Headgasket questions

[Mr2god]

Please dont just tell me to use the search button because I have, and I have found many different things that people say.

My question is, do I need to have the block and head resurfaced to run a MLS headgasket or just the head? Some people say both, some people say just the head. I know it depends on if the motor has overheated before. And I know I would obviously have to clean both surfaces very well first. Some first hand experience would be good.

Also, a side question. Would a composite mitsu gasket be good enough for a pump gas street car that will never see more than 22-24psi on stock internals w/ arps tourqued a little high or is that asking too much? I have heard many different opinions and i'm trying to actually get more first hand experience. Thanks

p.s. I plan on running DSMLink as well as meth injection with this setup to keep temps down to make it safer to do on stock internals.

 

[bane3d]

From what I know, the reason that most people say that you just need to machine the head is because it is aluminum while the block is cast iron. If you overheat the engine, you are much more likely to warp the head versus the block. So in most cases, you would only need to machine the head and just clean the block versus machine both. I hope that gives you a little insight. In any case, I think you should be able to pull the head, clean the block and then run a straight edge across the block to make sure it's true. Then just get your head machined. As for your gasket, I believe it's a multilayer (Multi Layer Steel) gasket so it is more accomodating to anomolies between the head and the block versus a single layer gasket.

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[Mr2god]

This is the option i'm hoping to hear. Because I want to run the MLS for security but i'm not planning on dissasembling the bottom end to get it decked. I do realize that I would have to check the clearences with of the block to see if it would be usable too. I know the heads need to be finished to a almost mirror finish of 30 RA or less. Does the block have to have that finish also?

 

[bane3d]

According to MLS: What surface finish is required to us an MLS head gasket?
A surface finish of 50 RA (roughness average) or finer, is recommended for a proper gasket seal. Anything rougher may conflict with the gasket design.
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So I believe that you should be fine. Just be sure to splurge the extra cash and get ARP studs and torque to specifications.

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[Mr2god]

Yeah the ARP studs are definatly going on no matter what HG I decide to go with. I really wish I could get some more first hand experience of people that have maybe had just the head resurfaced and what their results were. And thanks for the replies bane3d.

 

[laserspeeddemon]

You don't need to resurface either. What you do need is to check the surface of both. If there is any amount of warpage (ya I know, made up word), then have it/them shaved within spec. It they both are within specs, then you just need to clean and smoothen them.

But the chances that you warped the block is low, if you did you may want to look into rebuilding the block altogether. In my, oh, 10 years or working with DSMs, I've never seen a block get that warped without some other form of catastrophic failure.

 

[Mr2god]

By "smoothen" what do mean? You cant sand a block deck because of the risk of getting the sanding particles into the oil passages. Both the head and block will definatly be cleaned with a razor and brake clean. I guess i'm just confused what you mean by "smoothen". The head I'm not really worried about dissasembling and having that machined because it will be off, its the block i'm more trying to find out if I can get away with I guess. In a week or two i'll be back home from school and will be able to pull it all apart and see if everything is at least in spec and start cleaning and I guess i'll make my decision from that. Thanks for the responses, any more would be appreciated.

 

[GVR4592]

A Mitsu composite gasket with ARP's torqued to spec will handle your goals. If you want to go with a MLS and not have any worries, you need to resurface the block and the head to 50 RA or better.

 

[Mr2god]

Dang GVR4592 thats not what I want to hear, well kinda. I did want to hear that the composite will handle the power. I was just hoping that I could get the extra insurance and get away with just resurfacing the head. I have done alot research on the composite and it seems like some people say you can run 10's on it and some say never to go above like 18psi on it. The people that are saying its good say it just comes down to tuning. So the composite should be fine with no resurfacing but with cleaning and of course, if the flatness tolerences are within spec right?

 

[GVR4592]

The head needs resurfaced no matter what gasket you use.

 

[Mr2god]

Ok. I guess the head will get dissasembled no matter what. Maybe some cams and springs while i'm in there, who knows. Thanks for the responses.

 

[jw_55_55]

See this is the problems with the other HG threads...we have people saying one thing and other people saying other things. So what is the real answer?? obviously you should have the head resurfaced!! but the block how would you know without having it resurfaced?? because i have heard a lot of people just cleaning the block really well and not having any problems.

 

[tkelly27]

I have always read that the MLS gaskets are very sensitive to surface finish. The 50ra refers to both the block and the head. You may not need the block resurfaced if it's already at a 50ra.

