L24 misfiring, help? ideas?

[Chunky]

Hey guys! I'm hoping to get some ideas or suggestions. I just got done changing my thermostat and heater hoses as well as flushing my radiator. After putting everything back together my motor is misfiring (at idle there is a distinct clicking/ticking sound coming from the motor). I didn't let the car get up to operating temps to see if that helped, the missing bothered me.

 

While changing the thermostat, I had several bolts break on me. I ended up having to replace the thermostat housing itself. In order to get at the broken bolt(right side thermo housing bolt connected to the head, the shorter one) I had to remove the float bowl cover on the front carb. The bolt sheared leaving the rest of teh bolt inside the head, it had to be drilled out.

 

• I had to make a new gasket using that gasket paper stuff. would the thickness of the paper used affect the float level? The gasket I made is a little bit thicker than the gasket that came off.
  
• When I removed the cover there was gas in the bowl, when I was putting the cover back on I noticed the bowl was completely dry.
  
• The car's PO wasn't even running a thermostat. He did mention that he used to auto-x it and I've heard of some racers not running thermos. I'm not sure if it makes a difference but the motor was tuned (carbs adjusted and timing dialed in) a few months ago while the car was running thermostat-less.
  

 

When I first tried starting the car there was a "clank" sound and the motor wouldn't turn. I gave it a second and tried again and it fired right up.

 

• Is it possible the chain jumped a tooth? The car actually idles just fine when running at idle, not jumping around it holds steady. (just a random thought, I'm leaning away from this idea)
  

 

While I was working, I did remove the distributor cap with all the cables still attached and swung it out of the way. I did check to make sure they were all plugged back in nice and tight. It's dark out now and started raining earlier so I didn't have time to check for sure but I'll take a look at the inside if the distributor cap tomorrow.

 

I did research on L24 misfiring but the majority of the issues seemed to stem from ignition related problems(obviously) like plugs or valve adjustment even. my car sat over a week but nothing inside the motor was touched and the car ran fine before all this so I'm inclined to think that may not be the cause. I'd like to rule out things that I may have done that might directly cause the missing first.

 

I'm inclined to think that my tinkering with the front carbs float bowl cover has something to do with all this, but is it possible that by removing the cover and replacing the gasket, and consequently allowing the bowl to dry out, cause the misfire?

 

Thanks guys!

 

Ray

[NewZed]

One of the thermostat housing bolt holes is tapped through to the timing chain area. If you put a longer bolt in it might have pushed the chain guide in to the chain. Or you might have bent the guide when you were drilling and tapping the broken bolt out. Just one possibility. It's not uncommon from what I've heard and seen (one of the engines I have has a bent guide with a circular bolt mark on it).

 

Mine with the bent guide seemed to run fine, I didn't know it was bent until I took the head off. You might try replacing the bolt, and see if it stops ticking.

 

The mis-firing would be from something else. The odds of your chain jumping a tooth are tiny. The ticking could also be from an exhaust leak. More ideas...

[beermanpete]

The float bowl drying out will not cause a problem. As soon as you try to start the car the fuel pump will refill it.

 

The gasket thickness will affect the float level but not enough to cause a problem.

 

NewZed's comments are correct. Make sure the screw is only long enough to have about 1/4" to 1/2" of threads exposed past the housing.

 

Make sure there is no water in the distributor. Any moisture in there will condense on the inside of the cap and short out the spark to the plugs. Been there, done that.

[Chunky]

Thanks for the reply guys!

 

As far as the bolts go I got them from a local L-motor builder, so I'm pretty confident that they are the correct length. I will pull them though to check for any kind of contact. We're talking about the front bolt making contact right? I never had to drill out the front bolt(the longer of the two) The rear one I had to drill out but that hole doesn't extend all the way through the head. I can still try shimming the front bolt to lessen the amount of bolt threads but I want to be careful doing that because I still want it to grip when I torque them down.

 

I'll check the dizzy for condensation as well as the contacts.

 

Thanks guys!

 

Ray

[beermanpete]

Correct, front screw hole. The rear screw hole is blind.

[Chunky]

Update: I was able to check it out tonight in the last 15 minutes of daylight.

• Cap is ok, nothing out of the ordinary going on there.
  
• I shimmed the front bolt with a few washers so now it's a little more than 1/4" grabbing. I think it was fine before but it only took a few minutes.
  
• I paid a little more attention to the sound this time letting it idle for a few minutes. It's definitely a distinct tapping, almost clicking sound. At first the sound was somewhat random, after a few minutes it became almost rhythmic. A slight blip of the throttle and the sound increased in frequency with it.
  

Another thing that caught my attention, I noticed a small pool of gas forming on the bowl lid. It wasn't spraying out but it looked like a small leak. I will address this next by double checking both the rubber hose from the rail and the banjo fitting itself but it's something I thought I should mention. Not sure it it relates at all to my issue.

 

And so the quest continues...

 

Thanks,

 

Ray

[beermanpete]

Perhaps the distributor rotor is not fully seated and is touching the inside of the cap. Check for wear marks at the rotor tip and the inside of the cap near the electrodes.

[Leon]

I'd pull the valve cover and check for loose parts. If everything checks out then set valve lash.

[Chunky]

Hey guys! My apologies on the lack of updates. I decided to take a week away from working on the car hoping that I would come back fresh and see something that I missed the first time around. Here's where I'm at...

 

Fuel leak fixed.

 

I checked under the valve cover, all looked fine from a visual perspective. I went ahead and did a cold valve adjustment. Never having done it I figure it would be good practice to get the steps down. Then I can check the settings when warm. Good thing I did, the cold adjustments were way off! Out of 12 lobes on the cam... 1 was correct, 2 were loose and the rest were tight. I used the fit-no fit method, adjusting the clearances until the next bigger size would not fit but the correct size would. intake .008, exhaust .010 lining up the lobe with either an intake or exhaust runner.

 

With the cold adjustment done, I threw in new plugs(.034). I started the car and warmed it up. the clicking sound was still there, however, as the car warmed up it did settle down. Once the car was warmed up I played with the distributor a bit and I got it to a point where it was barely audible.

 

Next steps... oil change! Cracking open the valve cover was an eye opening experience. I changed the oil when I first got the car a year ago. Since then, I've put roughly 100 miles. I didn't think the oil would be that black! I guess those are the detergent properties kicking in.