New head - N42 - What would you do

[modular9]

Happy belated holidays

I am very lucky ( I mean that ) in that either my valve stem seals are stuffed or the guides are on my current E-88 head. So I went down to d3coy's place ( BTW he has a full turbo setup and a 300z that is making nice numbers and ... well i could go on ) and knicked his N42 head he had.

 

MYsetup so far :

 

Stock L24 ( at least i think it is )

Triple dellortos

Will have extractors and 2 1/4 system. ( stock wheezy 1.5 inch system )

Auto ( yeh I know ) with the auto diff as well.

Most driving occurs around the 2000 - 4000 rpm range.

 

I am going to buy these awesome ford valve stem seals (link below)

http://forums.hybridz.org/showthread.php?t=90825

 

But what else :

- Thinking of a 1mm shave. But I dont know what the pistons are like and dont want to whip the current head off. I dont want to go too high in the compression. I have the Lengine.exe application and straight bolt on gives me about 8.78:1 (assuming stock internals. )

 

- Cam options. I dont want something massive. In fact more power in the low end would be sensational compared to top end. Head came with a cam ( thanks d3coy again ! ) however almost sure it is stock. Good looking wear patterns though. Numbers are e30 on the length of the cam and an F on the nose ( end without the sprocket.)

 

- I know that the valves are already bigger in the N42 so I dont really want to phaff around with those but a small unshrouding would be good ?

 

The car is a daily driver in heavy traffic ( does about 150 k a week ) and needs to be relatively docile in lower end RPm range

 

Thanks for taking the time to read this. Basically I am after anything I may have missed and some cam choices and opinions. ( and dont say go back down to d3coys place and buy the l28et I am already in trouble for buying the head from the missus ! )

 

Mike

 

[pauly_adams]

good luck with your build. i have a L26 with a early E88 that has been shaved about 1mm and i have no problems with the pistons hitting the valves. i also have a mild ground cam and man does this combo make a big diffference to the power output just dont get a real lumpy cam as you use your car as a daily like me, as for L28 long live the L24 and L26

 

cheers pauly

[C.A.R.]

Hey Mike,

PLEASE do not shave the head any more then necessary!!! I can't stress this enough.

I STRONGLY recommend that you only take the minimal amount off the head - no more. Say .030" .

 

Removing more off the L series head has many drawbacks, include the possibility of head gasket sealing issues, timing chain aliment, cooling issues,

softening of the head material... etc.

 

ALL L-series engines should only have the CR altered buy the combustion chamber size, head gasket thickness & piston dish (or lack thereof).

 

FWIW, A particular well known L-series engine builder WILL NOT use a L-series head that has been shaved more then 1.5mm...

[pauly_adams]

mine is shaved about 0.6mm havent had a drahmah but i have larger cam towers etc. if you want some more power get a good cam and get your head fixed to new condition also a good eltrical system does help my two cents

 

cheers pauly

 

[Zedman240®]

The only time I get any cylinder head shaved is when its absolutely necessary! With todays crappy fuels it doesn't pay to have high compression unless you have a CAMS log book and can afford to buy Avgas! Just remember what you shave off you can't put back on! (unless you get thicker gaskets etc) Tune it for what fuel you want to mainly run it on.

[modular9]

Yes after posting the above i hopped onto the atlanticz.ca site and found out that I need a new chain etc etc. So more likely to be a valve shroud relief and a good 3 angle valve job though i also read that in most cases a L head wont need this as Nissan/datsun over engineered their heads as well !

 

I have found out that the cam is a stock cam from a p79 head off a l28E.

http://atlanticz.ca/zclub/techtips/cam/index.htm

 

Cant tell if the durations were measured at 050 or not.

 

 

[nat0_240_chevZ]

Shave smchave.

 

Shave as much as you like untill you reach minimum recommended thickness of the head. it just means you will have less life in respect to facing and re-facing for future rebuilds.

 

You can either shim the cam towers with the appropriate shims, (which i happen to make!! )

or slot the cam chain guide holes to allow a bit more adj to take up the slack in chain and to maintain tension from the cam chain tensioner. (or remove the factory tensioner and replace with a far superior adj ubit as seen on kameari engine works site and another 2 or 3 usa sites somewhere, uses the block off section @ front of head. allows these motors to safely run at 11,000 rpms, with resq'd mods of course.)

 

Piston to valve clearance does have to be considered, bit i ran (about 5 - 7 years ago) l24 dished pistons, N42 head with 2.25mm shaved, about 10.8-11.1 CR and this thing hummed, high revving high comp, big advance too, just had a small amount of ping when laboured at low engine speeds, but you never would do this unless just lazy with gear changes, (shouldnt anyway ya lazy pug). lets just say that motor taught a few of the commy v8 fellas a few things from a 1/2 size six cyl, all in a 2+2 mind you too. Mind you this was back when the VR-VS hsv only had 185-195kw anyways stuck with them and nudged a few off that werent driven or mantained very well.

 

The destruction however of this motor was the dizzy nut comming loose, timing went balistic and melted a piston @ 8500rpm, however the head was fine. Piston replacement and light hone was only costing me 200$ but had to sell this and my 240z to fund a new education!! hence where i am now!

 

shaving does not pose any other cooling issues except the higher comp makes more heat, but it certainly does not soften the head material, overheating the motor does.

 

look i found it works wonders, if i am to do it again iw ould only shave 1.5-2.0mm off depending on pistons and desired comp ratio, but would run forgies with a slight peanut on the top to quench even harder, oh yea did i mention i ran it on 92 ron? and on 95-98 it went even better with less rattle if you were lazy.

 

nato

[C.A.R.]

Personal choices apply here of coarse, but as it's a daily driver - & I would have thought reliability would be a major consideration - I wouldn't want to risk anything for the sake of a wee bit of extra performance.

 

Just my 2 cents...

 

[modular9]

No shaving for me ! I broke it all down ( i didnt take the camshaft towers off as the haynes ( blue hard cover version ) says not to ) and the cam is pushing the valves so far down into the combustion chamber i'd need to fly cut the pistons!!

 

I have a l28 short engine coming from d3c0y so I have a few decisions to make ( turbo + megasquirt or something )

but ...

 

First: The N42 head is the one with the injector notches in it. If I continue with the triple dellortos on the l28 will i need these welded up? I'd prefer to keep them in as a possible injector/turbo thing might be in the future.

 

second : camshaft towers . I assume that if i get a regrind ( thinking of the 812c from http://www.tighecams.com.au/profiles3/nissanlseries.htm ) then surely i am going to need to get the camshaft towers redone anyway so I can take these off ?

 

sorry to be such a questioning noob but the L6's sure arent v8 clevelands !