m9 head on 2.6 astron I

[iownasicsigma]

just wondering what sort of parts/alterations would be needed to fit this to my car?? also how much gain i would get from this upgrade??

[Scorpma82]

i think from memory u can bolt it on with good gains in power BUT (and this is only from memory)....you have to convert to an electrical fuel pump as apposed to a mechanical fuel pump

[A112H]

The biggest gains you will get is using the search button!

[iownasicsigma]

thats ok because was gonna get one anyway as i've got a 350 holley fitted, thanks

[damian]

we've just fitted an M7 head to an Astron I.
Bolted straight on.
used the old cam and ROCKERS as they are adjustable.
adjusting nuts - take off the top and put underneath so they have more to hold onto
our intake manifold with quad motorbioke carbies had both old and new bolt patterns (thanks Superscan811), so you may want to check you don't need a new manifold or adapter plate.

as A112H said, search the forums, there is a little bit of info in our thread in the introductions section

EDITED to correct rockers / lifters reference

[Benno]

We are running a Mechanical Fuel pump on our Astron 1 with the M7 head fitted, but I don't know if you can run one on an M9 head, it depends on if there is a hole for the fuel pump arm to go through or not.

Bolted straight on.
used the old cam and lifters as they are adjustable.
adjusting nuts - take off the top and put underneath so they have more to hold onto

and as Damian said we are using the original cam and adjustable rockers (not the lifters) and yes put the adjusting nuts for the rockers underneath of the rocker arm not on the top of the arm as per factory, because there isn't enough thread to do the adjusters up tight without stripping them, and we all know theres nothing worse than stripped nuts

you will need to use the magna rocker cover as an Astron 1 rocker won't fit properly.

you will find the later model head will make a difference as they breathe a hell of a lot better, they have bigger valve and ports, you'll need to fit a reasonsble set of extractors and fit a bigger carby or carbys to make gain the most benefit out of it.

[mic_77]

Get adjusters out of a mazda capella or I think from memory I used a set from a early laser carby model.

cheers Mic

[karl_2ltgc]

M9 head has the funny combustion chambers that look like ping city. They are designed for emissions, not power. M6/M7 are the best for performance.

[cheaterparts]

M9 head has the funny combustion chambers that look like ping city. They are designed for emissions, not power. M6/M7 are the best for performance.

strangly enough Karl I was looking at fitting one - it would be easier to get the comp higher than the larger open chamber type and still stay with flat top pistons

[81GL]

Bolting it 'straight' on there will lower the compression ratio. So if your wanting it for a power gain, I'd suggest resolving that.

[Superscan811]

M9 head has the funny combustion chambers that look like ping city. They are designed for emissions, not power. M6/M7 are the best for performance.

The M9 chamber is cast as opposed to machined so apart from the outside edges in the chamber, it would be less likely to cause detonation.

As Cheater had told me a while ago, with the flat top pistons, there would be a lot more "swirl" in the M9 combustion chamber when it ignites and that helps prevent detonation.

The biggest problems as I see it are the shrouding of the valves and the fact you would be hard pressed fitting larger valves without a fair bit of the "extra" material being removed.

BTW: A stock M9 head would be a good "no frills" upgrade for an earlier Astron-II head. Larger ports and valves along with a boost in CR.
Cheap and easy.

Cheers.

[cheaterparts]

.

BTW: A stock M9 head would be a good "no frills" upgrade for an earlier Astron-II head. Larger ports and valves along with a boost in CR.
Cheap and easy.

Cheers.

same sized valves as all astron 2 heads 46 inlet and 38 exhaust

[iownasicsigma]

I'm a lil confused, so if I was wanting more power what head should I get? M6, m7 or m9

[Benno]

I'd Be going an M6 or M7 rather than the M9

That's my 2 cents worth

[A112H]

If its non turbo go for a 2.0 head

[cheaterparts]

I'm a lil confused, so if I was wanting more power what head should I get? M6, m7 or m9

I know this may sound a little strange but what are you trying to do and what other parts are you going to use ?
are you fitting flat top pistons ?- are you fitting an aftermarket cam ?

are you trying to make a race engine - street engine

If its non turbo go for a 2.0 head

if he is replacing an astron 1 head on a 2.6 its the same head - both the 2lt and 2.6 used the same and with same ports and same valves
I think I chucked all my astron 1 heads in the scrap ages ago prefuring to open the air ways up and let the engines breath

[A112H]

Hey Cheater,
So mine is a Astron II (1987) with an Astron I 2.0 head. Was there and benifit to doing this or was the engine builder fooled by capacity? is: thought smaller capacity head meant higher compression?

[81GL]

He was kind of correct, more so that he used the astron 1 head to up the compression - nothing to do with it being from a 2lt, as cheater said, they are more or less the same head as the astron 1 2.6.

So yes you will be running a higher compression as you would have flat top pistons, combined with the small capacity head.

Although I'm with cheater, not really a fan of the astron 1 heads, small valves & ports. If you get the chance to grab an astron 2 head and take 3mm off the face of it you will not regret it Truth be told I think cheater has taken more than that off?

