ozconnection

EFI cars are much more precicely managed fuel wise than any car running carbs. The idea of heating the induction tract for carbs is necessary with a wet manifold design. Latent heat of vaporization. No heat, no vaporization.....that's why carbed cars take a while to "warm up"...the manifold has to do its thing evening up afr's between cylinders and minimize WOT mixture fallout...these things collectively called 'driveability'. Designed from the factory that way so granny doesn't get the shits when trying to drive the car to the shops, sells the car and vows never to buy another one of 'those' ever again. Damn carbies. We can put up with the rough running issues until it warms up...isnt that part of the appeal of owning a old skool,modified car? My car is modified too, but I do understand what the engineers were trying to achieve in the first place so kept the setup in modified form. It costs to put all that junk on a production car.....they would've junked it all if it wasn't necessary on some level. At the other end of the spectrum, water through the manifold can prevent runaway manifold temperatures as mentioned by Beandip. Dyno's can be a bit of a odd enviroment for cars but if you're seeking out the best possible driveability versus best possible horsepower, then you have your answer. The first few pulls may have more power (cooler induction temperatures) but power may eventually fall off as manifold temps goes rocketing skywards....get a laser heat gun onto it and see for yourself. I have!

I kept my coolant lines. I used a cheap water valve from the hardware store to set up a system where coolant could pass through the manifold, if required. I don't drive regularly in truely cold weather but I have. If I do in the future, I don't need to worry about letting the thing idle to warm up properly before I drive off or things like throttle plates icing up. I like the idea of having an 'option'. As far as performance goes, volumetric efficiency is improved in summer when the ambient temps are already high, the setup can be turned off. In winter, as I mentioned, there is some benefit to retaining something!

The last "s" can be "silly". That's not offensive! My gasket was new and weeped. Your gasket is old and weeps. I guess that's where I was wrong. Bite the bullet, replace it...replace it now (Arne accent required! )

Such as....? There is definately a place for a product like Bars leaks. If the the HG was 'blown' in that it was leaking compression/cylinder pressure I would have no problem recommending that Rocket88 repair the leak by changing out the HG. The main usage of Bars leaks is not to correct a blown HG. Now we'll start debating the term 'blown headgasket'. OMG! Just one more thing before I let this go...I have replaced my engine coolant many times since the original installation of the new HG. Never since have I needed to re-use any more Bars leaks to stop renewed weepage. I have written about this extensively on HybridZ and have even tested the pressure head generated by the mechanical LD28 water pump as being around 30 psi at 4000 rpm. I have a 20 psi radiator cap on my radiator to prevent nucleate boiling after shutdown. With these cooling system modifications, I'm happy to say that Bars leaks does a wonderful job of stopping HG weepage!!!! Probably more important is to keep your cooling system clean.....many don't change their coolant for very long periods, allowing scale to build up and clog radiators. I thing neglect causes far more problems than the appropriate use of Bars leaks mate!

Hang on a tick, I'm talking from personal experience. Let me fill you in on why I make the comments I make. My L28 had a new NISSAN gasket put on by me approximately 30K kms ago. In that time it has performed over 60 individual dyno pulls, gone on holidays with the family twice (3500km round trips each time) and has had many subsequent performance improvements to the engine and cooling system (LD28 water pump, reconditioned 3 core radiator, thermo fan, water wetter etc). Compression tests recently proved that all my cylinder pressures are spot on too. The point I'm making is that all of this is on "the HG that was weeping after I installed it". I solved the weeping problem with a dose of Bars leaks and have never looked back. I could've replaced the gasket at the time with another but I'm glad I waited and have had zero problems since then. "You don't need your appendix out if it's been so far diagnosed as pain in the guts" Treat your symptoms and see what the resolution is. Go from there. Like Zed Head suggested in his post........K.I.S.S.

I can only assume that whatever Rocket88 has told us in his introduction is what is actually happening. However he hasn't pointed out how much is leaking and whether or not there have been overheating problems. Why are we to assume there are other problems with the engine if they have not been mentioned by the author? This forum is a great place to help people but lets not pretend to know what is happening unless we are actually told so by the author! We could save this guy some money (yes, he may have to replace his HG eventually but not yet as I can see) and time if all he needs to do is stop some coolant weepage. Rocket88 you need to fill in the blanks for us now please. Good luck with the car.

