RB30 engine conversion (lots of pics) - Page 2 - GT-R Register - Official Nissan Skyline and GTR Owners Club forum

keith · 10th April 2006, 09:46 PM

Quote:

Originally Posted by R32 Combat

Keith,

Obviously you think I should, where as I think I shouldn't. I made those guides and I'm not making anymore.

I am trying to offer some advice here,the guides are a weak point on a rb26 head as it is and you have cut a big chunk of the guide away.
the last head i seen like this dropped a few valves

Keith

MONKEYmark · 10th April 2006, 10:47 PM

cool diy work.great to see someone having a go.great write up and pics.

R32 Combat · 11th April 2006, 06:07 AM

Keith,

I know about weak guides, I broke a nissan one a few years ago. The sintered iron guides are not very good and are very brittle. This is why I made my silicon bronze guides up. Also, the guides only break where they are not supported by the head. I no longer have this problem.

I've run 10,000 miles like this with no problems. I know this might seem a little unorthodox, but its worked ok for me..

keith · 11th April 2006, 07:25 AM

Quote:

Originally Posted by R32 Combat

Keith,

I know about weak guides, I broke a nissan one a few years ago. The sintered iron guides are not very good and are very brittle. This is why I made my silicon bronze guides up. Also, the guides only break where they are not supported by the head. I no longer have this problem.

I've run 10,000 miles like this with no problems. I know this might seem a little unorthodox, but its worked ok for me..

I am more worried about the affect the short Guides will have on your valves seating properly, the shorter the guide the more side to side play the valve will have.
that extra bit of guide is there for that very reason it would be a shame to wreck your engine over a set of new guides.

Andy if you are happy that it is going to be ok then go for it.

Keith

Pikey · 11th April 2006, 09:25 AM

Ive got bronze valve guides too

Not sure if they stick out or are flush - cant remember, although I can see advantages for both

cokey · 11th April 2006, 10:04 AM

I thought the inlet guides once replaced with a better material, were an option to grind away. But the exhaust guides were to be left alone.
More for heat transfer reasons.
Would be interested to hear more on this from someone in the know !
Cokey

MADsteve · 11th April 2006, 10:39 AM

This is a great Sticky, and I'm following it with great interest. Unfortunately my garage's full of cr*p at the moment, or I'd be giving it a go, too.

Im inclined to agree with Keith's comments regarding the guides, purely from my Cosworth cylinder head experiences (not the same engine, I know, but same principles none the less.) but I'd stick with building it how you want - that's the point of the thread, isn't it?

Cheers for sharing

Steve

R32 Combat · 11th April 2006, 10:52 AM

After examining the valves and seats before and after lapping, the exhausts were in better condition than the inlets and the contact area was larger.

The anti-lag had caused no damage which means we must have set it up well.

As for the guide issue, its not such a problem with a rocker less cam setup like the RB's. Although the cam does slide over the bucket, that can only move up and down. So the only force on the valve is along its stroke.

On the ehaust side, the valves are IIRC sodium filled. If you run a pointed valve guide, the narrowest part must get very hot, which I don't want.
I want the gas to heat as little as possable on the was out, hence flush grinding the guides.

andy42uk · 11th April 2006, 08:15 PM

I had experience in the past with grinding off the guides flush.
I have to say I wouldn't do it again, my main concern is if there is any 'wobble' on the inlet valve thet it may crack the seat, that's what happend to me, yes different engine but all the same. Also I agree about the heat transfer on exhaust side.
I have no doubt that flushed you will get more power, but the trade-off is not realy worth it, esp. if you are on a budget and planning to do it only once.
I say this to HELP, please ignore if you like.

R32 Combat · 13th April 2006, 11:47 AM

I've bored out the spring retainers to accept the peugeot 1.9D shims I'll be using. The reason for this is simple.
Jun camshafts are re-ground STD cam. To get greater lift, the base circle is reduced, meaning you need thicker shims.
My cams are 10.5 lift with a base circle of 30. The STD cams have a base circle of 32. This means me shims need to be roughly 1mm thicker than the Nissan ones. Although Jun sell the shims, they cost £7 each. The peugeot shims cost £2.50 each, thus a saving of £108. Also, my shims are an 'off the shelf' item. Nice

Nissan to the left, Andy to the right

R32 Combat · 13th April 2006, 06:34 PM

The heads build up although I've not yet shimmed it up

The exhaust manifold needed a little fettling as did the gasket, but so far, so good.

ANDY H · 13th April 2006, 06:58 PM

Looking good , cheers for the help today helped me make a decision!

Cord · 13th April 2006, 07:58 PM

A little late for you, but I'll say it anyway for others benefit.

You can buy buckets with the 1mm step included. And then use the original nissan shims.

rockabilly · 13th April 2006, 08:05 PM

cord. while your online, as andy is using jun cams like myself, mine being 264/272 9.15mm lift,how noisy are they going to be. i know you dont like jun but i bought them prior to knowing this.. are they really bad?. i know rod hates them .. sorry andy for the hijack.. bernie

Cord · 13th April 2006, 08:13 PM

Don't worry, they are noisey, but not excessively. You know what a picky bunch we can be!

13th April 2006, 08:05 PM	#29 (permalink)
rockabilly rb30 710bhp Join Date: Oct 2003 Location: lancashire Posts: 965	cord. while your online, as andy is using jun cams like myself, mine being 264/272 9.15mm lift,how noisy are they going to be. i know you dont like jun but i bought them prior to knowing this.. are they really bad?. i know rod hates them .. sorry andy for the hijack.. bernie __________________ fancy the south of france. http://st-tropez.mysite.orange.co.uk/

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10th April 2006, 10:47 PM	#17 (permalink)
MONKEYmark GTR Register Member Join Date: Apr 2003 Location: Leeds Posts: 220	cool diy work.great to see someone having a go.great write up and pics.

11th April 2006, 06:07 AM	#18 (permalink)
R32 Combat New Users Join Date: Jan 2004 Location: Berkshire Posts: 4,329	Keith, I know about weak guides, I broke a nissan one a few years ago. The sintered iron guides are not very good and are very brittle. This is why I made my silicon bronze guides up. Also, the guides only break where they are not supported by the head. I no longer have this problem. I've run 10,000 miles like this with no problems. I know this might seem a little unorthodox, but its worked ok for me..

11th April 2006, 09:25 AM	#20 (permalink)
Pikey GTR Register Member Join Date: Feb 2004 Location: Cheltenham Posts: 4,151	Ive got bronze valve guides too Not sure if they stick out or are flush - cant remember, although I can see advantages for both

11th April 2006, 10:04 AM	#21 (permalink)
cokey GTR Register Member Join Date: Sep 2003 Location: edinburgh Posts: 1,113	I thought the inlet guides once replaced with a better material, were an option to grind away. But the exhaust guides were to be left alone. More for heat transfer reasons. Would be interested to hear more on this from someone in the know ! Cokey

11th April 2006, 10:39 AM	#22 (permalink)
MADsteve GTR Register Member Join Date: Nov 2004 Location: GTR Heaven Posts: 2,294	This is a great Sticky, and I'm following it with great interest. Unfortunately my garage's full of cr*p at the moment, or I'd be giving it a go, too. Im inclined to agree with Keith's comments regarding the guides, purely from my Cosworth cylinder head experiences (not the same engine, I know, but same principles none the less.) but I'd stick with building it how you want - that's the point of the thread, isn't it? Cheers for sharing Steve

11th April 2006, 10:52 AM	#23 (permalink)
R32 Combat New Users Join Date: Jan 2004 Location: Berkshire Posts: 4,329	After examining the valves and seats before and after lapping, the exhausts were in better condition than the inlets and the contact area was larger. The anti-lag had caused no damage which means we must have set it up well. As for the guide issue, its not such a problem with a rocker less cam setup like the RB's. Although the cam does slide over the bucket, that can only move up and down. So the only force on the valve is along its stroke. On the ehaust side, the valves are IIRC sodium filled. If you run a pointed valve guide, the narrowest part must get very hot, which I don't want. I want the gas to heat as little as possable on the was out, hence flush grinding the guides.

11th April 2006, 08:15 PM	#24 (permalink)
andy42uk GTR Register Member Join Date: Sep 2005 Location: Oxford Posts: 829	I had experience in the past with grinding off the guides flush. I have to say I wouldn't do it again, my main concern is if there is any 'wobble' on the inlet valve thet it may crack the seat, that's what happend to me, yes different engine but all the same. Also I agree about the heat transfer on exhaust side. I have no doubt that flushed you will get more power, but the trade-off is not realy worth it, esp. if you are on a budget and planning to do it only once. I say this to HELP, please ignore if you like.

13th April 2006, 11:47 AM	#25 (permalink)
R32 Combat New Users Join Date: Jan 2004 Location: Berkshire Posts: 4,329	I've bored out the spring retainers to accept the peugeot 1.9D shims I'll be using. The reason for this is simple. Jun camshafts are re-ground STD cam. To get greater lift, the base circle is reduced, meaning you need thicker shims. My cams are 10.5 lift with a base circle of 30. The STD cams have a base circle of 32. This means me shims need to be roughly 1mm thicker than the Nissan ones. Although Jun sell the shims, they cost £7 each. The peugeot shims cost £2.50 each, thus a saving of £108. Also, my shims are an 'off the shelf' item. Nice Nissan to the left, Andy to the right

13th April 2006, 06:34 PM	#26 (permalink)
R32 Combat New Users Join Date: Jan 2004 Location: Berkshire Posts: 4,329	The heads build up although I've not yet shimmed it up The exhaust manifold needed a little fettling as did the gasket, but so far, so good.

13th April 2006, 06:58 PM	#27 (permalink)
ANDY H GTR Register Member Join Date: Mar 2005 Location: maidstone Posts: 1,213	Looking good , cheers for the help today helped me make a decision!

13th April 2006, 07:58 PM	#28 (permalink)
Cord GTR Register Member Join Date: Aug 2002 Location: RB Motorsport Posts: 1,559	A little late for you, but I'll say it anyway for others benefit. You can buy buckets with the 1mm step included. And then use the original nissan shims.

13th April 2006, 08:13 PM	#30 (permalink)
Cord GTR Register Member Join Date: Aug 2002 Location: RB Motorsport Posts: 1,559	Don't worry, they are noisey, but not excessively. You know what a picky bunch we can be!