head decking

03blackrt · Post by **03blackrt** » Tue Aug 01, 2006 8:00 pm

I'm going to be decking my head in december (if i still have a neon) and did a little caculactating to find the effects decking has.

here is a chart i came up with showing the relation of decking and timing/cr (this is only good for 9.8 stock cr, all 2.0L non-mag ngc motors have 9.3-9.4 cr. removing materal from the block and/or the head gasket will result in slightly different numbers too).... i belive that the cr is very accurate and the timing change is within +/- 50%

I found to get the 11:1 cr that i wanted i need to take off 0.04084" and my timing will change 0.73523 degrees (retarded i think).

anyways, this chart may be of good reference to anyone looking to deck their head. i will update it for accuracy when i have the work done and can take some actual measurments of stuff.

edit: for retardedness!

eastwoodsn352 · Post by **eastwoodsn352** » Tue Aug 01, 2006 9:59 pm

decking a head? what is that??

03blackrt · Post by **03blackrt** » Tue Aug 01, 2006 10:06 pm

decking the head = milling the surface of the head that mates with the block.

this will effectivly reduce combustion chamber size thusly increasing compresion.

OB · Post by OB » Tue Aug 01, 2006 10:36 pm

interesting idea. not many have gone down this road before from what ive seen, so i look forward to seeing how it goes for you. only advise i can give is make sure u consider every possibility and make every calculation perfect before doing this. hope things turn out well

03blackrt · Post by **03blackrt** » Tue Aug 01, 2006 10:41 pm

decking a head is nothing new, even for neons (or at least 1st gens). tho i haven't heard of many 2gens doing it. i have yet to hear of an ngc'er doing it.

OB · Post by OB » Tue Aug 01, 2006 10:41 pm

yeah i was referring to 2gns, not cars in general haha

03blackrt · Post by **03blackrt** » Tue Aug 01, 2006 10:54 pm

ya, i figured that

I will have an after dyno and may have a before/after 1/4 time. While I have the head off I plan on a nice port/polish job on the head and intake and maybe a 5 radius valve job if i have the cash.

OB · Post by OB » Wed Aug 02, 2006 2:06 pm

sounds like a great plan bro. good luck, cant wait to hear about the results!

white2000neon · Post by **white2000neon** » Wed Aug 16, 2006 11:19 pm

Im decking my head .030" can anyone tell me if it retards or advances timing so i can get a cam gear set back to the real 0 or at least close.

03blackrt · Post by **03blackrt** » Wed Aug 16, 2006 11:23 pm

Decking should retard (i havn't look at the rotoation of the cank to see, but the all knowing other dot org says retard so that's what im goiing with) it about 0.5-1.0 deg (to the best of my knowledge (some say im mildly retarted tho

)). I hiope to actually measure this when i deck my head.

phenomeneon21 · Post by **phenomeneon21** » Thu Aug 17, 2006 1:01 am

Wouldn't the best way to start is by reducing the size of the headgasket? I thought I remember reading on neons.org that this was the best place to start because the gasket itself was pretty thick and could shave some room between the block and head...or maybe I'm just retarded and thought I saw that somewhere, lol.

03blackrt · Post by **03blackrt** » Thu Aug 17, 2006 1:09 am

phenomeneon21 wrote:Wouldn't the best way to start is by reducing the size of the headgasket? I thought I remember reading on neons.org that this was the best place to start because the gasket itself was pretty thick and could shave some room between the block and head...or maybe I'm just retarded and thought I saw that somewhere, lol.

yes, you can remove the middle layer of the multi-layer gasket. This does two things...

1) reduces "dead" area in the combustion chamber

2) removes greater volume per unit of material removed compared to removing materal from the head itself. (make sense ???) This keeps the valves farther (and therefore safer) away from the pistop top for a give desired compression ratio

If you remove the middle layer (lets call it 0.026") (0.026" says a guy on the other dot org, antoher guys says its 0.20"

) will net a 0.826 increase in compression (removing material from the head gasket resiults in a 119.7% larger gain in compressin comapred to removing material from the head (because the cc in the head is 89.3% smaller then the bore of the piston, remove head gasket material is like removing materal from the block)

OB · Post by OB » Thu Aug 17, 2006 1:18 am

What are u plainning on doing for a gasket after you mill the head? just a stock replacement, or are u gonna shoot for a better quality one? (if there is one available, that is).

phenomeneon21 · Post by **phenomeneon21** » Thu Aug 17, 2006 1:36 am

haha, i wish I understood this kinda stuff more...I'm just happy I remembered that you could remove material from the gasket but I'm sure you already knew that, hahaha. Thanks for giving me the technical aspect of it though, it's always neat to learn something new...

OB · Post by OB » Thu Aug 17, 2006 2:36 am

yeah im learning a lot about this stuff in school right now, so its fresh in my mind. car stuff is simply amazing, i love learning everything I can. when people do this kind of thing to their neons its really interesting to read about their plans and the results. hopefully things turn out well in this case!

white2000neon · Post by **white2000neon** » Thu Aug 17, 2006 7:48 am

I'm going to try to find a better quality gasket because of the increased cylinder pressures, but even if i can't i know many have done it on stock head gasket and dont have a problem. I'm hoping that my project will be finished by the end of winter as i slowely get parts. My setup will consist of a P&P magnum head with 3 angle valve job that will be milled .030" (that will be here today yay), ff LTH, box style intake manifold, afx R ecu, 60mm tb, crane 14 and gear, 2.5" exhaust piping, CAI, UDP, Thermal r&d rear section. I'm shooting for 14's but well see.

N_gin · Post by **N_gin** » Mon Jul 27, 2009 9:57 pm

removing the middle layer will give you better squish wich is more important cause it creates turbulance. in other words you can run lower octane with higher comp.

aceborn · Post by **aceborn** » Mon Mar 04, 2013 2:37 pm

My question doesn't require a new thread. So I figured I'd post it here, seeming it was most relevant to my question. And answered most of the questions I had with the MLS gasket and Cr.

When you remove the middle layer of the MLS gasket is it necessary to replace the rivets in the gasket?

Post by **occasional demons** » Mon Mar 04, 2013 7:48 pm

I wouldn't. What would you replace them with, that will crush to the same thickness of the modified gasket? I would just let the dowels line everything up. Maybe use a few dabs of High Tack before installing the head, to help prevent minor shifting during install.

aceborn · Post by **aceborn** » Mon Mar 04, 2013 8:44 pm

Ok cool, removing the middle layer seems more reasonable than shaving the head. Same amount of material removed, but the head remains unmolested. And .020 is all I need removed to bump me up to my desired 11.1 cr

red2k2rt · Post by **red2k2rt** » Tue Mar 05, 2013 2:09 pm

so technically if one did the dohc head swap and just removed the middle layer of the mls then that would bump the compression back up to about 10.1 which would be over the mag level of 9.8. thats if the math in the earlier posts is correct.

aceborn · Post by **aceborn** » Tue Mar 05, 2013 7:29 pm

Yeah that's what I take from it. The dohc head swap would put you at 9.3 and that .8 Cr bump would put you at 10.1ish. My pistons are 10.5 and I wanted to be at about 11.1.

I think it's a good alternative to shaving the head. If you just want a 0.5-1 bump in cr. I've been searching the org for the other post motioned, to get more info. But cant find it

red2k2rt · Post by **red2k2rt** » Wed Mar 06, 2013 10:24 am

from what i've been reading on the other .org i think if someone planned to remove a layer from the mls it might be better to get a cometic .027" gasket instead. i know its like 93 - 100 but i'd rather be safe than sorry if i went that route.