Block finish and head gasket mating (mhg or graphite?)

[DazbaVBz]

if you are going to clean the deck of the block up your self, donot use one of those air operated sanders, or anything like that, sure you get a nice finish but i have seem many a block wrecked with one, you to your local hard ware and buy a oil stone, brake the oil stone in on a old piece of metal then do you deck surface with the smooth side, you will be able to see any in perfections in you deck as well as not affecting you gasket seal ring, then put a straight edge from one corner to the other and try to see if you can get any feller blades under the edge, if so being a 7m get it decked, also about 'O' ringing a block in this day and age and quality of gaskets you should not have to, and whats not to say that you will have tight seals on the o rings ends, i personally am not a fan of it,

[jeffro ra28]

also about 'O' ringing a block in this day and age and quality of gaskets you should not have to, and whats not to say that you will have tight seals on the o rings ends, i personally am not a fan of it,

If this day in age the qaulity of the 7m gaskets is so good why do they persist to cause BHG problems?
O-ringing the block is a sure way to improve the sealing capabilities of a composite gasket. Its fact, not fiction.

[Kedderz]

After chatting to a local engine builder (for about 3 hrs picking his brain!) he has given me a technique to prep the block. I am going to use this technique to hopefully get a finish which is as rough as factory. We spend some time on one of the old blocks he had in his shed and showed me how to get a finish he has used thousands of times, so things are looking up ;-)

On another personally dont see how a mirror finish will help sealing and this was confirmed by my now mate Ian who has been building enignes for 30 years.

All the rubbing back will be done by myself and Ian has said he will come over and check the finish, if its crap he has offered to help me break down the engine then it can be decked but he is 100% sure that it wont have to be. I will also be using the cometic MHG I have bought.

Edit- I have also bought a nice scaper which has taken off 90% of the gasket.

[supra_cam]

how has the cometic head gasket been for you kedderz? Looks like I got another bhg Looking at the different gaskets available and a bit confused. I only used an ACL head gasket and the standard head bolts last time, but this time I want to do a proper job and make it bloody strong. Looking at the range of gaskets on suprastore.com theres HKS stopper type and bead types, is there much difference between these? I may even go for a Cometic, by the sounds of things there pretty good.
A question to people who have had blown head gaskets with their 7m's, was that only with the stock gasket or a cheap gasket and crappy bolts or have you had bhg's with more expensive gaskets and arp head studs?

[Kedderz]

due to not getting my block decked I didnt go with the cometic gasket in the end. My block was not warped/damaged (checked with feeler gauge/straigh edge). I cleaned it up with emery tape and gasket remover.
I purchased a brand new toyota item ($90) which is the latest revision gasket. I used this in conjunction with ARP head studs and nuts, torqued to 80 ft/pounds.
Car runs like a dream now, still breaking "it in" however as shes not rego'd atm.

[supra_cam]

Good to hear you've got it fixed! Are cometic gaskets only good if the blocks warped?

[Kedderz]

the cometic, or any metal head gasket, is good only if the surface is preped accordingly. Cometic reccomend a 50 ra finish, which means getting the block decked/machined. A graphite gasket is always more forgiving than a metal one due to its composition.

That said any gasket tightened with ARP bolts is 1000% better than stock ever was.

[jeffro ra28]

the guidelines set by MLS gasket manufactureres are the ideal circumstances. Plenty of times myself and other people have gotten away with factory finishes on their blocks.

Namely, factory surface grinds that have proved to be adeqaute with me so far are 1jz, rb26, rb25, rb30. These however where all in excellent condition otherwise.

However i wouldnt trust a factory grind on any ford, chev or american hum dunger. Likewise, with kia, hyundai etc.......

[jeffro ra28]

double post