure? If you were making enough power to require arp mains you probably woulndt be posting here.

bigjangin said:

in fact more problems can arise when you use arp mains. You should get the crco dowel kit to get them aligned, and you have to get your block align honed. Just because ARP head studs are always a good idea doesnt mean you should buy every single ARP product just because its ARP. How many people have you seen lose an engine due to main bolt failure? If you were making enough power to require arp mains you probably woulndt be posting here.

Click to expand...

john shepperd has posted here, just a little side note

has posted, but he doesnt post a lot like some of us It'd be nice if he chimed in with his opinion. The last I heard(which could be totally totally wrong) was that he was using stock mains until recently.

While I can understand why some may have concerns about the quality of the machine work some shops offer, I don’t understand why would they even take their work to a shop they don’t trust that will provide them with a good quality product.
Stop believing everything you hear and start thinking for yourself. And use common sense.
I would like to know who is that influential person who started all this nonsense about ARPs being “thinner” than stock bolts and about the fact that you need the CRCO Dowel kit to “get them aligned”.
Why don’t you just do yourself a favor and start with checking the mains to see if they are in specs. There can only be two ways:
1. They are not in specs
2. They are in specs
After you have the results “put the tools down and step away from the … engine”, have a seat, open a pop, light up a cigarette and think: What do I do now?
1. They are out-of-round and/or not straight so I will have to get them Align Honed. Well, since I also should get new bolts, why don’t I get a better fastener?
2. Since they are checking out good I can stick with a new set of stock bolts and be done with it. But I could buy better fasteners. Nah I don’t need those since there are guys that are running xxx horsepower on stockers and I will probably never get to that level. But wait a minute! Those guys have the car tuned almost perfectly and things work the way they should inside the engine and I might not be able to do everything right from the start and have a “knock free running” engine plus I’m sure I will change my mind about what my “power goals” should be. So maybe I should try to build my engine as strong as I can because that way I will have the peace of mind that I did the best I could.

Bottom line guys, do what ever you think it’s best for you but do not think for a minute that if you stay stock you eliminate the need for an Align Hone and all the potential “problems” that can arise! You may or you may not have the mains in specs with stock bolts just do not ASSUME that! Whether you want the best you can get or not is up to you and the fact that you chose not to spend that extra $150 to have the mains perfect might or might not make sense. Just think for yourself, use common sense and stop spreading false information. Most of the guys on this forum are here to learn more and false information like this is what makes guys say thins like “I would like to change the rod bolts but I hear that the big end don’t have to be touched because they are capable of xxx HP the way they are” or “I’d like to reuse the stock main bolts because that way I don’t need to Align Hone or Dowel the block” and other bullshit like this.

http://www.dsmtuners.com/forums/showthread.php?t=117015

OK, I am still waiting for a single example of a failed main bolt… Anyone? Now, you see failed connecting rod studs all the time, but not the mains.

If factory bolts have a factor of safety of 1.5 (just a guess), then what is the point of increasing that FS to 2.0? Would it be stronger? Yes, but what benefit would it bring you?

And I do not care how good your machine shop is, EVERY machining operation bring with it a possibility of a screw up.

Leon
RR

If you think a bolt fails when it breaks, you and I will have to keep on waiting because I have never come across main fasteners that broke. A fastener does not have to break in order to FAIL TO DO WHAT IT WAS SUPPOSED TO DO. There are fundamental differences between what a rod bolt and a main bolt are subject to.
I’m going to say this one more time. Factory main bolts are very good and they do their job well in a lot of applications but choosing them instead of better fasteners does not eliminate the need to correct any potential problems that the main journals might have. I’d rather have the machinist machine the mains to make sure they are in specs since, unlike a production operation, he will double check his work and stand behind what he’s done. Can you take your engine back to a manufacturer to confront him with the quality of machining he has done? Somebody who takes his engine build seriously, like a professional racer, does not care if the Prime Minister of Japan himself was supervising the machining process on the block he has. He knows that the factory tolerances are very “forgiving” since a manufacturer makes the money based on quantity not quality and therefore they will always chose to do it the “safe way” (usually oversized) just to get it “out the door” and past the warranty. A racer will always make sure that he starts with a block that is as close to perfect as possible so he will have the mains machined and guess what: he will do that again the next time he rebuilds the engine and replaces the fasteners.
Don’t forget that the “monkey” operating the machines in a factory does not care about your desires and he will never have to talk to you in case something goes wrong. All he cares about is to put in the hours and get the paycheck at the end of the month.

