datzenmike Posted October 5, 2017 Report Share Posted October 5, 2017 Well you want the carb with the 6 wire plug on the back. And you need the air filter with the pipe down to the exhaust manifold 2 Quote Link to comment
Charlie69 Posted October 5, 2017 Report Share Posted October 5, 2017 I say you need a real Weber, egr and do a complete tune up. Order the Weber from Pierce Manofolds. You might need to rejet the Weber depending on your altitude. 2 Quote Link to comment
datzenmike Posted October 5, 2017 Report Share Posted October 5, 2017 If all you have to do is pass the emissions tailpipe test then any carb that get's you past it will do. I imagine the stock emissions pass is very low for the ECC carb and will be hard to beat with an other carb. The stock uses the AIS and catalytic converter, the variable primary jet and O2 sensor feedback to run at stoichiometric. It also has EGR ported vacuum. The weber won't have any of that. 1 Quote Link to comment
mx71 Posted October 5, 2017 Author Report Share Posted October 5, 2017 I don't care what carb it has, as long as it passes. 1 Quote Link to comment
Charlie69 Posted October 5, 2017 Report Share Posted October 5, 2017 Mike I run the stock egr and the cheapest catalytic converter I can buy with my Weber. The last time I failed emissions and all I did was replace the catalytic converter. King cab passed emissions today, good for 2 more years!!! Here are the last test results after installing a $30 cat. Emission Inspection Results Vehicle Test Emissions Allowed Result Hydrocarbons (HC) in grams / mile: 0.95 3.00 Passed Carbon Monoxide (CO) in grams / mile: 7.79 25.00 Passed Oxides of Nitrogen (NOX) in grams / mile: 3.16 4.50 Passed Remember this is a non smog legal Weber 32/36 DGEV carburetor. 1 Quote Link to comment
racerx Posted October 5, 2017 Report Share Posted October 5, 2017 Here in Cali. the seller is supposed to smog before you buy a car 76 and above since 75 does not require smog. Is the law like that were you are from? if so he did not smog before you bought? Quote Link to comment
mx71 Posted October 5, 2017 Author Report Share Posted October 5, 2017 No, very little laws here compared to CA. Mechanic called and it needs a new carb. I think I’ll just get a used Hitachi off eBay. Quote Link to comment
datzenmike Posted October 5, 2017 Report Share Posted October 5, 2017 Find out whats required for smog testing before buying anything. Quote Link to comment
mx71 Posted October 5, 2017 Author Report Share Posted October 5, 2017 If I just have the Hitachi put on it (it's the one with the 6 pin connector), will any air filter housing from 84-86 fit, or are they different depending on the carb? Quote Link to comment
mx71 Posted October 5, 2017 Author Report Share Posted October 5, 2017 Find out whats required for smog testing before buying anything. The shop is saying new carb because they can't get the crap one that's on it tuned properly. Quote Link to comment
datzenmike Posted October 5, 2017 Report Share Posted October 5, 2017 If I just have the Hitachi put on it (it's the one with the 6 pin connector), will any air filter housing from 84-86 fit, or are they different depending on the carb? All close enough. Get one from a 2wd. You will need the pipe from the exhaust manifold in order to get the AIS working. . Quote Link to comment
racerx Posted October 6, 2017 Report Share Posted October 6, 2017 The shop is saying new carb because they can't get the crap one that's on it tuned properly....u sure that mechanic knows how to tune a carb. Not too many people today know how. Most have retired. We live in an efi world now. I would ask him if he ever tuned a carburator before. How old is this mechanic. Quote Link to comment
mx71 Posted October 6, 2017 Author Report Share Posted October 6, 2017 This is an older family run business that's been here in Boise for 30 years, and are qualified by the state for emissions repairs. I trust that it needs a new carb, as the Holley that's on it looks like junk, and it looks like there's pieces missing from it. I'm just going to have them put on a new (remanufactured) Hitachi and just put it back to stock. In my old age (I'm either 32 or 33 now), I'm now becoming the type of person that likes things stock and starts reliably. I don't care about power or noise. Even though I have no experience with this shop, I trust them. The only smog requirements here are less than 1.2 on the CO, and I was 7.5. All vehicles get tested after 1981, and this is an 85. It passed everywhere else other than not having the injection pump. Test is ever two years, and if you make a good faith effort to repair problem and spend at least $300 (not including replacing removed parts like an EGR valve