Lazeum

So you've got what's needed to make your engine run properly Getting low timing would not help, especially if you're breaking in the engine. Give it what it needs. Regarding knock, it happens only if you have too much pressure in your cylinders, this is not going to happen at low load where you do not fill them up sufficiently. You should definitely plug the MAP sensor on your build, it will help you a lot & will make your engine runs cleaner. I'm running a TPS since it was much easier to setup & to install but outcome would be similar (MAP is better since it gives you more resolution on your map, drawback is low vacuum with huge cams). My L28 seems to be outbreathing my 40DCOE with 32mm chokes, your L31 will most likely follow the same path. I wrote "seems" because I have a fuel supply issue, I'm running lean at high rpm - not sure yet if it is because of fuel pump or carbs... If you need some guidance regarding how to tune your ignition, I've made a thread on Autosportlabs forum that could help you if you'd like. Datsun 240z with L28 & 3x 40 DCOE, MJLJ w/ TPS

Your timing seems not appropriate to me. I'm running a much more conservative setup with CR at 9.5:1, quite aggressive cam from Rebello for the street with some overlap (don't have numbers, Rebello doesn't share data, you have to measure if you want to know), L28 with F54 & ported P79. You're not saying which head you're running, since combustion chamber has a major impact on detonation & max timing to get max output, it's important to know. Anyway, I'm running 20° at idle (with no load, obviously) whereas your setup is much more aggressive so you should be in that range too. 32-36° is the range where max hp is reached so you should be good there. Regarding knock, it usually happens at high load, mid rpm range (where max torque is). You're likely running classic distributor and I believe this is why you run such timing at idle. You should check what timing you need at idle and get your dizzy recurved. Running such low timing at idle means also you're running very low timing at cruize, fuel consumption is probably very bad and you're not getting the torque the engine is capable of. To check knock, you can also build your own detcan with some noise cancellation helmet at $7 from hardware stores, some fuel hoses and a copper pipe. Total cost should be $20 max. Once more, with proper timing management, you could most likely run your engine at proper timing at WOT & manage to reduce timing only where it needs to be reduced to avoid knock. At cruize, you're running between 11 & 33° (most likely around 20° at 2000rpm) whereas I'm running 50° with my setup. It makes a huge difference. I've switched from dizzy to distributorless system with engine load input last winter, I cannot be happier.

In Europe we have some kind of liquid wax we spray inside hidden areas. It is very liquid, you spray it and it goes everywhere. We call it literally "hollow part wax". I would be very surprized not to find similar product in the US. I've got some pieces of raw steel hangging in the air in my yard with different kind of coatings on them, waxed part is clean after 3 years outside (as well as part with only one layer of regular paint bought at autozone - which was unexpected)

I'm glad to hear Let me know, whenever you've got the chance, if you have a good column available.

Would you take the hassle to ship abroad? If yes, I'm looking for a steering column (going from the steering wheel up to the steering coupler - not the plastic covers) with no lash or rotational clearance. That would be neat! Thanks!

Your damper is damaged because: - Either the key & damper haven't been installed properly (key not fully in position). Crankshaft bolt has been used to force the damper to get into position. The key put some loads (high stress) on the damper which is bad. There should be no load at all between the key and the damper. The key is just an index to install the damper with proper orientation. - Or, crankshaft bolt hasn't been torqued properly. If it gets loose, all torque from the -now- loose damper is taken by the key & the damper resulting in the failure mode you've experienced. Ckeck also you crankshaft to make sure it is not damaged. I do not see anything critical here but timing might be off a little if index key is offset.

As Leon said, we need to shoot for MBT, not always max timing. this is true at every engine state. Bumping up the compression ratio often makes the engine knock limited which makes MBT timing = timing before knock for max power. This is also true for turbo application where max timing often means MBT. This is true statement only at certain conditions related to rpm, engine load, temp, intake pressure, etc. We are talking about timing but not about how to achieve it. Once more, timing management is the key here. I use to run F54 block with N42 head combo with flat top pistons. It was knocking with Mallory dizzy and 34° max timing at around 2500/3000rpm while cruising & going at WOT whereas I could start at 0 speed and going WOT through all gears at full load without knock. So only option available at that time to get rid of knock was to lower max timing to lower timing at 2500rpm. I went to 29° total. I lost some power, for sure. I've played after with springs inside dizzy, it helped a bit but I wasn't able to run 34°. With good timing management, I could have lowered timing at 2500/3000rpm and keep 34° at high rpm with no knock. So with same engine, one could say "I can run only 29°" and the other could have said "34° - no problem". Since, I've changed the head for the reasons involved above: This is exactly what I've done I've delt with Paul Ruschman (Braap on hybridZ) and he's built for me a P79 head for street (torque at low rpm while still having decent power, not all power head with no relevant torque before 4000rpm). So he improved flow for low rpm application, basically ports haven't been increased in size at lot - they were just raised a little, valve seats area has been ground, comb chambers CC'ed & modified, valve unshrouded, valve seat chamfered, head milled a little (1mm only). Valves size remained unchanged. We expected power to max at 6500rpm so there was no need for "as big as possible". Bottom end would have needed some serious modifications also that I did not need for street. Paul and Dave Rebello have worked together to provide me a cam that matches head work so I've got a "street" cam grind from Dave with relatively high lift (+0.49") & asymmetrical lobes. The torque increase is dramatic between both setups whereas compression ratio has been lowered (9.5:1 if not lower). With same dizzy, I was able to run 34° with no knock. Next step, this winter, was to change ignition management. I went with Megajolt + EDIS with load control (with TPS) instead of regular dizzy. I can now shoot for MBT at every engine condition & it makes a big difference. Change is amazing: engine runs cooler & a lot smoother, torque has increased at lot everywhere, total timing is set at 32° since I cannot feel any difference in power ( I need a dyno session too!) and fuel consumption is much lower since engine efficiency is better. Big change was also timing at same rpm but different load. This is something that happens when you accelerate on the street. Engine feels much stronger during throttle transition. With acceleration starting at 3000rpm steady, timing goes from 49° to 32°. For race engine where they run at WOT most of the time, load control is not so important. Good dizzy system well setup could probably be enough. MSD makes some programmable 6-AL2 box that should work great.

