Cylinders 5 and 6 on my F are not firing. I have 95 to 110 compression in all of my cylinders. I have replaced the cap, points, rotor, condensor, spark plug wires, and spark plugs, and it is still missing. As I said in my previous post, I am thinking of switching to electronic ignition, but I was wondering if anyone else had any ideas as to why cylinders 5 and 6 were missing. The spark looks a little weak in those two cylinders also. Any info is greatly appreciated.

When you say not firing do you mean nothing at all or missfiring? Does it seem like it is out of time even though it's not? How old is the cam? I know, strange questions but I had an experience where the cam went flat and it only affected #3 & 4 in the old chevy truck.

I mean nothing. I have no idea how old the cam is. it is probably the original.

If you have spark but no fire in the hole it could be that the intake valve is not opening. Pull the valve cover and check to see if the springs are intact and watch the valves with the engine running. I did not see your previous post but how long has it had this problem? Did it happen suddenly? I don't think your problem is electrical if you have spark. Sounds like a fuel delivery problem to me. You might also want to pull the carb and see how much fuel, if any, is sitting in the manifold.

its been doing it since I got it 2 months ago. haven't had a lot of time to work on it though (its in Turlock at my parents house, I am in Sac). I had a rebuilt carb put on it so that it would pass smog. when I pull the plugs they are wet, so fuel is getting there. I also used hotter plugs when i replace them. I will pull the valve cover and check that out when I go home for Christmas. The cruiser sat for a long time before I got it and was running really rough due to a carb in need of a rebuild, old cap, rotor, points, etc... You can't really tell it is missing until you accelerate and it sputters and surges.

I posted your problem to the LCML. I'll forward any responses to your e-mail address.:D

Thanks

Have you checked the points gap on each lobe of the dist? I had one lobe that seemed excesivily worn and would not fire #4 very well. So after much frustration I checked the gap at each lobe found the variation and set them at a happy medium. It has run pretty decent for the last year, I do go through points fairly reguraly though. Also recheck firing order {wires to cap and at plugs}. Have seen more than a couple of rigs towed in after shade tree did a tune up and "now it won't run right" Really pisses them off when you double check the firing order only to find two wires crossed, swap them and the rig is running fine before thier done paying the tow truck driver.
Good luck

I just reread your post. 95-110 is pretty poor compresion. You might try retorqueing the head bolts and then adjusting the valves, after this recheck the compresion both dry and wet. Even with good strong spark the mixture will not fire very well with such poor compresion. When you do the compresion test have the throttle wide open and the battery at full charge this will give you the most acurate test.

What should the compression be? I have already rechecked the firing order and it is correct.

My 2F engine seems to run pretty strong at 120-125. Not sure if that's wet or dry. I just threaded the gauge in the spark plug hole and cranked while it was cold.

How does one do a wet or dry test and what does it tell you?

compression should be 130 to 155 depending on age, anything lower and I would think twice about spending too much money on it.
Some problems that cause low compression are,
leak in head gasket between 5&6 or water jacket
leak in the intake manifold on 5&6
burnt exhaust valves (possible from running hotter plugs)
leak in the brake booster or vacuum line leading to 5&6
bad valve adjustment
worn motor
or bad lobes or bearings in distributor (wiggle the shaft to check for play)

steven@extremebends.com

I e- mailed you

A wet comp test will help isolate if the low compresion reading is from worn rings. If you squirt about three shot of motor oil in the spark plug hole before you install the gauge the oil will temperaly compensate for worn rings and the reading will be higher than the previous DRY reading. Just don't go over board with the oil or you might accidently hydro lock it and bend something. about three squirts from one of those grandpa oil squirter cans works great.

Thanx for the info Slacker. So does one do a compression test with a cold or warm engine?

The book calls for the test to be done with the motor at operating temp. You can drop me an E-mail at slacker@bendnet.com if you have any other questions. Always happy to help as many have helped me out.

Thax Slacker, think I understand now. No wonder I ran so good w/ 125 PSI, I did my com. tests cold!

I got my cruiser running on all six. Not sure what I did though. I replaced the in-line and bowl fuel filters with 1 in-line and have been driving the crap out of the cruiser. Not sure which one did it, but just happy everything is working. Thanks for all of the help and info.

i have the same problem with my 74 cruiser im not sure what to do tho. i parked it for like 3 months after driveing it pritty hard and i fired it up and it runs like shit i did a compresion test and all 6 cylenders are at 120. i changed the oil and there was 2 gallons of gas in it so im thinking that it has a flat cam in it. i rebuilt the carb thinking that was the problem but it was not. so if you could help me out it would be great thanks.

This is a 6 year old thread... You may just want to start your own and ask for help... It will work much faster that way, just a thought...


Also, read this: http://www.pirate4x4.com/forum/showthread.php?t=430159


Basic engine diagnostics and PROPER testing of the different systems on the rig are required. A more than basic understanding of how each system relates and affects each other is what it takes to acurately diagnose a driveability issue.

Start your own thread, add every bit of info you can CLEARLY so it can be understood, include specs on the rig, engine/carb/ign system/running history/etc.

Posting a couple pics of either side of the motor might help as well. Use IMAGESHACK to post if you dont have a star.

Welcome to Pirate :flipoff2:

Good luck

Chris:cool2:


Edit: Just saw your help thread.... No need to keep posting your question in other threads...