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Old 03-17-2006, 07:54 PM   #1
Hurley 2.5 WRS
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Default STi V4 Type RA disassembly




things to note:
the pistons are still the old design, with the square dish. (figured as its still phase I)
Open Deck- not semi closed



also, for the rebuild, anyone think there is an overwhelming "yes" to go with ARP head studs over new stock?
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Old 03-18-2006, 04:41 AM   #2
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its just wierd seening all my tools.... ya soon to be running car!!
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Old 03-18-2006, 01:01 PM   #3
RS_to_WRX_swap
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Can you share a pic of the intake ports on the heads?
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Old 03-20-2006, 08:21 PM   #4
Tim Sanderson
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Things I find interresting:

Cam sprocket bolts are not allen head.
The hex to hold the cam sprockets are 6 sided not 12.
All plastic cam sprockets.
No idler between the left head intake sprocket and the tensioner.
No belt keeper thingies on the rear t-belt covers

That's pretty different from most of the stuff I've seen. Thanks for the pics.
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Old 03-20-2006, 08:32 PM   #5
Scoobie Steve
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I am also shocked about the lack of belt keeper thingies. My car jumped 2 teeth because I wasnt running the rear timing cover.
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Old 03-20-2006, 09:43 PM   #6
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i wondered about the lack of the small idler myself, but after p[ondering it a while, i think it is there because the 205 head gaskets are thinner, and they did that to keep it timed right, though i dont know what the other side would have.

also wondered about the keeper/guides for the cam sprockets then too, but i dont see how you skipped teeth without some considerably high loads. anyone else skip teeth with motors not having the keeper/guide for the cam sprockets? (fyi, for the people that dont know, they are the same thing as the one over the crank gear)

and by hex to hold the sprockets, you mean the one that surrounds the cam bolt visually?

the cam gears are plastic with a metal inside, that only goes out to that hek in the gear. when a valve hits a piston, the cam gear shatters, kinda as a safeguard mechanism.
ill get intake port pics asap
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Old 03-20-2006, 11:00 PM   #7
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Actually, this isn't all that different from an EJ25D head.

It has been said that the EJ25D (Phase I 2.5 DOHC) heads have same casting cores as on the Ver3/4 STi.

I can clearly see why, plus I have disassembled EJ25D heads before, and they are identical to the pics you've posted. That goes for the 17mm bolt to the cam gears, to the all plastic cam sprockets, lack of smaller idler, and no keepers to keep the belt from jumping teeth, etc.

-paK +1
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Old 03-21-2006, 01:19 AM   #8
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yeah, they are very similar. the ports may be bigger, and different valses/springs ect, but the casting is definatly derived from eachother.

also, do any of you ej20g guys have the small idler? im pretty sure thats a new thing. (205/7)
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Old 03-21-2006, 11:01 AM   #9
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The small idler is a result of the change in the timing belt tensioner design. The two go part and parcel. I have never seen one on any pre-01 Ej series engines of any variant. But the blocks are still the same, and as long as you have the right back plate, you can use either tensioner and pulley on any series of block. Some of us consider the old design superior. This is because the new tensioners tend to be a single use tensioner, while the old larger ones generally are good for at least one timing belt replacement...

I also have not ever seen any sort of keeper on the cam gears nor allen bolts until phase II DOHC engines.

Glad to see this thing finally coming apart and progressing in the right direction. This car has been down far too long. This is not a criticism, since I know how things are in life, just a personal desire to see your build done and the car back on the road. Let me know if there is anything I can do to help things...
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Old 03-21-2006, 12:03 PM   #10
ImprezMeWRX
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Hurley,

on my firend sti version 4 ra engine, the intake and exhaust pulley are in steel, why your is not ?