You would need to change timing to get max power out of your new cam but it shouldn't allow you to start the engine. I would advice to check again. First, do you have sparks? are you sure gas is going through carbs? Then, I would check firing order to make sure it is ok, check also dizzy orientation at TDC. Check timing while cranking also if you can.

This is what the engine likes so it is. Why not 50° if you ask me? just because... If you want to know more => Autosportlabs - 240z with MJLJ

Regarding idle jets, I had good luck on several L-engine with f9 units (I'm running 50f9 with fully built L28). I can hit the trottle with no bog easily. Engine is ultra smooth to drive since I've got distributorless ignition (running 49° advance at cruise)

I see AFR at very light cruise with choke system engaged as low as 11.5. Quite frankly, I don't think you should bother with AFR. I never engage choke lever fully. I play with the lever until engine idle nicely, that's all. When engine is stone cold, idle is around 800-900rpm choke engaged , without it, engine stalls. after 1mi., rpm at idle are around 1200 so I play with choke lever to get back to 1000rpm. As soon as water Temp needle starts to move significantly, I close choke and engine idles at 800rpm. I have no clue about my setup inside my carbs

Did you control valve clearance before taking it out? I had a major cam failure with rocker pads so damaged that one broke into pieces only after 300mi after head rebuild. I found no evidence of oil galleries being plugged. D. Rebello told me after having seen pictures that it was due to poor lubrication (destroyed brand new cam was coming from his shop). My analysis was that valve lash has reduced to none after some miles. So no gap existed anymore, lubrication did not occur properly, heat was created, metal treatment disappeared with heat resulting in total failure (cam lobes severely ground, metal chips everywhere inside engine, crankshaft bearing destroyed, oil pump damaged, etc.) Since full rebuild, I've checked valve clearance every 100mi. I've noticed valve clearance decreasing dramatically on the first 500mi. Since, I've run the car for +1000mi no problem, valve clearance does not move anymore.

I'm looking at this thread and I don't have all those problems with my very similar setup (3xDCOE, Cannon manifold). I was able to get the 3 heim joints to align almost properly. I do not have return springs on my system except the ones in the carbs. I had to play with the 3 heim joints on a bench. I switched them in between threaded holes until it went ok. I've seen alignment being very off by 3-4mm by just turning heim joint 180° which proves setup is not straight. At the end with some perseverance, it now works. Regarding Zedyone_kenobi's setup, 2 heim joints are ok and that's the way linkage should be setup to remove any alignment issue. Issue is you put return spring and throttle cable right were the rod is the easiest to bend (in the middle with no support). First modification I would do would be to move throttle cable & return spring the closest from heim joint (where the system is the stiffest). If you move throttle cable support from carb#1 to carb#2, it would be much better. Only deflection load the rod would see in the middle is load from internal carb#2 spring. My carbs can easily go from full throttle to idle with just internal spring actuation. There should be no need of any extra spring to allow that with only carbs in the system. If you can't do it, it means something is wrong in your carbs: either throttle plate is not located properly, throttle shaft is bent or throttle shaft bearings/o-rings are shot. Then comes friction in throttle cable; there should be very little. I would spray WD40 inside cable & make sure it does not have curvature radius too small. I still have stock throttle linkage so I cannot really compare but mine have very minor friction so carb springs are enough in my case. If you need a spring I would also check if you cannot put one on top of the pedal. I've never had the need to try it so I don't know if it would be doable... Besides those remarks, the setup is very clean, I like it a lot with the fuel rail Good job!

You've got a golden back-up At least, there's some positive outcome to this failure.