Yes, it is important who builds your engine, but is also very important to understand that your machinist is your only friend: he cares about how your engine will perform and he will do his best to make you a happy costumer. His success in the business is based on quality not quantity. He does not pretend to know everything, so if you have any concerns or have heard anything that have made you worry (like certain things that “happened” to others) make sure you bring it to his attention. While you might take what you’ve heard as the letter of the law, just because a very influential person said so, the machinist will look at the information through a different perspective and will use all his experience and knowledge to decide what credible information is and what not. Yes, he can make mistakes too, but he takes his work seriously and even if he was interrupted by the phone ringing while he was doing something that needed all his attention, he will double check his work when done. That’s if you didn’t make him go crazy trying to beat him up on price and tell him what and what not to do, even though he believes you need to address certain issues regarding that particular engine. But he cannot match the precision of the factory CNC machining you will say. Oh, really? Then how come Mitsu has those valve seats so misaligned in the bowl area? Do you think the design was like that?

You guys really believe that OEM cannot be matched in quality, but if you would deal with factory “brand new” replacement parts like I often do and therefore have the chance to see and check first-hand the quality of workmanship, you would probably think twice. Let me tell you a few things about manufacturer’s way of doing things. The good part with OE starts and most often ends with the design of that engine. Everything goes downhill after that because they will do whatever it takes to cut the costs and crank up the numbers. Do you expect them to deliver high performance and reliability out of a car that is so low priced to begin with? They would starve to death if they would build something that would perform very well for more than a too long of a period (past the warranty). Who would then buy their next new car? So they will choose to only do whatever they think will work “good enough” for that particular application. They also take into consideration the fact that the tooling they use to machine stuff wears out so they will start oversized to compensate for that. Then they figure that after a certain number of operations things start to alter the results so while they make some random checking during the run they only start checking more seriously when they get to the number they figured. That’s why some engines perform better and longer than other from the get-go and you don’t want to have a so called “Monday or Friday engine”. A Custom Engine Rebuilder on the other hand will check his work every time he does something and will try to get you the best performance out of a longest lasting engine possible.

Examples of the “factory approach”:
Guides ID are set at the high end of specs to be “safe” which makes them not very long lasting. It’s the “That’ll work, it’s not like we build a race engine here” philosophy at it’s best.
Seats are cut “close enough to work” and concentricity is not checked on every seat. To check the work and rectify any mistake would cost them a fortune and “it’s not like…” (see above).
Torque plates: yeah right. “It will be close enough without it and we save a bundle”.
Adjusting shims clearances on Toyota’s and Nissan’s are set loose so they won’t hold a valve open. “What if it’s .016” instead of .010”? A little more sound deadening material will fix that”. Toyota does a factory recall on valve stem seals and replaces them with guess what: the exact same seals. And they will not cover any other machine work that might be needed when the head is opened up to replace the seals.
Guys should know that there is no comparison between a production operation and a custom rebuild when it comes to quality; unfortunately most guys think the price comes first and what better way to reduce costs, other than “mass production”?

For most people just run the stock main hardware.

For all out racing on a 6-bolt (like I'd bother with a 7) use the CRCO 10 piece full race kit and ARP studs. You will have to modify the pan and the oil pickup..

For a full race engine don't comprimise anything anywhere.

These guys are right..

CRCO

Also since lateral loads push the cap against the dowel and not the stud and cap the stud is now even stronger since it only handles the clamping load.

GRNDSM said:

What exactly are you guys trying to be “safe” from? Can you list a single example of failed main bolts? I am not saying that it never happened, but I just never heard of it (and I have been around for a while . However, I have seen people making 700+ whp on factory bolts.

As several people already mentioned, you MUST line bore your block when you install ARP studs, why give machine shop another potential place to mess up?

I prefer to use new factory bolts in my motors…

Leon
RR

Click to expand...

