Mark Maras

@jalexquijanoIMO, it looks like the rear carb is too rich, and the front carb may be too lean. Both nozzles down 3 1/2 turns. I'm left with the float level(s) being wrong. @siteunseenCan the difference in the later lids be a possibility here? I've only dealt with the early lids with identical float hinge bosses.

I'd try BP6ESs.

Obviously, the plugs are still dark. Two questions. Did the plugs clean up well and is this all new fouling? How well did it run at 2 1/2 turns down?

If the floats are correct and I believe they are, 2 1/2 turns down should be close. I seem to recall yours being 3 to 3 1/2 turns down.

Replace or clean them. If the engine is running stronger with the wire change, the carboned-up plugs may (hopefully) be too much fuel. How many turns down are the carb nozzles?

@jalexquijanoI agree, time for new plugs. How many turns down are the carb nozzles now and how much better did it run?

@jalexquijano

@NocturnalEmber What was different when you said "slightly different positioning"?

If cranking is describing the engine turning over using the starter, the coil has nothing to do with the starter. The engine will turn over using the starter without any coil.

Yeah, I remember they were ZTherapy carbs. What I was wondering was how many times have they been adjusted (specifically balance and float level) and if they were adjusted properly. Last year we were dealing with #4 fouling and I thought (at least in my mind) that the problem was somewhere in the cap, rotor, wire, wire connection, and plug, all of which were replaced with quality parts. So, I was left thinking it was a bad sparkplug wire connection. Now we've got five plugs fouling. What happened between then and now? Any thoughts or explanations?

I used the bread method on a RX7 a few years back. I'll never use anything else in the future.

@jalexquijano If you'd like someone in Panama City to check out your carbs there's a JDM shop there. Also, look into any British or Volvo repair shop that has an older mechanic. Volvos used Hitachi SUs (I think) and any older British mechanic should know SUs inside and out..

Well, I can't imagine why a stock cam wouldn't work. It might not be the first choice but it would certainly work. I think more compression tests (wet, dry, plugs out, throttle wide open) are a good idea. Fresh #s may show something new. I'm curious if you have any theories as to why more plugs are fouling now when it was only #4 in the past. Be sure to try the downhill 4000 RPM throttle-off test. It may provide a clue if there's oil consumption.

It appears you've got the carbs balanced. The mixture screws at the bottom of the carbs are the secondary mixture adjustment. The primary mixture adjustments are the float levels. I'd check those next. They don't have to be exact, just close.

Nine years you've been dealing with these problems. Were all the valve seals replaced and did the problem get worse (more plugs fouling) after that?

@jalexquijano Last year, as I recall, we were dealing with #4 plug fouling. Now it appears the problem has spread to all but one cylinder. What has been done to the engine since then? Were all the valve seals changed? Next time you're out driving find a nice steep hill, drive down the hill with the engine at around 4000 RPMs, and take your foot off the throttle pedal. Watch in the rearview mirror for blue smoke. Tell us what you see.

I ran into this problem of the engine hitting a wall. I was on the freeway when the car slowed to 45 mph, Wouldn't go any faster regardless of which gear it was in. It would free rev to 6000 with no load. It turned out to be a partially plugged fuel filter. The fuel pressure (mechanical pump) was fine but the fuel volume was restricted. Have you tried a fuel volume test along with the pressure test?

@jalexquijano Was the engine running worse back in March and was it still fouling one plug? Now it seems to be worse. All but one plug shows fouling. Random question, does the engine use a lot of oil?

I'd do another compression test (wide open throttle, all plugs out) before I opened it up. My thought is if it's got good (enough) compression, it's got to be fuel or spark.

I'd start by cleaning it up, remove anything that's loose, and then go at it with a wire brush on an angle grinder. Once that's done poke around any suspicious areas with an ice pick. That will tell you which areas are thin.

I've always coated both sides with a thin layer of grease. I've cussed every paper gasket I ever treated with grease, but it was always when trying to remove it later. Never any leaks.

It eliminates air restriction to the cylinders. That results in a faster cranking speed. I've never done a C test without removing the plugs but I'm guessing it wouldn't affect the numbers more than a few psi.

Did you pull all the spark plugs first, Turn it over until you had oil pressure, and hold the throttle wide open during the test? The 140 on the fourth time around was probably because the engine was getting oil pressure.

They make new crush washers?

Any good contact adhesive will work.