ozconnection

I went ahead and did some recording of my currently installed 280zx distributor (P71) and also a spare one (S67). The results are with a warmed up engine and the vacuum advance disconnected and plugged. The two distributors are D6K8-02 9105 part #22100-P7101 and D6K9-05 3605 part #22100-S6706 The P71 was tested first and then immediately swapped for the S67 which is still in the car now that I'm here writing this. Just as a side note, the vacuum advance canisters add a further 16 degrees @ idle connected to manifold vacuum. 700rpm 14/14 850rpm 14/15 1000rpm 14/16 1200rpm 17/17 1400rpm 18/18 1600rpm 21/21 1800rpm 24/23 2000rpm 26/25 2200rpm 30/26 2400rpm 32/26 2600rpm 33/26 2800rpm 34/26 3000rpm 34/26 degrees ATDC. The first number separated by the / is from the P71, the other is from the S67. When you graph these out, there's a huge difference! As far as engine vacuum is concerned, vacuum was high due to me just opening the throttle via the idle adjusting screw on the Holley. It never fell below 16 inches. (idle is 19 inches in neutral). Things I need to consider is the amount of advance that the vacuum advance mechanisms add. The idle is very 'rough' with 36 degrees at idle with the S67. 20 degrees static is acceptable, with 32 total from 2200rpm!!! I'm thinking of connecting the vacuum advance back up to the ported vacuum port on the Holley since connecting to manifold vacuum, it's too advanced IMO. Thoughts?

Yeah, that's worrying. The small compression readings suggest cam timing alright. Hot comp. test? Sound build up, comp rings put in correctly, cam timing verified by degree wheel, ignition verified by timing light? I wish I could jump through the computer to help you out. Other than what I've written here you're just have to triple check everything you can. Obviously something like the rings is something you can't easily check visually. A leak down test might help here. Don't assume anything to be correct until you have checked/tested it. Good luck mate.

Ummmm, yes, it's a Schneider cam mate. You should thank the guy, afterall he did that research for you!

Hi Nigel, I didn't even think about "at what vacuum", that shouldn't be too hard as I have an autometer vac. guage under the bonnet for dyno sessions, checking vacuum to see when the power valve cuts in, for example. Im just thinking at what rpm intervals I will test at? Suggestions? What are your intervals on the MS II Nigel?

Thank you gentlemen for all your inputs so far. My timing is verified by an Innova timing light, one of those fancy jobbies that tell rpms, dwell and volts along with the actual number of degrees advanced. Lovely bit of gear! With this timing light I could easily build up a timing map of degrees advanced versus engine rpms. I could then test another dizzy (thanks Pete, I'll take that L24 unit ) and do the same with that one. I can look at the character of the curve and test both in car to decide which one responds better. As for the cam, I could try retarding it a bit, and test that. I have so many cams here it's silly, all bought for projects I haven't built yet. I really need to get a wriggle on and build an engine with a decent static compression ratio so I can try some of 'em. I can't believe that 10 to 1 compression with a stock cam gave you 215 psi cylinder pressures at 28 degrees advance without ping. Was that a flat top, stock piston with with a stock N42 head? (All bets are off if the head was modified though). As for my camshaft drive, it was all replaced when I first bought the car some 40K km's ago so I'm happy it's still all in good, serviceable condition. As for L28ET's running 180 psi cylinder pressures, their camshaft is so mild, isn't it just like the one I'm currently using? Just how do you get a decompressed 7.5:1 engine like that to run 180 psi though? I just stopped to think about this situation again and came up with "the" question I guess I'm trying to ask. What is the highest static compression ratio I can go with a stock profiled camshaft? Caveats are pump gas, no turbo or super charging and no nitrous. (have I just spoilt the party for any of you? ) And not more than 30 mins ago I got my Kameari 0.8mm HG. Oh, its beautiful Thanks guys!

