luk3333

I'lll try less advance then. I dialled the cam in.

Lex, I have a wideband, AFRs up around 5000RPM - 6000RPM are around 12.5. A little rich, but it runs that way for most of what and doesn't both it lower down. Could try leaning it out a bit. 5K's have the same stroke as a 4K so it should be good to rev to 8000RPM in theory. I woulnd't think any of the modifactions I've made would cause power to plateau around ~5000. I would think too much advance would lead to a small power drop off the pinging and I'm not getting pinging.

So you run base 10* and then +35 by 3000RPM? so a static 45* after 3000RPM. That kind of leads me to my second question. How should the advance curve be defined? I understand the parameters that affect it (RPM, Cylinder filling, AFRs...) and what I want to achieve by advancing it, but how much, when and what rate? I would have assumed a curve like this would roughly characterise a curve for advance vs RPM for a specific throttle position. Which correlates with what you said, sharp early rise, then eases off, but how do you know where it should ease off at? I've been working on a side project which is a programmable ignition module using an arduino for the math, mosfet (solid state relay) to trigger the coil and a current sensor hooked up to the points as the trigger. My plan was to program an advance curve comprised of a steep early section up to 4000RPM (+8 Degrees/ 1000RPM) and then a flatter section (+2 Degrees/1000RPM) from there on. Does that sound like a reasonable base curve or should actually plateau?

I've got a over-bored 5K, 280/285 cam, 40mm Mikuni sidedrafts, compression, headers etc. The power picks up properly at about 4000RPM (I think it should start earlier, but the 39mm chokes may be causing the air to stall) but then plateaus pretty quickly after 5000RPM. I'm still running the stock dizzy and mechanical points with the mechanical advance and no vac advance with about 18 degrees static advance. With this cam I'd expect a decent power band out to at least 7000RPM. I'm about to build a new head to take advantage of the cams power band, but would like to sort this power-dropping off issue before I finish and install it otherwise there is no point. One of my friends with a similarly built Datsun motor also running mechanical advance has the same issue. Does anyone have any opinions on what the issue is? My hypothesis is that the mechanical dizzy stops tipping in advance around 3500RPM and by the time it gets to 5000RPM its begging for more.

Having done a manual swap on a K power ke70, it was a very good bang for buck performance mod. Would 100% recommend. Also, if you want to save money get a 4 speed, same ratios just minus 5th.

If you want to have some quick and cheap fun and want to get your hands dirty, stick with cam/carb/compression on a 4k. If you want something faster with an old school feel get a carbed T or A engine. Cam - $120 (Get something with a relistic powerband, 2000- 5000RPM, or you'll have a bad time) Shave head - $80 (Learn to calculate how much to remove and what compression ratio you want and the difference between dynamic and staticCR) 32/36 - ~$100 setup (It will work fine, maybe not optimal but for a 4k you won't care, put effort into jetting and getting rid of vac leaks) Timing advance is free ;) Exhaust will be the most expesive part, so put a less restrictive muffler on or replace it with a resonator depending on your taste and call it good. Pick up a second hand set of extractors if you really want, but the standard aftermarket ones are crush bend and unequal anyway. You'll get more out of the car if you spend money on tyres and suspension setup. Just get the engine running nice and hit up a few twisty roads and enjoy the thing.

Those GRP4 struts look the way to go... if I had money to fill them with Bilstein goodness. Now that you mention it I do remember seeing that weld on the bottom :/ I've got access to a lathe at uni so I could cut it flush with the casting and then turn out the inside... Otherwise I'll just have to leave a bit of tube at the bottom and accept there'll be a weld on the tube somewhere. Only reason I'm bothering with the Ae86 gear is because I've already got it, but you think converting to RA40 struts and arms would be easier?

