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Truck not getting spark after head job/bottom end job


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So me and a buddy tore down my 74 620 I just bought...

We've replace the pistons got the head remilled and hot tanked... we slapped everything but the alternator and the radiator on ,


tryied to crank it to see if it would start we're getting fuel but no spark on the plugs/wires checked the ground on everything... everything seems to be inplace...


the truck was previously tinkered with before I bought it so ... but how ever when i did buy it we got it to run at least


any idea's

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A spark issue needs more info.When was the coil last replaced and with what?What distributor is in there?Points?EI?Points gapped?I would hope that you at least changed the spark plugs and wires.??

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Just recently purchase the car from the original owner,


spark plugs have been propperly gapped to 30, coils and wires havent been changed yet from what previous owner says its been change before the head went.


I'm completely new to this so I don't know what distributor system is running on it... I know is that it has a 32/36 weber and thats boout it... the wires in engine looks spliced and what not But we did get it running before we tore it apart


so I pulled a plug wire and plugged it directly to the coil and tested for spark got nothing...

I notice the coil pack had a wire comming out of it into something look like a little fuse box of some sort... but going to have to look at it tomorrow sicne i need to rest for work in a few hours.. and its getting cold at this time of the night..



heres some pictures hope they will help









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Looks like its probably a points dist.Turn the key on and pop off the dist. cap.turn the motor or dist. til the points are closed if they are not.Use a small screwdriver or something and open the points.Do they spark?If it has points change them if they have not been.

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So L18 1 , Home team 0... I got the spark still no crank checked the compression got 0 0 15 0 noticed the head had alittle oil... I shouldnt have let my friend do the gaskets... anyhow we reused a metal heasd gasket that was pretty much brand new... well I'm thinking now that the block is warped, from the the looks of the engine when we took it apart the previous owner didnt know wtf he was do and prolly damaged everything there is ..


going to go buy a new head gasket tomorrow and this Time I'm going to do the gasket job.. and idea's or suggestions?





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what is that coloring on the block? Rust.


kiznook Felpro does sell a gasket spacer deal as a specer to raise the head up instead of cam tower shims. I seen this before from I took apart a motor and found what looks like a copper head gasket but it more of a spacer.


clean up the head surface and install dry or maybe spary some Permatex coppercoat. If you like.


the block looks good(pistons)

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When you say you had the head done, What did they do to it? Machine shop should have checked surface for square and pressure tested it, valve grind? Cause no compression could be a number of things. Did you get the timing chain on in the right spot. If your valve timing is messed up that could mean no compression. Is the valve lash preset.


Matbe you have an Aussie cam in there cause down under they turn the other way:lol:

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Guest DatsuNoob

I doubt that block is warped, L motors are pretty rock solid, but if you want to check it, and the head, get a STRAIGHT two or four foot level and check to see if theres any gaps underneath. You mentioned getting it running with the PO? If you got it running once, chances are you'll get it running again. How did you check for spark, did you do the old arc the screwdriver in the boot trick? Cause I'm pretty sure Datsuns dont have coil packs ;) Joking (but they dont). That little box that looks like a fuse box as you said might be your ballast resistor. Couldn't hurt to see that those 2 wires have a clean and secure contact. Those wires in your hand, if they trace back to the core support behind the driver's side headlight could be stock carb wiring, in which case they're useless now, but dont quote me on that because I couldn't see where they came from and I'm color blind, just a possibility. Ditch those points if that's what you got and go electronic. You got an electrical test light to see if there's any current passing through the coil? Dollar store's got 'em if you dont. Good luck man.

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Here's asafer way to test for spark:


Take the coil wire off the distributor cap and stick a spark plug in the end and place on the valve cover or any ground and crank the motor over. Look for spark.


No spark... coil may still be good, just not getting power on one side or good ground through the points on the other. Check for voltage on the + side of the coil in the start and the run position...


No voltage... check ignition switch.


Yes voltage... Check that points are closing and opening when cranking. Be sure that distributor is properly GROUNDED and coil to distributor wiring is good.


The carb wiring for the idle cut solenoid, auto choke heater and BCDD cut (if equipped) goes to the firewall behind the carb and over to the pass side.


Spark... put coil wire back on and remove one of the plug wires and do this again. No spark... check distributor cap (cracked?) rotor (broken, missing)




The ballast resistor working or not has no effect on spark while cranking. It is only in the coil circuit in the run position.


