Negative Nancy

[papasmurf]

Hello, this is my first post so I figured I'd put it here in the project section, where else should I start off than by telling you all about why I'm here. My girl is a 1978 datsun 280z clad in the beautiful factory orange paint with 15in centerlines yada yada. Some history-

I traded my first car a 1991 pontiac sunbird YUCK for a beat up wreck of a 78 z. She was rootbeer brown originally but some ass painted her with a glittery blue and drove her to death. I got the engine running right and the drive train replaced and upgraded the brakes etc. She was on her way until a 16 year old girl up the hill parked her bmw in neutral and didn't set the e brake. I had just parked the car on the side of the road and went inside for a nap when bang! The unmanned demon german deathmobile attacked my car. It was a total loss and after almost a year of fighting with the insurrance company I got 2500 dollars. That DAY I went up to everett and picked up "nancy" on the way home she had an electrical fire and the clutch line went out on me. Bad start. But after a few months of rewiring and plumbing she was on the road. This is my project.

 

I've had her for almost 3 years now and as with any good project the work never ends. A short time in the airforce slowed me down but here is where she stands now-

 

15in centerlines with 1/2in shims behind them

4 piston yota calipers on the front with drilled/slotted rotors

tokico illuminas and lowering springs

l28 n47head with early 240 su's

crane ps40 ignition coil with taylor plugwires

4speed transmission (it's snappier alright)

rewired fusable links to a more modern fuse box

 

Theres lots more but it's hard to think of everything. Anyways I drove her to portland a few months ago to work with some family and she died. The engine siezed up and though I got her unstuck eventually she wasn't running right. On close inspection I noticed that the crankshaft pully was loose and the key that holds it in place had been stripped out. This engine had to go! So in portland I managed to find someone on craigs list who was selling an l28 for cheap and I was poor so I went and had a look at it. Turned out it was an l26 though someone had scratched the 6 into an 8 haha. I bought it anyway desperate to have my z running. Between work I managed to get it installed in a week which was quite a feat but she wouldn't run. A months worth of troubleshooting and 500 dollars later I had the engine running but there was a LOUD knock coming from the block and it only had compression on certain cylinders some of the time. This block is bad was bad. I managed to trade my old Z which the insurrance company had let me keep for parts and my silver 75 which I had purchased several months before for cash and another l28. This engine was delivered to me 3 days ago and I've been too busy working to really dive in and look closely at it.

 

This is what I know about the new engine. It has recently been rebuilt and never fired. It has new rings, new valves etc. It's been dipped. The head is an n42 square port. The cam is not stock. I have to investigate this cam further it says cwc d2 on it and thats all I can find. The springs look like they were once red but it seems to me the person that went through the head didn't know what the hell they were doing as the lifters are missing their retaining clips and thats what kept this thing from running. I may have to rebuild this head or use one of my other 2.

 

So the project is here: I have the car in the driveway, the broken l26 still under the hood. The old dead l28 and the new l28 sitting in the driveway. I have everything I need to make her run I just have to find the best configuration. I'll probably go with the N42 if it's not damaged or at least salvage the aftermarket cam and go with the n47 from the old l28. She's going to run carbs and I'll probably go with a 1mm head gasket for a slightly higher c/r and I'm gonna make this baby scream again.

[nismopu]

hopefully its not a flat top engine because I hear that combo detonates!!! Next tuesday you should make it down for a meet and maybe schedule a time to work on your Z. peace.

[521Lvr]

the n42 head will give you the most "cr" and is the 2nd most sought after head after the p90

depending on the pistons 1mm gasket might give you tooo much "cr" for pump gas in street tune.

if the pistons are flat tops use an oe replacement hg. if they are dished the 1mm will up the cr. if they are dished. put a 2mm on it and turbo the hell out of it

peace

tc

[Bleach]

dished pistons with the N42 head is stock compression of 8.3:1

A 1mm head gasket probably won't raise your compression over the factory 8.8 of the later L28. You'll be fine.

N47 is the same quench and cr of the N42. Sounds like you're working with all the older L-series parts so you're fine on compression ratios.

 

The Square port heads had the softer valve seats that are prone to damage if they haven't been replaced. The round port head is a more solid head but might not match to your exhaust manifold.

 

Welcome to the site and good work keeping the Z going! :)

[nismopu]

I am sure papasmurf already saw this

 

Papasmurf,

 

PLEASE oh please read the links below before you commit to this combination you proposed. Your combination of a flat top piston L-28 and N-42/N-47 head for a street pump gas L-28 is a very poor combination. Read on