240ZMan

I finally got all the pieces for my new exhaust and assembled it all but can't get it to start. What I've done: - Removed my tired L24 and replaced it with an L28 block bought on ebay with my existing E31 head on it. - Installed a new MSA 6:1 header and 2 1/2" exhaust - I did not remove the oil pump so I figured I could just put my old dizzy w/Pertronix back as it had been on the old motor. - I didn't change any settings on my carbs as they ran pretty well before. What happens is that during cranking now and then a puff of gas comes out of the carbs. I also hear something from the exhaust, like a muffled backfire? The engine never sounds like it's about to start. I've moved the timing around within the limits of what the dizzy can move (+/- ~10 degrees) but it doesn't make any difference. I connected the timing light and it flashes when cranking. I checked and when the crank is at TDC the rotor in the dizzy is pointing to the #1 plug wire. I'm out of ideas without starting to tear things apart. Of course, I'm tired and may be missing something obvious. Thanks in advance for any suggestions.

Thanks Ken, that makes sense. And that would solve my issue as well. Just kind of frustrating to have paid them over $400 for a header and muffler system that's supposed to be bolt-on, and then need to go spend even more money to get it kluged. In fairness to them, I'll call them when they open and see what they can do. Daniel

Ken, I think you're describing exactly my situation. So it sounds like you had them weld the 1st piece of muffler pipe to the flange for connecting to the header so that it could go down at more of an angle? This would be angling down from the engine towards the rear of the car? Did that cause any problems with the other end of the pipe hanging down too low? Just wondering if you spoke to MSA and what they said as well.

Ok, must be something with mine. I'll have to call MSA.

SteveK, in my case I was also burning a quart of oil every 500 miles, even worse when I drove it hard. If my engine had not been using oil and had lower miles, then I wouldn't have been concerned about the lower readings. It was the combination that lead me to believe my rings were worn.

The picture is typical of all 6 pistons/cylinders. This is a 73 L24 and all the pistons are fly cut. The walls are very shiny and glazed. The block is original and to my knowledge, the pistons and rings have never been out. Mileage is 200k+. The last compression test I ran resulted in: 1: 155 psi 2: 155 3: 165 4: 160 5: 165 6: 170 The head was replaced with the E31 head and I was told by the PO that it had been recently refreshed with steel valve seats. So my assumption was that the rings were worn. BTW, most of the "un carbon" portions are on the portion of the piston next to the sides of the block, not the front/rear. I think this would support the idea that the rings were worn and the pistons had too much clearance, at least side to side, in the bores. Anyway, that block is now out of the car and my "new" L28 is in. Not sure yet what I'm going to do with the L24.

I agree with Billcap that for belts your local parts store is probably best and easiest. But for hoses (except perhaps radiator) my local parts houses don't stock for early Zs. I found MotorSports and Victoria British to be the best. But get their paper catalog. Their on-line catalog leaves a lot to be desired. And defiinitely order via the phone. I'm not trying to slam them, it's just that they are better set up to deal with paper catalogs and live phone calls than on-line. Plus, the catalogs are a good way to see what years use the same parts. Makes it easier when you are "getting creative" :classic: .

I'm putting my new MSA 6 into 1 header and exhaust on and am running into clearance problems. I'm surprised because I had heard that MSA's was just a bolt-on. The issue is the outlet is just a little too high. The results in the pipe that connects to the outlet hitting against the transmission rear cross member. If it was about 1/2" lower, I think all would be fine. So I've tried "rotating" the header on the head as I tried to illustrate in the picture. But in order to go any further I'd have to remove some material from the flange as it's hitting against several of the studs right now. Of course, I hate to start grinding on something brand new, especially since I've got the ceramic coating. So my question is if any of you have used the MSA headers before how did you resolve the clearance issues. And if grinding is the answer, give me some advice. I've never done that before (save using a file by hand).

I understand your thinking. On this engine, although you can't see it in the picture, all the pistons have identical cutouts for the valves, so I don't think there was any interferance. But anyone have any ideas on the discoloration (actually, lack of carbon) near the arrows in the picture?

What do you see that makes you think there was interference with the pistons and valves sometime in the past?

Take a look at this picture of the piston top from my L24. It's got 200K miles and is about to be replaced. The compression was low on all cylinders and rose with the addition of oil. Are those shiny clean areas around the edge of the piston from blowby due to worn rings? I've got an L28 that is going in, and this block will likely not be used again by me, so I'm just asking as part of my ongoing Z education.

