hard cold start/valve lash adjustment

[ez73]

my 73 240 (round tops) is very hard to start when cold. My mechanic nissan factory trained and certified,says valve adjustment is critical. Since no accelerator pump relies on vacuum. He gave lash at .006 and .008 book says .010 and .012 cold ,which is right? He is their #1 mechanic at this very large agency. Read several engine thread entries today and a lot of guys are adjusting them hot. I always thought it should always be done cold. he also said the carb nozzles looked a little worn . he put the carbs back on after they were rebuilt (mainly gasket carb rebuild kits). any advice on doing the valve lash adj. d***

[Bambikiller240]

In checking the FSM, I find that it specifies BOTH WARM adjustment and COLD lash adjustment figures. It describes the recommended process as adjusting the valves COLD, then warming the engine and checking them HOT and adjusting to WARM spec as/if necessary

COLD Spec .008 Intake

COLD Spec .010 Exhaust

WARM Spec. .010 Intake

WARM Spec. .012 Exhaust

Keep in mind that theses engines are indeed cold-blooded for the reasons mentioned in your post. Do you still have Intake Manifold/Carb Pre-Heating water system functioning on the car? How cold of temperatures does the car live in? Snow? Phoenix, AZ?

Just my opinion, but I wouldn't adjust my valves as tight as your mech suggests.

[ez73]

thanks for the reply carl .I made a mistake I talked to him today he gave me the correct spec.s (the factory specs .008 and .010 ) the engine is basically converted to a 72 no hot water .72 balance tube ,linkage no smog equipment no air injectors no smog pump temp sunday am was around 48 degrees I live in san bernardino calif thanks d***

[Daniel]

Why they don't like to start cold. Chokes not working correctly, worn spark plugs or wires or both, dist cap,points,timing, bad fuel pump check valve that allows fuel to drain back into the tank overnight. Is your fuel filter the clear type ? Does it have fuel in it in the morning.Does it start fine the rest of the day then after many hours of sitting be difficult. The cold valve adjustment is just a rough starting point. Hot adjustment is the correct procedure.

[Gav240z]

As Daniel says i've found the items listed will indeed improve start up procedure 100% choke being the main and spark plugs a big help.

Check your dizzy cap for wear and rotor button.

[ez73]

I acquired the car this last spring. It sat in storage since the late 80,s. the car had 67,000 miles on it.The previous owner(wife of a friend of mine) took it out a couple of times to service it etc. She replaced the mech. fuel pump with another in the late 80,s.Carbs all varnished up,had them taken apart and put new gasket kit in them.btw they are round tops off 72 or earlier. The chokes are set,and work fine.The mech. that did all the original work at Nissan said the nozzles might be a little loose letting in air. The spark plugs are new ngk the wires are new red heavy duty from Motorsport. cap and rotor not changed. There is gas in the filter in the morning.Car had two broken studs on exaust, had head taken off decarboned piston tops had head hot tanked,pressure tested ,cleaned up new turbo studs put on then put back together. Been starting with throttle part way opened,told tokeep throttle closed with choke on . this seems to help. Am in process of having starter rebuilt,want to keep original,will probable adjust valves after putting starter back on. d***

[sblake01]

d***, you are in my neck of the woods. The weather has gotten colder in the mornings recently. My Z and my 810 are both fuel injected so I don't have a problem starting them in this colder weather. But the carbed cars are a different story. You probably didn't notice the problem as much when the mornings were a little warmer. Carbureated cars I have owned, especially the Z's, are just cold blooded. And without the water going through the intake, they're even worse. You'll probably have to experiment with starting techniques until you find what works best. Carl's valve adjustment description and settings are what I have always used on L series engines.

[calliebrat]

You adjust the valves with the engine hot. I have had 6 Z's. Intake valve is .25 mm's or .0098 in. Exhaust is .30 mm's .0118 inches. When the carbs were rebuilt was the jet needle and main jet replaced? These don't come in a standard rebuild kit and have to be bought seperatly. Last time I priced them at the dealers it cost about $80.00 per carb. That should help. Stacey and Michael in San Diego

[beandip]

With the low mileage you state I doubt vary much that there is wear on the get unless the needles are bent and rubbing. These engines as has been stated are cold blooded and are hard to start if you do not use the choke. If you set the valves too tight you will burn them, if you are going to error do it on the loose side. You must realize the non fuel injected engines require you to think for them , no computer , . Cold temp to an engine for good smooth running is anything below 170 degrees. It takes some time for the block and all to get up to the temp where it will run well with out a richer mixture of fuel to air. So when first starting the engine in the morning do not touch the foot , accelerater . Just pull back on the choke leaver and turn the key , when the engine begins to catch , push the choke lever part way forward . At this time you can apply some added fuel with the foot ''pedal''. Let the engine idle for at least a min. or so before attempting to drive the car. It may stumble some untill it warms up , but this is normal . You will find that as the engine gets up to temp you will be able to decrease the choke , untill it is all the way forward. This is vary basic but I dont know how use you are to driving a 30+ year old car. All the Best Gary P. S. valves are like little children . when they are quiet you dont know what they are doing when they are making a little noise you do. it's true

[sblake01]

P. S. valves are like little children . when they are quiet you dont know what they are doing when they are making a little noise you do. it's true

I like that! I've always believed that but I've never heard it put that way. :classic: