n/a advice please

[jxnkyle]

i recently put together a money pit for a motor. here's the setup: ka24de, sohc(89) pistons, 248(+5*)/248 cams, egr and swirl control removed, ported out exhaust ports, greddy header, high flow cat, strait-through fart can, and a cone filter. i used nippon piston rings, a felpro head gasket, and new oem head bolts from nissan. i've blown the head gasket twice now. the first time to a water jacket and eventually between cylinders 2 and 3. it ran only 3 days before it blew. i didn't have the head mic'ed and just bought new bolts from nissan and another felpro gasket and put it back together. it ran 4 days before developing a leak and blowing past an oil jacket and straight out the side of the motor between the head and block at cylinder 4. the only reasons i see that would cause this are: warped head, even though it blew in different spots each time; or cumbustion temps to high- i have no fuel support (i.e. pressure regulator) and bosch platinum 4 spark plugs. any other potential causes i should consider/investigate? i don't want to put this thing together again just to have it blow in a few days again. i'm not running a thermostat so the engine takes a while to warm up and will stay a little below normal if i have the heater on. p.s. i'm using 93 octane to help reduce detonation. any advice would be great.

[ss82480]

Well maybe get a SAFC to fine tune the fuel, its also nice because you can monitor the knock. Did you get the block checked and all when you put in the sohc pistons? And what you mentioned check the head to make sure it isn't warped. Good luck to ya!

[LingeringSuicide]

get rid of the Bosch 4's to start. Getting the head and blocked decked is a good thing because its one less thing to worry about and it will up the compression a little bit.

[jxnkyle]

i've decided to go with a cometic mls gasket and arp head studs. i'd like to avoid removing the motor again if i can. will having the head checked/decked sufice? i really don't see the iron block warping.

[LingeringSuicide]

I have seen iron blocks warp before. It all depends on how much of a beating that engine has taken. Even so you would have a fresh surface to work work with and it never hurts to raise the compression if your going for a high compression n/a motor.

[jxnkyle]

thats the plan then. i'll get the head and block checked and decke next week. another idea i've had on the back burner is sohc truck engine main bearing caps. from what i've found, the block is bored and decked before the girdle is bolted in, which lines up close enough for a factory fit, but is not exact. this causes a very slight distortion in the block and adds to high rpm vibration. some na guys are running the truck caps for high rpm setups to releive some of this distortion and reduce the vibration. does any one have experience with this or more insight? i'll take any information i can get.