Removal and inspection of RB20DET head.

[Gold Digger]

Ok gang.Next week I am going to be on vacation and actually have some time to really tear into my engine that I have sitting around. All I have left to take off is the front accesories, the timing belt cover and water pumps and the head. After that, the rest of the stuff I'm not to worried about. I just want to get the head and water pump off.

Now, the questions.

1. Can I take the head off as a complete unit? As in cams, valves, etc.

2. What should I look for in an easy visual inspection?

3. What kind of tools am I going to need to completely dissasemble the head and it's components?

4. With supporting mods of aftermarket cams, larger injectors, fuel pump, exhaust and boost controller, will a port and polish and valve job make any noticeable difference or not?

Thanks for your input.

Neal

[Carl H]

you can remove the head as a loaded unit, but you will have to pull the cam gears off to get it off the block.cams make all the diffrence on the rb20, get a set of good cams and you'll be amazed at what the old girl can do.

[Darius]

I have done this a few times with the RB25 head so I'm assuming the RB20 removal is the same.

1) Yes it can be taken off of the block without removing the cams etc.

2) For a visual inspection you should look at your lifters and cams for wear. Look at the valves for physical damage or carbon buildup. If there's significant wear or damage it should be fairly obvious. I'm assuming nothing is wrong with the valve train and that you're just upgrading, correct?

3) All you need to completely disassemble the head and its components will be a socket wrench and a valve spring compressor. I found one for $80 shipped that worked really well. It has to be the kind that presses the valve from the bottom and has the "cage" attachment pressing down on the retainer so that you can get your fingers/tools in there to readjust the retainer clips upon reassembly. Tools included magnet on an antenna from sears, tweezers, and Q-tips to clean the valve spring seat. (Let me say for the record that reinstalling valve springs is a B_TCH until you get the hang of it.) I used the smaller diameter retainer "cage" attachment and it worked much better because there was more play side to side that you could manuver the clips into place better. That's when I stopped swearing and throwing stuff. Are you planning on replacing the valve guides or guide seals?

4a) As far as the performance of a port and polish goes, you might not notice a difference, but it all depends on how aggressive you get with it. Probably won't make a huge power gain, but you can always argue for doing modifications to the head while you have it off and disassembled.

4b) Valve job might be a good idea for reliability, but I get nervous with giving my local shop technical stuff to do. My motor only has 40,000 miles on it so I don't think I've gotten to a point where it would be beneficial. That one is your call, and will probably be pretty expensive for minimal benefit.

[Gold Digger]

2) I'm assuming nothing is wrong with the valve train and that you're just upgrading, correct?

3) Are you planning on replacing the valve guides or guide seals?

4b) Valve job might be a good idea for reliability, but I get nervous with giving my local shop technical stuff to do. My motor only has 40,000 miles on it so I don't think I've gotten to a point where it would be beneficial. That one is your call, and will probably be pretty expensive for minimal benefit.

My plan is to just freshen up the motor a little. Cams (aftermarket hopefully), either an RB25 turbine or if I have the funds HKS 2530 (I think that is the number of it...lol), gaskets, port and polish if needed, head work if needed, and probably rings depending on wear and what not. I am only shooting for about 250-300 WHP with will be quite nice for the Laurel. Right now, I have 205 stock at the flywheel, and I am guessing total with current mods about 210-215.

All I have as far as performance is Blitz filter, front pipe and exhaust. And I have never had it on a dyno. But I figure if the engine is rated at 205, I am pretty confident that 210-215 is a safe guess on HP.

Thanks though for your advise and information.

[greenmonster80]

As stated above the head is pretty easy to remove. Allen wrench is all that is needed and a couple wrenches. RB26 cams drop right in. Just a thought. I picked up some N1 cams on the cheap. As for head mods. The main restiction on the RB20 head is the small valves. If you can figure out what valves will fit in and a little machining you will have a beast. Please post what you decide to do..

