x Wild Bill x

Alright guys, got a fresh short block in the car with my old heads and cam. Old motor threw a rod, heads seemed okay, I replaced an intake valve because it was bent. Now, motor starts great but it backfires every 10-15 seconds or so. It is a loud sharp crack, deff. out the exhaust, kinda like the fuel is loading up in the exhaust and then lighting off. When I check the primaries when first starting the car 7 of them will be at say 200* and then the number 8 primary will be at 150*, so quite a bit cooler. When I pulled the plugs, most were black, but the number 8 cylinder was white... Now I haven't run the car for more than 5minutes because I don't know what is causing this. Valve lash is good, oil pressure good, coolant good, no fluids seem to be mixing... Now, when I crank the motor over by hand, I can hear air "hissing" through the motor, but it is much more noticeable on the passengers side. I have no clue what to do next, I think I am going to pull the injector on the #8 cylinder and see what happens, pretty sure the popping will go away. Next, I am thinking do a leak down test...? Any other ideas, could the opti cause this? If there was a small crack in it would it cause this?

Thanks, throw all the ideas at me :-)

Bill

horcpowr

Was the intake valve you replaced on the #8 cylinder? if so sounds like you bent the exhaust valve as well which is why it is popping out the exhaust. If all other cylinders are firing good then its not spark plug wires but i would check those also to make sure the firing order isn't messed up. Good luck let me know if you figure it out.

x Wild Bill x

Yeah, that's what I was thinking too and why I am going to get a leakdown tester to check that cylinder and the others as well... Only weird thing is I hear air entering ear cylinder loudly on the passenger side, but not the drivers side. Probably just me, I dunno lol... Anyone have a good source for a leak down tester? Harbor Freight has this one pretty cheap http://www.harborfreight.com/cpi/cta...emnumber=94190 I just want to know if the hose is flexible enough to bend to the #8 cylinder or if they make like a 90* extension.

Thanks,
Bill

x Wild Bill x

So does anyone know of a better place to get a leak down tester from? Autozone, Advance nor NAPA sell them, as far as I can tell... The one from HF seems to have a short hose, is there a 90* adapter I can buy or an extension that anyone knows of? Or can I just use a regular quick fitting and my own air line..?

Thanks,
Bill

purpleLT1

check if the PCV is hooked up, or it sounds like you injector is leaking and too much gas is getting into the combustion chamber before the plug fires

CRAZZ28

iTrader: (13)

If im not mistaken white on the plug means that cylinder is lean. I would swap the #8 injector to a different cylinder and see if the lean condition stays at #8 or moves with the injector.