ka pistons in a napz?

[ssnapz]

What compression ratio will it put me at and can I get away with 91 octane. I started having a light knock at 2500+ under load, so I plan on building my old motor on a budget. Here are my options: put ka pistons in and port the head or good napz pistons and 8psi out of a ford probe turbo on a suck through system. I think power and price will be about the same. Non turbo will be less work and fabrication. I'm currently running a 350cfm Holley, home made header and mild cam. Looking for advice and suggestions. Have no money and need to keep it on a budget. I have the probe with a blown motor that I can take the turbo system off of so no cost in parts there. Cost wise I'm looking at gaskets, bearings, pistons, rings, and machine work for either motor.

[datzenmike]

Z24 with KA24E pistons.... 9.521

 

 

Your dizzy should have a forth (white) wire with it's own plug taped to the dizzy harness. This is to deactivate the exhaust side plugs to reduce engine noise under heavy load. A switch senses low manifold vacuum and grounds the white wire.

 

Unplug it and run a ground wire to it and try driving @2,500 under load. If the noise is gone then the vacuum switch that senses load has failed or something is unplugged. Be sure to remove the ground wire after testing.

[ssnapz]

9.5 I thought around 11. As for the dual spark, I set mine up before I found the wonderful world of ratsun. I have both coils running off the same switch wire so I doubt that's my problem. I went through my vavle lash today and had a cfouple loose ones but not bad, noise is still there. I'm afraid its probably a piston skirt. So I will try to rebuild my last motor I blew before this one goes.I was planning on building my twin cam napz but don't have the 5k+ to build it now, so budget build here I come.

[datzenmike]

There is a wire for each coil from the distributor so no need to run them off only one. This may overheat the module.

 

I checked the answer and stock Z24 with only KA-E pistons added is 9.52134189 compression.

 

Valve lash is 0.012" hot. Start there. I guess you could trim that down slightly but a tight valve is way more dangerous than a loose one. The valve is cooled from the length of time it is sitting on it's seat. Well the hot exhaust is.

[ssnapz]

Thanks, maybe that wire still connected is advancing my timing but I got more problems to fix first

[datzenmike]

 I have both coils running off the same switch wire

 

Misunderstood you. Thought you were running both coils on one wire.

[ssnapz]

I am, my intake coil is hooked up stock, my exhaust coil gets its switch from a jumper wire coming from the neg on the intake coil, and the old switch wire for the exhaust is the only dizzy wire not connected. I will hook it up the way you described, but it doesn't sound like a ping to me, comes on at 2500 under load and goes away or gets drowned out by exhuast above 3500 or full load. I need to replace a wheel, axle shaft and clutch then chase that down.

[datzenmike]

Yeah that's running both from one side of the module. The module has two sides one for each coil ... I would wire it properly. Most Z dizzys hav only 3 wires to the dizzy a POWER and an INTAKE and an EXHAUST wire for each coil. Some have an extra forth wire to them and it has it's own plug... I think I posted a picture of it earlier. All you have to do is leave this plug disconnected and the dizzy fires both coils all the time. ... easy.

[ssnapz]

Thanks mike