Yeah mate, try Bar's first. HG's do weep sometimes, and this may be all that's needed to sort things out. Your boys HG weeping is worse when the engine is cold because the coolant/block pressure is higher before the thermostat opens. Does that year use the coolant bypass from the thermostat to the water pump inlet? (The bypass was designed to reduce coolant block pressure for those who ran straight out onto a freeway with WOT and a cold engine. It would work to reduce HG weepage, like your seeing). Still, try the solution in a can first especially if there are no other symptoms of a wasted HG. Cheers.

Just be aware that a faulty master vac can cause a really stiff pedal. I got mine reconditioned. I assume that you Zee guys can get yours done if needed?

I don't know if your balancer is stock if the notches are on it? However, I agree that the rocker cover coming off is perhaps the easiest option and that he should buy the timing plate if it's not there. Good place to start!!

Whoa, slow down mate!!! Please don't start fiddling with your fuel system YET......unless to fix your enviromental disasters. We're not done with the ignition yet. Cylinder 1 is closest to the radiator. The valve cover could be taken off OR take all the plugs out and turn your crank over with a big 1 1/16 socket and put your finger over cylinder one spark plug hole. You'll feel pressure build as the piston rises on the compression stroke, look for the notch on the harmonic balancer rising clockwise and take your dizzy cap off and see if the rotor button has the electrode pointing forwards toward the radiator. (the dizzy thing will be correct IF no-one has previously rebuilt the thing and put it together 180 degrees out of phase....then the rotor electrode will be facing exactly the other way, towards the engine firewall.) You have a front cover, its the thing that your water pump, oil pump and distributor is attached to. It is this cover that your timing plate bolts to also. The timing plate is about 3 inches long and has a serrated or jagged edge on it with numbers on it 0, 5, 10, 15, and 20. There are two common positions for its location and in either case close to the harmonic balancer. Sometimes they are to the distributor side of the front cover, sometimes to the alternator side. Harmonic balancers and timing plates are a matched pair so its critical to see where your notch on the HB is at TDC so you can get the correct timing plate on your engine. (Who was the dumb arse who removed it in the first place....what a retard!!) Oh well, you're stuck with the problem until you can get one if it isn't there. I do have another solution for you, but if you can't be bothered with taking the rocker cover off, my other tip is too labour intensive perhaps. See how you get on. In the meantime, get it to run as best you can but remember that getting the engine timed is critical to proper performance. Anything else you do from this point will be in vain. That's the bottom line. I think anyone who reads this will agree with me. Do you have a Factory service manual? Get one as they're good bedtime reading. It'll help you heaps with this and later with any other work you wish to undertake on your engine. Cheers

Very nice!! I like the look of that bolt and washer on the end of your crank....heavy duty parts from the KA24 perhaps? That washer with the lip for balancer registration is the go, I have the same setup for my next buildup Cheers!

Sorry to be going back to the original posting, but I think that a few things here need to be sorted before you can get your timing as it should be. Do you know how to find top dead centre (TDC) on cylinder one? If you do, thats great and if no, we really need to start with the basics. Not that is a problem by itself, it just means you need to do some homework/research on how to do this. A factory service manual or other manual that discusses L engines is your best friend at this point. Once TDC has been found, you need to look at your harmonic balancer (you called it a flywheel). Its the fan belt pulley thing on the front of your engine. Bolted to the aluminium front cover is a small jagged edged plate with numbers on it. Since you're on TDC, there should be a notch on the harmonic balancer that matches the zero (number 0) on the timing plate with the jagged edge. They should be lined up at TDC. Now get some white paint and mark the edge of the balancer exactly opposite the timing marker at zero. There should be a notch in the Harmonic balancer and it should line up already, sometimes the paint comes off or gets covered by dirt or grease.....clean it and see! If the notch doesn't line up, it could mean other things. Please post us your results at this point. All this work so far will allow you to use a timing light to correctly set up your idle advance. As a starting point and with your vacuum advance hose disconnected and plugged, you could try 12 degrees advance. It should idle with this much advance, if not your mixtures could be off or your idle too slow. I agree with everyone who has told you that your distributor/oil spindle drive is out by one tooth. Before you undertake changing its position, you must get the engine to TDC on cylinder 1 FIRST. Order of operation is critical with this kind of work. Do you have the confidence to do this yourself? As A boy, I used to watch my dad do stuff like this and slowly built up the confidence to try things like this myself. If you're not sure you could find an experienced friend or mechanic to help you out until you become a bit more familiar with the trusty L. Good luck, keep posting, tell us how you're getting on.

