Everything posted by Mark Maras
- Nissan 400z Rumors
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Nissan 400z Rumors
It looks like an over-inflated Z balloon to me.
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240z (barely) runs very unevenly!
Coughing from the carbs or tail pipe? I'm thinking it may be running lean. Is it possible that you changed the float setting when it was pushed with the straw? Also, did you remove or inspect the needle valve for crud?At this point, I'd pull both float chamber tops and compare the fuel levels.
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COVID-19
I can think of one person!
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240z (barely) runs very unevenly!
The WD-40 straw is a great idea. I'd also pull the float cover, inspect the needle valve for foreign matter holding it open, float and float pivot to find the reason for the excess fuel.
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240z (barely) runs very unevenly!
I'm leaning (snort) to a fuel problem. I've experienced similar symptoms and found them to be water related. If you have any clear fuel filters, check those for water. I'd also pull a float chamber top to see if there is water in the bottom of the bowl(s).
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Which Header?
Original tubes thread?
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Rough when driven at constant speed
Congrats on the success. 23mm down is good. I'd try turning the nozzles up 1/4 turn just to see the effect and then probably reset them to 3 turns. 20 wt. oil is recommended. The thicker the oil the slower the piston and needle rise during acceleration but doesn't prevent the piston from going all the way to the top. That slow rise (restricted venturi) and the open butterfly, speeds up the air coming thru the venturi (piston bottom), drawing more fuel from the nozzle. That slower rise replaces the accelerator pump that is found on most carbs. I ran ATF in mine with no complaints.
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73 240z restoration 904 White
Grab an implement of destruction (I use an ice pick) and probe everything that is suspect. You'll soon have a better idea of the extent of the damage and what will need to be replaced.
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Carbs not getting vacuum
Search using the word "floats" and you'll find pics and discussion. You'll be looking for the depth of fuel in the float bowl. Measure form the top edge of the bowl down to the fuel level. Pics would be great. Also, while holding the cap and float assembly , with the floats hanging down, blow into the inlet tube. You should be able to blow air through it. Now slowly lift the float while blowing into the tube. When the float is lifted to about 9/16" from the bottom of the float cover, you shouldn't be able to blow through it.
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Carbs not getting vacuum
The carbs have no elec. wires. I'd pull the float covers and take a look inside and take a measurement from the bowl top edge to the fuel level. If you've verified you have spark at the plugs, try spraying some starting fluid (ether) into the carbs and see if the engine starts and runs for a few seconds.
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Carbs not getting vacuum
Tell us the history of the carbs. Did anyone rebuild them? Not that I think they need it, just looking at a possible screw-up during assembly. If there is fuel in the carb. fuel lines, the banjo fittings on top of the float bowls contain a filter screen. Clean those and then verify your float fuel levels are correct.
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Gauges Misread Randomly
I'd also verify the coolant temperature with a thermometer to find out if the gauge is wrong.
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Rough when driven at constant speed
1) "Difficult first start of the day" is not enough fuel. Misadjusted choke cables are often the reason. Have you checked the float levels. They are the primary mixture adjustments.
- Fun post for Tuesday
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front end clunk/steering
We didn't torque tapered roller bearings "back in the day". We would spin the wheel while tightening the nut until the nut was snug and usually tighten it until the next slot in the nut aligned with the hole in the spindle. On my 71 the next alignment slot felt too tight, so I backed the nut off. That slot left the wheel bearings with an almost imperceptible amount of play. I consulted my Dad (ex-logger) about the looseness and he said a tapered wheel bearing would last a lot longer a bit loose than a bit too tight. I don't know why, to this day, but I left the bearings a bit loose and other than occasionally greasing them, I ran them over 175,000 miles. I did have to tighten them, temporarily, for novice races. Tech didn't like loose wheel bearings.
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72 240Z question and mechanic in North Dallas needed
Even compression #s (or close to it) in all the cylinders is more important than high #s in an old engine. Your second reading looks good. I've not limited the # of engine revolutions when testing compression in the past. I suspect that given a few more revs the #s would have popped up a few more p.s.i. I think you're good to go.
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72 240Z question and mechanic in North Dallas needed
As the car is hesitating while pushing on the accelerator, gradually add a bit of choke and see if the hesitation goes away.
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72 240Z question and mechanic in North Dallas needed
Be sure to hold the throttle wide open when testing the compression.
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72 240Z question and mechanic in North Dallas needed
Addressing the acceleration problem, grab a repair manual (any will do) and tune it up. It's quite easy to learn and do. The tuneup includes resetting the valve lash which may bring those compression #s up. They should be above 165.
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Kyosan Denki issue
It looks like an unfinished project to me. The crack does look like a hacksaw cut but unless that cut was filled with weld the gap would close up eventually. "Seemed like a good idea at the time". We've all had them.
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Virus face shields, masks - ideas and designs
Mesh size is certainly relevant but the ability of a fabric to readily absorb moisture, water and lipids (oil, grease) is equally as important. The moisture absorbing properties of cotton, wool and polyester are vastly different.
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HELP!!! S/U wont idle
and a new set of spark plugs.
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HELP!!! S/U wont idle
We need some background info. What negative symptoms caused the rebuild. Who rebuilt them and were the linkages, throttle shafts, float bowls totally taken apart? What source are you using as a reference guide for tuning and what have you tried to get it running correctly? The float setting is the primary mixture adjustment.
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L28 w/ SU Carb runaway idle?
The engine has to be drawing more air to increase revs. Have you checked for vacuum leaks? The pistons should be difficult to lift, They will rise slowly with constant pressure and drop much faster with an audible tap when they hit bottom. Heavier oil delays the piston rise during acceleration which acts the same as an accelerator pump. The nozzles must return to the top when the choke knob is in the off position. Misadjusted cables are often the cause but frequently the flat bar linkage that pulls the nozzles down needs a bit of twist to precisely align it's mating surfaces. Lube the pivot points and the exterior of the nozzles with lithium grease.