I've got a set of Ae86 struts that have been converted into coilovers but I'm not happy with the quality. Essentially I want to replace the cut and welded stock tube with a new not-welded tube with a nice new gland nut thread cut in the top (threads damaged currently). The strut tube doesn't appear to be welded to spindle casting, so I was wondering if anyone had tried removing it with a bit of heat. I'd like to know before I go ripping the suspension out of my car preferably. Thanks

Use 2k to buy your gf her own car, use other 2k to have someone put a manual and 5K in ;) everyones happy

Best laid plans of mice and men... It's not the first track day of the year but I have booked a spot for Wakefield on the 22nd of March! Very keen for it, it has really sparked some motivation again. I've removed most of the sound deadening, just need to do under the drivers seat/ foot well then its paint time. I'm thinking of not worrying about the carpet for now, I thought it would be noisier but its really not that much different. I've bought new rear shoes and slaves as my handbrake wasn't gripping (shoes lubed up by brake fluid), and I have a slow brake fluid leak so I'm guessing the slaves are done. (Thought it was just the master cylinder, but kept losing brake fluid after I replaced it). I've got a set of Celica tie rods and rack ends now, just sorting out Lca's and then I can have not dodgy camber! I remember how much of a difference it made when I went from stock to longer, can't wait to have that extra front end grip back. I decided the Quad carbs were going to be too much effort considering my limited fabrication skills and lack of garage so I invested in a pair of Solexs. God they sound so good! I love how I can cruise around relatively quiet then go full throttle and make the most guttural noise. After a few minor repairs including setting up the linkages for better leverage, resealing one leaky accelerator pump, reattaching a accelerator pump linkage, buying a set of booster venturis from Wolf Creek Racing and some smaller fuel jets I had it running fairly well. Even with a poor tune I could really feel the car pull much harder and much further through the rev range than the stock carburettor. Running an aluminium air box I folded up with a K&N panel filter, but I've since ordered some trumpets and socks. I was looking at the T3 ones but found a set of 4 on ebay that were $100 cheaper so i went with them. I figured I'd rather spend the $100 elsewhere... Currently it runs rich on the slow circuit, typically about 12:1 (It's hurting my wallet :( fuel is too expensive!) so I've ordered a pair of 57.5 and 55 jets to replace the 60 slow jet it currently has. Midrange is good, but I can't open full throttle till over ~4000rpm or it leans out to 15:1, so I'm replacing the 210 air with a 150. This may be too small but it is a lot easier to get them drilled larger than buy a smaller one or solder and redrill. The current 120 fuel seems OK. It originally had a 140 and was very rich everywhere other than idle. I think the midrange issue could also be because I haven't got the accelerator pump on full throw because it make the Afr's drop right off, I've bought a 30 jet to replace the 40 and hopefully it helps. My jet decisions have been made based on research from other forums (mostly datsun), blown 5k's advice and by using small pieces of copper wire to effectively reduce the jet size. Sounds weird but its a lot quicker and cheaper than getting them redrilled or buying more. One other thing I'd like to change would be the venturis from 39mm to a 37 or 36 for a stronger vac signal from the small engine, but wolf creek doesn't sell them and I haven't really looked around otherwise. I've started working on the data logger again, but I'm going to make a separate thread for it.

How's the vid going?

Can you remember your cam specs? I'd be interested to pop the details into the calculator if you don't mind :)

Also I was just playing around with the boost setting on the calculator, if you put 6psi with 9.5CR and inlet closing at 20ATDC you get a DCR of 13, but people use those sort of setting and don't get detonation. Is it harder to detonate an air fuel mixture under pressure?

Yea, they use MON and we use RON or something? Pretty sure its means is rated under different test conditions. Punching 11.2CR and the other stats for my engine in and it gives a DCR of 8.72 which isn't that far above their apparent limit of 8.5 and if our 98 is of higher octane than their best pump fuel it would probably be ok.

My 5k with 20thou over shallow dish pistons and shaved 4k head. DCR of 8.22 SCR of 10.5 280/286 cam inlet closing 66 ABDC standard rods Looking on the hot rod forum in america they say a DCR of 7.75-8.5 is suitable for pump gas. It seems like only the hot rod guys are really interested in DCR for what ever reason. There is a DCR calculator here. What DCR's are everyone else running in their modified K engines?