Which ARP head studs to buy?

[slowpoke]

Okay here's the deal real quick. I just put alot of bolt on mods to my car and after all of the installation, I started the car up and it started leaking oil between the head and the block. My car has the original headgasket and the head has never been touched before. I don't know if sitting for three months now could have done it. I just think it was just time. Well anyways, of course I will be using the md349347 head gasket and ARP head studs. Now the question is which one do I get? I have two part numbers: 207-4203 and 207-4702. These both are for the 2g's but the 4702 are U/cut studs. What is that and someone that knows please let me know what is my best option.

Thanks,

Gil

 

[Coup D E'Tat]

Just to make sure : you are talking about the head gasket, and not the valve cover gasket, right?

Just asking, but quite often the valve cover gaskets tend to leak.

 

[trbotaln]

leaking oil from the valve cover may look like its leaking from the head. Be careful tightening the valve cover on the 4g63 because they love to crack!

 

[slowpoke]

leaking oil from the valve cover may look like its leaking from the head. Be careful tightening the valve cover on the 4g63 because they love to crack!

It is not from the valve cover. I had three other guys confirm it with me and it is definately from the headgasket. I even tried to retorque the factory headbolts and it still leaked in the same place right between the head and block.

Gil

 

[MNGSX]

http://www.arp-bolts.com/pages/products/pages/headstuds/headstuds.html

You will also note that ARP® offers specially undercut studs for several engines. This procedure (done only to the shorter studs) more equalizes the “stretch” of both studs, which makes for a more consistent clamping force—and one that compensates for head gasket compression when the cylinder heads are installed. This helps prevent blown head gaskets, and assures optimum engine sealing!

Simply put when you tighten them all using the same tq and proceedure they exert equal force on the head with the undercut studs.. Only some of the studs in the kit are undercut. Long studs normal short cut... It equalizes the stretch..

http://www.arp-bolts.com/pages/products/pages/headstuds/links/technote.html

If everything is right, the stud should be installed finger tight. Then, when applying torque to the nut, the stud will stretch only on the vertical axis. Remember, an undercut shorter stud will have a rate similar to a longer, standard shank stud. This provides a more even clamping force on the head. Because the head gasket will compress upon initial torquing, make sure studs and bolts are re-torqued after the engine has been run.

EDIT..

The head has the same installed nut height on all bolt holes... So

 

[slowpoke]

Thanks for an answer to my question. I thought that all 10 head studs would be the same size. Anyways, I am leaning towards the undercut studs because I definately don't want to go through this bs again.

Thanks,

Gil

 

[MNGSX]

All four on a 4g63 are the same length

Only reasons I can think of for doing it are...

U-cuts are Head/Block 2gH/2gB and the larger diameter are 1gH/2gB.

Email ARP?

 

[slowpoke]

All four on a 4g63 are the same length

Only reasons I can think of for doing it are...

U-cuts are Head/Block 2gH/2gB and the larger diameter are 1gH/2gB.

Email ARP?

Okay I will email them and see what they have to say about it. If anyone has experienced using these undercut studs please let me know what you thought of them and if you have any other info on them.

Gil

 

[Tongboy]

undercut is supposed to supply a more even clamping of the head with a higher torque pressure possible on the bolts.

they aren't that popular because most places don't stock the undercut ones, the only place I found with them was summit.

in the vw rings they were mostly used by people running really crazy engines and even thay didn't know if they really saw any difference in them.

all I can tell you for sure is that they are about 30 bucks more then the non-undercut ones and nobody I know of runs undercuts

summit has the best price on either of them though

 

[slowpoke]

I just talked to one of the tech guys today at ARP and he recommended just sticking with the non undercut studs. Reason being is that he said the undercut studs were initially made for the Ford, Chevy, etc... all aluminum block and heads. They are needed for keeping the head gaskets sealed during expansion and contraction. He said the undercut studs will work but they will not be as strong as the regular ones for my application. He also recommended not to torque the studs no more than 75 ft pds. with the supplied moly lube. I told him that I was planning on boosting up to 32 psi. He said if I was just boosting no more than 25psi than the undercut studs would be the way to go. Well anyways, I thought I let you guys know what I found out.

Gil