Jump to content

Knox

Members
  • Posts

    34
  • Joined

  • Last visited

About Knox

  • Birthday 06/11/1997

Profile Information

  • Gender
    Male
  • Location
    Gosford, NSW, Australia
  • Cars
    '73 Datsun 180b SSS (610)
  • Interests
    Working on old cars, BMX, guitar/drums

Knox's Achievements

Newbie

Newbie (1/14)

2

Reputation

  1. Yeah I should probably do that, heaps has changed since I wrote the first post. The cam should, in theory, be up to it, has 290deg duration with .490 lift, but there could be issues with the way its set up, but the problem was more or less identical with the previous cam, so I'm not sure whether they were both set up incorrectly or what, but it feels like it should be cam related. I did at one point have a wideband o2 sensor set up, with the exact same setup I'm running now, with the same dellorto sidedrafts, jets, etc and it pretty much always landed at the high 12:1s at the HP redline, except when it gets bad vapour lock on hot days.
  2. I thought I explained in my earlier posts; its not a rev limit anymore, its basically a horsepower redline, it CAN rev past 5000rpm in lower gears, but the power is completely over by 5000rpm or earlier; in, say 5th gear it will not budge past 5000rpm. Up until 5000rpm the engine is smooth and the induction sound is crisp, but as soon as it hits 5000rpm it doesn't sound 'in tune' or crisp anymore and starts running rough, not misfiring or anything like that, it just vibrates like crazy and just doesn't sound like it wants to go that high. For what the engine is it should make power up until 6000rpm or higher, but it struggles to make any power past 5000rpm
  3. Alright finally put together a little video, so hopefully it can give a better idea of what its doing: Car was running pretty good when we did the shots, managed to wind it up to 6500rpm in second, but power was well gone after 5000rpm. Would've liked to film it at the limit in maybe a higher gear to see better where the power drops off and how the engine sound changes (you can still sort of hear when the engine stops making power and starts running rough above 5000rpm), but the road we were on was too short to do anything above 2nd/3rd gear. Also should've done a neutral free rev clip as well, but I might try and do another little vid at some point. Might look into the plugs, but I don't think they're the cause of the main issue I'm having. The carbies still need some tuning, maybe playing around with different air correctors (running 210's at the moment) and emulsion tubes might help things, but the emission dellortos aren't really ideal, I'm thinking of leaning towards some dcoe 45s or maybe even an efi setup at some point. But again I don't think thats the cause of the main issue at the moment. Never touched a dial indicator to be honest, I'm sort of considering getting a complete new setup that I know will work; cam with matching springs and lash pads, from a reputable place. I was thinking of looking at isky cams, but does anyone know some good places that do good datto stuff?
  4. No real update, been sick for the past week and haven't been bothered to fiddle with the car. But I'm pretty certain I did some experimenting with different tooth/dowel combinations at some stage. First time I ran this cam setup I went stock no.2 dowel, and didn't see any point advancing it any further it, made the power feel even flatter than it already was. Retarding the cam seemed to improve things a little, I think the furthest I went was a tooth retarded, in the no.1 dowel, it ran better than the stock timing but nothing magical happened. At one point I looked up the grind number I found on the back of the cam, but I couldn't find anything in the Crow catalogue, the stuff I found out about the cam was just from measuring open and close points of the lobes while it was on the engine. I also tried running it as close to symmetrical timing as possible. I don't think valve float is the issue, I haven't tested the springs or anything, but I've ran both the stock and aftermarket valve springs and didn't notice any real difference, unless they're both crap. Does valve float create a sort of fixed rpm limit or does it not affect free revving as much? - I'll still try and post a video at some point. I'm definitely not seeing any signs of detonation on the plugs, after a power run they usually come up a nice, if a bit on the rich (sooty) side, rusty tan colour. The carbies are second hand, the guy I bought them off ran them on his 2ltr pinto engine escort, he said it got 86rwkw (115hp). He didn't run it on e85 or anything fancy, it had 32mm chokes and 145 main jets, 210 air correctors with fairly lean emulsion tubes. Haven't measured the mains or the air correctors if they're drilled out but I'd say they're untouched.
  5. Oh and timing is around 8 degrees idle (I'd imagine it shouldn't even idle with this timing and cam duration - but it does!) and 35-36 degrees max.
  6. Alrighty the block is a semi recently freshened up l20b with stock internals, 11cc dish pistons, ect. The head I'm running at the moment is the closed chamber a87 head off my l18, valves are stock 42mm/35mm and exhaust ports are stock as well, I've taken the intake ports out to 36mm and put in the crow 290deg cam and matching springs that were on my u67 head. At the moment I'm running the cam a tooth retarded in I think the no.2 dowel position. Carbies are twin dhla40 dellortos (emission type) running 36mm venturis, mounted on soft O-ring style mounts. I'm also running a stock fuel pump. My afr gauge stopped working probably a month ago, but last time it was running it was in the high 12:1/low 13:1s at the limit rpm, with the same setup. The headers are 4 into 2 into 1 (haven't checked pipe sizes, but I think the primaries are over 1-1/2") all mandrel bends, into a 2-1/4" exhaust with a resonator at the end. Ignition is run off a Bosch electronic dizzy found in some 200b's, I've now removed the module and replaced it with an msd cdi box, the coil is a blaster 3 coil. Plugs are BP6ES I think. I think that's about it...
