cycloid

Okay so I purchased both L series books. I have started on the how to modify book. I am feeling a little bit more comfortable with the situation. I hate to sound dumb but I would please like to know if using a dual su carb or triple carb setup with a different cam, new valves and exhaust will be okay to use with the flat top pistons. what other mods might I be looking at? could someone give some advice? what would you do in this situation? here is my end goal Id like to have a dependable daily driver. something to have fun in. not looking to build an extreme race car. I would like to go with a triple carb setup Id like to keep my budget at around 2000-3000 (not including paint, tools, labor) Ive started on cleaning up the block like it says in the L series book. I am wondering what to do next with the head. should I have the head sent out to a machine shop for reconditioning or could I simply replace my bent valves and start looking at some cams?

Hello I just wanted to start a thread dedicated to rebuilding my Z. I have already removed the head and the exhaust manifold. I still have a few other things to remove tho. I plan on giving the engine bay a paint job and also powder coating the z parts since they are out of the car. I have been very careful in putting all the nuts in bolts in bags and labeling them. So far everything has been great. I haven't broken any bolts or cut any wires. Thankfully have not had to break out any penetrating oil either. All is well. At this point I am almost ready to start inspecting and cleaning up parts for the rebuild. I do however need a little assistance. I cannot fully rely on the service manual since my pistons are not the original ones. I am not sure how I should go about this. A fellow forum member told me that with my combo the compression ratio is close to the detonation threshold. He also told me that this combo is not uncommon. I'm sure with the proper tuning the engine will run fine. Im hoping to get some help from someone who has worked with a similar setup. flat top on n42 crank case and head. I first want to start off by selecting parts. I am not to sure exactly where to begin as far as part selection. I think the best place to start tho is going to be with the header selection. Is there a recommended header for my setup? also while Im at it. Id like to get my block painted up. Is there any good cleaning solvents that someone recommends? I don't want to use anything that will hurt the cylinder walls or the deck surface. any block cleaning tips would be greatly appreciated Id love to hear some advice from you guys and would greatly appreciate some guidance in my Z journey. some vids and pics of the car as of now. my freind and I tried to replace the timing chain. on the startup after the chain replacement I heard a valve get bent and also the car would not stay on. I did the chain work myself and this time it stayed on but I was unable to avoid the valve issue that occured when the work was done on it the first time. This just goes to show that you cant always rely on an automotive mechanic school graduate. the stuck valve loose rockers cylinder walls

Thats a real bummer to hear. I thought It was original for the most part. I have a huge folder with all the receipts for the work it has had done on it. What you recommend personally? I dont want to blow up my engine. Should I get the proper pistons?

Hello. the block and head say N42. the exhaust manifold says N47 here is the manifold from a different angle.

Hello. Yes! I was able to take the head off. there was no problems. No broken or stripped bolts. I can see the marks on the pistons where the valves hit. It doesnt appear to have caused any major damage. The cylinder walls look very clean. there is no rust and no scratch marks. Ill post a video later.

http://www.classiczcars.com/forums/showthread.php?42420-77-280z-head-removal-step-by-step-photos&highlight=remove+intake I think this may help me

I'm really eager to see the condition of the bore and I am confident that the issue is bent valves. I am going to start by removing the intake first. I tried looking thru the FSM but was not able to find the part that shows how to properly uninstall the intake. I presume that you have to unbolt the large set of bolts next to the fuel injectors? Do they have to get removed in a certain sequence? There is also something that confuses me a bit. Before I remove the head I will get piston 1 at tdc. But I do not know If i use the mark on the crank pulley set at the 0 mark on the timing cover. Or if I have to get the woodruff key at 12:00 which advances the crank pulley timing mark about 5 degrees.

btw here is a pic of the Z

UPDATE!! last night I removed the valve cover in an attempt to figure out where the tapping sound was coming from. I started on the last valve and moved my way up. I moved the rockers up and down to see if there was any play. Some of the rockers felt pretty firm. While a couple of others where slightly loose. When I got to exhaust valve on cyl.2 I felt a LOT of play on the rocker. I was able to make a tapping sound with the rocker hitting the cam. When I rotate the cam I can see that the valve sort of pops up into place as the cam lobe heads towards 12 oclock. ( a result from the bent valve?) A video of the valve "popping" into place. you can see the valve pop up at the 38 second mark. It happens pretty quick so you gotta pay close attention. and also another video which shows me moving the rockers. In this vid you can see how bad the valve is on cyl. 2 the FSM says that you have to run the engine to operating temperature before adjusting the lash. I dont want to run the engine the way it is now. Is there a way to adjust the valves while engine is cold?? Should I not bother adjusting lash and work on removing the head? I am hoping that the I can still adjust the rockers and get rid of that noise.

