heavy85

Thanks for all the info - this is a great site. I've now done everything short of rebuild them and it runs a lot better but still backfires occassionally at idle and it stumbles real bad at midrange (not sure the exact RPM as autometer isn't hooked up yet - yet another PO thing). Still not the real inspiring performance that I would expect with this set-up. I'm going to get a carb rebuild kit, Mikuni manual, sync gauge, and timing light and go from there (any suggestion on ignition timing setting would be much appreciated - it's got a MSD 6AL if that makes a difference). Thanks again Cameron

Thanks for the info. There was some play in the linkage which I have now fixed, it now goes to WOT with the pedel after playing around with it, plug gap now set to 0.040, and the jets are actually screwed in place. It'll be a few days before I can pull it out of the gargage to start it but I'll post the progress. My regulator only lowers it to about 4.5 PSI - I found one just like it in the Summit catalog and it's minimum setting is 4.5 PSI so I guess I'll have to find a lower pressure regulator. Jets are as follows: Top end of the long jet - 200 Bottom end of the long jet - 150 Jet next to the long one - 545 (not sure as they were hard to read) Jet out by itself under a small plug - 40 What I assume is the idle mixture screw is two full turns out Engine is a 2.8 liter w/ mild cam, 6-2-1 header, tripple 44 mikuni's (I could not find any model # on the carbs but they measured 44 mm), MSD 6AL, not sure what else but manifolds are port matched to carbs - manifold has F.E.T marked on it if that means anything. Do these jets sound reasonable for this set-up? Thanks again. Cameron

I drained the trans oil the other night and it was full of very fine brass and steel - even had a gold tinge to it. The magnetic drain plug was full of what looked like gritty anti-seeze. I'll refill it and try it again but looks like this one's shot. and for PO not tell me before shipping it across the country! Oh and yeah I do heel-toe but never had to double clutch a car before. I assume that's where you clutch - shift to neutral - release clutch - rev - clutch again - put it in gear? By some off chance it wouldn't require double clutch just because is a comp box would it? I cant imagine someone would make a box like this on purpose - would be a real PITA to double clutch. Last question - what's up with the 50/50 oil/atf mix? Why not straight gear oil? Thanks for the info. Cameron

Thanks for the info - would that SWEPCO stuff improve being able to shift into second? Any alternative fluid like synthetics that would be locally available maybe do the same thing? I looked on the GPR site and they dont list it and the SWEPCO company site lists several grades and types - any idea which one I would need? I've got the flanged output shaft so it's the earlier one. I also talked with the PO who didn't mention this problem originally and he said the PPO (pre,pre owner) told him to double clutch it? I cant see where it would have been built like this on purpose but I'm not a tranny guy so could there be any truth to this? Finally, I will be autox'ing this car on ocassion (sp?) and some day would like to turbo it so what tranny should I be looking at that could take some abuse if I need to replace mine? Thanks Cameron

Thanks for the info. Fuel pressure is about 4.5 PSI so I'll lower it to about 3 if the regulator will let me. It's set-up pump-regulator-carbs (no return) and I've seen a lot of debate on the order but this is what I currently have so I hope it works. I reved it up after dark and saw that it was only #3&4 cyl that backfire and #3 has the raw fuel ahead of in the velocity stack. Not knowing what was behing door #1, I started by taking off the cover in the top center of the 3-4 carb. It turns out this covers the jets and the long jet-like thing (emulsion tube maybe? not sure the name but a real long brass tube with holes around it and a screw-in jet at either end). Well the long jet-like thing wasn't even screwed in. The first thread of it was crossed so it would only go in about 1/2 a turn so that's where it was left by PO (I'm really started to not like POs - you ought to see the wiring, sigh). I'll chase the treads on the jet and see if that gets rid of the backfire and raw fuel smell. I also checked the spark plugs and they were all BLACK with heavy soot so I cleaned them up with a wire brush. This tells me it's running real rich on all cylinders. Also notice the gap was only 0.028 but with the MSD I would think I could go up quite a bit - even our minivan has 0.050 gap (that's a fun job with transverse V6). Anyone know where the mixture screw is or which jet to change - there's something that looks like a mixture screw on top next to the mount flange but there's also a screw sticking out the bottom at an angle? Once I get it running right then I have to figure out how to make the pedal actually open the carbs more than 1/3 the way....hmm wonder why it has little power! Any advice on adapting the carb linkage to the pedal and actually have the pedal open the carbs up all the way would be much appreciated. Thanks Cameron

Thanks - I have yet to jack it up and see what's all underneath (I was trying to fix my jack tonight so I could do just that but no luck) but at least it'll be easy to tell what I have. Is there, in general, an advantage from one box to the other? I assume the earlier box being close ratio would be better - that's assuming you can hit 60 in second but that depends on a lot more than just the tranny. By the way, how hard is it to repair a manual trans? I've rebuilt an engine and do all other auto repairs but never actually opened up a trans to see what's inside. By the way what do used 5 speeds go for anyway? Thanks Cameron

Just got my 240Z this week (shipped in from Cali) and discovered an unexpected issue with the tranny. Basically it grinds a little going into second gear from first but 3-5 are fine - oh yeah it's got a 5 speed of some vintage which I dont know. The other thing is it's nearly impossible to downshift into either second or first when the car is moving at all. My initial thought is the synchro's or something in the tranny is shot. Supposedly there was $1500 dumped into the tranny to build it for autocrossing but....maybe I just got screwed. So my question is twofold - first is there anything I can do or check prior to just swapping in a new tranny and secondly is there a difference in early datsun 5 speeds. Someone I work with has a 5 speed sitting in his garage collecting dust and I could probably get it but should I be looking for something specific? Last thing it's got a new clutch (again supposedly) that seems to work fine. I tried searching on here but the new site must not be working right because I can't get it to find anything. Thanks Cameron

Well I just got my 240Z this week and am in the process of working out the bugs. One of the first issues is what I think is the carbs. It's got tripple Mikuni's but not sure exactly what type - they seem to be about 40 mm dia. Anyway it backfires a lot through the carbs and really smells of raw fuel. I checked for fuel leaks and didn't find any but I noticed that you can see fuel laying in the bottom of the carb throats when you turn the car off (not sure what it looks like when it's running). I tried a search for 'Mikuni' both on this site and the internet and haven't come across anything. Everything is for motorcycles or snowmobiles even the Mikuni.com site doesn't list the two barrels that I could find. Anyway my question is where to start? What do I look for to adjust the carbs, any good books out there, recommended parts suppliers, etc. Should I just rebuild them and start from scratch? Basically I know nothing about Mikuni's but need to learn real quick. Any advice would be appreciated. One other piece of info it's got a MSD 6AL (+ mild cam and header) but I dont think it's an ignition problem. Last thing it's got little power but I think most of that is because the yahoo who set up the linkage made it so WOT on the pedal only opens the carbs about 1/3 the way. Thanks Cameron

I searched but didn't find anything. I'm getting my 240Z delivered this Wednesday (two days ago in San Diego, yesterday in Albequerque, now in Springfield MO on its way to Illinois - I can almost taste it now). Anyway it's got tripple Mikuni's with no filters just velocity stacks. While it looks cool this way I thought it would be a good idea to an airbox with a cold air intake. Anyone done this and have advice / picstures to share? Thanks Cameron