Hi all…
So, Esmerelda (my 67 XR7 with 289 2v) still doesn’t really have much power. So my son and I decided to check the distributor cap and pulll one plug at a time and see if the engine “dips”.
It did for 7 of the 8 wires we pulled.
So we checked at the spark plug end… and there was a spark (my cousin told me to hold the tip of the wire near something metal so it could ground…and we got spark to arc).
So we changed the distributor cap, wires, and spark plugs (just to experience that).
Then, we borrowed a tool that you stick into the spark plug area and check the pressure of the cylinder (sorry I don’t remember the name of it).
We did this for all of the cylinders and they were at 180 (though one hit 200).
Checking the manual. This is a bit high for the car. But my cousin said it wasn’t horrible.
He then had me check each exhaust pipe (god… I know I’m not getting the terms right) next to each spark plug and spray with water to get a “tssss”
This checked to see if the cylinder (the one I wasn’t getting a reaction to when I pulled the plug) was creating heat.
It was.
So… my question is. Is it possible the cylinder is working? But just not enough to register a dip when I pull the plug?
Or… will I need to open the valve covers (as my cousin suggested) and check to see if a “rocker” or valve is off?
I’d start there, set the timing and make sure everything is to spec and see how smooth it runs.
Additionally you can hook the light to the other wires and validate that it is firing while running (don’t set the timing off of the wrong cylinder, but an even flashing light means it is firing as it should).
Too little timing can really hurt power too so if you hook it up and find you are at 0 with the vacuum disconnected you may have found the source of power issue.
Spraying the manifold/header tube to find the one that’s not firing is an interesting approach that I’ve not heard before, but SHOULD work if the car hasn’t been run very long. If it’s been run for a bit and everything is warm you may still show heat there. There are i/r thermometers from harbor freight and the like for reasonable prices now that would get a better reading as to where the exhaust temperature is on each cylinder.
Edit: There’s more to putting the power to the ground than the engine, a slipping or gummy transmission can draw a lot of power out of things as well and make it seem down. Additionally a 200hp rated 289 does not compare favorably to a modern 200hp engine as the rating systems are completely different.
Did the plug from the cylinder with high compression show any oil leakage or burning? Are you getting smoke in your exhaust?
The higher compression might be an indicator of oil seepage from a bad valve seal or something.
Once you changed the plugs and wires, did you still get no change in idle when you pulled the plug on that cylinder?
It could just be timing, but if you’re getting really smokey exhaust, it may be something wrong with the head.
When you tested for spark with the disconnected wire, what color was it? A bright blue? a dull orange? Compare it with a disconnected wire that did show a dip in engine performance: any difference? These are important clues as to whether the problem is in your wiring/distributor/plug or within the head/engine itself.
Thanks!
There was oil on several of the spark plugs (around the threads… but not where the spark is). We think the valve covers may be leaking.
No smoke in the exhaust.
The engine seems to run the same after the spark plug, distributor cap, spark plug wire change.
We (my son and I) thought it sounded/felt better after… but I think it’s the same after you give her a bath and she seems to run better too.
I think we’re going to check the timing and the valves next.
This is beginning to sound like it might be the coil. The coil takes a low voltage and multiplies it to create the energy to create the spark needed. The coil could be starting to go…sometimes they leak, overheat and lose effectiveness. You could test it, but as they are not very expensive I would just replace it (unless it is known to be recently changed).
Anyone a guru at reading spark plugs? I swapped my plugs, wires, cap and rotor last night. Wasn’t really having any particular issues, but as they were all of unknown age and history, I figured it would be best just to update them. Aside from the dust bunnies on cylinder 1, can anyone see other issues? Not sure why cylinders 1, 3 and 4 has so much oil on them. Could that be from the valve cover leaking?
The oil on the plugs is from external source, they don’t look like even burn across all plugs, second from L/F looks to be closed up and would cause a miss on that cylinder, # 3 back L/F looks lean. All should look like #3 on r/h side.