[/hijack]

[cheaterparts]

Hey Cheater,
So mine is a Astron II (1987) with an Astron I 2.0 head. Was there and benifit to doing this or was the engine builder fooled by capacity? is: thought smaller capacity head meant higher compression?

I dont know what your engine builder was trying to do - an astron 2 open chamber head with 3.5 mm shaved off has the same small head capacity as an astron 1 but with valves and ports that can flow better
and on of the biggest things on the 2.6 is to get it to breath
how many times have you seen posts about the 2.6 not being able to rev - its because the breathing ability of a lot of the early heads stop any sort of flow at higher speeds

now not knowing how your builder went about porting your head - how well does it rev say in 3th 4th or 5th gear
I know in 4th on my car I run to 7200 with a 3.89 diff ( end of the straight @ sandown with sandown gearing )
max power is at 6100 but easy over revs to save on gear changes

I run an open chamber astron 2 head with 11.2 :1 comp with flat top pistons than dont sit higher than the deck so I know it works - it still runs happy with 30deg total ign and on 98 oct
its simple machining again I know - I dont just build my own engines but do almost all my own machining in house

I'm a lil confused, so if I was wanting more power what head should I get? M6, m7 or m9

I know this may sound a little strange but what are you trying to do and what other parts are you going to use ?
are you fitting flat top pistons ?- are you fitting an aftermarket cam ?

are you trying to make a race engine - street engine

just figured out your into

Hey everyone, small and quick introduction, i'm 16 and race an 84 model GJ sigma which is my pride and joy, few upgrades have been done; 350 holley, extractors, 2.5 inch exhaust..

Normally I compete in dirt time trials on a tight 1km track, but on the 3rd and 4th of march i'll be competeing in a bitumen sprint at east sale raaf base.

I have been a member of MADCC myself and use to run a GH sigma in the under 2 lt std class ( not that well ether - car was good the driver not so good )
I also was a member at GCC for a while when they use to have Morwell hillclimb again running a sigma ( quite a winning car in its day there - best result was the 2004 aust hillclimb champs at morwell I won the 2001 to 3000 Improved production class in a time of 35.87 sec that was faster that the over 3000 class )
I've played at sale airbase a few times always a fun track

first being 16 your budget isn't going to be that high so here goes the things that will make a lot of different to your siggy
and fairly cost effective
if possable look around for a 2 lt gear box and a small patten block so you can use the 2 lt flywheel and clutch - this will make a huge difference in acceleration
remove the balance shafts that also helps
if you are going to fit an astron 2 head you will need to have flat top pistons
a cheap way around that is to pickup a complete magna engine
it will have flat tops and the later head - however the front timing cover will need to be changed to a sigma one for the water pump and the water pump hole in the back of the block will need to be blocked
magnas have the small pattern so will match up to a 2 lt gear box
the mounting holes for the engine mount are on a magna block in the same places as a sigma

hope that helps

[A112H]

The hi-jack continues, lol

now not knowing how your builder went about porting your head - how well does it rev say in 3th 4th or 5th gear
I know in 4th on my car I run to 7200 with a 3.89 diff ( end of the straight @ sandown with sandown gearing )
max power is at 6100 but easy over revs to save on gear changes

It is happy to pull cleanly to 6500-6700 in 3rd. Haven't been game to do it in 4th or 5th, beside that would be irresponsable outside of a controlled enviroment
I haven't pulled the engine down but was told it has over size 3 angle valves, faced and ported with a big cam.
I know this is kinda vague but it is all I have, lol
Block is stock with flat tops.
Twin DHLA 48mm Dellortos, custom headers with 2.5 inch system

[iownasicsigma]

Hey everyone thanks for your comments it's alot of help and will help me build my engine into a power house lol, by the way i'm trying to build a race engine, I seem to have a fair bit of rev's and top end power, what would I do for some torque? Thanks :-)

[cheaterparts]

Hey everyone thanks for your comments it's alot of help and will help me build my engine into a power house lol, by the way i'm trying to build a race engine, I seem to have a fair bit of rev's and top end power, what would I do for some torque? Thanks :-)

trying to build torque into a 2.6 is not realy a problem they have plenty anyway
it will alway be hard with the holley - a set of webers are are better option ( note - also not a cheap option )
or you could go for fuel injection also a better option

get as much weight out of the flywheel and crank - the std 2.6 fly wheel weighs about 16 Kg - I run less than 5 kg flywheel
I dont know what the clutch weighs - my clutch weighs about 2.5 kg total and is smaller in dia
there is also 2 kg removed from the crank
removing weight from the crank and flywheel is less weight for the engine to speed up the power instead goes to the wheels
speeding the car up

getting the compression up is another way to build power and torque over the whole rev range but if you are running a fuel with an oct rate of 98 dont get to carried away with the comp it will also depend on the cam you use

my veiws are the 2.6 can take huge after market cams and not suffer to much at the bottom of the rev range

of cause all of these mods dont come cheap