Captain Obvious

I think you are being overly concerned. Sync is air volume (basically) and nozzle wheels are fuel. Changing the nozzle wheels shouldn't do anything to change the volume of air, and hence should not require a re-sync. Of course, if you have the time, there's nothing wrong with doing it anyway. Don't cost nuthin'. Out of curiosity, have had to make significant sync changes after messing with the nozzles? (Assuming, of course, sync at the same RPM...)

Use mine? Are you nuts? I'm not going to use my own car as the Guinea Pig!! That's why I suggested using yours! Seriously though... That problem on my car is so far down the priority list that hopefully I'll still be alive when my car gets to that level of repair. I'd be happy to use mine, but I've got significantly bigger fish to fry!

Nice. Was there originally some kind of seal there when new, or was it never sealed at all?

Jim, My driver's side is just like yours, and I believe you hit it exactly with the above. You can lube it all you want at this point, but as soon as it rotates around to the flat, you're back to where you started. I'll offer up another alternative... If you want to rebuild your original hinge - Take it apart, send me your old roller as a template, and I'll make you a new one.

Haha! I did something similar a few years back with my piece-o-crap daily driver. I wanted to get just one more year out of it before I retired it, and I knew it "shouldn't" pass inspection. I cleaned it up all sparkly like before I took it in. The plan was to distract the mechanic with brilliance so that maybe they wouldn't see as many imperfections? It passed, but I'm not sure if it would have failed if it were uglier. You don't ask questions... :laugh: About your hard lines - I've had to replace the rears that wrap around behind the backing plate. They didn't rust through, but they twisted off when I took off the wheel cylinders. I tried my best to salvage them, but could not. They weren't all the way through, but were compromised by rust and that's why they were so weak. I made replacements from parts store tubing. If you're asking "Should I go looking for trouble?", my answer would be to play it by ear and give everything a good look over while your back there, but I wouldn't replace them simply because they're old.

Excellent. I hope you have those issues licked and have all the horses you're supposed to have. No rolling chicane for you!! Good luck!

I know that PA's regs have no bearing on your situation in VA, but you got me curious about those braided lines... In expected fashion, PA's regs are governmentally vague and do not specifically exclude the braided lines. There are essentially two parts to the regs that pertain to the brake hoses: 1) Brake lines shall be approved for use as brake lines. 2) Reject if - The hydraulic hoses or tubing leak; is flattened, restricted, insecurely fastened, improperly retained; or have exposed cords. If they are DOT, they should be OK for the first part, but the sticky part is the visual inspection part. The story I've heard is that some mechanics say "Because of the braided jacket, I can't see the hoses. Can't see 'em, can't inspect 'em. And because I can't inspect 'em, I have to fail 'em." From what I gather, PA's inspections are tighter than a lot of other states. And they've gotten way looser today than they were years ago. Anyway, thanks for the spur to look into it, and good luck with the upcoming brake work!

Don't know about VA, but the stainless braided hoses "should" not pass the annual state safety inspection in Pennsylvania. I say "should", because lots of people have those hoses on their cars and pass inspection anyway. Not supposed to, but... Rebuilding the 77-78 rear cylinders is mind-numbingly easy. Only thing that can go wrong is if the cylinder body is corroded where the piston seal contacts it. If that's the case, the cylinders are toast. Also, since this is a DD, getting the drums off shouldn't be a chore either. Assuming the adjuster mechanism isn't frozen solid, you should be able to pull the access nubbin and adjust the shoes back far enough that the drums will almost fall off. Easy for me to say this sitting from my chair, huh?:laugh:

Hi Jeff, I took a look at a map and it's not "close", but it is closer than I thought. I don't think I'm going to make this one on short notice though. I should have started thinking about it two weeks ago in order to have arrangements in place. As for your cam, I have no idea. Again, I'm very surprised that you haven't gotten lots of responses from people who have done cam swaps!

I think the car is beeauuutiful and if I were closer to you, I'd offer to come to the race and turn a wrench or two. Would probably get in the way more than not, but I'd be there in a heartbeat to help out where I could. So are you going to be able to get any track time at all before the race to see if the fuel pump and/or thermostat made any improvement with your WOT at high RPM issues?

The work sounds like it's going well. I like the part about the thermostat housing... It's always something! That 3.5 psi is "engine running, sitting still, with return line in operation", right? About the thermostat, I wonder how much of a difference in required ratio the thermostat would make. By that, I mean... Is it conceivable that the change in temp from 130 up to 180 would change the optimum fuel/air ratio enough that maybe the carbs were working as designed all along, but it just wasn't enough fuel for an engine that was perpetually "semi-cold"?