Couldnt agree more, My line bore was perfect in my 6 bolt block, so I used stock studs. Why take the chance of the machine shop f'king it up just to put in arp mains that really are not necessary. Something else will fail before the mains do IMO. I was gonna put ARP rod bolts in my 1g rod/2g piston motor, but I didnt like the way they fit, they have to be POUNDED into the hole and they stretch out rod end making it out of round. I would only assume this also happens to the mains.

As far as their headstuds, I have them except for the head oil feed hole. Reason for this is the ARP stud is ~1mm thicker in diamater and hinders the flow of oil to the head. ARP is too much about universal studs. I really think they need to revise their set for the 4g63 6 bolt. If you look at a stock stud you will see they taper down in the center.

Stock main bolts are great up to a point.
ARP main studs are better.
Doweled caps are a great idea. Unfortunately that’s all they are: an idea. It is a concept based on wrong assumptions. While it would definitely help, it is supposed to fix a “design flaw” in an engine that was not designed for Dowels.
The idea started on the assumption that the bolt holes in both caps and block were machined at the same time: FALSE. Take a good look at the difference in size between the holes in the caps and the ones in the block and explain why they are different if the two pieces were machined at the same time? BECAUSE THY WERE NOT! Furthermore the caps have the bolt holes significantly bigger for the very simple reason that, since the holes were not machined at the same time, there is a need for a certain freedom of movement in the thrust direction of that cap to be able to adjust the alignment of the thrust bearings. When dowels are installed in the block and the caps are machined to the size of the dowels you loose al that adjustment margin and this is when you are screwed.

Rod bolts ARE SUPPOSED TO FIT TIGHT and it makes no difference if the big end is out of round (that’s if it is not excessive) because it will be reconditioned and brought back to size.

The difference between the bolt hole bore size and the diameter of the studs leaves more than enough room (volume) for the oil to get to the head; in fact the oil passage for the head is smaller than that opening. Just measure and do the math.

On a 6 bolt 4G63 with the thrust bearings adjusted correctly, the so called Crankwalk is not an issue. Yes the thrust bearings wear out but if installed right they shouldn’t wear out prematurely, that’s if everything else is on size including the main bores. Now if the thrust bearings are misaligned you end up with an “oil scraper” instead of a thrust surface.

Bottom line, there are two reasons for a 6 bolt to “walk”: misaligned and/or difference in the size of the thrust bearings upper and lower halves. Just because there is more wear on one half of the bearing than the other does not mean that the cap “shifted”.

When will you guys realize that there is a “contradiction in terms” regarding OE bolts vs. ARP studs? Everybody agrees on the fact that when ARPs are used there will be higher clamping with higher quality fasteners that will have fewer chances to stretch. Yet stock bolts are considered “safer” to use! Like using them implies no need for an align hone which is totally untrue. Align honing the block assures that the main bores are on-size and true (straight, concentric, inline, call it whatever you like) and this should be the way to start a rebuild. It is up to you if you want to take your chances without doing that just because you supposable use bolts with the same specs as the original ones. Just don’t forget that not only the factory’s machining may be questionable but that block also went through a lot over the years so make sure you have those mains checked. I prefer to be able to control whatever I can when I build an engine and trust me, when the block gets align honed, I can control that.
Some take their engine build seriously and build their engines right, ending up having stronger and longer lasting engines than others who put their faith in the Almighty OEM. I wonder why

I guess I should go to sleep now because there are guys out there waiting for their stuff and don't want words from me: they don't want me to be tired tomorrow and not being able to work on their projects. So please be kind to me when you will disagree with me so I won’t get upset tomorrow and get to make the usual “machinist mistakes”.

The difference between the bolt hole bore size and the diameter of the studs leaves more than enough room (volume) for the oil to get to the head; in fact the oil passage for the head is smaller than that opening. Just measure and do the math.

Click to expand...

If using a 6 bolt block, 7 bolt head, the 6 botl ARP stud DOES block enough oil that the head gets hardly any, none at idle acutally. Now I should of bored the head out 1mm, but most said it wasnt necessary. Now that I looked to see where the head gets oiled, I see this is a very important thing if using ARP's. I put the stock stud in that corner now, better than pulling the whole head, if it fails it fails. 1mm in diameter adds up to alot of extra volume that can move around that bolt. ARP are good studs, but they are too universal with their products, they should be designed identical to stock, but with more tensile strength.