  7. The problem pretty much hasn't changed from when I started the thread, except for eliminating a few other problems that made it a lot harder to diagnose. But I'll try and describe in depth what it does (I might try and post a video later on) The engine will pick up pretty well at around 3000rpm give or take a couple hundred rpm, it'll pull well and sound smooth until 4500rpm, from here the motor takes on a really buzzy, whiney, ringing sort of sound and starts vibrating like crazy, but it's NOT misfiring or popping or anything like that. In 5th gear it'll only get to 4500rpm if I'm lucky. There is absolutely no power more beyond this rpm. In lower gears I can squeeze it out to 5000-5500rpm, 1st can sometimes go out to 6000rpm. In neutral, foot flat, revs will climb to 6k, then slow a bit then climb out to 7200rpm (the rpm I set the cdi ignition limiter at). At this rpm it is so unbelievably loud, it sounds like it's revving at 10,000rpm, but it's not misfiring or popping, it just buzzes and vibrates like crazy, it doesn't have any real engine tone it almost sounds like white noise, it's pretty hard to explain. Oh and btw I compared the tach to a digital timing light and it was spot on. I don't know whether I touched on this before or whether you guys are going to hate me for saying this now, but the engine itself is really sensitive to temperature, on hot days it runs real rough and just goes 'flat' when you open it up; in 5th gear it won't even go past 3800-4000rpm sometimes, but on really chilly nights or mornings it'll go like a rocket (comparatively) it runs a lot smoother and sounds crisp, but still hits the wall at 4500rpm in 5th. It could just be rich jetting though. Also for some reason it hates thermostats; at the moment I'm just getting by with a higher flow thermostat with a few coils off the spring so it opens earlier just so it doesn't go past operating temp. With normal thermostats it overheats after about 5mins of driving. I've gotten a new alloy radiator and water pump and it does the same thing. So not sure what the deal is there and whether it's related to the rpm wall. Sorry if this comes across really confusing or misleading, it's hard enough trying to troubleshoot a problem that shouldn't really exist given the circumstances, but hopefully someone can make sense of it.
  8. Hey guys I still haven't solved the problem, power will still come in good up to around 4,5k then just fall flat. I've since chucked my ignition module and coil and replaced it with an msd cdi box and blaster coil, pretty much eliminating any chance of spark breakdown, but it didn't get rid of the wall. I also got soft mounts for the carbies and that helped with the fuel frothing issue and it now hits the wall at a more consistent rpm. I'm currently running my a87 head with the 290Deg cam, springs, etc. But I'm looking at doing up my open chamber u67 head, maybe chucking in some 44mm intake valves, sourcing some bigger exhaust valves and taking out the ports, particularly the exhaust. I also have a spare complete stocker l20b I recently got which I'm considering running as is just out of curiosity but I think I'll end up building a better motor out of that while I have it on the stand. At this point I think it's just running out of breath with the a87 head I'm running now, it just doesn't act like a very peaky motor, I can get it to idle pretty good below 900rpm and pull up hills fairly well below 2500rpm despite the 290Deg cam, oversized chokes and bigger intake ports. I think this could have something to do with the exhaust ports on the a87 head, the ports on the u67 head were a fair bit bigger, when I ran that head it didn't pull as well down low but picked up a little better up top but I think I was still having slight troubles with the ignition and carb mounts which might have held it back slightly. But there is still a huge chance this just another glimpse of false hope and won't resolve anything but to me it's worth a shot doing up this head to see what happens.
  9. I did swap to the points dizzy and it did the exact same thing. My dad is an electrical engineer and we actually have an oscilloscope, we hooked up the other day to check the electronic dizzy's signal when the car was running, the dwell time is pretty consistent and the voltage spikes were up around 250v at idle and 150v at 5k, I'm not entirely sure what this voltage is when it comes out the coil, or whether the voltage spikes are in the wrong place value, but I assume 150v should be enough for a 15000v spark?
  10. To be honest it feels like the cam isn't behaving the way it should, for example, if I tweak the idle I can get it to idle at around 700rpm quite easily (not sure if that's easy to accomplish with anything around 290 degree), and although it lacks power anything below 3000-3500rpm, I think that's just due to port size. I'm wondering if I should invest in a valve train setup that I know should work. What some good cam/valve train component companies and grinds I should look at?
  11. Oops sorry I meant metric, over here in Aus pretty much everything is metric, the manual spec for lash are in mm, so 0.20mm should be 0.008" and 0.25mm should be 0.010"