Hmmm... I'm no expert on this stuff and I would gladly defer to someone else who's been through this before, but I guess I would come out of the gate with this: Mechanical pump still attached, but outlet routed back to inlet (because there's still residual fuel inside and you don't want it spraying on your cooling fan). And the reason I would take the mechanical pump out of the loop is because it may provide an unwanted restriction to the electrical pump, and in theory, the electrical pump should be able to provide all the fuel the engines needs, even at WOT high RPM, right? Electrical pump mounted as close to the tank as possible (because the documentation for those cube pumps says that, while they are self priming and can do 12" lift, they are really pusher pumps). Regulator located after the last carb pickoff point from the rail, and then outlet of the regulator returning back to the tank. Question... Are you running the original fuel rail? If so, what (if anything) are you planning to do with the original fuel rail "regulator" restriction orifice? If you're installing a real regulator elsewhere, I would remove that orifice. You don't want a pressure drop there anymore. You could drill it out or cut an inch off the end of the hard return line tip. And... "Good luck. We're all counting on you." PS - Crap! I was out late last night and didn't check the forum when I got in... Just looked at the posting time, and you're already on the track!

Just found one more interesting piece of info. On this website (which looks like a Chinese second source to the 40106 pump) http://www.aliexpress.com/store/301124/209377070-452432241/Facet-Red-Top-Electric-Fuel-Pump-40106-squre-shape-.html It lists a curious spec "Shut-off pressure : 4-6psi" The implication to me is that these pumps, being solid state and all, have actually got some pressure sensing technology in them and the pumping action is actually controlled to maintain the pressure between the two pressure points listed. In other words, the implication is that the 40106 pump will turn off when the outlet line pressure is above 7 psi, and will turn back on again if the outlet pressure is below 4 psi. And if you stay in the hysteresis band between those two limits, the pump will always run. So, if you've got a pressure regulator between the carbs and the return to the tank you just pick the Facet pump that has your regulators pressure at approx the middle of it's operating range. This is all inferred, of course.

After much digging and cross referencing**: NAPA 610-1077 contains Facet pump number 40106 NAPA 610-1078 contains Facet pump number 40104 Slightly more info for those two pumps can be found here: http://www.facet-purolator.com/index.php?option=com_content&task=category&sectionid=7&id=16&Itemid=31 PART # MAX-MIN PSI GPH 40104 4. - 1.5 25 40106 7. - 4 32 I still don't know what the specs mean, but here... This graph should clear it all up. This is what happens when Marketing asks Engineering for some documentation that they can put on the website that couldn't possibly cause anybody to actually be able to be held accountable for anything at anytime.:mad: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ **Here's the NAPA page for the 610-1077 - https://www.napaonline.com/Catalog/CatalogItemDetail.aspx?R=BK_6101077_0334661226 on that page it lists the mfg #NAP12SV. Here's a pdf catalog from Facet/Purolator - http://www.facet-purolator.com/images/facet_guide_2004.pdf At the end of that catalog it lists the solid state cube pump P/N FEP 12SV At this point, it's pretty clear that the NAPA 610-1077, Facet FEP 12SV, and Purolator PRO 12SV are all the same thing. Then on this page - http://www.facet-purolator.com/index.php?option=com_content&task=category&sectionid=5&id=38&Itemid=62 there's indication that the FEP12SV and PRO12SV are clamshell kits containing a pump number 40106 and other associated items. Similarly (without listing all the intermediate steps), the NAPA 610-1078 is a clamshell containing the 40104 pump.

Don't you hate ambiguous specs. I did a little digging and came away more confused than when I started. I don't know for sure what those numbers mean...:mad: What are the part numbers for the pumps you bought?

Cool. So... What happens if all the investigation into fuel delivery doesn't turn up the problem? How can you tell if the fault is actually ignition, and not fuel delivery? Other than shotgunning it and replacing modules to see if that makes any difference, is there any other diagnostic work ahead of time that can be done? I've done no work with the Z ignition to date, other than plugs, wires, caps, etc... maintenance stuff. Thankfully, I've never had to do any diagnostic work, and consider myself blissfully ignorant. Maybe the spark is timed correctly, but doesn't have the strength to fire through the densest gasoline cloud that occurs under your problem conditions. You wouldn't see it under light load conditions. Could rev fine all the way to redline while sitting still, but might not work so well once on the track and you're pulling all that fuel and air into it? I'm not trying to be pessimistic... Just thinking about contingencies now because once you're at the track, it's all willy-nilly fire drill, right?

That sounds like a great plan. I sure hope you find the issue!! Couple of quick comments before it's too late... Why are you going to remove the mechanical pump? The 260 originally had an electrical pump in back feeding the mechanical pump up front. And, just because you're not using it, doesn't mean that the pump has to come off the side of the block, right?. You could leave it in place and plumb around it. You could even get fancy and pipe the outlet back to the inlet! But if/when you do remove the mechanical pump, you should be able to easily fashion a block off plate out of some sheet steel or aluminum. There isn't anything complicated about the shape. Flat works fine. Cut to rough shape, drill two holes, cut some gasket material, smear some goop, and you're done. I'd hate to see you spend out of your $500 for something like that! And... If you're going to put a thermostat in, you should probably have a working temp gauge.