I really appreciate the response Zed Head. You are right. I did get a little ahead of myself. Im not in a rush to get the car on the road. I just want to get it running right. Is it a possibility that the head needs to come off now? I presume that there is no reason to adjust the lash when I got a bent valve now?

Hello. I turned the crank over by hand did not get any resistance. When I turned the engine back on I could hear the sound again. I ran a compression test last night and here are the results. cylinder no.1 =92 cylinder no.2 =0 clyinder no.3 =58 cylinder no.4 = peaked to 120. gradually went down to 34 cylinder no.5 = peaked at 90. gradually went to 30 cylinder no. 6= erratic. jumped between 90 and 95. how can I check the lash pads? Is there a way to properly adjust valves without removing head?

I think I have bent valves. I put it back together correctly. but the damage has been done from the previous work. can someone confirm this for me please?

Hello. I have started re assembly of the timing chain here is exactly what I have done so far. I turned the crank over by hand very gently. I did feel some contact with the valves, so I carefully moved the cam a bit until I was able to move the crank over some more. I got the woodruff key near 12 o'clock. I placed the timing cover on the engine. Then I put on the balancer, and moved it until the woodruff key on the pulley lined up with the 0 mark on the timing cover. I took off the cover. I made sure the front two cam lobes made a v shape. and the highest peak of cam lobe no. 8 was facing 12 o'clock. I put the chain on and matched the colored chain link with the mark on the crank sprocket. Then I put the no.1 sprocket hole on the cam. I then put the timing chain guide that is on the right side. I also put on the part that had the spring. It was really hard to put the spring on without moving the crank just a little bit. I only moved the crank about 5 degrees clock wise, which also took out the slack on the right side. I was able to easily put on the spring and the tensioner on the left side. The woodruff key now appears to be at exactly 12 o clock since I advanced the crank those 5 degrees. I am wondering if I should have moved the crank before or after putting on the distributor? Or maybe not have done it at all? I think by using the timing cover as a guide allowed me to easily put on the tensioners and spring. When I moved the the crank the 5 degrees it completely removed the chain slack and put the woodruff key at 12 o'clock exactly. I hope I'm good to finish up with putting on the distributor.

Thank you guys for the big help. I will follow the steps and post a video of the final results.

Okay I gotcha. I have a question tho. So is the woodruff key on the crank is at 12'oclock. does that mean the piston no.1 is at TDC?

Hello I need help putting my z motor back together. the car is a 1978 280z with 5 speed transmission and it also has ac. I will try to be as clear and as detailed as possible. Here is is the low down. A few weeks ago my car was running. It ran pretty good. The only thing that was wrong with the car was that I could hear the chain slacking when I went above 65 mph. ( I am pretty sure that's what the sound was) So I bought a timing chain kit. It came with with the cam gear, the crank gear, chain and gaskets. I took the car to a friends house. We then removed the valve cover, we put a mark on the timing cover to note the location of the distributor rotor. then removed the ac bracket, oil pump and then the timing cover. At that point. everything was good. What messed up was that my friend had had tightened the crank bolt and to put the crank pulley back on he had to unloosen the bolt and basically get the crank off top dead center. He turned the crank around again and tried to get it to tdc. We eventually put the gear and cam gear on the engine without determining what way the cam gear would be installed. We also did not pay any attention to the colored links in the timing chain. And I believe that the oil pump shaft and distributor were not installed correctly. when we turned on the car it would not stay on. it had a rough idle and the car would die out. we also heard some weird clicking noise. I was able to keep the car running and I drove it about 5-8 miles to get it to my house. Since then the car has sat. I called around a few places and they were telling me that it would cost around 500 dollars to get the engine timed correctly without replacing any parts. I honestly would rather not pay and try to fix it myself, which I should have done the first time. If the valves are bent then so be it. But I want to try and adjust the timing first and see how things go before I start spending some serious money. So now that I have that out of the way, I would like to explain what I have done to the car so far. I have removed the radiator, timing cover, valve cover harmonic balancer, cam, chain and distributor. I need to get the crank on TDC first. I have no idea how to to do this on this engine. would I be able to tell by the dot and the crank gear? can i tell by the orientation of the crank snout? is there some special trick for getting TDC on a L28? Secondly. how do I setup my cam? what lobe has to be in what direction? do I have to compensate for a new chain or cam gear? I will also not be running AC either. after I have my cam and crank timed. How do I setup my distributor? I don't trust the mark that was made on the timing cover. I saw a video on youtube that talks about using the marking on the oil pump to properly set the distributor. Im hoping there is an easy way. So that's pretty much it. I would really appreciate it if I could get some assistance. I am eager to get my Z back on the road. some pics of the car http://img687.imageshack.us/img687/823/img0617oh.jpg