My engine needs help!!

[yoshi_w]

So I was changing my struts, and a friend who also owns a z was helping me and noticed I have an l28 in my 73, but with carbs, not fuel injection . At the moment, I dont know if I have flattop or roundtop carbs as a previous owner did the swap and I've been too lazy to check. Now, for the issue, while I was working on the struts, my friend messed wit the throttle linkage,but just pulling it, not adjusting or anything, and when i turned the car on to go home, the idle was ridiculously high, like it sounds like its steadily revving (I dont know how many revs as the tach doesnt work :S). Even before the messing with the throttle linkage, the car took awhile to turn on, and still does. Plus there has been a clinking noise too. I have thought about getting a carb rebuild kit, electric dizzy converter (as maybe high idle is caused by messed up timing?), or rebuilding the engine as it is old and feels enormously underpowered, which I will do eventually as cash permits. Please help!! I dont wanna drive the car in fear I blow my engine, plus I need a cheaper solution as I am on a super tight budget. Thanks!

[olzed]

It's very easy to tell the difference between the carbs. Flat top is just that, the other type have a definate rounded edge.

At a guess, your 'friend' has increased your idle. The car was idling OK before he fiddled.:stupid:

[yoshi_w]

yea, i guessed something like that may have happened.how would i fix that? and do know what could be causing the other problems? thanks!

[olzed]

It's time to buy a manual on your car and learn how to do some basic tuning.

Does the engine smoke from the exhaust? Does it use much oil. I'm assuming you check the oil. Suggest you lift the hood and with the engine off, work the throttle linkage rods. You should be able to see where the adjustment is.

If you have round top carbs, there is a screw at a central position on the linkage just above the carbs, that your "friend" may have given a turn. Try turning it to the left with the engine running and see if the revs drop. There is also syncronizing screws lower down on the linkage . Do a search on this forum for carb information. If the engine is down on power the timing could be off, the compression could be low, the carburettors could be way out of tune.

Look at the simple stuff first. I would start at the carbs.I don't know about flat top carbs, but they seem to be no good. Buy a book.

Others here have great knowledge on these cars.

If your friend has one of these cars, ask him or doesn't he know anything.

Its time to become acquanted with what is under the hood. It's not all that difficult. Given clean oil and water and some attention, these engines will last a very long time. The killer is neglect. Heres another thought. maybe it's low on oil.

[yoshi_w]

First off, I recently bought the car so neglect is definitely possible. Second, the oil is brand new and full, but not overly full so thats fine. I wouldn't doubt the timings off, so is it a good decision to lose the points and get a 280zx dizzy? And yea, i definitely want to learn everything about the engine, so ill definitely be getting a book asap. thanks for all the help

[olzed]

Sorry, but I have a 240z with the origional engine,and know nothing about 280zx dizzy. I have stock 72 dizzy and have not had any problems. Sounds like basic tuning stuff could be your problem.

Another thought --whoever fitted the carbs may not have ever had them jetted correctly for the 280 motor so your engine could be running lean, hence it would not run too well.

These engines can perform really well if in good condition or tuning is correct.

My 240 motor has done 120,000 miles, uses no oil, and is still capable of giving me a few thrills.

[grantf]

sorry but start with easy stuff first, this could sound stupid but is you're throttle linkage stuck?

[yoshi_w]

I just checked the engine and adjusted the idle screw, and now it runs smooth and everything, but still feels really underpowered . Btw, is it the round top carbs that have the idle screw on top of the linkage and carbs (if that makes sense)? i noted that theres some oil around the whole head of the engine though... is that just age or leaky headgasket? and would this cause me to lose compression? thanks for all the help so far!

[olzed]

Is the oil coming from around the rocker cover( the long aluminum cover on the top of the engine)? If so it's a very easy fix. take the cover off and replace the gasket. If the oil is coming from a few inches further down, it might be coming from between the head and the block. To fix this you need a bit more knowledge than you have at the moment.Does this engine smoke from the exhaust.? If the oil pressure gauge works, what pressure does it show.

Someone with carb expertise might chime in and give some advice on jetting 240 carbs for a 280.

This thing should be very lively.

The round top carbs have a very round edge, and the flat top have abrupt edges.

Buy a book on Zed maintanence. A good idea would be a compression test. Do a search on here, on the subject.

Take the cap off the dizzy and check for disconnected wires, or disconnected wires any where for that matter. This lack of power could be the advance mechanism not working as well.

Edited October 15, 2010 by olzed

[FastWoman]

Yoshi, just to be clear, you should buy a Nissan factory service manual specifically for the 1973 240Z. The L28 isn't really much different from the L24, particularly when fitted with carbs, so you'll want the manual specific to the rest of the car. You can pick up a Datsun factory service manual used on either Ebay or Amazon. It will cost you as much as $80, but I bought mine somewhat tattered and scribbled in for about $25. It's definitely worth every penny, and the scribbled-in manuals might have notes about common problems, discrepancies in the manual, clarifications, etc. (The scribblings in mine have been enormously helpful.)

If you're short on money, you can also download a manual for free, but it's FAR more useful, IMO, to have an old-fashioned paper manual you can lay out in front of you -- something you can lay out on top of the engine or in the passenger seat of your car.

[yoshi_w]

I'm pretty sure the oil is coming fom the rocker cover, but I'll double check later today, sounds like an easy fix. But I was looking at replacement gaskets and it seems like what year z the engine is from matters, and I don't know what year z the l28 in my car came from?? How can I tell to get the correct year?? I'll be sure to check the wires and compression for sure. As for the manual, I just downloaded an online one as I am really short on cash, but I am definitely finding it helpful already thanks!

[d240zx2]

Except possibly for turbos, an L28 is an L28.