Hi Jeff, Of course, armchair troubleshooting is fraught with potential incorrect diagnoses, but from your description, I agree with the assessment that it's a problem getting fuel TO the carbs, not a problem inside the carbs themselves. Have to start with the simple stuff like filter screens though, right? So next? A fuel pressure gauge between the pump and the carbs is a must at this point. And I wouldn't block off the return to the tank until you know what the pressure is. You don't want to overwhelm your float valves and blow fuel out the overflow tubes especially if you put an electrical pump in series with the mechanical. You should be able to test the "sucking air" theories by running without a gas cap. I haven't completely digested the original tank venting system details, but I believe the original system is "supposed" to run at a slight vacuum. That vacuum is controlled at the stock filler cap. No filler cap - No possible vacuum - No pressure differential - No sucking air. (Of course, unless you're creating a pressure drop elsewhere with a clogged filter or something.) Just remember on left handers that you've got no filler cap. The ID of the tube between the float bowl and carb bodies is 3/16 ID. If you want to do more than check the bowl levels and actually run the car with some clear stuff, I would recommend the gasoline grade F-4040-A Tygon. http://www.tygon.com/tygon-f4040a-tubing.aspx. How about some Tygon between the float bowl and the carb body and an engine bay cell phone video cam taped to the fender well?:bulb: If you see bubbles coming through that tube, you're sucking the bowls dry. At least you'd have the "what?". All you would need to do is the "why?". I don't have any Tygon, but I do have a plenty of suitable Buna-N black opaque 3/16 ID tubing if you need some. If you're worried about kinking or collapsing at the bend, you could probably put on a length longer than usual and include a strain relief loop. PM me if you want to talk about it. As an aside... 29 replies in 300 views. Now that's what I'm talkin bout! Glad I could break the ice.

Hi Jeff, I'm sure you know already... "It could be lots and lots and lots of things", right? But from what you've described, I would guess fuel delivery issues. Sounds like you're getting enough fuel under all conditions except at high RPM full throttle conditions when, of course, you need the most of it. Only thing that seems to contradict that is this part: Could you put a pressure gauge on the fuel rail so that you can see it as you drive, and take a run with it installed? Have you checked to make sure that the inlet filter screens in your SU's are clean? You might also pull the needle valves and make sure crud isn't partially plugging them too. I've seen paper towel fibers get through the fuel lines and gather like a wood pulp wad in the needle valve. They built up gradually and can act intermittent. As an aside... Wow! I'm surprised you don't have fifty responses with help by this point. I would have expected a post like yours to draw in all the experts from world around!

No, no... Don't worry about the float volumes. Those measurements I took were with needle valves and floats installed and working as used in application. I was thinking about it and was giving myself a headache trying to decide if there was validity in measurements without floats and Archimedes appeared to me in a vision and made fun of me because I couldn't figure it out.:stupid: So I just bit the bullet and did it with valves and floats installed. I didn't spend a lot of time getting the float levels spot on, but they're pretty close. (That's one of the "shortcuts" I allowed myself to take.)

Hi Bruce, I'm sorry, but I'm not sure I understand your question... What we're trying to show here is the volumes of the two float bowl chambers. This spawned from another thread that was discussing differences in the design of the venturi bridge between the round tops and flat tops. At request from Blue, I made the measurements above. I wasn't sure if it would have been better to post this in the original thread, but since it really had nothing to do with the content of that original thread, I thought it would be better posted in a new thread. Here's the original thread where the request came up: http://www.classiczcars.com/forums/showthread.php?43440-SU-Bridge-Evolution-Round-Top-vs.-Flat-Top-(Comments-welcome)

Upon request, I have measured the fuel capacities of a typical round top and flat top carb. Note that due to shortcuts I took to make the measurements easier, I'm not claiming accuracy to the cc here, but the results should be fairly accurate. Here's the round top: And here's the flat top: The bottom line is that they are close, but it appears that the flat tops have a greater capacity in the float chamber.

Please don't get me wrong, I'm not poo-pooing the idea. I agree that acme threads are a better choice than standard threads for an application like this. I just came in here to offer you some lengths of acme threaded rod for the cost of shipping if you wanted to mess around with the design before you spent real money on material of known lineage.:classic:

Yeah, those spindle pins can truly be a pain. What I'm saying is that I've got some acme threaded rod if he wants to give it a try, but I can tell you from experience that I've run across some spindles that weren't coming out in one piece using a "puller style" tool no matter what kind of all-thread you used. Sometimes the forces holding the spindles in are greater than what the threaded ends of the spindles themselves can withstand. If that's the case, the spindle itself will yield before it will budge. BTDT.

Oh. Right. So you aren't running the original intake manifolds, balance tube, or air cleaner, right? That makes things more difficult.