or AIP), then I qualify for a waiver. This carb install is going to cost at least $1,000, and if all the parts it's supposed to have are put back on it, I'll qualify for the waiver. I didn't want to do it as I had $1,600 in this truck, but I've realized I'm going to keep this truck for a while so it's worth it for me to spend the money on it to have it run right. At this point, I'm more worried about it being right than cheap. Now, will an 84 air cleaner housing for my 85 KC 4x4 manual trans Hitachi carb? There's one on eBay with little details, so not sure if it will fit. http://www.ebay.com/itm/1984-Nissan-Air-Intake-Carb-Breather-Housing-Assembly-720-Truck-Filter-/222550613519?hash=item33d10cde0f:g:cp0AAOSwSlBYxBkI&vxp=mtr Quote Link to comment
datzenmike Posted October 6, 2017 Report Share Posted October 6, 2017 Family run business is only relevant if someone working there is over 45 and was a mechanic when there were carburetors still. The 720 did not have an air pump so they don't seem to know this. The AIS is a totally passive system using exhaust pulses to draw in air for the catalytic converter. It's a totally passive system using exhaust pulses to draw in fresh air. Quote Link to comment
flatcat19 Posted October 10, 2017 Report Share Posted October 10, 2017 I would trust a new Weber to be more reliable than some random rebuilt Hitachi built by some 12 year old Taiwanese girl. You can install the Weber yourself with a bent 12mm wrench and tune it with a flathead screwdriver. 1 Quote Link to comment
datzenmike Posted October 10, 2017 Report Share Posted October 10, 2017 Depends. Already failed because no 'air pump' which I think reads 'missing AIS'. So a new Weber isn't going to fix this and it's still going to have to pass emissions equal to the ECC (feedback) carb and all it's emissions gear on it. Quote Link to comment
flatcat19 Posted October 10, 2017 Report Share Posted October 10, 2017 It could be tuned lean enough to pass. Air pump ain't stopping it from passing unless strictly visual. Tune it lean. Advance the dizzy to keep it running. Go through test hot. Set back to "stock" with pass slip in hand. Quote Link to comment
datzenmike Posted October 10, 2017 Report Share Posted October 10, 2017 Not enough info to say. I hear dumping in a gallon of alcohol on a quarter tank also helps dilute and lean it out. Quote Link to comment
mx71 Posted October 10, 2017 Author Report Share Posted October 10, 2017 Depends. Already failed because no 'air pump' which I think reads 'missing AIS'. So a new Weber isn't going to fix this and it's still going to have to pass emissions equal to the ECC (feedback) carb and all it's emissions gear on it. Yep, this. Quote Link to comment
mx71 Posted October 10, 2017 Author Report Share Posted October 10, 2017 It could be tuned lean enough to pass. Air pump ain't stopping it from passing unless strictly visual. Tune it lean. Advance the dizzy to keep it running. Go through test hot. Set back to "stock" with pass slip in hand. It is failing because isn't isn't seen visually. The shop talked to the president of the air board, and the only way they'd pass it is with the stock carb. Quote Link to comment
mx71 Posted October 10, 2017 Author Report Share Posted October 10, 2017 Keep in mind, this is a vehicle from 1985 with unknown maintenance (although it appears well taken care of) with 175,000 miles on it. For all I know, rings are on their way out and blowing oil into the exhaust. Not sure it's worth the risk to throw a weber on it, have it not pass, be out $350 and my time to install it. I'd rather just get it over with. I basically only use this truck to teach my wife to drive a manual, haul dirt bikes and mountain bikes to and from trails, pick up furniture, and transport dogs to and from the vet. I don't care about how much power it has. Quote Link to comment
mx71 Posted October 16, 2017 Author Report Share Posted October 16, 2017 Good news. The shop installed a remanufactured Hitachi carb and it passed the emissions retest. Bad news, some air port on it was broken and they need to replace it, but it passed! Who would have thought a 1985 720 that probably has changed hands multiples times with 176,000 miles would pass? Quote Link to comment
racerx Posted October 16, 2017 Report Share Posted October 16, 2017 That's great!!! 1 Quote Link to comment
Cheetahking Posted October 16, 2017 Report Share Posted October 16, 2017 Its a Nissan - of course it did! 1 Quote Link to comment
datzenmike Posted October 17, 2017 Report Share Posted October 17, 2017 I'm not surprised. NAPS stands for Nissan Anti Pollution System. The Z series are pretty good at it. 1 Quote Link to comment
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