How much to shave?? HELP!!!

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slugma
Posts: 53
Joined: Wed Feb 22, 2012 8:17 pm
Location: Mt Gambier

How much to shave?? HELP!!!

Post by slugma »

Hey guys, so after doin extensive research on this forum, ive decided EFI and turbo are too damn hard so wont be doing it.
Instead ill just shave the astron 2 head to suit the astron 1 engine.
But i really dont know how much to shave off to get the compression back up to at-least stock, if not a fraction more.
I spoke to the bloke who will be shaving the head, and i mentioned 3mm to him, and he said that would be EXTREME!!!!
And also mentioned with that much shaved off, i will probly have other issues such as timing chain not fitting back on properly. (Too loose maybe???)
He even said, just turbo it!!!
So i was wondering if anyone could tell me, or point me in the right direction on how much to shave off to get the comp ratio back up?
Engine is bone stock, and for the moment will stay that way, and ive been told by someone on this forum that the comp ratio will be approx 7.7 if i just put the head straight on.
I have the flat top pistons but really dont want to take the motor out.
Can i get the outcome i want by just shaving the head?
Or will it simply just not happen??

Any helpful advice would be greatly appreciated.

Cheers, Matt.
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83 GJ Sigma
A112H
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Joined: Tue Mar 24, 2009 5:01 am

Re: How much to shave?? HELP!!!

Post by A112H »

It really is something your engine builder needs to decide mate. On a stock head you can take 3mm and I have even heard of 3.5mm but with a second hand head you have no idea if it has been shaved before.
You engine builder will be able to take measurments and work out what is safe.
If you really can't assed, turbo manifolds are cheap out of the US and stock CA18 or SR20 turbo's are cheap, maybe turbo is the go?
slugma
Posts: 53
Joined: Wed Feb 22, 2012 8:17 pm
Location: Mt Gambier

Re: How much to shave?? HELP!!!

Post by slugma »

The thing is, we arent actually "building" anything, we are just wanting to replace a bad head.
Turbo would be ideal, i can get turbos for for next to nothing, but a manifold and carby i cant.
From what ive read on this forum regarding turbo carbs, it sounds like an expensive process.
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tubby
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Re: How much to shave?? HELP!!!

Post by tubby »

how hard is it to get an astron 1 head really? wouldnt that be easier/cheaper than getting a mismatched head machined?
'81 GJ Scorpion, '87 GN Panel Van, '77 Sigma sedan
slugma
Posts: 53
Joined: Wed Feb 22, 2012 8:17 pm
Location: Mt Gambier

Re: How much to shave?? HELP!!!

Post by slugma »

Well i didnt find it that easy! Well not one that i could get delivered cheap!
This is what i have now, it was a bargain price, and i cant afford to buy another one!

Unless.....

Some one has an Astron 1 head they want to part with?
And i mean swap for the M28 head i got?
Comes with 4 flat tops
New rings
New engine bearings
Inlet manifold
Cam
Reco rocker arm.
Head was supposedly bought brand new, he said it was on his engine for 4 hours before the bottom end went.

I would swap it all, and there is a bit more stuff too, for a COMPLETE guaranteed working Astron 1 head.
MY05 GT Liberty
83 GJ Sigma
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