Just to recap, because a few of you guys are asking questions about stuff I've already mentioned. 38 degrees total timing all in by 3500rpm. (mechanical advance) 18 degrees static timing with 16 degrees in the vacuum advance mechanism. This is connected directly to manifold vacuum. The cam is a stock grind. 240 degrees intake with 248 degrees exhaust duration. Very mild. Camshaft is advanced to 8 crankshaft degrees (4 camshaft degrees). So many times guys have posted their compression pressures and they're around 130-140 psi. The comment made is that that's alright. So, is my stock cam causing such a high reading (average reading in my L28 is 180 psi) or the fact that the stock cam is so far advanced? So this lends itself to the next question, does the cranking compression vary when the cam is advanced or retarded? Is this the reason that advancing the cam helps with low end torque by improving the compression pressures? Increasing the compression ratio by changing HG's may send the compression pressures to over, say, 190 psi. Perhaps by reducing the advance on the camshaft, peak pressures may be lower but the overall spread of compression pressures may be wider/over a greater rpm range. What do you guys think?? We know what happens when we put a bigger cam into an engine but can we do the same with an existing cam? Have any of you guys with pinging engines retarded the camshaft a little to reduce detonation? Does it work?

My plugs are one heat range colder, BP7ES NGK's. 280zx dizzy with MSD 6 ignition. My cooling system has been a topic of discussion lately. To sum up, I'm running a modified 3 core radiator, new 180 degree thermostat, water with water wetter, thermostatically controlled electric fan with factory shroud, LD28 water pump and a 20 psi cap. Sorted as far as I can tell. I was pushing the timing issue and wanted to see how far I could go with some minor upgrades to the cooling system etc. I do believe I've engineered enough headroom to accomodate the slight increase in compression, but as we all know, I like to proceed with some caution, especially since I'm already seeing excellent cylinder pressures with an 8.3 compression (stock) motor which BTW has seen years of abuse (over 120 dyno pulls) and multiple interstate hauls and the usual weekend thrashing. What would I expect to see cylinder pressure wise after changing the HG? 190psi? Is this too much for the old L28 and am I just asking for trouble?

Premium unleaded pump gas in Oz is supposed to be 98 octane. That's what the label on the bowser says!

LOL, I already am! But thanks mate.

Just curious about this scenario and would like your input please. I did a hot compression test yesterday on the L28 and the average value was 179.6 psi. There is only a 5% variance amongst all the cylinders. This is a stock N42/N42 combination with a stock Nissan headgasket and camshaft. I recently ordered a Kameari 0.8mm headgasket to bump my compression up from 8.3 to 8.7 to one. My question is whether this mild increase in compression will throw my engine into severe detonation? At 38 degrees total advance at the moment, I can still get some flash detonation with rapid acceleration (but this is usually dependant on how hot the day is). I'm hoping to gain some more torque without having to drop the timing down heaps (below 30 degrees for example), which would defeat the whole purpose of the upgrade. What do you think?

You put a 2.8 engine into a car that had a 2.8. And the problem is.....? Too small a radiator? That doesn't make sense. Am I missing something. To answer your question as what coolant to run, you have many choices and they should be based on your end usage. For most applications, your over the counter ethylene glycol anti freeze anti boil coolant will be more than adequate. As mentioned, give the cooling system a flush. Good place to start right there.

Hey, I'm running an stock N42/N42 L28 and with some work to the cooling system, I'm running 38 degrees total @ 3500rpm. In addition, I've got vacuum advance connected to manifold vacuum which adds a further 16 degrees advance. My engine runs beautifully and has a responsive throttle that is ping free until the days go 35 degrees celcius or over and I'm at WOT getting into it. Fifty plus degrees on a light throttle is very do-able.

Sorry to hear that Tony, great time of year and a lovely E32 sittin' here for ya...... Standing offer though!

I measured the manifold runners internal length, the 'hypotenuse' if you like.

redline 240z manifold is 5 inches.

Ah yes, I forgot about what Bryan had done there, thanks for reminding me. Like I said, just let us know when you're coming Tony! Cheers.

