engine missfiring

[pauly_adams]

hey all ive got a problem with my motor. my motor was running fine 2 days ago and then today it was running like crap it was missing and carrying on, any way i continued to drive it and then it started blowing alot of black smoke which nearly killed me, then all of a sudden it nearly died so i turned it off and then back on and it was still doing it. now for the strange part, i cracked it and thort if it dies i dont care i had enough then it came good and had awsom power output and is now running fine. so can any one tell my why it is doing this as its realy anoying.

 

(also i have changed my head, points, rotor button, dizzy cap, leads, but i am yet to change the coil and plugs as they where only 6 months old did clean them though)

 

please help me cheers pauly

[Zeddophile]

Random guess, something sticking in the carby, or being held open by a little bit of crud.  If the needle that the floats push down to allow the fuel bowl to fill up sticks down, the carby will just keep filling up with fuel, till the float bowls are completely full and you have un-atomised fuel running into your motor.

 

Only evidence for that theory though is the black smoke and the fact that it randomly came good, could conceivably be any number of other things.

[reverendzed]

Hey pauly,

It could have been some crap that got through to the carbs, what are you doing for fuel filtration? I had a similar thing a while back however mine was blowing more blue/white smoke, however it runs fine now?

Rev.

[Scoota G]

Just a thought but maybe one of the chokes got stuck on. :-\

[sydney mike]

I found that if I flooded the carbs and started driving, or started driving before warming it up I would had the same problem- she would run rough, cough and black smoke  for quite a while, had me worried the first time it happened but then I revved the crap out of it and it came good, so maybe you flooded it?

[tattoo_ink]

hey pauly havnt you got a holley on her still ?

 

if so theres a fair chance you got crud stuck in the needle and seat .

 

give it a cupla light taps on the retaining screw on the front of the bowl with the handle of a screwdriver, if that doesnt clear it up take the needle and seat out and blow it out .

 

just make sure when you put it back in its the right hieght , just letting fuel dribble out the site plug on the side of the bowl and you should be on a winner hopefully !

 

holleys are prone to this drama, maybe wack a new fuel filter on too.

 

[pauly_adams]

thanks all and yes i do still have the holley and no im not keeping it as soon as i get a set of twin sus its gone and thanks for the advice tattoo ill give it a try

 

cheers pauly

[Glen]

http://cgi.ebay.com.au/Nissan-240-260Z-SU-Side-Draft_W0QQitemZ160213288104QQihZ006QQcategoryZ6763QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

[gav240z]

http://cgi.ebay.com.au/Nissan-240-260Z-SU-Side-Draft_W0QQitemZ160213288104QQihZ006QQcategoryZ6763QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

 

They don't look like 240z SU's. They look more like British SU's bolted onto a 260z (n36) manifold.

This seems to be a common problem with Ebay people list them as 240z SU's when indeed they are not.

[PZG302]

Sorry to be pedantic :D, but Nissan never used SU carbies on the Z's.

 

Nissan used Hitachi Side Draft Carburettors, basically an SU copy. SU carbies are a common mod as they are available in a bigger range of sizes, and were much more common in Australia because of all the Pommie cars that used them that were avialable here in the '60's. SU's were used on Triumphs, Jags, Rileys, Daimlers, Morris, MG and plenty more I can't remember.

 

The model numbers, from the FIA homologation papers are:

 

H(L)S30 - L24:   HJG46W

R(L)S30 - L26:   HMB46W

 

[gav240z]

Be as pedantic as you like . Suits me and hopefully it will clear up alot of confusion.

 

I want to write a 240z / 260z buyers guide soon so that it will help newbies understand common issues with Z's and I think the SU / Hitachi one is a big one. Many cars are sold with "240z SU's" when in fact they are not .

[pauly_adams]

yeh i did see them and also noticed they where not 240z carbs i think they may be jag carbs im now thinking of efi. does any 1 dissagree, also i have a new cam,polished ports ,widend inlet and exaust and larger valves in my early E88 head and its sweet as

 

cheers pauly