  12. Stoffregen, It really feels like it should be a fuel issue, but I've seen several times the afrs are in 12s to low 13s at the limit rpm, and it makes no difference whether it's under load or not. Are the nismo soft mounts similar to the Volvo ones BRE used in their trans am 510? At the moment I can can actually move the carbs by hand relative to the manifold, before I literally couldn't, so I'd say its an improvement. I haven't been able to adjust the valve lash properly for awhile since I lost my good set of metric feeler gauges and I've had to use a weird set of imperial feeler gauges with huge gaps between gauges so I've had to settle for I think cold lash 0.203 inlet and 0.279 for exhaust. Would it be worse to have excessive valve lash compared not enough for high rpm? Either way I've gone out and bought a set of metric ones with 0.20, 0.23, 0.25, etc gauges. I've adjusted them to 0.20 inlet and 0.25 exhaust, but I don't feel much difference at the limit. The symptoms you described are spot on, as soon as it approaches 5k the engine manages to buzz, scream and hum all at the same time and you can almost hear it vibrate through the chassis, it sounds like a car without a limiter that's at its actual limit. I have tried swapping the coils but I haven't tried any hei type coils yet. Datzenmike, I tried the jumper wire, I ran it through into the cabin with a switch just for safety, still didn't notice any difference :/.
  13. Hey guys sorry for the long waits between posts, Okay so even after I tightened up the dizzy slop, I found that the engine would still sometimes lean out at the top of 5-6k, even sometimes at 4.5k, so I thought the carbs might still be frothing up from vibration. So I finally ordered some proper soft O ring carb mounts from redline, installed them, took it for a drive and it never went lean again, even if I held it at 5k at part throttle in second gear (the engine used to absolutely shit itself if I did this), it ran silky smooth. But I don't know if its fixed the leaning problem completely yet. Since I've installed the soft mounts, the afrs are around 12.5-13:1. But there is still a wall at 6k . I've spun the engine out to 6k a few times now, and I'll be honest, it really doesn't sound like it wants to be there, it sounds like an engine at its limits. Really, it doesn't feel at home at anything beyond 4500rpm. It makes me feel sick stomping at on the throttle when it just starts to pick up 3500 rpm only to have to change at 4500 before power drops off, the engine may as well be a diesel. I have to find out what the cause of this wall is. I've also checked the timing with my new digital timing light, and its spot on to how I set it statically, so I don't think timing is the issue. Has anyone had similar issues with poor engine ground by any chance? Any problems with car internal wiring?
  14. Alright so I made a bit of progress this afternoon. I took this dizzy off the check if there was slack in the oil pump spindle gear, there was very slight slack but nowhere near 7 degrees, but I noticed the tip of the spindle drive looked worn around the edges, so I did what nad015 had suggested earlier: I dug through the recycling bin and found a tin of come sort, cut a strip from the base, I was a little too scared to mess around with it near the oil pump spindle, so instead I jammed it in the dizzy drive slot with a flathead so it formed a U inside the slot, bolted it on and the slack was completely gone! I started it up, and immediately noticed the idle was a lot smoother and throttle response was crisper. When I took it for a drive something strange happened, when I took it to 5k it still seemed flat but when I held it there it didn't start going sick and leaning out like it usually did, instead I could hold it there and it could actually crawl up to 6k, but by the time it got there, the engine sounded like it wanted to kill itself and smoke actually started to float around in the cabin. My theory is that by eliminating a lot of the slack in the dizzy, the ignition was more stable and helped the engine run smoother as a result. I think this has benefitted the carbs by reducing vibrations that might have caused the fuel to froth and go lean at the limit (which might have been why the afrs would suddenly go lean after holding it there). However the engine still seems rough at the 6k limit, and although some of the vibration is reduced, there could still be something ignition related causing the engine vibrate severely and sound sick at the limit...
  15. Driving along in 4th at 50MPH (being a '73 model, the speedo is already mile an hour before aus changed to km/h) the tach sits at around 2800. The tyres are 205 60 r13. I've set the ignition timing statically, this was easy with the points dizzy but the electronic one is a bit rougher to set, because you have to line up the magnetic pillars with the rotor points visually. I've set it at around 15 degrees idle, and 35 degrees all in. At the moment I don't have a timing light to confirm this, our old one seems to have shat itself, but I will try and get hold of one during the week. The dizzy shaft has a bit of play, when I was setting the timing statically, I found out that the shaft play was equivalent to about 7 crank degrees, this isn't rotor button play, but the play of the actual rotor shaft. So I'm not sure if this really is the play in the oil pump drive gear, or whether its the play in the distributor drive slot. Is there a way the fix any of this play? Wow, stock fuel pump must be more than adequate for my motor to keep up with anything on e85, (doesn't that need like twice the amount of fuel to burn the same as petrol?) Yes that was me! Didn't know anyone on this forum was from around here! You wouldn't have been driving your 1600? I don't remember spotting one. Are you from the central coast as well?
×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.