WTF Misfire on cylinder 3

[SHAMUS'WAGON]

First of all. This is just a stock L16 That I bought from a salvage yard in 1999. Don't know what year make or model it came from. Long story short this motor wasn't as temporary as I hoped it would be. But for the $150.00 I shelled out for a running yard motor. It has served me pretty well.

My car started running like crap right before we moved in April. I knew what it was just from the way it was running. About two weeks after the move I made time to pull the valve cover to see if I was correct, and sure enough. Cylinder 3 Exhaust valve stuck partially open. made the adjustment, put it back together, fired it up. Misfire gone.

Here I am 3 months later. My car is running like crap again, and now backfiring through the carb on the freeway I've been playing with the mixture, playing with the timing and looking for a vacuum leak. Today as I got out of my car at work I thought," I'm gonna pull that plug wire to see if it's that damn number 3 cylinder again." I took the plug wire off , and no difference. So now I'm about to rip my hair out. Because now that I think of it. I have to do this about every three months for the last ten years I've had the car. Can anyone tell me what might be going wrong. Gonna do the valve adjustment again on my next day off, and hope nothing is broken by the time I get to it.

[datzenmike]

When you found the valve partly open what was causing it. Was the adjustment too tight, no clearance? or was the valve stem stuck in the guide? I'll assume lack of clearance which is adjustable. Maybe another valve is out? Check and adjust all of them.

 

I have heard of bad valve jobs where the valve slowly sinks into the head until there is no more room for adjustment. Seems like an ok moor, at the worst get another head. You do live in the PNW.

[banzai510(hainz)]

Simple fix!!!!!!!!!! if you have the parts and soem skills.

 

If you narrowed it down to #3 clyinder then no need to adjust mixture and suck since #3 isnt firing

Now I have to assume the plug and #3 plug wire is good???????

 

pop the valve cover see if a lash pad has falling off top of the valve stem. Most time when this happen its pretty much instanly noticed.

 

if over time it looses power the exhaust valve will loose it valve lash gap inbetween the Rockarm and cam. What happen is the seat is soft and sicking in to the head. TYoull need to adjust the pivit post down so you can get a feeler gausge under there. Once you have the pivot post all the way doen and you can get anymore adjustment the valve is pretty much done . You can swap another head on there if you have a timming chain tool and run that.

 

also another note is your car cuts out back fires, always check the distributor for shaft wiggle. esp on point distributors/even EI units with alot of miles. and maybe swap out a condensor. .Condensor is ussaually right above it it cuts out. a worn distributor can make it look like a carb.

 

 

if you swapped out coils with a wrong value low resistance type it could burn up the points or if you removed the ballast resistor . so im hoping those are all this the same stock stuff.

 

save this

http://www.olddatsuns.com/620tech.htm

 

PS PM (datto510) he lives down south.

he could maybe give you a hand.if hes not on the boat

[SHAMUS'WAGON]

When you found the valve partly open what was causing it. Was the adjustment too tight, no clearance? or was the valve stem stuck in the guide? I'll assume lack of clearance which is adjustable. Maybe another valve is out? Check and adjust all of them.

 

I have heard of bad valve jobs where the valve slowly sinks into the head until there is no more room for adjustment. Seems like an ok moor, at the worst get another head. You do live in the PNW.

 

I found out that I'm not off of work again until next Thursday. So I put my car into the garage tonight. Pulled the valve cover, and inspected the suspect valve. Tried for an hour and a half to adjust the pivot down. Then I realized it is all the way down. Adjusted it as far down as I could. put it back together and cleaned up. Now it's time to brain storm. This is my daily driver.

 

Option A: Find a motor quick before I get my vacation time for time to install.

 

Option B: When I first started driving the car it had an L18 with a blown rear main. The motor ran fine though. I even had the car going faster than my dad said it would go. Anyway, Took the L18 out and "stored" it at my dads. SO about 4 years roll by and I ask my dad if I can come pick up my motor. When I get there it's sitting in the dirt without an oil pan on it not, and grass growing out of the open valves. Thisis what Ihave to work with now after 10 years of sitting.