[Yellow4g63]

CA18 valves are 1mm bigger, saw it on Skyline Australia.

[SeVa-S13]

As stated above the head is pretty easy to remove. Allen wrench is all that is needed and a couple wrenches. RB26 cams drop right in. Just a thought. I picked up some N1 cams on the cheap...

Have you installed them yet? That'd be a cool thing to know, but I was under the impression that 26 cams were not interchangeable with 20/25 cams, seeing as they use completely different valvetrains.

[greenmonster80]

Valvetrains are identical....Where does the totally different idea come from? Sr engines are totally different. Maybe somewhere along the way SR20 and RB20 got mixed up..Will try posting the manuals for both the RB26 and Rb20 so others can see they are the same..No luck files are too big. Was able to cut and paste pics from the manuals to show they are the same. Top is from the RB26 manual bottom is from the RB20...Hope it helps...

[Carl H]

no they are not.rb20 uses hydro lifters while the rb26 use solid lifters, thus neccisitating diffrent cam profiles.

[greenmonster80]

Now I am definitely going to have to take the head apart to make sure I haven't forced something to work here. They bolted in fine. I do not have a timing belt yet so I have not rotated the engine thru to see if there are any clearance problems. If this turns out to not work this is going to sux as I threw away my RB20 cams...Went for this based off of Ausie pages info. They seem to post it as a common upgrade.

[SeVa-S13]

no they are not.rb20 uses hydro lifters while the rb26 use solid lifters, thus neccisitating diffrent cam profiles.

Beat me to it; thought I was taking crazy pills for a minute.

[greenmonster80]

Ok it can be done but there are a few more mods that need to be done to the head. No longer as excited to do this as before. Will have to replace them with RB20de cams. A little more aggressive than the DET cams. 264de versus the 260det. Curious to hear if someone else has tried these.

[SeVa-S13]

The stock cam profiles are probably closer to 230/232*; not 260* for damn sure though.

I think there was a pretty heated debate between either WDRacing or TMS and somebody else about if the NA cams were actually slightly more "agressive." If they are, it's probably not really much an upgrade; but hey, you need to replace the cams you inexplicably threw away, right?

Edit: I'd be interested to know what other 20 guys have cams here.Yellow's got his Tomei (?) 270's, Carl has 260's (forgot brand), and I'm lame with my HKS 256's...

[Carl H]

na rb20 cams are worthless, less duration and the same lift...wooo.if anything swap a redtop intake rb20 cam into a silver top for 8 degrees more duration.

[greenmonster80]

Well I am going to have to get a nice set of cams. The stockers were a bit rusty so I got rid of them and looked at different sites for upgrades. Turns out they are not what they seem. Damn internet info. That's what I get for trying to do this engine on the cheap...Already bored and stroked. Big turbo with new manifold. Injectors are next after cams are fixed...

[Eikon]

Anybody know if Cefiro cams are the same lobe and duration as the skyline cams in RB20s.

I read something a long time ago by an aussie who said the cefiro had more aggresive cams than the skyline to make more torque since it was a heavier car. The skyline was given better higher end due to the blowoff and ecu tuning.

That's just what I remember reading... anybody know?

I ask because based on this info, I picked up a rb20 head from a cefiro. It's just sitting in my garage waiting for some money to port an polish and replace eventually. It would be really nice to know that the cams in there are a little better.

[Yellow4g63]

Well I am going to have to get a nice set of cams. The stockers were a bit rusty so I got rid of them and looked at different sites for upgrades. Turns out they are not what they seem. Damn internet info. That's what I get for trying to do this engine on the cheap...Already bored and stroked. Big turbo with new manifold. Injectors are next after cams are fixed...

Hey Green try and give Webcam a call. There located in Riverside Cali, They can rework the stock cam to almost any size you want. I know a 4 cylinder is 550 to do not sure about the inline 6. Give em call if you don't want to buy the Tomie's.