Before you go too far, you should check the clearance between the front of the engine and the radiator. I recently spent some time at both Checker (same as Kragen) and Autozone looking at their fans. Even the 14" models were 3" thick, and all suggested 2" of clearance. I have at the most a little less than 4" between the bolts on the water pump and the radiator so it would be rather close. And moving the fan to the side would mean taking off the fan shroud which would reduce cooling. Some say you can mount the fan in front of the radiator, but everything I've read says this is not as effective as putting it behind in a "puller" configuration. FWIW, I don't believe my 73 has been in any accidents.

While we're on this subject, I have another question. We're fortunate in the Denver area to have a guy whose entire business is working on Zs. He has been a great source of information and advice to me. When I called him about the broken bolt, he said he didn't know as he had never broken one. At first I thought he was kidding, but he was serious. And I'd have to guess he has removed literally hundreds of heads. I broke a bolt on my second! So my question is what "tricks" are there to taking the head off? I think I followed everything I've read in books, but as we all know, there is a lot that isn't in books:stupid:

Just got my block back and the broken bolt is gone. There isn't a trace I can see. I ran a stud in and it goes in smooth, and still feels tight. The bad news, if you can call it bad news, is that it cost $110. But in the scheme of building up a motor, I guess that isn't too bad. Best of luck to you, 1975yellowBSPZ. Since my block was already out of the car, I took advantage of it. I hope it doesn't get to that for you.

Thought I'd close this out for anyone considering buying air equipment for the first time like I just did. Today I returned the 250 lb-ft impact wrench ($40 model on sale for $20) and purchased their "earthquake" 650 lb-ft model. I chatted with the store manager for a while who had nothing but good things to say about the earthquake unit. He even gave me another $10 off the $79 sale price. So the difference is amazing. The unit seems to use much less air than the old unit, and had no issues taking the lug nuts off my Expedition (needed to rotate the tires anyway) on only the #2 setting of 6 positions. While I doubt the #6 is 3 times higher than #2, it performed exactly as I hoped it would. So lesson learned is that for impact wrench torque, divide the max spec by about 3.5 to see what you're likely to get in the real world.

I tried heating but got nowhere. Even the Easy out "threads" are now damaged. Through a series of phone calls I found a shop in Denver that can disintegrate the bolt. As my engine is on a stand, I figured I would cut my losses and just take it in. He says they get an arc going to the bolt itself, and then immediately quench it. This thermally shocks that part of the bolt and causes it to break up into small pieces. He says they can do this without damaging the threads in the hole. I suspect there's more to it than he described, but as long as he knows how to use the tool, I'm not too worried if he can't explain how it works. I'm supposed to get it back tomorrow so we'll see how it goes.

I don't think I'm running hot. I recently went over all my connections (not a small job) and while I had seen some temp flucuations prior, after cleaning the contact on the sensor it has been pretty solid. Also, I recently changed the thermostat for good measure (180) and the gauge reads just to the left of the midpoint almost all the time. I wish I could lean the carbs out more, but I've got them so lean that driveability is already compromised. You know, jerky response to mild throttle applications. I do notice that when re-starting under these conditions it takes a few seconds more before it fires up, but it's not anything more than 2-3 seconds total. Also, I have to hold the revs up for about 30 seconds or so otherwise the idle is so slow that sometimes it dies. The rest of the time I have the idle set a bit high around 900 rpm. I agree with you that vapor lock doesn't make sense in that when the tank is less than half full I can hear the fuel returning. So clearly the electric pump is able to move the fuel. But just for the sake of discussion, if the fuel was boiling somewhere past the electric pump, wouldn't that explain what I'm hearing? You know, the pump is mounted right near the tank where it's nice can cool. I obviously can't explain this (which is why I'm posting here!) but it sure sounds like I've got too much heat near the fuel line somewhere in the engine compartment. I am shortly going to be putting an L28 in along with a header (ceramic coated). I plan to fabricate a larger heat shield as well to better protect the carbs. So for now, I'm going to wait until that is done and see what happens. Of course, adding the header to an engine that may already have a heat problem has me nervous, but I know others have done it, so I figure there has to be a way! Thanks!