I looked at Kamerai USA and they have a spreadsheet PDF file that lists all of the metal headgaskets they have and their prices. They sell HG's for standard bore L28's. 86mm versus your 84mm isn't a problem as I see it. I ran an L24 HG on a L20A block 'cause I couldn't get an L20A HG. 83mm's versus 78mm's for the L20A. Ran perfectly with no leaks or problems at all. :classic: http://www.kameariusa.com Cheers!

Don't waste the block!!!!!!! There are 2mm (80 thou) and the like headgaskets out there that would solve your problem. Kameari make them, or you could find a custom thickness copper gasket that'll get you outa trouble. What is the casting code on your block outa interest?

The L26 and L28 crank is the same item.....look for a number cast into one of the crank counterweights. IIRC its N42 A diesel crank will be VO7 The L24 will be P30 IIRC And heck, I can't remember what the L20A one is without popping out to the shed, sorry. But I hope this helps.

Kameari

Can I just ask, was the head modified in any way other than the o/s valves and valve seats? You said you spent a lot of time modding the head yourself. I'm hoping that you didn't 'undo' any of the good work if the above question was answered 'yes' Why don't you try your head with the same cam after your porting? Then you're able to assess how much power you've added to your engine with just the porting mod. Porting the head AND changing the cam, you'll never be certain which modification is really contributing the most to your power increases. Could be the porting was dud and the cam good but the net effect is little improvement. See where I'm heading? I'm not wanting to rain on your parade here but I like the response the engine retains with stock ports. The idea of changing cams is great because for whatever reason you decide a cam is too big, just put a smaller one in its place. The problem I see with head porting is that if the ports are too big, well, buy a new stock port head and do all the work that's needed all over again, not including ripping off the old one and putting the new one back on. Any guy with an old skool SBC would love to be able to swap cams as easily as we can. :paranoid: Just thinkin' out loud mate. Good luck with your project.

The thermostat is a good place to start. Check the new one that it works before you put it in. Piece of mind, I had one once that was new but didn't open. It was a real pain in the arse and kept me very busy freaking out, spending time and money looking for other problems that didn't exist. Check the tension and condition of your fan belt. How old is your water pump? Maybe the impeller blades have corroded but the pump doesn't leak or squeak. When was the last time you cleaned your cooling system? Scale can build up inside the block that can prevent the proper transfer of heat to the coolant. How clean is the outside of your block? Thick crap ie mud and/or oil can make the engine overheat. How's your radiator? Have you used any stop leak products lately? Special oily products that block leaks can also reduce the efficiency/heat transfer ability of the engine and radiator by blocking some of the coolant tubes and the oils used in these products can act as a thermal insulator. What's in your radiator? Water, water wetter, ethelyne glycol, propylene glycol, many choices and many different results. I personally use distilled water with a bottle of water wetter. No problemo's Do you use a fan shroud? What is the condition of your radiator cap? How are your heater and radiator hoses? All in good condition without any fraying or collapse? Scale can and often builds up on the inside of the hoses and can drastically reduce coolant flow. How much ignition timing? Vacuum advance connected to ported or manifold vacuum? Mixture strengths by itself won't cause an overheat but in conjunction could make a bad situation worse. Idle speed? Choke on all the time? Easter is here, seems you could spend a little bit of time 'checkin' things out' under that palm tree!

A Manifold Absolute Pressure (MAP) EFI setup relies primarily on the vacuum seen in the intake manifold along with other imputs to determine how much fuel is needed over a range of operating conditions. Vacuum in the intake manifold is an excellent indicator of engine load. When talking about older throttle body injection, the fuel is added to the air close to the throttle blades, usually a long way from the intake valves in the cylinder head. With these setups, the 'wet manifold' is effected by manifold vacuum in exactly the same way as a carburetor setup. More modern multipoint or direct injection EFI systems don't have a wet manifold to deal with. Fuel is sprayed by the injector under high pressure as a 'mist' of very fine droplets straight onto the back of a hot intake valve in the head. Some fuel enrichment is still needed, but its much less than any of the other systems mentioned when the throttle is cracked open and the intake manifold vacuum drops towards zero. And when the turbo spools there isn't any vacuum that I know of in the induction system Is there? :classic:

