Captain Obvious

Yeah, but it's just the principal of the thing.

Tis a puzzlement to me as well, but I can tell you... You aren't the only owner with this issue. I, on the other hand, ran SU's for quite some time and never had this problem. I don't ever remember having to add fluid. Unless I took it out on purpose, it never changed. And I doubt the gas smell has anything to do with it. You pull a part out of your carb and it smells like gasoline? Color me surprised!!

Good pics. I don't see anything that screams obvious problem. Two things catch my eye. First is a couple missing clamps on things like the brake booster and PCV vacuum lines. Not the cause of your problem, but might be providing a little vacuum leak. Second thing is what's with the hole in the middle of the EGR mounting casting. It's not sucking air through that little hole in the center, is it? As for potential heat related ignition issues, before you drop time or $$ on a different system, you could shoot a hot hair dryer at your existing module to try to recreate the problem. And buy a $5 can of circuit cooler at Radio shack to cool it off and see if the problem goes away.

You're using the wrong shielding gas. For general purpose MIG on carbon steel, you should run 75% CO2 / 25% argon mix. If you use 100% argon with the MIG, you get proud beads and very narrow fingerlike penetration. You'll be tempted to turn the power up to get the bead to spread, but that's not the solution. The solution is to use the correct shielding gas. I went through this myself about a year ago because I was trying to minimize the number of bottles I had to maintain. I figured that I could share the same 100% argon bottle between the MIG and the TIG, and I was mistaken. It doesn't work right.

Since the time of that other thread, I have disassembled a round top suction piston and have verified that the round tops are machined from one piece of steel and don't have any seams at the bottom. So if you're running flat tops, they might leak out the bottom, but your round tops can't. I'll snap some pics of the round top tube in disassembled state when I get the chance. I know that won't help your diagnosis though... Only makes it more difficult.

So the car started it's life as a 260 with a manual trans, right? Who swapped out the original flat tops for the current round tops? Did you do that swap, or was it like that when you got it? Also, how much of the original 260 stuff remains now that you're running round tops? Did they swap to 240 intake manifolds and balance tubes too, or are you running the original 260 stuff there? I'm just trying to get my bearings... Got any engine bay pics?

There are no seals involved. Everything is metal on metal. Nothing that would dry out. Here's a recent thread that dealt with the same question: http://www.classiczcars.com/forums/carburetors-s30/46939-su-oil-consumption.html

Yes, that sleeve is in there to act as a stop for the large washers, and yes... Even with that sleeve installed, the bushings deform significantly when the nut is tightened to bottoming. I'm with ya, it's more deformation than what is usually considered "normal", but it's correct. That's why the bushings you took out look very little like the new ones you're putting in.

Haha!!!! Good call! Thanks for the laugh!

Same thing has been said about me at times.

I've got something similar with my FI throttle body: http://www.classiczcars.com/forums/fuel-injection-s30/48078-sticky-throttle-body-hanging-idle.html I think I have traced the issue to wear in the throttle plate shaft. The shaft is chrome plated for wear resistance and the plating is worn through in spots. The softer gummier steel underneath gets sticky against the soft steel bearing inserts that are pressed into the throttle body casting. I've "temporarily" fixed it by increasing the return spring force. Addresses the symptom, but not the cause. Eventually I plan to come up with a better solution that addresses the cause instead of just the symptom.

What did the recall do? Do you have any links to more info about it?

a) Yes. 2) Yes. III) No idea.

Thanks Zed Head, I'll double check the locations of stuff. My original thought was to go with the 77 intake because I liked the way it looked, so I was happy to hear that the 83 stuff didn't fit right. Provided the validation and justification I needed to swap it onto the 83 motor. But then I was looking over the 83 intake system and I'm seeing some beauty in the functionality. I like what they did with some of the items like the BCDD and the PCV systems and now because of the functionality, the 83 is looking more attractive to me than it did before. So now I guess I could go either way. I'm thinking that if the location changes are not as significant as you originally alluded to, then I may try to make the 83 work. Heart says 77, buy head says 83? Does that make sense?

Well if you're convinced that it's a fuel delivery issue it should run on all six cylinders if both carbs are getting the right amount of fuel... Pull and plug the fuel supply tubes off both carbs and fill the float bowls with a funnel and a short piece of tubing while checking the float bowl level with a clear piece of tubing on the outlet nipple on the bottom of the bowls. Once you're convinced that both carbs are filling to the correct level, then start the car. If you're right, then it should run well on all six cylinders for at least thirty seconds until the float bowls are sucked dry. If not, then it will still run like crap.

FastWoman, Haha! I was thinking about the exact same potential solution, and the answer to your question is yes... There are plenty of unused ECU connections on the stock connector. Problem is, however, that the receiving connector on the wiring harness shrouds all the connections whether they are used or not and you would have to chop an access hole into that connector or the rubber boot on the back side of it. IMHO that violates one of the prime "plug-n-play" directives of this endeavor.

What about the lower end? I've heard reports that the oil pan designs are different and the oil pickup tube is in a different location? I can certainly swap pans and sump tubes between the two, but if I don't have to, it's less work. Anyone have any more info about the situation?

Sorry Jeff, my bad. I'm looking for input and didn't even fully describe what I had. I'm planning to drop in the P79/F54 combo, and I'm not even going to pull the head off the block right now. I know it runs now and I ran a compression test on it as well. It's 180 psi across the board, so I'm going to drop it in as is. If I open it up sometime in the future, I'll probably mill a little off the head, but for now, the plan is that it's going in as is. Chas, Thanks for the input. So the general consensus is that the webbing is simply a heat shield... OK... I can live without that. If there are indeed fitment issues like where the throttle body ends up, then I'll probably redress with my 77 intake. So my bottom line at this point sounds like it will be: P79 head on the F54 block Use the 77 intake manifold because the 83 intake moves the throttle body Use the 83 exhaust manifold because it has an O2 bung that I can use for a wideband

Seal off the holes and pressurize the tank to a couple PSI. Then dunk it in your neighbors swimming pool to check for bubbles. Easy peasy. :laugh:

I may be completely off base here, but I think you're off in the weeds... I think what you're calling oil on the rear three plugs is actually gas and not oil, and I think that when you disconnected and plugged the fuel supply to the front carb you were still running off the front carb and were simply consuming the fuel that was in the front float bowl. (The engine will run for at least thirty seconds with the fuel line disconnected.) So... When you disconnected the front carb supply and the engine started suddenly running on the rear three cylinders, how did you verify that it was the rear three? Did you suddenly discover that the rear three exhaust tubes were now hot and the front three were now cold? Or were you just assuming that since you had the fuel line to the front carb disconnected, the engine must be running on the rear carb? If your rear three plugs are wet, I think your rear carb is running too rich. So rich, in fact, that those three cylinders won't fire and the plugs are drenched with unburned fuel, not oil. I don't think you ruined your rings. I don't think you're having a problem with the restrictor orifice... I think you're dumping in too much fuel through your rear carb. I think you're overcomplicating this. Like I said, I may be off base, but that's my read.

Thanks Jeff. My 83 engine is a non-turbo, so I've got the F54 block with flat top pistons and a P79 head, not dished and a P90 head. I thought the compression ratio of the non-turbo motors was pretty good even without milling the head. I thought dropping the N47 on with the flat top pistons resulted in an unusually high CR. Did I miss something?

You're right Jeff. I currently have the N47 head and it sounds like I've got round exhaust ports unlike what I said above. My desired plan on the exhaust manifolds would be to keep the 83 manifold on the new engine and use the O2 sensor location for a wideband some time in the future as suggested earlier. The reason for the engine swap? My current engine runs fine, but has dubious quality: My oil pressure is good but not great. My compression is good but not great. I think I've got a minor head gasket leak. I've got a couple stripped valve cover bolt holes from an overzealous PO. I've got a stripped distributor mounting hole on the timing cover from a PO. I've found one or two glass beads coming out of the oil pan on two successive oil changes. Bottom line is there's a bunch of small stuff wrong with it, none of which is known to be insurmountable at this time. But I'm figuring that if I'm going to invest time and money in a motor, I could start with a better base. Of all the items above, I'm most worried about the head gasket (and the glass beads). My PO did a head gasket right before I bought the car and I think I've still got issues. I've seen pics of hairline cracked N47's and I'm thinking that might be what's going on with mine. I know the different head/block combos have been talked to death and I know the answer to the question I'm about to ask is available out there if I were to search for it, but... Off the top of your head, do you know what compression ratio I would end up with if I were to plunk my current N47 on my new F54 block? Assuming the head isn't cracked of course...

Cool. I like the idea of the injector driver chip. Assuming the availability is stable, I think they'll make for a better end result. So, if you would like another set of eyes on the schematic and/or board layout, I'd be happy to have a peek. I'm probably not previously familiar with any of the parts you're using, but that shouldn't stop me. PM me if you're interested.

You guys have pretty much nailed my thoughts... All things considered equal without any other input, my plan would be to strip down the 83 and redress back up looking like a 77. A little simpler, a little lighter looking, and certainly more authentic for a 77. But I'm happy to give up on looks if there are tangible reasons such as performance to do otherwise. My 77 is square exhaust port, but I'm running a header that the PO installed. I was planning to switch back to a cast iron manifold of some sort as part of this job, so in other words... I know I've got some exhaust work to be done no matter what route I proceed on. I don't like the exhaust work from my PO and I was planning to rework everything anyway. So it sounds like there are some fitment issues with the ZX intake in the earlier years, and no known performance gains to be had by using the webbed manifold? Zed Head, I'll take a look at that intake manifold taper you mentioned and the location of the throttle body. I didn't notice either of those. There are six years of technological advancement possible between my 77 and the 83... You would sure hope that there were some improvements, right?

Way cool. Never seen anyone cut into a gas tank before. Thanks for the view!!