Head gaskets brand? metal? thickness?

[carl johansson]

Ok guys,
redoing the head gasket on 87 7mge. So i find HKS at rediculous prices, i find cometic and titan metal gasket at a reasonable price, and of course the toyota OEM. we run this thing basically stock, but it does run 18 hour endurance races, where it essentially goes between 2500 and 6000 RPM continuously for the whole 18 hours. We are after durability here. The last HG - Toyota OEM ran for 7200 race miles - pretty damned good!

Also what thickness do I need? Is the thickness relative to wether the head has been shaved?
One more thing - any one know why in the left corner of the first response to each post - you get part of a dialog box that say unable to open link? only happens on this website?

Carl Johansson

[Sonyps307]

A metal head gasket will not last unless u shave the head and the deck of the motor. A good set up is the Toyota oem gasket with arp bolts or studs and shaved head then torque to 78-90 lbs. That's a good set up for the turboed motor so it should hold up good on the 7mge.

[cre]

Cometic and Titan (strongly believed to be made by Cometic) are the most forgiving, but yes, any MHG requires extra preparation. The block and deck must be more than just cut, they need to be very smooth. If your shop can't provide a very low RA then you will need to lap the block with a precision lapping plate and diamond lapping compound of progressively finer grades.

Torque head bolts according to the manufacturer's specs and according to the type of lubricant you are using. Make sure to chase the threads in the block as well, this is critical.

The thickness is chosen based on a number of criteria but yes, for your needs it will be primarily based on how much material is removed from head and block. Stock is 1.37mm compressed, IIRC. To maintain the stock C/R you would take 1.37mm + whatever is removed and that is the thickness you would want. If you want to increase your C/R you would go with a stock HG or thinner after the head and block are shaved.... the opposite to lower the C/R.



EDIT: Oh and the link not found thing.... possibly the placeholder for an advertisement for an advertiser who's not up and running? I don't see it on my screen. If it's between the first and second post then that is what it is... I've seen it using other browsers before. I'm not sure why the forum owner hasn't fixed it.

[Sonyps307]

Hey if the motor has been rebuild and the block has been cut and the head was shaved. Could I swap to a metal gasket. The motor only has about 6,000-8,000 miles on it or bad idea.

[cre]

It's not the best idea, if the composite has bitten in anywhere you'll have issues with most MLS MHGs. You would at least be looking at needing to give both surfaces a good lapping. The last 7M I tore apart with low miles on a composite HG had about 20K and did need work... a lot of lapping was required to get it back in shape for a MHG. Taking that much material off with a lapping plate you have to constantly check that everything is perfectly flat.

You really wouldn't know for sure until you got the head off though.

[carl johansson]

False Alarm guys, turns out, on further review - nothing but a leaking hose. So I guess it is on to our next race - an even dozen with the same motor!

thanks for all the help - esspecially you CRE

[supraheelfan]

Reviving old thread: I'm confused (surprise) as to what needs to be done to use another stock Toyota head gasket: From my understanding, it doesn't matter which HG I chose I'm going to have to machine the block for proper fitment, Is this correct? Or can i just get another stock head gasket and ARP head bolts torque them properly and be happy? Also, does the OEM head gaskets come in different sizes like the MHG?

I know everybody recommends the MHG, but I'm not planning on making much more than 300 horses.

[cre]

The requirements for a composite/graphite HG are much more relaxed and in one respect its needs differ from the MHG's requirements. For the most part if everything checks out fine as detailed in the TSRM for inspecting the cylinder head and block the you are fine to use another composite HG.

BUT, as these are old blocks the likeliness of significant pitting of the block's deck is quite high and may require machining to cut past it in order to get a sure seal. Also you'll want to get the head machined as it will have impressions from the old HG and you'll want to be rid of those. While it's out I recommend you have the shop inspect for cracks and proper sealing and replace the valve stem seals.

The difference I mentioned is that when using a composite HG it's generally accepted that you do NOT want the mirror finish which MHGs require. A little texture helps the head and block bite in and provides more surface area for sealing.