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ive tired EVERYTHING!!!


illestmatic

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Do some cheating here.

open valve cover. as the cam lobes are pointing Up see if the rocker arm is loose. If loose then you know the valve is closed. if tite even cold this is a big proplem as the valve is not fully closed and is riding the rocker arm. If tite it will feel like you lost a cylinder as its blowing out the exhaust and not igniting.Most time its the exhaust valve/rocker that will get tight.

 

the carb look in the the main barrel. this will be the barrel closest to the valve cover. when you cycle the linkage on top of the carb is a little tube. it should squirt GAS in there on the down stroke. this is to enrich the circut as the butterfly opens so the mixture come out right. Once you reach a steady speed the vacuum takes care of the rest with the main fuel jet./ There should be a lever on the out side of the carb that pushes the accel pump on side of the carb. Sometime the accel pump diaphrame is put in wrong (if that is even possible)

 

Most time when rebulding a stock carb people screw them up

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To tight of valves could definitely make it run like a total pig like you described.

  

Adj your valves HOT, reset your timing, and CHECK YOUR ATF level on LEVEL ground and WARM

  

Do some cheating here.open valve cover. as the cam lobes are pointing Up see if the rocker arm is loose. If loose then you know the valve is closed. if tite even cold this is a big proplem as the valve is not fully closed and is riding the rocker arm. If tite it will feel like you lost a cylinder as its blowing out the exhaust and not igniting.Most time its the exhaust valve/rocker that will get tight.the carb look in the the main barrel. this will be the barrel closest to the valve cover. when you cycle the linkage on top of the carb is a little tube. it should squirt GAS in there on the down stroke. this is to enrich the circut as the butterfly opens so the mixture come out right. Once you reach a steady speed the vacuum takes care of the rest with the main fuel jet./ There should be a lever on the out side of the carb that pushes the accel pump on side of the carb. Sometime the accel pump diaphrame is put in wrong (if that is even possible)Most time when rebulding a stock carb people screw them up

  

Yeah. A tight valve will (or can) run unnoticed at light throttle but spit back through the carb and run poorly under heavy. It's just something to eliminate and move onto the next thing until it's fixed.

I want to take the time and THANK YOU guys verymuch for all your input and reccomendations. it was indeed my valves I adj. Them today warmed it up and took it for a late night cruise the truck ran flawlessly. I can't believe one year of tackling this problem was my valves. You Datsun fam are the best. My trucks running better than ever ill sure be sleeping well tonight. Lol four valves were to open by 2thoudsands of an inch and one valve was to closed. Thank you guys again.

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The valves tight lowered the intake vacuum and this is the same vacuum that is piped down to the modulator valve on the transmission. Engine vacuum is an indicator of engine load and the automatic would 'think' that you were driving at full throttle all the time and naturally move the shift points way up so all it did was rev up.

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I want to take the time and THANK YOU guys verymuch for all your input and reccomendations. it was indeed my valves I adj. Them today warmed it up and took it for a late night cruise the truck ran flawlessly. I can't believe one year of tackling this problem was my valves. You Datsun fam are the best. My trucks running better than ever ill sure be sleeping well tonight. Lol four valves were to open by 2thoudsands of an inch and one valve was to closed. Thank you guys again.

 

 

Remember to adjust them every other oil change and you should be good. :)

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I have one more issue I want to tackle. The truck seems to be running fine tho the temperature goes up. Pretty much to the "H". The timing is set right, the valves are adj, but at the moment I have water in the radiator since I'm flushing the system. is there anything that can make the temp. Go up.

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I have one more issue I want to tackle. The truck seems to be running fine tho the temperature goes up. Pretty much to the "H". The timing is set right, the valves are adj, but at the moment I have water in the radiator since I'm flushing the system. is there anything that can make the temp. Go up.

 

 

How quickly does the temp guage rise to the "H"?

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The cooling system transfers heat from the water to the air so...

 

Poor air flow...

Rad shroud is missing. The shroud increases fan efficiency at low speeds.

Dirt/bugs plastic bags blocking air through the rad. Fog lights, license plate moved?

Clutch fan excessively slipping. This affects low speed more than on the highway.

 

Poor water flow...

Thermostat stuck part open or not at all.

Head gasket blown.

Bottom rad hose soft and collapses from suction at highway speeds.

Rad core blocked inside from scale or rust.

Improper mix of water and antifreeze coolant.

Thermostat by pass hose missing or plugged.

Heater leaking and hose bypassed from head directly to lower rad hose.

