Engine runs only when choked...

[240Zdragon72]

IT IS ALIVE! I changed the cap and rotor and made sure the wires were in the right firing order. Choked the carbs...turned the key. She sputtered and then fired right up!! White smoke covered the backend of the car and from the back of the exhaust manifold. I had this annoying "popping" sound from there. Remembering back to the day me and a friend did the engine swap, we accidently snapped this 13" long tin tube off the backend of the manifold leaving a quarter size hole. I would try to give her a little gas, but more smoke came out and she started to backfire. The only thing I could think of is to take the manifold back off the engine and see if someone can weld it shut.

On top of this, my radiator is leaking! :tapemouth I'm going to go crazy! (if I haven't already!) Thank you everyone who has read my post and is trying to help.

[TomoHawk]

You might try to plug the hole with some J.B.Weld. It's a cheap & easy way to know for sure if it was the problem.

[240Zdragon72]

Sounds like a plan. How long do I have to wait before I can start the engine? Will it also be heat resistant so I can drive the car to a local shop? If so, I will stop at Auto Zone today and pick some up.

Thanks...

[TomoHawk]

Put a glob on a scrap piece to see when it gets hard. Depending on how you mixed it, it should be a few hours before you can BRIEFLY try the engine. It takes overnight to harden completely (like an epoxy).

J.B. weld should be available in autoparts/hardware/D.I.Y. stores, et al.

[240Zdragon72]

Thanks Tom. I will post a result soon.

[240Zdragon72]

I put some "weld" over the hole and waited a whole day until I started the engine. She fired right up again and this time there was hardly any smoke out the back. I tried to give it some gas but the back carb only "hissed" at me and the engine wanted to die. After running idel for around 5 minutes, The weld melted off and it was back to smoking and wanting to die out.

Now, I thought it might have been the carbs. Having a spare set from the other motor (SU 4 bolt round tops), I put some damper oil in and mounted them to the engine......Nothing. Tried to start her for a minute and all I would get was backfire through the carbs.

Having to hold the choke on the carbs (choke wires cut off :tapemouth ), my Wife was turning the key. It started in choke and I held it for a while. Approx. 2 minutes. I then let off and the engine came back down to idel....bogged out and died. I looked at my wife and then pointed to the engine like I had a gun in my hand and shouted "BANG!!"

Shut the hood and walked back into the house. I am so upset! I wanted to have a running car when I was rebuilding the turbo engine. I don't know what to do. I've spent too much money on this carbed 2.8L engine, and I haven't touched the turbo. I plan on breaking down the 3 bolt round top SU's and cleaning them real good. After this, I'm out of options besides putting the money into the turbo.

Sorry for rambling on, I had to vent..... :sick:

Thank you all....

[Zs-ondabrain]

I know you don't wanna hear this, but whats the possibility that during all that back-firing you might have slipped the timing chain a tooth or 2??

I can't figure it out either, If it ran 2 hours before the pull and you changed nothing, it Should run.

Start over with the engine on T.D.C on Compression stroke, check timing and spark plug arrangement again. If anything, do it for your own sanity, Just so you know in your head that it's all correct up front. Then go to the carbs.

My 2cents.

Good luck,

Dave.

[240Zdragon72]

Zs, Could it be possable to check it while the engine is still in the car? If I remember correctly, the face plate might have to come off? I will have to look in my "How to rebuild your Datsun OHC" book again.

Thanks!

[240Zdragon72]

I have been fussing with this still. As the engine runs (very roughly while the choke is on), what looks to be "oil" or maybe "fuel" is dripping out of the exhaust ports from the cylider head. The new gasket is soaked in it. I can't tell a specific odor, a cross of fuel and oil. I called my local Z guy, Mike Bear, and he says that I may be flooding the head out and some of the gas is not being ignited and just leaking out. :tapemouth I have broken down and cleaned the carbs 2 times already and put new gaskets on. I have a feeling the needle is sitting too far in the nozzle that the only way the engine will get the fuel is by choking it. I have the option of buying SM needles and ZT nozzels. Would this help the problem or are the carbs a loss?

Upset and feeling hopeless.......

[beandip]

Woah here stop bouncing around and settle down to one thing at a time and think this through. was the engine running ok before you made the swap ? If yes , did you pull the carbs off the manifold ? did you remove the dist form the engine ? Are you used to driving a car that has a manual choke ? These engines if tuned correctly will barely run when cold with out the choke on. They will , in most cases , refuse to even start without the choke. Leave the choke on and run the idle up to about 900 rpm and let warm up. As the engine warms you will find that you can ease off on the choke a little by little.This may take 10 or 15 min. Once at normal temp THEN you can adjust the carbs. If you ''blip'' the gas like to raise the rpms quickly before it is warmed a back fire is expected , it's a lean pop . Go to the tec page and make a surch for adjusting SUs. If you have been trying to adjust the carbs already chances are they are all out of sinc. Follow the step by step instructions. It is really quite simple. If you have a timing light see what the timing shows you , set it at 10deg BTDC , at about 700rpm and with the vacume advance disconnected , and pluged. You will need a uni-sun to ballance the carbs air intake. The white smoke is most likely just from attempting start the engine . It should clear in a few mins. Before you try to fine tune the carbs , just get it running reasonably well and see to the timing then finish the carbs. If you had the carbs all apart then it could be anything. Float level to high , the needles set wrong in the piston and or bent , the jet set to shallow or to deep. the butterfly leaking air. I think you said you had a set that you hadent gotten into , if this is so put them on and adjust them.

[240Zdragon72]

"As the engine runs (very roughly while the choke is on) "

I can't get the engine to even idle...... more like a crawl. Anyway I'll figure it out. :mad:

I haven't touched the dist, carbs, or timing before the swap. Nothing. I really wish I could get it to run. I don't see why it would run in the old car, and not in the new one?

[JLPurcell]

Sounds like an intake manifold leak to me, let us know what you find. JLP