Not a bad suggestion at all. When I first tried it the setting was at 1 (of 4) and I don't think it would have removed the cap off a Coke bottle. But I resorted to the manual and switched to the 4 setting from then on. I put a 3/8" QD on and shortened the hose to 20'. At this point it's got around 75 lb-ft of torque. I think the real solution is a better wrench, and I'll go by HB later to see what else they have. After all, there's a reason this model was on sale for $20:stupid:

Lance, The gun calls for 5 cfm at 90 psi so I figured I wasn't going to be too far off with this compressor. The hose is 3/8". I have 2 QDs in the path so I'll take one out. The hose is 50' long but now I'm wondering if that's hurting things too much. Do you think going to a 25' would make much of a difference? Or I guess I could go to a 10' (if that's even available) and wheel the compressor closer. How much impact does the length of hose make? Lastly, the gun's input takes fittings with a 3/8" ID. If I understood you correctly, you were suggesting I put a 3/8" QD on it and the hose? Just want to confirm as I didn't notice any at HF yesterday (although I wasn't looking for them either). Thanks, Daniel

I was at HarborFreight yesterday morning and picked up an air compressor and impact wrench and a few misc. tools to go with it. Its main use is for those occasional bolts attached to something that moves, such as flywheel bolts, cam bolt, etc where a ratchet isn't going to get it done. The compressor is rated at 5.0 scfm at 90 psi and has an 8 gallon tank. I realize this means I can't use it for continuous use, but as I said above, that's not what I bought it for. The wrench is supposedly rated at 260 lb-ft of torque at 90 psi. Yet I'm not getting anywhere near that. As a test, I loosened a wheel lug, set the wrench on its highest setting, and tightened the bolt as far as the gun could go. Then I took my torque wrench and gradually turned the setting up until I could move the lug. It appears that the wrench can't go much over 75 lb-ft. So my question, before I go back to HarborFreight, is if you think I need a bigger gun, or if the problem is really with the compressor being too small. Please don't say both

Thanks Phred, your suggestion is encouraging. Unfortunately TIG welding is beyond my abilities so it looks like I'm off to find a machine shop tomorrow.

Here's the header picture. I guess I can only attach one picture per post.

One of the head bolts broke last night on my "new" L28. Picture is attached. Based on other threads I've read on this site, I've been keeping it wet with penetrating oil since then. I also have drilled a hole into it to use an easy out. At this point I suspect the remaining bolt is rusted in the threads. The picture makes it look redder than it does in person though. I've twisted as hard as I think I should on the easy out and it's not budging. I read some discussion about heating, but I'm not sure if I should try that here, and how to go about it. I do have a propane torch (the kind used to solder copper pipe for plumbing). The block is on an engine stand right now so I could get it to a machine shop if necessary. So my questions are: 1) should I try heating, and if so, how to go about it? 2) what could a machine shop do that I can't? 3) if it just wont' come out, can it be drilled out and tapped? I suppose that head bolt would be different than the the others? Thanks, in advance. This is so frustrating! Yesterday my new exhaust from MSA (header and 2 1/2" piping) came in, and I can't wait to get this going! Picture of header attached as well, just for a positive note :classic:

Lance, thanks for the timing suggestion. I think I'm going to try that this weekend. On the vacuum leak idea, what's strange is that it acts like it's way rich, which would be the opposite of a vacuum leak, unless I had the leak the rest of the time and it stopped when warm. I tried that theory for a while, but just couldn't find the source, so I gave up on it. To be honest, I suspect the fuel in the float chambers is overheating. The symptoms fit. It's just that it happens when things are no where near as warm as I would think they needed to be. BTW, if you're interested, here's the link to the latest from this afternoon. http://www.classiczcars.com/forums/showthread.php?s=&threadid=12323

I've been trying unsuccessfully to track down an over-rich idle problem when hot. So I'm really sensitive to anything with fuel system right now. Today I noticed when I pulled into the garage with a full tank of gas, that when I turned the engine off I could hear a bubbling sound coming from the gas tank. It went on for about a minute after shut off. As an experiment, I turned the ignition back on wihtout starting the engine to get the electric fuel pump running. The bubbling sound began again. I let it go like that for about another minute then shut it off. This time the bubbling sound went on for several minutes. It sounds like the gas is boiling in the lines in the engine compartment and escaping as a vapor in the full fuel tank. What confuses me is that my engine is basically a stock L24 with round top carbs. I have the exhaust manifold heat shield nstalled. Today was about 70 degrees and overcast. I had just been driving slowly for the last few miles before my house. I read about people living in much warmer climates who don't have vapor lock problems with their Z's so I'm at a loss for what to look for here. Suggestions?