ive tired EVERYTHING!!!

[illestmatic]

(1973 Datsun 620 pickup truck with L16 motor)

ive tried everything to get my truck back in running order and it seems like no matter what i do my truck is playing games!!! ill state everything that i have done. The prime issue with my truck is that it doesn't accelerate tho it boggs out. the weird thing is that when i slightly step on the pedal it runs perfect, but obviously ill have to be traveling sloooooow all the way to my destination. its when i STEP on the pedal further more when it just revs but doesnt go anywhere. it lacks power. 

 

Things ive upgraded; new rebuild/refurnished stock hitachi downdraft carb, converted dual point dizzy for a matchbox dizzy, fixed all vacuum hoses, bought a new mechanical fuel pump, changed fuel filters twice, had my ignition timing set to 5dgs btdc. as instructed on the hood label, switched pcv valve, spark plugs (ngk), spark plug wires, and 

new alternator.

 

i am completely stumped at this point and dont know what else to do. i know i shouldv just swaped the engine since the beggining but i wanted it original. oh i forgot to mention the motor has 41,800 miles as its marked if this even helps.

 

please any advice or input is very much appreciated its been close to a year that ive been tackling this problem i just want to drive my truck already .  .  .

[datzenmike]

Timing is 12 degrees BTDC not 6.

[datzenmike]

(1973 Datsun 620 pickup truck with L16 motor)

....the weird thing is that when i slightly step on the pedal it runs perfect, but obviously ill have to be traveling sloooooow all the way to my destination. its when i STEP on the pedal further more when it just revs but doesnt go anywhere. it lacks power.

From that description it sounds like the clutch is slipping.

 

 

oh i forgot to mention the motor has 41,800 miles as its marked if this even helps.

The speedo only goes to 99,999 so it may have 'gone round' at least once maybe twice. 142,800 or 241,800???

[illestmatic]

@datzenmike hey mike just the person i wanted to talk to. your my only hope at this point. so you say its 12 degrees okay ill take your word for it. i only set it to 5/6 degrees btdc because it was stated on the label under the hood. 

[illestmatic]

From that description it sounds like the clutch is slipping.

 

 

 

The speedo only goes to 99,999 so it may have 'gone round' at least once maybe twice. 142,800 or 241,800???

oh i forgot to mention the truck is auto.

 

hahahah yeah i had my doubts.

[datzenmike]

Well I thought all L series were 12 degrees. I have the '73 FSM and you're right 5 degrees. +-

[illestmatic]

damn well on that note im still stumped. i think ive done everything a mechanic would of told me to check. is there something im missing?

[datzenmike]

When you say you step on it and it just revs up does the speedometer speed up also? Does it do this in 3rd and 4th mostly?

[banzai510(hainz)]

I seen 7 to 12btdc with man trans but one should time it with it in gear holding the break if I remember right on olddatsuns.com  Mike or datsunalholic would know more

 

key is is your accel pump working on your carb. does it squirt  gas in the main barrel when you push the gas.

 

also when you put the matchbox in is it time correctly and mostly close to the center of the timming plate. maybe slightly adv.

if the dizzy is crank all to one side then your off a tooth and that is a proplem.

 

Im not a automatic expert on these but there is vaccum lines that trip the trans also. Im sure Mike knows more on this

[illestmatic]

well it only has 3 gears since its an auto. the problem accures at every single gear. even when i come to a stop the truck is slow. the speedometer does move. dont get me wrong the truck does move but it revs more than it moves. by the sound of it; it sound as if the carb needs more fuel. the carb sputters fuel as i accelerate its only when i slightly step on the pedal when the carb works at its best. tho i changed the carb 4 months ago and i rarely used it since the truck never ran correctly.

[datzenmike]

Check the plug wires 1, 3, 4, 2 is the firing order. Counter clockwise on the dizzy cap. 3 and 4 mixed up will sputter back through the carb.

 

Check the valve clearance as a tight valve can cause the carb to spit back on hard acceleration.

 

Check the automatic fluid level. There is a dip stick above and behind the starter motor. Over full and under full can cause the slipping. What color is the fluid?????

[datsunaholic]

The 5 btdc is because of the dual point dist-  add in the 7 degree lag, that equals the setting of a single-point system (with spark delay valve) of 12 degrees.

[datzenmike]

Ahh Perhaps set really at 5degrees. Disconnect the second set of points and try 12 degrees full time.

[illestmatic]

the wire firing order seems to be correct. 

 

the valve clearance is something i havnt done. is it to hard of a task for someone to do?. i have years of experience with tools and mechanics i just never done a task like this but im confident in trying.

 

by automatic fuid level you mean the trany fluid, its perfect and its a red color.

[illestmatic]

mhmmm that does make some sense with the 7 degree lag so should i set the timing to 12 then and how that goes. 

 

because to be honest the problem accured even with the dual points dizzy installed and set to 5 degrees btdc. this is the reason why i converted to matchbox dizzy. but it made no difference. 

[datzenmike]

 

by automatic fuid level you mean the trany fluid, its perfect and its a red color.

 

It sounds good! Should be ruby red and clear.

 

 

http://community.ratsun.net/topic/16539-l-series-valve-adjustment/

[illestmatic]

yes!! its clear as day and red. 

[datzenmike]

Valve adjustment tutorial...

 

http://community.ratsun.net/topic/16539-l-series-valve-adjustment/

[illestmatic]

Valve adjustment tutorial...

 

thank you for the link ill definitely be looking at this tomorrow. so would you suggest i check the valve clearance first since alot of the other things have been taken care of?

[datzenmike]

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.

[illestmatic]

okay sound good ill get to it tomorrow depending on what time i come home from work, but ill keep you updated. i really will i want to tackle down this issue once in for all. bye for now. 

[bananahamuck]

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

[Eagle_Adam]

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

[banzai510(hainz)]

Dude you read my post?

Ck the carb for squirting gas when you cycle the linkage.

 

maybe you removed the ballast resisitor for the stock coil.

There is alot this can happen to.

 

maybe you installed the vacuum lines wrong like to the manifold instead to the carb port.?

 

L motors are not hard

[illestmatic]

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

  

Dude you read my post?Ck the carb for squirting gas when you cycle the linkage.maybe you removed the ballast resisitor for the stock coil.There is alot this can happen to.maybe you installed the vacuum lines wrong like to the manifold instead to the carb port.?L motors are not hard

It's good to know that someone has some input with these valves and the way it would run of thiere not set right. I'll check them today.

 

Okay so ill heat up the truck first before I adj the valves. Right?

 

I've checked this before and I'm not to quite sure how its suppose to squirt but ill explain my observation. As I barely pull the trottle I don't see any gas squirting from the carb I hear air suction more than anything. It's not until I pull the throttle more where I start seeing gas but it tends to hesitate but as soon as I pull the throttle hard gass spurts fluently. as far as the resistor goes I didn't remove it. I cant determine which hose goes where I've just always put them back in their original possiaion Since I got the truck.is their a diagram you may reccomwnd me so I can make sure thier in there right place?