I'm sorry also to hear that. Was it on your L28 with L24 crank? I'm posting also to follow up on your findings Bleed valve from the oil pump should be able to maintain 60psi at 3000rpm but also at 6000rpm. Could too high pressure at 3000rpm be related to by-pass restriction since it should be capable to do the job also at twice the rpm? I would suspect something is going on inside the pump. I would also check galleries inside the block between the sender and the pump. Regarding crankshaft clearance, too much clearance would make the oil layer to fail withstanding high pressure resulting in metal contact => failure. I don't know what are the limits, they might not be that small. Bearing failure could also come from clogged galleries inside crankshaft.

You need to better describe your problem. How does it smell? where does it come from? What are the conditions when it happens? What have you tried to determine the root cause. It is happening windows up or down? what speed? Any speed? Engine running in high rpm? low rpm? How is the tune on carbs? How does the car feel? Have you tried leaning out the AFR to test? For now, we do not know what is going on besides you've changed your carbs & it smells bad. Only answers would be bad tune or bad install with leaks.

You can really disconnect your coil & dizzy from your car to perform checks. If you read 6-7V with ignition on "start" & 9V with ignition in "on " position, your problem is elsewhere. You do not need to bother with distributor or coil (yet!) First you can disconnect the wire from the starter to avoid it to crank the engine during trials. Then you need to find why you have a delta between battery and tension at coil. Wires from the coil go to the main harness, thru the firewall below your battery. right behind firewall inside the cabin, you have plenty of connectors, make sure they are clean, here's your first source for corrosion. Check the voltage here. Wires to be checked at Black with white strip and black with yellow strip (see diagram to be sure which one is for "start" & which one is for "on"). Are voltages the same than the ones at coil / ballast. If yes, issue is not under the hood. Wires go from the connectors to the tachometer (only the one for "on" position), then to the ignition switch then to fuse box and finally to the battery. Check voltage at those points and see where the drop occurs (most likely ignition switch or fuse box) You absolutely need to get 9V & 12V before sorting anything else. Low voltage means resistance somewhere unexpected. Resistance x Intensity² = heat! & less voltage to get same power means more Intensity = more heat also! It seems issue is limited to "start" ignition position, so it is only for a short time period. Another check you could do it to measure voltage at starter solenoid. If you read also 6-7V, I would check ignition switch in priority.

I had a noise occurring only on bumps on my car after full restoration. Everything was tight as it was supposed to be. I made sure of it at every step of the process. It appeared shock (Bilstein unit) inside strut housing was loose. What happened was gland nut was tight against shock during assembly but it was most likely not well installed inside the nut. At the first bump/load, the strut moved back inside gland nut creating some loose condition. I had to take apart rear suspension & spring to find the issue. Since spring is putting pressure on your system you couldn't feel it otherwise. As soon as preload disappeared, issue became obvious. I just had to tighten the gland nut to bring back everything to normal. It was a 1 hr fix with the right tools (you need to disconnect brake lines to do so). Not sure it's your problem but it might be worth a check if you do not have stock suspension... (who does not after 40 yrs of service?)

I did not see this topic until then. Car looks fantastic! Good job!

To get 90 pistons, you need a L28 block. You won't be able to machine your L24 to get that much bore. 90mm on L28 is doable, people on hybridz have done it many many times. Just look for L31 stroker to get more details about it. GEtting into bore modification will lead you to stroke modification, head modification, custom cam, induction change, ignition, etc, etc. Good luck with your build. I haven't bored my block (only 0.30" to repair it) but I have done any other modifications and I love it Look also on this board for engine build, there're tons of info to gather also. Books such as "how to modify your Datsun OHC engine" and "How to Rebuilt Your Nissan/Datsun Ohc Engine" will help you a lot in the process.

I had a F54 with stock N42 head with what was called a stage II Cam (Schneider stage II 274/274 you can get at MSA). With regular distributor (Mallory Unilite) I wasn't able to get easily the advance the engine would require to get full power. I was only able to run 29° max advance. With spring kit, I could have been able to adjust somehow timing (maybe!) Going bigger on cam allows also engine to run with lower dymanic compression ratio where ping accurs. it should help to get engine running good. Regarding driveability, you're driving a 2300/2600lbs car with 2.8L engine, you should be smooth to drive. Today, I've got a much more agressive cam made by Rebello (called street cam with tight lash - I've got a reference number I need to dig from my documents if you'd like to know) on custom p79 head, 3xDCOE & Mejajolt ignition. Engine idle is set at 800rpm. In traffic jam is goes as low as 600rpm without any problem sometimes. At 2000rpm in 5th gear on roads going up with a 7% slope was no problem at all (but I run Megajolt so timing at this condition was 49° - it is hard to get on regular dizzy) So go BIG also

If that could help, with my Rebello cam & Megajolt system, I have to run 20° to 22° at idle to be good. With overlap on aggressive cam, you need a lot of timing advance compared to stock unit at low rpm. I run 49° at cruise under low load.

Whatever, my real first name is Mathieu. So Mat or Matt does not change much!

Check for broken cables. My temp sensor, my fuel sender had some corroded wires that became brittle over time. I cut them, installed new connectors and it solved the problem.

Here's the file Mallory Unilite Ignition Curves.xls