Block full of scale and in need of a good flush.

 

 

Other...

Gauge sender or gauge faulty.

Carb running lean

Timing retarded.

Brakes dragging.

 

 

At this time of year my 710 L20B reaches the bottom of the 'run' range in less than two Km. It's 1/3 of the way up the 'run' range (which is normally where it always runs) in three Km or less. Today it began reading just up from full cold in about 4 blocks after sitting for 9 hours. 

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I have one more issue I want to tackle. The truck seems to be running fine tho the temperature goes up. Pretty much to the "H". The timing is set right, the valves are adj, but at the moment I have water in the radiator since I'm flushing the system. is there anything that can make the temp. Go up.

How quickly does the temp guage rise to the "H"?

  

The cooling system transfers heat from the water to the air so...

 

Poor air flow...

Rad shroud is missing. The shroud increases fan efficiency at low speeds.

Dirt/bugs plastic bags blocking air through the rad. Fog lights, license plate moved?

Clutch fan excessively slipping. This affects low speed more than on the highway.

 

Poor water flow...

Thermostat stuck part open or not at all.

Head gasket blown.

Bottom rad hose soft and collapses from suction at highway speeds.

Rad core blocked inside from scale or rust.

Improper mix of water and antifreeze coolant.

Thermostat by pass hose missing or plugged.

Heater leaking and hose bypassed from head directly to lower rad hose.

Block full of scale and in need of a good flush.

 

 

Other...

Gauge sender or gauge faulty.

Carb running lean

Timing retarded.

Brakes dragging.

 

 

At this time of year my 710 L20B reaches the bottom of the 'run' range in less than two Km. It's 1/3 of the way up the 'run' range (which is normally where it always runs) in three Km or less. Today it began reading just up from full cold in about 4 blocks after sitting for 9 hours.

 

As soon as the truck warms up it'll start going up from there none stop.

I figured the temp would go Down on the highway but I'm wrong it still goes.

 

Wow mike that's a lot of good info. It could be anything at this point lol

I'll check off things from your list.

*my truck is getting good air flow therea nothing blocking the rad.

*I can't tell if the fan clutch is bad so ill keep this in mind

* my truck doesnt have a thermostat at the moment so it couldnt be that

* I'm not going to lie the previous owner had changed the head gasket.

AND I believe it got oil in the rad. So I'm thinking either my problem is a clogged rad or yet another blown head gasket shit man. I ahouldv just swapped the engine in the first place... :/ that's what I get for trying to keep my truck stock..

* I'm doubting the timing is off; mine is set to 5degrees btdc and the carb seems fine.

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Fan clutches suck, this is most likely the culprit. I would recommend changing over to a non-clutch fan or an electric fan. You could wire in a cheap fan from a Volvo from pick n pull to trouble shoot the clutch.

 

 

Not having a thermostat will do one of 2 things. The motor will never warm up to operating temp or it will heat up to oblivion.

 

The thermostat is needed to keep the coolant in the radiator long enough to transfer the heat from the coolant. If it doesn't stay long enough it will continue to heat up and up and up.

 

 

Is there currently oil in the coolant? Water in the oil?

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Fan clutches suck, this is most likely the culprit. I would recommend changing over to a non-clutch fan or an electric fan. You could wire in a cheap fan from a Volvo from pick n pull to trouble shoot the clutch.

 

 

Not having a thermostat will do one of 2 things. The motor will never warm up to operating temp or it will heat up to oblivion.

 

The thermostat is needed to keep the coolant in the radiator long enough to transfer the heat from the coolant. If it doesn't stay long enough it will continue to heat up and up and up.

 

 

Is there currently oil in the coolant? Water in the oil?

I like the electric fan idea I might just get into that.

As far as the thermostat goes ill get one today and install it and see what happens ill go the cheapest way out them go from there.

And no as of right now I a "flushing rad." Liquid that mixes with water I barely see oil within the water. There's only oil in the rad and NO water in the oil I've checked every other time I open the good just to make sure.

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Once above 30-40 you don't need a fan as vehicle speed will push enough cooling air through the rad. If you run cool on the highway but get hot waiting at lights it could be the clutch fan is slipping from loss of the silicone oil inside it. Engine off flick the fan around with your finger. If it is firm but movable and stops moving as soon as your finger lets go, it's fine. If loose and spins a few inches it's slipping.

 

If it runs cool at low speed but over heats when revved up on the highway pull over and rev the motor while looking at the lower rad hose. If soft, it will collapse from the water pump suction. Get a new hose. 

