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Location:
Toowoomba
Registered:
May 2002
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NA 18r-gu headwork question
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Wed, 20 November 2002 09:11
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Hi everyone, I need some help with this. As some of you probably know, I have a basically stock 18r-gu, apart from decking block and head, basically all I have done is a complete rebuild bout 30,000km ago back to original specs and a nice 2 1/2" exhaust system. I am removing the head again very soon and want to know what work I can do while it is off, keeping in mind I am converting to EFI at the same time. What should I be doing to ports, valves, cams etc. I need it to be streetable as 90% of my driving is around town but I do want a nice improvement in power. I don't plan on doing any block work and better injectors/fuel pumps to go with my microtech mt-4 (thanks crostek) are an option later on. Can someone point me in the right direction please  .
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Toymods Social Secretary
Location:
Sydney
Registered:
July 2002
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Re: NA 18r-gu headwork question
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Wed, 20 November 2002 09:44
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cam grinding, or replacement cams.... grinding would be a bit milder i think.
Head port and polish
Larger valves (head for the EFI valves, or bigger even!)
Weber DCOE45 carbies
amoung a few...
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Location:
Canberra
Registered:
May 2002
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Re: NA 18r-gu headwork question
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Wed, 20 November 2002 09:57
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What is a good size to regrind 18rg cams to? whats else would need to be done to accommodate the reground cams
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Location:
Toowoomba
Registered:
May 2002
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Re: NA 18r-gu headwork question
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Wed, 20 November 2002 12:01
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sorry, did I forget to mention that I'm cnverting to EFI??? Any Idea what valves I can use?
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Location:
Canberra
Registered:
May 2002
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Re: NA 18r-gu headwork question
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Wed, 20 November 2002 14:30
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No idea what valves, but at least get some Datto Z valve springs, i hear they kick ass and fit in.
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Location:
Toowoomba
Registered:
May 2002
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Re: NA 18r-gu headwork question
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Wed, 20 November 2002 15:08
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are the standard 18r-g ones no good? I don't think I will go too crazy, I've given up on forced induction and just want a nice N/A job instead. I do only drive it round town and occasional long trips, no serious racing of any kind and not very likely, maybe a day at the track for some fun one time but nothing serious. Has anyone got an EFI rg with some work done? I'd like to know how it performs and what has been done. If I get my cams ground, how do I find out how to get them ground or should I be doing that at all? What sort of thing would need to be done to get around 160-170hp'ish? Anything I should know being a newb at performance engines?
Know it seems like a lot of Q's but give me a break, i'm new in this area. (think that might be my new signature)
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Location:
Canberra
Registered:
May 2002
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Re: NA 18r-gu headwork question
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Wed, 20 November 2002 22:09
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Dylo: Any more info about the Datto Z springs in the 18rg??
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Location:
Brisbane
Registered:
May 2002
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Re: NA 18r-gu headwork question
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Wed, 20 November 2002 23:22
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I wouldn't get too carried away with head work; GU heads already have big valves and ports, so unless you're building a race engine there's not much point upgrading these. If anything just clean up the ports a little (get rid of casting dags etc).
Reground cams are the way to go if you want a bit more power without spending a fortune, but to get the best out of them you'll want to raise the compression ratio to at least 10:1. I can't help you with cam specs though, but if you can find some TRD cam specs that would be a good place to start.
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Location:
Adelaide and Queenstown T...
Registered:
September 2002
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Re: NA 18r-gu headwork question
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Wed, 20 November 2002 23:46
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How do you increase the compression ratio to 10:1?
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Toymods Social Secretary
Location:
Sydney
Registered:
July 2002
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Location:
Toowoomba
Registered:
May 2002
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Re: NA 18r-gu headwork question
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Thu, 21 November 2002 00:50
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thanks norbie, good info. THE WITZL, that was a good read, some good info there too. Now all I need to know is how to get them cams ground and how much this is all going to cost me
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Location:
Canberra
Registered:
May 2002
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Re: NA 18r-gu headwork question
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Thu, 21 November 2002 10:31
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"Toysport.com: For the Full Race set-up use 320 intake and 304 cams. For the Rally set-up use 304 /288 or 304/272 cams. For the Street racer, the 304/304 set-up is very streetable and have a nice mild lobe at idle. It is very discrete! These cams cannot be used with stock pistons!! (The 288/272 cam set-up maybe used with stock pistons, as long as the head has not been cut.) "
Can someone explain to my why these cams cannot be used with stock pistons... is it to do with the valves being open at the wrong time?
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Location:
Brisbane
Registered:
May 2002
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Re: NA 18r-gu headwork question
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Thu, 21 November 2002 13:43
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Too much lift and/or duration means the valves can hit the pistons at TDC. The solution is to have the pistons flycut for clearance.
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Location:
Canberra
Registered:
May 2002
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Re: NA 18r-gu headwork question
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Thu, 21 November 2002 22:12
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Wouldn't this weaken the pistons?
Is there a way to find out how much the piston need to be machined?
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Toymods Social Secretary
Location:
Sydney
Registered:
July 2002
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Re: NA 18r-gu headwork question
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Thu, 21 November 2002 23:05
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if you start getting crazy with ideas like this... then it's probably a good idea to talk to an engine builder... there's a few blokes in canberra, since celicas are so popular there.
I wouldnt know specifics, but it would be an idea to also consider the age of your pistons if u want to machine them!
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Location:
Western Sydney
Registered:
May 2002
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Re: NA 18r-gu headwork question
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Fri, 22 November 2002 08:39
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You don't need big cuts in the pistons and anyone who's seen RG pistons will know the actual piston platform (if you could call it that) is pretty thick. Getting the standard cams reground isn't a problem. The lobes have heaps of meat on them. Just make sure you compensate with thicker valve shims.
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Location:
Brisbane
Registered:
October 2002
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Re: NA 18r-gu headwork question
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Sun, 24 November 2002 10:26
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I have been ringing around for prices on cams for an 18RG
JHH engineering in springwood on brisbanes southside want $175  for a pair of regrounds or $1000 for billets
cheap cheap
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Location:
Canberra
Registered:
May 2002
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Re: NA 18r-gu headwork question
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Sun, 24 November 2002 10:59
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Does anyone know about stiffer valve springs? is it worth doing? dylo mentioned Datto Z springs has anyone heard of this b4?
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Location:
Brisbane
Registered:
October 2002
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Re: NA 18r-gu headwork question
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Mon, 25 November 2002 10:24
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call JHH perofromace on brisbane's southside they want $90 for a set of stiffer springs.
call them on 07 32086274
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