ozconnection

Don't stress about a few crumbs on your plate friend, you must've enjoyed your meal! The 'Fine China' in the cupboard is only used for special occasions. For me, every meal is a special occasion! Cheers!

If you look at the piston from 1 fast z, you'll quickly see that there has been no machining of the piston skirts to shorten them. That is the answer to your original question.

I had my sensor in exactly the same position as Big Phil. It was even the same (factory) sensor. The only potential problem I see with this position is its proximity to the head. There's a lot of 'noise' up there, it could create some problems with actual knock detection. The factory positions its sensor much lower. Valve train noise would be dampened down there, the software able to filter out these 'other' noises much more effectively. Having said that, the upper position worked well enough for my aftermarket 'Link' knock sensor. All I had to do was turn down the sensitivity so that the knock lights didn't flash up all the time (and I knew the engine wasn't knocking). Therefore, was it able to detect light engine knocking??......probably not. The advantage of using a stock sensor in a stock (or stockish) position.....they're calibrated and 'designed' to work there. Anywhere else is a compromise IMO. Cheers.

Yes, one manifold has the opening directly opposite exhaust port runner 5. I don't know their numbers because I owned neither of these particular manifolds. It's a picture posted by some guy here in Oz wanting to sell the top manifold, wanted to show the differences to the 'more common' bottom version. Dunno for sure but if my memory serves me correctly, the top version of exhaust manifold came from an upspec'ed L20A Japanese turbo engine like the one I'd bought in the late 80's. That engine also had the beefy L20A bottom end and the factory water to oil cooler and a twin blade throttle body etc. Unfortunately, I sold off a lot of that gear to finance other projects I had at the time, unknowing perhaps how 'valuable/desirable' the parts would be today. Damn. Who knows, that could've been my old manifold he was selling!

Here you are!!

Looks like the head is defective IMO. Valve seat became unseated? I've not seen this although it's entirely possible I guess. Talk nicely to the head builder to see if they can fix it for you. That piston with the throttle plate screw marks......were there marks like that on the P90? I'm assuming there were! What is your gut telling you to do? With as much that has gone on with your engine and all the money that you've already spent on it, you need to get it fixed right this time. I would pull the engine down completely and inspect everything, especially the pistons. You owe it to yourself. Peace of mind is something that'll not haunt you like suspicion. And get that 2mm gasket too if that's what you need OR rework the chambers so that you don't need a 2 mm gasket!! Good luck!

You're math's is correct and you're measurements are spot on. Unfortunately, you shouldn't just go out and machine 120 thou (3 mm's) off the top of your pistons. This is just asking for trouble. Sounds easy enough, however there are probably a dozen reasons why it shouldn't be done. Getting the right piston straight off saves in so many ways, especially the rest of your motor. Even more so if it's a boosted engine you're wanting to build. Pay your machinist to put in the right pistons, not modify the wrong ones. Arizona Z sell pistons exactly for this application, although you might need to talk to them about their suitability for turbo applications. Cheers.

Why, Are you thinking that lighter pistons will let you rev your engine harder? Personally I suggest you don't do it. The piston skirt is designed to prevent rock or tilt of the pistons as they move up and down the cylinders. Shortening the skirts will upset ring seal with the bore, so you get more blowby and greater oil consumption. This situation is worse with engines with a smaller (numerically) rod/stroke ratio, like the L28 and L26 engines. If you think that you can free up some power because of reduced 'drag', you're wrong. Virtually all the friction is from the rings, not the skirts. Cheers.

Why did you find it necessary to port the intakes like this for a 'street' car? Haven't you just slaughtered your low rpm , off boost torque by doing this? Please tell.

I play with my cam timing quite a lot, so I take the cam sprocket off and reposition it to suit my application all the time. For me, the easiest thing to use is the 'good ol wooden chock'. Mine is quite small so its easy to drop the camshaft sprocket into the guts of the head once the camshaft sprocket bolt is removed. I then roll the chain over the sprocket and pull it back up to put the bolt back in etc. The chock measures 18mms thick, Measures 68mm's aolng the top edge, measures 35mm's along the bottom edge, and is 88mms tall. There is a right angle from the top right down. I like this although a shoe stopper would work and is still available from Kameari, so you decide. My tool took 5 minutes to make and cost virtually nothing. To get the chock out , just turn the crank slightly when everything is ready and out it comes. To jam it in, I use the handle of a hammer upside down. A few firm taps are all that's needed. Cheers.

Funny you should mention that, same bloody thing happened to me once too. Good one for spotting it.