 

For about $10 (don't be cheap! A $2 thermostat is no good when it leaves you on the side of the road with a blown head gasket) a really good name brand thermostat of 180- 185F and replace it. Often this fixes 50% of heating problems and probably due for a change anyway.

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Once above 30-40 you don't need a fan as vehicle speed will push enough cooling air through the rad. If you run cool on the highway but get hot waiting at lights it could be the clutch fan is slipping from loss of the silicone oil inside it. Engine off flick the fan around with your finger. If it is firm but movable and stops moving as soon as your finger lets go, it's fine. If loose and spins a few inches it's slipping.

 

If it runs cool at low speed but over heats when revved up on the highway pull over and rev the motor while looking at the lower rad hose. If soft, it will collapse from the water pump suction. Get a new hose. 

 

For about $10 (don't be cheap! A $2 thermostat is no good when it leaves you on the side of the road with a blown head gasket) a really good name brand thermostat of 180- 185F and replace it. Often this fixes 50% of heating problems and probably due for a change anyway.

To be honest my truck seems to be hot while I'm at a stop and or on the highway. but I don't have a thermostat to begin with I bought a 10$ Murray ultra thermo. Right now before I got home from work.

But wait there's more! Something strange happened while driving home from work. As the trucks' temp. Was high the truck started running better than ever. No Boggs, no choke, accelerated flawlessly. Its the first time this has ever happened to me. Ant ideas?

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when most fan clutches go bad they lock up what I seen so its like a stock 510 water pump.

 

So I will diassagree with a few here.

I dont think it the water pump or fan clutch.

 

 

On a cool day and your positive the stat is not in there the motor should be cool.but as Redey said above is also tru.

 

 

On really Hot days all my datsuns runa little warmer than I like in stop and go traffic

 

 

 

make sure to run 50/50 mix antifreeze

 

is this a datsun with the mated intake and exhaust as 1pc set up?I hate those stove type heated setups

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when most fan clutches go bad they lock up what I seen so its like a stock 510 water pump.So I will diassagree with a few here.I dont think it the water pump or fan clutch.On a cool day and your positive the stat is not in there the motor should be cool.but as Redey said above is also tru.On really Hot days all my datsuns runa little warmer than I like in stop and go trafficmake sure to run 50/50 mix antifreezeis this a datsun with the mated intake and exhaust as 1pc set up?I hate those stove type heated setups

Well I have been driving my car on these hot ass days but its xtrwnly hot I mean there's no smoke or anything bit the temp gauge is high .

My Datsun has stock intake, stock headers, but it is straight piped with a magnaflow exhaust

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Did you finish with flushing the radiator? 

 

Did you put ant freeze back in?

 

Is you bottom radiator hose sucking closed at high RPM.

 

Did you change you temperature sending unit?

 

Are you running after market temp gauge?

 

If all else fails have a radiator shop rod your radiator.

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To be honest my truck seems to be hot while I'm at a stop and or on the highway. but I don't have a thermostat to begin with I bought a 10$ Murray ultra thermo. Right now before I got home from work.

But wait there's more! Something strange happened while driving home from work. As the trucks' temp. Was high the truck started running better than ever. No Boggs, no choke, accelerated flawlessly. Its the first time this has ever happened to me. Ant ideas?

 

 

This is confusing. How do you know you don't have a thermostat? unless you just tried to replace it with the new one?????

 

 

 

 

 

I would borrow an infra red thermal heat gun and 'shoot' the thermostat housing when warmed up. If around 185-190 the gauge is at fault and there never was anything wrong.

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  • 2 weeks later...

Soo I cracked down the issue with my trucks temperature gauge.

Original gauge marked it was hot "H" I bought an aftermarket gauge and it shows its at 180f at all times ir doesn't even move from there. There was nothing wrong with my truck smh oh and I've flushed the system three times and put coolant as well.

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  • 2 weeks later...

i was goin to recommend checking the coil resistance and the vacuum advance pot on the dizzy.

ive personally had too many problems with them on other models of vehicle and i see this all the time a a problem on older cars

 

my advice to you.....

invest in a vacuum gauge. the use of a vacuum gauge is more important that most other testing equipment it can tell you almost everything that is wrong with an engine and you can even do timing with it!

it also would have found your tight valve ;)

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If you are concerned about your distributor vacuum pot failing have your distributor re-curved using only centrifugal advance (weights and springs) by a shop that has a distributor machine.  Most good speed shops have this technology.

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