 

Then I remeber the story behing this head. My dad got it out of a wrecking yard. Iv'e identified it a late L20b "SMOG" head that my dad flat filed and slapped on the L18 in the car at the time. My question is. Can I put an L20b head on my L16? I know the bore is different, but does that make a difference? If I could just clean up this head, and throw it on there. It would buy me some time to find better.

[datzenmike]

That's from a '78 and on L20B.and if installed on an L16 will give a compression of 7.85. Sorry.

[banzai510(hainz)]

all L heads fit just the exhaust ports might be different on the late model L20 as they use a round port instead of square.

[banzai510(hainz)]

i think maybe spend soem money and get it redone

[SHAMUS'WAGON]

That's from a '78 and on L20B.and if installed on an L16 will give a compression of 7.85. Sorry.

 

So are you telling me this is a low compression head not worth dicking with in the first place. Or that it just doesn't go well with the L16 block? I noticed that the smaller valves were marked EX. I always thought exhaust valves were supposed to be the bigger of two. Any way , now I have to consider rebuilding my L18 that's been sitting, unpreserved, for the last ten years. I don't even know how to get started on this thing. Toying with the idea of Electrolysis. Any advise would be awesome.

 

 

 

[MicroMachinery]

Eegh... unless you have some serious sentimental attachment to that L18, I'd just find a different core. If you're not dead set on building a new engine, I'd just find another head. People give away L16 heads. Shouldn't be hard to find.

 

Also, the fact that it backfires out of your carburetor makes me think it's a problem other than that exhaust valve that you originally had sticking open. If it was the intake valve sticking open it would backfire out the intake. Exhaust valve sticking open would just give you a dead cylinder/misfire.

 

Like Hainz said, I'd check your ignition out before I go start blaming the mechanicals. I'd say 98% of all my misfiring issues have been related to ignition. Plugs, wires, cap n rotor should be closely examined/tested, as well as point gap.

[banzai510(hainz)]

get another block

 

PM datto510 he can help maybe.

[datzenmike]

The W-58 head works on a larger 2 liter motor to give an 8.5 to one compression. If placed on a smaller 1.6 liter there won't be enough to fill it and the compression will be lower is all. It's not a low compression head as such just the wrong size for your L motor.

[SHAMUS'WAGON]

Looks like it's time to move this shit to PROJECTS. I just picked this up in Portland today.

Everything seems to be there for me to put this back together, but does any body wanna trade me this book

For this book

I have no use for the How to modify book. I don't need to build a race engine. Just a running engine.

[SHAMUS'WAGON]

get another block

 

PM datto510 he can help maybe.

 

 

I followed your advice and got another block. Hell, I got a whole other engine. Well, an L20b in pieces. Is the L20B swap into a 510 pretty straight forward? I saw some post on other forums of people having trouble with automatic trans. What have you heard? By the way the reason I'm asking you is I watched your badass tear down video, and figured you're the most knowledgeable.

 

 

[banzai510(hainz)]

when it comes to automatics I know nothing.

 

L motos are all the same except the L20 is taller and uses a 6 bolt crank which makes the clutch set up different as you can use the set up you have. unless you have a 200mm flywheell. 200mm are getting hared to find . The l20 that cam ein cars like the 610/710 and 77-79 200sx will work.

If the L20 came from a truck they use a 225mm trans and youll use that T/O bearing /sleeve clutch set up.

 

also use the 510 motor mounts pickup oil tube and 510 oil pan.

 

 

PS theyr alot of other good knowledgable people on here just soemtimes they dont awnser.

 

L motoras are EZ but if you dont have acces to alot of parts it coule be hard and carefuel of interchangesable parts that dont match up. like different model distributor set ups ect and the cluthes but otherwise the L motors are the same. O yeah, L motor Timming chains are 2 links longer on the L20 and the front timming cover is longer also.