You're welcome. The Sus run a 'variable jet' and Webers run a 'fixed jet', like a Holley. Sudden opening of the throttles at low induction airspeed will cause a stumble because vacuum returns to atmospheric and the fuel falls out of suspension. That's certainly the case with a Holley, for example. The great thing about the SU's is they don't suffer with the same problem and don't have or need an enrichment device like the fixed jet carbs. SU's maintain some of their manifold vacuum by the piston rising slowly in response to airflow increases through the manifold. A simple design that can provide a very healthy level of performance when setup correctly. (says the man who runs a modified Holley under the hood of his own car :stupid:)

The things that influence engine vacuum are; A running engine will always see some 'vacuum' in the intake due to inherent flow restrictions from port walls, runners, intake valve and the throttle plates. This is even true at wide open throttle. Although the guage shows 0 vacuum, get a sensitive enough manometer and you will see some vacuum. The other way to look at vacuum is to think "restriction" The greater the intake restriction, the greater the vacuum. Reduce restriction, reduce vacuum and theoretically you increase intake flow and build horsepower. Think individual runner triple carbs as minimum restriction max power setups. Have you also heard about those guys having enough vacuum to run vacuum advance mechanisms on their distributors? Tapping all six runners is needed to gain a 'dampened' signal to run one effectively. Brake boosters also require vacuum to operate well. Some resort to vaccum tanks or accumulators that save the vacuum when the throttle is closed and the engine is on the overrun, changing down gears for example. The camshaft profile. Specifically it's the valve overlap period of the cam profile which will affect vacuum. Ask any guy that puts a big cam into an engine what happens to intake vacuum. (and ask the guy that runs a Holley what he needs to do to the power valve after the cam change!) The mechanical condition of the bores, rings and valve seats effect the vacuum seen in the intake too. Change the size of the engine doesn't seem to make any real difference. The throttle needs to be cracked open slightly to let sufficient mixtures into the engine so that it can at least idle. Put a lawn mower carb on an L28 and you may get it to run with a throttle that would be fairly open. At 800 rpm. (idle) the vacuum would read around 20 inches of vac with a stock cam and that's the same as with the original units with the engine at the same idle rpm's. Don't forget that vacuum is important for mixture vaporization. It reduces the boiling point of the fuel so it can vaporize better in the induction system which results in better fuel mixture homogenization and cylinder distribution. Torque is generated this way. In a carbed car, that's why acceleration can 'feel' stronger at part throttle than at full throttle. Gas speed is involved here as well, and vacuum is maintained with a partially open throttle with its inherent advantages. That's why double pumper carbs are not suggested for street use, too little vacuum (WOT and low rpm's) and the fuel falls out of suspension and the engine loses torque. Too much carb mate. At WOT and higher rpm's (gas speed), the problem before becomes an advantage now! (low restriction)

E31 with flat tops is 9.6 compression.

You know when you read something sometimes and you just go Huh? Its cool. As you can see, building an engine with 2.4 crank and rods with L28 slugs in a L28 block can be done quite easily! Capacity is 2575 cc's or 157.1 cu's Bore it 40 thou and you get 2636 cc's and 160.8 cu's With an N42/N42 engine, it yeilds 7.8 compression......fantastic high boost/high rev turbo engine right there. N42 has big valves. Could use a P90 with flat top L28 pistons for 8.0 comp. ratio. R/s ratio @ 1.8. Great! Going back to normally aspirated, flat tops with the N42 head gives 9.27 compression. Stock HG's and bore with the above combo's. Now, go build.

Thanks for the definition mate Glad to hear that your machine is running strongly!

Ummmm, I just read the posts here and the information given to you is not correct. Deck heights were quoted when piston pin heights were supposed to be quoted.....the pin height of the L24 and L28 piston is the same at 1.5 inches or 38.1mms. L24 and L28 blocks are identical except for bore size (The L24E Maxima block has different main journal sizes and the crank and rods are light duty) and have the same deck heights of 207.85mm's (page 54 Datsun rebuild book, Tom Monroe). As for camshaft interchangeability, check to see what type of oiling setup the cam uses. Some cams (early) use an external spray bar for lobe lubrication, others (late) use a camshaft that is self oiled via a series of passageways internal in the cam. For a full explanation, the book I mention for you to buy has it all in plain English. Get it mate. Page 4 and 26 of Honsowetz's book is where I'm quoting from for the piston and part interchangeability. I strongly suggest you get this book as well and read it yourself. The information there will help you build the engine your after with accuracy. Good luck with your project. Ps I'm toying with the idea of running an L20A crank in my spare L28 block for even more of the same. R/S ratio is something like 1.9 :classic: