I want to freshen up my 68 block that had been bored 30 over. I've been reading alot about zero deck height and have a few questions and I guess I want to use the KB237 pistons, Elderbrock rpm 84cc heads and matching heads and I want to use a hydraulic cam. I'm not for sure what a good carb would be, I was guessing a 870 street avenger?? But what I want to know how exactly to get the Zero deck height and what gaskets to use? My block has never been square decked. I can work on engines doing basic stuff but kind of a lost to the tech stuff. Thanks!

The KB237 piston should get you close to zero deck. I think those pistons are 0.020 down in a blueprint block. Zero deck is a suggestion not a strict rule. For aluminum heads I usually build engines with the pistons 0.005 down and then use a 0.036 MLS (Cometic) gasket.

I used those heads and my pistons(old heavy sealed pro 6pak pistons with a coating on the skirts)were approx .020-.026" down in the bore. The motor has been together for 10 years now and makes plenty of power. I wouldn't worry about being at zero deck personally. You just don't want them .080-.09" down in the bore like the low performance stuff was.

I used blue felpro gaskets or whatever edlebrock recommended.

So if I wanted to build it like yours I would need to square deck the block 0.015? I'm sorry just trying figure this out.

Get on KB web site, United Machine, and get on thier compression calculator tool, plug in the stroke, bore, piston information and head gasket inforamtion and then play with different deck hieghts to see what compression ratio you come up with BTW, when using numbers for deck hieght and dome volume negative numbers, IE -.010 are actaully for above the deck or - 7.0 CC is for a dome piston, + .010 is below or + 7.0 CC is valve reliefs or a dish Doesn't make sense to me either IHTHs

NO !! What you want to do is measure the current deck height and work from that. You also want to measure it at least at all 4 corners and make your calculations based on the shortest height. In reality, getting the decks square could end up yielding shorter decks than "zero" so you want to figure this out and work available gasket thicknesses into the equation.

As an example, in order to get the decks square on my block the pistons ended up .016 out of the hole. Luckily there are .051 gaskets !!

In a perfect world that is what would happen but you have to remember that these engine blocks are 40+ years old now. Best bet is to get the block to an engine shop so they can clean, inspect and measure it before you buy any parts.

Do you have a copy of the BB Mopar book that I wrote? If not you might want to start there. It is only $20 and it might save you some money in the long run.

Well I'm going to take it to a machine shop. I was just wanting to talk to some people that actually have done it and don't get me wrong I know nothing but from what I've read. I've read many posts and people's opinions about zero decking and I know it's not a strict rule but from the people who strictly do it seem to get the most HP with the dyno sheets to prove it.

The trick is to get the quench height correct, not so much the zero deck part. You can have the pistons 0.015 down and use a 0.026 gasket or have them 0.005 down and use a .036 gasket.

One approach - the one I used - was to get the block cleaned up and checked and minimum mill cut to square the deck. Measure again and work from there. Figure rod length, piston height, gasket options ect. If you/your shop can take it in stages, its easier to get nice result and less chance for oops.

Ok I understand it now better. So I'm running Aluminum heads and you stated before you like the pistons .005 in the hole with a 0.036 gasket? So does anybody really what the best quench height is or is it just a guessing game? In those builds where they really were getting good hp and torque numbers they never really said what gaskets and so forth but it was just a zero deck build. I want to run an engle k58/k60-110lsa hydraulic cam but I'm still lost with carb set up. I think those people used a 950 hp holley but do I really need one that big? Whatever I use I want to run an electric choke.

That's exactly what I did above, and I was able to measure, order parts, and tell the machine shop exactly how much to mill to arrive at the exact deck height that I wanted with my gasket. If you measure before the machine shop mills it square, you will be off after they correct it.

Kinda the same here. I try to get zero deck with pre machining measurements, but plan on doing it twice. I prefer the zero deck so I can run the any of the 0.040" gaskets that are available. 0.040" is the rule of thumb for clearance and relatively safe, but the specifics of the build might allow less.

About .040 to .045 is a very good quench. Many like to build it a zero deck and just use the .039 felpro head gasket which gives it good quench. But as many have said you dont have to be at zero deck as you can get quench by changing the head gasket thickness some. Myself I do all the math to see where my pistons come out at and then I assemble the crank and the 4 corner pistons in the eng and take my measurements. Then I work from there so I know I will usually be taking the engines I build back apart a few times but thats all part of getting it right. The eng in my car now came out with the pistons .007 down so I just used the .039 felpro head gasket and have .046 quench which is on the high end but it has worked great for me. When it was that close I decided to go with it as I did not think it was worth pulling it back apart to mill a few thousands off my block. This combo has worked good for me. Ron

Ok so Ron somebody said it really doesn't have to be Zero deck and they also said they like aluminum heads at least .005 in the hole but what's the difference if your quench is still .040 in the hole or at Zero deck. If I use the KB237 and they are .020 in the hole and I use a .020 gasket wouldn't that work and save me the cost of zero decking?

When it comes to piston to head clearances you need to check the deck hieght on both sides(cam side and outside of the block ) of the pistons, all 8 of them. Bring the piston up until it is at the end of its upwards travel and then use a thin bladed screwdriver or what ever you want to use, to get between the edge of the pistons on the cam side and the block and rock the piston towards the opposite side, read, measure, the deck hieght write it down Then do the other side of the piston and write that down I have found that I needed more than .035 and less than .041 piston to head clearance to have no marks on either of them after running for awhile at the track and on the street Good luck

Ok but still yet does it matter where you get quench at? If its .020 in the hole or Zero deck. Does it make any difference in Horsepower where you get it from?

Not in my opinion, quench is quench, correct If you have a piston in the hole .015 with a .022 thick steel head gasket with a closed chamber head you have .037 quench distance, correct? If you have a piston that is +.015 above the deck and use a .052 thick head gasket with the same closed chamber head you still have .037 quench distances, correct BTW, check the piston rock clearances

I sure will. THANKS!

Yes it will work as you will still have .040 piston to head clearance. Many go for the zero deck since .039 is a standard felpro gasket thickness and its an easy gasket to get many places. Different sizes like the .020 are not as easy to find and many sizes need to specially made like some cometic gaskets. Which is ok but the special size gaskets cost more and usually take longer to get. Also you need to make sure your comp ratio will still be ok. On one 440 I used .074 special made cometic head gaskets and they were about $150 for the head gaskets and that was about 10 years ago. The heads had been milled .060 so I needed the .074 gaskets to get quench and have about 10.0 comp.
What Cab is saying is anytime you check piston deck height you need to rock the piston and check it in a few places as it can vary as much as .005 to .010 if you check it without the rings on the pistons so you need to know the most and least clearance's and take that into account. Many times when mocking up my eng to take readings I will put the pistons in without the rings on them and of course they will rock alot like that. I use the tightest deck reading so I know it cant get no closer quench then that clearance. Ron