If you reused an old gasket you might want to replace it. But first check the valve lash to be sure the valves are closing and there is some clearance. While the cover is off, set the crank to top dead center compression and observe that the #1 intake and exhaust cam lobes are in the 10 and 2 o'clock position. This will confirm that the cam is reasonably timed in relation to the crank. While at TDC take the distributor cap off and see that the rotor (as seen looking down from the driver's fender) is pointing between about 10 and 11 o'clock. This will confirm that the ignition is timed close.


Very unlikely the block is warped, maybe the head but not enough to have no compression, even using an old gasket wouldn't give zero compression. On three cylinders. Even ring end gap. The valves are adjusted tight, or the tester is buggered.

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the wire in the second pis is your body ground wire if i remember correctly, it goes under one of the rad mounting bolts and should be grounded before you try to start your truck again

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Grahem from Duncan? Even if it isn't, welcome to the site. It should still get spark but it's important to have that ground to the body sheet metal. Without it, the only return to ground is along the throttle cable to the block.

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So I found out it wasnt the head gasket today ( went out bought a new one ) still got 0 compression... we took the valve cover off and decided to test the compression without retainer ( so all valves would be close) this way we would know if the 0 compression wsas due to valve's or piston rings or what not turns out it was the valve lash.


We reajusted the valve lash ( had to cut the tool to make it fit) did a compression test again and got 150 120 and so forth but this was due to a weak battery.. so engine start slow was unable to crank over... I'm haveing a buddy charge the battery and am going to try to start it again tomorrow with a fully charged batter


PS the copper stuff on the block was ( Copper spray ) I will post what happens tomorrow.


On the side note I might be getting a free LS2 for my FD

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without retainer ?????????


WHAT!!!!! sounds like a waist of time pulling them out


Just set it to .008 intake and .010 exhaust using feeler gauge. put lobe straight up ,stick feeler gauge between lobe and rocker. set lash. wiggle the rocker arm. if loose you know the valve is fully closed.


i wonder if the points just are grounding out?

Ck for spark again. I just pull the center wire from the dist cap and put it near gound and start it. Should make a snapping arch. if not find the proplem. I some times change points it wont work put the old one back in then it works then put the new one back in then it works. It happens to the best of US.


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So I've tried starting the car today without the Alternator and radiator on...It cranks over but just wont start I'm getting Air Fuel and spark.... I just Don't know what going on now... The base of the engine is so simple... But then when I bought there car theres some Wires that are cut in the engine bay...


Could anyone tell me what the wire is that I was holding in the picture near the battery holder? its black So i think its ground and have it plugged in the ground...

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Could anyone tell me what the wire is that I was holding in the picture near the battery holder? its black So i think its ground and have it plugged in the ground...


the wire in the second pis is your body ground wire if i remember correctly, it goes under one of the rad mounting bolts and should be grounded before you try to start your truck again





So I've tried starting the car today without the Alternator and radiator on...It cranks over but just wont start I'm getting Air Fuel and spark.... I just Don't know what going on now... The base of the


Thought you had no spark??? When did you get spark????


If you have fuel all you need is properly timed spark and valves.

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Please answer this question!Have you replace the plugs,wires,coil and points.If not then do it before you waste any more time fucking with it.

If you had to cut a gap blade down then you are trying to adjust on the lash pad and not between the cam lobe and rocker surface.Totally wrong.

I have had spark before that looked decent but would not run.Needed new PLUGS!I believe that lone black wire is a ground and the other 2 are likely for secondary points.

Show us the front 2 lobes of the cam when the block is at tdc.Also tell us how far apart the points are gapped.

Where are you at?

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Sorry BEE but I have to disagree....

Just replacing things doesn't solve the problem and can possibly create more.


If you have spark, you have spark...but, is it getting to your plugs? Trace it - from dizzy, to coil, to dizzy, to plugs.


If you have spark, fuel and air in your cylinders the only thing left is to time it correctly.


Did you install the dizzy wit the oil pump drive gear in the correct location?

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Plugs replaced , Wires were replace before I purchase the truck, Coil pack is the old coil pack& old points... Lash is ajusted to specs of .08 and .010.


we're slapping on the alternator to see if that helps. sad that I can work on complicated cars and yet such a simple engine I cant get runnign. -_- .


Thinking It might be the carb since I don't know which wire plugs to the carb


Compression is checking out


1) 165

2) 165

3) 163

4) 163



I'm located in Northern California, Bay Area


When doing the timming Cam lobe intake @ 10 o'clock exhuast @ 2 o'clock

cylinder 1 @ tdc

I believe timming was correct

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