Ok, a couple of things here. Firstly, your engine isn't on top dead centre. To get everything aligned properly, you must start with the engine in this position. I can tell its off because of the position of the keyways on the crant aren't pointing straight upwards relative to the engine block. To get the chain tensioner shoe and curved chain guide in proper position, you're almost there. Loosen the top and bottom bolts on the curved chain guide. Use your left hand and push to the right the whole guide from the middle until you have achieved a lovely radius that takes out that kink you seem to have just around the tensioner shoe. Then snug the bolts so that the curved chain guide stays in that position until your torque the bolts up later. Check the position of the cam. Take off the chain and the camshaft sprocket. The camshaft locating pin that fits into the cam sprocket should be at the top looking from the front of the engine, similar in orientation to the keyways on the crank. I can see the 'bright' links on your chain. The distance between these links are not the same , so the 'short' side of the chain is the side that you'll be needing to work with. The little sprocket on the crank has a spot or timing mark on it, so long as it was put on the right way around. Put the chain on so that one of your bright links or link plate is directly over the 'spot' on the crank spocket. The short side of the chain runs up along the straight chain guide so now the second bright link plate will sit on the right side of the camshaft sprocket, usually two complete links sitting on the cam sprocket. The first link plate only half sits on the cam sprocket. I did not count this one, so its two complete link plates on the sprocket...understand? With a fresh chain, set your timing on the camshaft sprocket to number one unless you have a different camshaft that requires you to set it up via the timing card specs. There are heaps of articles on this site that can help you out with stuff like this. Search, read and then read some more. One thing about engine building is to never be in a hurry. Not to be unkind, if you haven't got the time nor patience perhaps you should be paying someone else to be doing it for you. Inexperience is another thing and the way to learn is to have a go and that's always a good place to start. Good luck.

Hi there, I've just finished building a new four barrel carburettor for my next development phase on my L28. The Holley originally started off as a 'run of the mill' 450 cfm (list 4548) vacuum secondary four barrel. Since then, it has been extensively modified and upgraded to suit my requirements. Some of the features it has are: 4 corner idle mixture adjustment Downleg booster venturis Electric choke Reworked metering blocks to include adjustable power valve channel restriction and idle/off idle circuits via screw in jets Percy's adjustable metering blocks for primary and secondary main fuel Centre hung fuel bowls Quick change secondary spring unit and A blended 600 cfm 4 barrel base plate. The next phase of engine development includes a new cylinder head where I'm concentrating on improving low engine speed torque. The head will have a much better quench around the valves and will boost my compression from 8.3 to 9.9 to one. The ports are round exhaust with liners like the P79 heads and the intake ports are smaller than the N42. (30mm's versus 34.7mm's). The intake manifold is an older candilabra single carburettor type, Nissan code E30. This manifold will be adapted to suit the Holley carburettor and it has 30mm runners, matching perfectly the Y70 head which originally came off an L20A ET engine in Japan. The head is currently at a headshop being reconditioned with guidelines not to touch the ports other than to clean up the bowl region and improve the valve seat areas for better flow. A special smooth radius valve job will be tried instead of the usual 5 angle. It came with strong recommendation so I said yes to that. The head should be ready fairly soon. I'm very curious (and committed!) to giving this a go. I will be doing a series of dyno runs soon to establish my baseline at the moment and then gradually change over to the new parts to see their effect on performance. Remember, my aim is to improve torque at low rpms, so talk about big ports, valves and camshafts may not be what is needed, unless you can convince me otherwise! Sure, I would still like it to rev to say 5000rpm, but it is what happens when you change to the next gear higher that interests me, what happens at between say 2000 to 4000 rpm's! Read Torque Monster!

L20A ET cylinder head. Y70 code.

Not a Z, but it is an L28. Cheers!

Wooow! Nice and clean. Do diesels really run that hot that something like that is needed? Please tell.

I have this 'thing'. I got it years ago with one of my L20 turbo engines. I haven't seen too many of these units being used so I'm wondering if anyone has seen one or is using one on their engine? I can't find any information on it at all. Impressions?

It's been a long time since I've had these manifolds. I sold them to guys who wanted them for their L28 turbo buildups here in Oz. From memory, I think not. Don't quote me, though!

You could start it, like Big Phil suggests, but try just cranking the engine. Start with the plugs in, then remove them and see if that changes the cranking sound/ valvetrain sound and you can watch the whole lot if someone turns the motor over for you. You will see if the oil pump is working too without spashing oil everywhere. Good luck.

Heh Heh, I know what it's like to drive with an L20A, decompressed for turbo, without the turbo! The funny thing is, in Japan most of them run the smaller engines anyway from what I've seen!! Add air, steer and an auto trans and WTF!! "I hope you're not in a hurry"

I dunno about both of those comments. People put eights into their Z, they're pretty heavy. The only thing about the swap might be the amount of weight sitting forward of the front axle centreline with the long six cylinder donk. Horsepower is something that may not be record breaking, but the torque...... And an RD28 wouldn't be particularly light, about the same as the L I would've thought.

A couple of piccy's, as promised. Nice stock chamber shape, what do you think?

I just saw your vid on youtube. When did the noise start? Was the engine cold when you took that video? Do you punish your engine or do you drive it with some respect? Is power down? When was it last serviced? Have you done a compression/leakdown test? And this is like a crime scene. Gather as much information about your engine as you can and then tell us what you have found. Then we have a greater chance of figuring out your problem. Good luck mate.

You killed it.

The idea behind using devcon on the ports is an interesting one but I don't see it as particularly straightforward. Reshaping the ports in this way and I'm assuming you mean the currently installed N42, would preclude the whole 'simple' exercise. If I had lots of money and time to develop this concept, I'm sure I would achieve an excellent result but since I have neither in great quantities, I would have to opt for the 'simpler' and 'cheaper' option of just swapping heads. Thanks anyway Tony, your inputs have been noteworthy. Cheers. Smaller holes..............naughty boy.