It's already been stated that the stock mitsubishi gasket will be fine at those power levels. So you're going to tear apart your engine, get everything resurfaced, to run a gasket that's overkill for your application? There are many cars at those power levels that have never even had the head off, no ARP's.

In my opinion a weaker head gasket is a good thing with stock pistons. It can act as a fuse, blowing under detonation before the pistons are destroyed. Then again, I never resurface my heads, so who knows.

 

[Splitpi]

I cannot imagine any block that has already had a head gasket installed having 50 ra or better surface. 50 ra is very smooth.... i.e < 50 micrometer bumps. ra = Absolute value of the surface height averaged over the surface. Maybe others are just really good at cleaning and removing the HG deposits better than me...

 

[Mr2god]

It's already been stated that the stock mitsubishi gasket will be fine at those power levels. So you're going to tear apart your engine, get everything resurfaced, to run a gasket that's overkill for your application? There are many cars at those power levels that have never even had the head off, no ARP's.

I think i'm just going to take my chances with the mitsu composite. I have heard so many different things and the majority say that both surfaces need to be resurfaced. Because I dont plan on dissasembling the bottom end during the rebuild. The motor only has 90,000 miles and ran great in the car. I'm just going to do water pump, oil pump, every gasket, and other little stuff. No need to go inside for the power i'm looking for.

In my opinion a weaker head gasket is a good thing with stock pistons. It can act as a fuse, blowing under detonation before the pistons are destroyed. Then again, I never resurface my heads, so who knows.

This is exactly my belief to, i'd rather have the HG go out before I blow a hole in a cast piston.

 

[Bender]

No, they both do not need to be machined from a machine shop. They do however need to be smoothed out. Wet sand them with 800 grit sandpaper. Be sure not to cause unevenness thought. I have used cometic MLS headgaskets on two dsms, and they are a lot better than the graphite composites. They do not blow as easily, and seal a lot better. It is just tricky to get them to seal. Follow the link, I recently helped someone with the same problem.

http://www.dsmtuners.com/forums/newbie-forum/276183-fetl-vs-mls-compression-change.html

 

[daren_p]

The stock composite with ARP's will be fine for your application. I know guys that have ran 22psi on the stock gasket & studs without any issues & initial spool of around 26 psi. I run the stocker with ARP's & run 23-24 psi daily & have ran 26 or so at the track without any issues. I know guys running this combo in the 30 psi range as well.....

 

[Mr2god]

No, they both do not need to be machined from a machine shop. They do however need to be smoothed out. Wet sand them with 800 grit sandpaper. Be sure not to cause unevenness thought.

I will probably just get the head machined because it will already be off and I might as well, plus i'm doing the 3g lifters anyway so i'll most likely have it all apart. As for wetsanding, I read somewhere not to sand on the block because of the possibility of getting the bearing killing sand grains into the oil galleys.

 

[GVR4592]

No, they both do not need to be machined from a machine shop. They do however need to be smoothed out. Wet sand them with 800 grit sandpaper. Be sure not to cause unevenness thought. I have used cometic MLS headgaskets on two dsms, and they are a lot better than the graphite composites. They do not blow as easily, and seal a lot better. It is just tricky to get them to seal. Follow the link, I recently helped someone with the same problem.

http://www.dsmtuners.com/forums/newbie-forum/276183-fetl-vs-mls-compression-change.html

In all of my years working on cars, I've never seen an aluminum cylinder head that didn't warp when it was removed from the block. They are never flat after the installation/removal process. I've also never seen a stock head that didn't have composite gasket material stuck to it, if you scrape it off you will scratch the surface of the head, it's almost guaranteed. Resurfacing costs around $40 so there's really no reason why you shouldn't just do it.

 

[Bender]

A local machine shop did a terrible job at resurfacing the head in the past. The grooves were too deep to seal. The wet sanding smoothed it out. Since then I have done this to all my heads after removing the old headgasket.

What are you doing to scrape the head like that? I use fantastic and a rag to get the initial grime off. Then I let it soak in just normal engine degunker. I then use a medium bristled toothbrush to agitate the graphite. After that I go back with a razor blade and slowly peel off the remaining material. When it gets too dry, I spray some more degunker on. Right before installation I use a clean rag and more fantastic to get all the degunker off.

 

[Mr2god]

Yeah I have no doubt that I will get the head machined once I find a good shop here in Michigan near me. Thats not a big deal.