Thanks
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Old 03-21-2006, 12:16 PM   #11
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From my understanding those are mechanical heads, but from the pic they look like HLA.
Could you clearify?

thanks
kirill
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Old 03-21-2006, 12:32 PM   #12
Matt Monson
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Oh,
And don't bother with the studs unless you plan on tearing it apart again anytime soon. Reusing the stock bolts will be fine. There's many threads arguing about it in the AFI forum, but myself and many others reuse stock bolts all the time...
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Old 03-23-2006, 06:41 PM   #13
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really bad shot of the intake port, ill get more soon
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Old 03-29-2006, 04:35 PM   #14
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theres more shots of the intake ports, and a shot showing the difference between version 4 (left) and version 7 (right) pistons.

i did some measurements as well.

STi Version 4 RA head combustion chamber: 45cc

V4 pistons: 15cc dish, comes aprox. .4mm above the deck at TDC

used V4 head gasket: 1.4mm

V7 pistons: 7cc dish, aprox. 1.3mm under the deck at TDC
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Old 03-29-2006, 06:54 PM   #15
Matt Monson
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Now those are some numbers I can work with if I were to run some CR numbers...
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Old 03-29-2006, 07:26 PM   #16
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ya, gunna order gaskets today or tomarrow!

numbers are there to have it documented, couldnt hurt
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Old 03-29-2006, 07:27 PM   #17
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IMO, the money for ARP studs can be better spent elsewhere.
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Old 03-29-2006, 07:59 PM   #18
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Quote:
Originally Posted by Hurley 2.5 WRS
ya, gunna order gaskets today or tomarrow!

numbers are there to have it documented, couldnt hurt
Where are you getting gaskets from? Im looking for the complete set for the same motor. Just curious...
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Old 03-29-2006, 08:39 PM   #19
Hurley 2.5 WRS
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im just getting some cometics

edit: the cometics are a bit thinner, but i need that, and the other gaskets should be like a 98 RS motor id assume

Last edited by Hurley 2.5 WRS; 03-30-2006 at 03:48 AM.
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Old 03-30-2006, 12:01 PM   #20
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I have a version IV STI RA myself and I blew a No. 4 Rod bearing so I had the engine rebuilt by Techworks engineering and they had a custom headgasket kit made for me from Cometic I think that's the proper spelling...They are out of Australia I believe and their Head gaskets are suppose to be one of the strongest made...It's a metal type gasket with fiber...
I also had my heads ported and polished and quench clearence has been reduced....Crazy thing about this engine is the timing belt is the same as the 1998 2.5RS...So some parts are real similiar for those years....
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Old 03-31-2006, 08:44 AM   #21
Skully
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I personally would not reuse the stock head bolts. Spend the extra money and never have to worry about bolts again and get the studs. Also the studs provide more even clampload on the head which will help prevent headgasket failures. One other nice thing about the studs is they wont stretch like the factory bolts will. Large amounts of boost for extended amounts of time will stretch the factory bolts and cause possible head gasket failure.

-Thomas
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Old 03-31-2006, 12:03 PM   #22
Matt Monson
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Skully,
I don't think Tyler is gonna beat on this motor the same way you do.
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Old 03-31-2006, 05:52 PM   #23
Hurley 2.5 WRS
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at least not for a while

o, there will be track days. o yes!
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Old 03-31-2006, 06:17 PM   #24
Matt Monson
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Quote:
Originally Posted by Hurley 2.5 WRS
at least not for a while

o, there will be track days. o yes!
Skully has managed to blow up not 1, but 2 built EJ22T's that I sold him the cores to build from. He's a drag racer who treats engines like most guys treat hookers, disposable...
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Old 03-31-2006, 07:38 PM   #25
Hurley 2.5 WRS
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lol

ok, heres some pics of the older STi version 2 RA heads and block for more references for you guys.

Quote:
heres a ver 2 STi-ra botom end. piston dish has little arches.



heres a EJ20H bottom end



ej20H pictures.

im guessin the V4 had same naked shorty as a ej20h with revised pistons and difernt heads. heads have diff dish im assuming?
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