[Simonsz]

G'day all,

Posted this to the Banter & Chat forum (twice!!) by mistake. Still learning this internet chatboard thing. I'm not usually that stupid I promise!! Anyway - sorry to those who have read this three times - please help still!!

I searched previous topics and couldn't find one that could help me out.... so I thought I'd ask and see what happens.

I have a 260Z two seater (1978 in Australia so might be a 280 over in the US?)
Anyway - has been restored and has had a L28 put into it - with flat top pistons etc. but no head work (cam etc.)

I've had 240Z SU's put on by a mechanic who I trust has done a good job (he own's and races a Z and loves them so I figure he knows what he's doing)

Now the problem is that when I take it out on the track (or a nice long straigh freeway) it starts to cough a bit around 5,000 rmp in 4th and around 4,000 in 5th and stops pulling. Needless to say it gets a bit frustrating when it stops accelerating 1/3 of the way down the straight at about 180kph.

My thoughts (with a bit of advice!!) is that it's fuel starvation and that I need to have a look at the fuel pump/filter. Wanted to see what some of you thought before I started pulling my baby apart tho.

Any help would be much appreciated.
Cheers,
Simonsz.

 

[blittle]

I've had that problem, took me a long time to track it down. For it to happen only at high revs at the end of a long straight means fuel starvation.

-make sure your lines are clean and a decent fuel pump is being used, 3-5 psi.
-change over to SM needles. A L28 is 17% larger, and with the larger valve head needs more fuel for high performance.

 

[MK 72 240]

You also sound like your not getting enough air...you should consider getting your head ported as well...This is one of the most beneficial things you can do to a engiine and real gains will be hindered until the car can properly breathe.. I found a good book that I am using for reference since I am porting my intake manifold now and the head is next..the SU intakes are pretty crappy inside but get a flex shaft grinder that will turn out at least 10K RPM's and go crazy..My air flow through my intake should be about doubled by now with the amount of porting I did..My only fear is now that I can't get the exhaust ports big enough... I'll get em smooth as glass but I have'nt found out how much can be removed and my headers don't look to wide open either.....

Anyways that's just my $.02 it could be something else all together...


Oh by the way the book is : By MBI Publishing Company and it's the
PowerPro series: How to build & modify cylinder heads, camshafts, and valvetrains. by Ben Watson



Z ya later
Mike k

 

[aceant]

I would have to agree with Mr. Blittle. It does sound like a fuel starvation problem. I would check or replace the fuel pump, lines, filter, gas. Have the fuel pressure checked to see if you are getting the right amount of fuel pressure. Do you like the fuel injection system? Less problems.....

good luck and hope you find the prob.
Sy of United Z Club.L.A, LB.

 

[Simonsz]

Thank you all for your help.

Pretty much confirmed what I thought re: the starvation.

Thanks for the tips on how to deal with it. Came up with some rippers - definately somethings worth thinking about.

Cheers,
Simon.