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.
ka pistons in a napz?
Posted 07 March 2013 - 06:27 PM
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.
Posted 07 March 2013 - 10:47 PM
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.
Posted 27 March 2013 - 01:44 PM
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.
Posted 27 March 2013 - 04:47 PM
Thanks, maybe that wire still connected is advancing my timing but I got more problems to fix first
Posted 27 March 2013 - 06:39 PM
I have both coils running off the same switch wire
Misunderstood you. Thought you were running both coils on one wire.
Posted 28 March 2013 - 01:10 AM
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.
Posted 28 March 2013 - 06:43 AM
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.