I'm impressed by the amount of effort you went to to document your problems. Well done!! Your timing is perhaps a little retarded at 8 degrees. I would like to see at least 12 degrees to improve your engines performance at idle and on the throttle. Your current timing could also cause your temperatures to be registering as high but it can also be influenced by other things such as thermostat temperature opening point and the condition of your cooling system. My guage shows the same as yours and I know my cooling system to be in good working order! As for setting up your carb's, I can't help you with that. I'll let others who know these things better chime in. Cheers

Why? These guys who remove the liners, did they do so because they flow benched them first? Dumb idea to wreck what 'may' actually be a reasonably good flowing port as it is. Has ANYONE flowed the P79/N47 exhaust ports?? ITB's will be very cool Pete, email me some pics as soon as you can please, love to see it 'finished' As far as why Nissan ran E88/N47 heads concurrently on the R30's is up for debate. Since these were the last of the R30/L24E's for exporting ot Oz, maybe it was to empty the shelves. Dunno. Cheers

That's no typo Pete, R30's here in Oz did also have N47 heads, I had one, then tried to take out the liners and was left with a junk head. I threw it out shortly thereafter. That was years ago though when I didn't know what I had. The intake valves are 42mm and the exhaust are 35mm. Cheers

Isn't there a sticky that relates to all kinds of valvetrain mods....balancing the valvetrain? Worthwhile mebe? Nothin' wrong with overthinking mate......it's the thinking part that's important. HeHe! (that's my therapy!!) Cheers

"What i wanted to achieve was, squelsh and high compression but still be able to use pump gas (95)" Chris, this is something that I've been spending a lot of time researching. I do still have that lovely Y70 head sitting in my garage, waiting for me to put it on. The E30 head you have was also fitted to the L24S (single two barrel Hitatchi carb) spec. engine. It had 1.5 inch and 1.3 inch valves in it, and the ports were small at around 30 mm's. (The exhaust ports were square and not like the Y70 which has round with liners). So, that E30 head must flow reasonably well to bolt it straight onto the 2.4 litre engine by the factory without any immediately apparent modifications. Bolt that E30 head to a stock 2.8 bottom end, like the N42 bottom end with factory spec dished pistons, the potential is there for a 9.9 to one compression engine with a stock bore Nissan factory HG.. To add to that, without porting ie making larger, the ports would have incredible gas speed for low speed torque with a stock or near stock engine. The smaller valves were deemed to be an advantage (by me) over the stock L28 valves which are heavier. With some attention to this, a very high revving valvetrain could be achieved on the E30, coulped to a bigger cam profile to take advantage of this rev-ability, which was also deemed acceptable to bleed of some of the cylinder pressures at low rpm's which could have thrown the engine into detonation. That's another reason I wanted to hold off with the Y70 instal. I wanted to see how much of a headroom above stock I could build into the cooling system, with coolants, fans, thermostats, radiator caps, radiators and water pumps all being tested. In conjunction, there've been changes to my spark plugs and engine oil ratings as well as some thermal wrap on the headers and heat shielding around the carburettor. I should, but haven't yet, improved on the air induction temps into the carby by ducting cool air straight into the carb. From what I've gathered, you want this head for a street engine. Now you could build an engine like mine at the moment with the completely stock N42 head. (It pulls pretty bloody well with all the recent mods by the way!!). OR you could dive into modding the E30 and throwing that on. It's up to you. With the E30, I wouldn't go crazy on the ports or valves otherwise just use the other head like your E88. The stock cam will give you an awesome low end but detonation could be a problem unless you're willing to chase that issue. A bigger cam will make much more power at the top end. I honestly believe it's the choice made here that will ultimately determine the way your engine performs. The camshaft will truely be the brain of the setup but several different grinds may need to be tested before the best one (for you) is found. Expensive!? Hmmmmm, not too bad if you want to work to develop this combination and just sell off any parts you know you won't need/use afer you're done. Just a thought. Cheers.

They're all forged from the factory Pete!

Cheers Shaun, have one for me! Mate, man, whatever, it's all good Cheers, Mark. PS We love your contributions, keep it up!!

Are you going to put that motor back together? That E30 head is the perfect 'clean slate' for a radical head build up, especially the inlet ports being as small as they are. Just a thought.

http://forums.hybridz.org/index.php?/topic/78714-32l-twin-turbo-l28-stroker/ Pete, this is interesting stuff here and what Daeron was suggesting to look for. Cheers.