KA: Decked head changed cam timing - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

KaT FTW · 01-18-2011, 11:53 PM

I have a n/a s13 ka bored . 5 over, 10k miles on the rebuild. I was having some problems with it and turned out to be the head gasket, so i changed that and had the head decked before it was put back together. Did a compression test after it was done and was 160 across, i feel it should be more than that. Right now It runs real rich,but it has a brand new fpr, fuel filter, and pump. I had the fuel pressure checked and apparently was 2psi over stock, but you can see some black smoke out of the exhaust and it fouls plugs like crazy. Voltage to the fuel pump checks out and all the vaccum leaks were fixed with the aid of a smoke machine. Also, the egr and all the components were removed. I've tried multiple maf's and ecu's, replaced the rotor and the cap is good. I tried another external coil thing. Someone told me that since the head has been decked 2 times it could have changed my cam timing, so that my valves are opening differently causing me not to have enough vacuum? And to fix this i would need adjustable cam gears?Could this be why my compression seems low?

blo0d · 01-19-2011, 02:09 PM

1) how are u checking the fpr psi? maybe youre doing it incorrectly
2) also how much material was removed from the head? skimming/decking the head twice may not have a significant effect on cam timing if minimal material was removed in both cases

3) are you absolutely sure the cam timing is correct? incorrect cam timing can lead to strange motor behaviour

sidewaysil80 · 01-19-2011, 02:13 PM

i have had the same problem and thats exactly what it was. i needed adjustable cam gears because the head/block were bother decked 2x a piece. but i am not sure if that is your problem. if you are 100% timing is correct then that is def. a possibility.

KaT FTW · 01-20-2011, 11:19 PM

Quote:

Originally Posted by sidewaysil80

i have had the same problem and thats exactly what it was. i needed adjustable cam gears because the head/block were bother decked 2x a piece. but i am not sure if that is your problem. if you are 100% timing is correct then that is def. a possibility.

The fuel pressure was checked at a shop. I am positive that the timing is correct. Everything checks out, i dont know what else it could be. What adjustable cam gears did you go with? All that i have seen are JW that are like 140, these Tomei's that are 200, and some sketchy DIY that idk if i want to attemp.

01-18-2011, 11:53 PM	#1
KaT FTW Join Date: Dec 2010 Location: Austin, Tx Posts: 4 Trader Rating: (1) Feedback Score: 1 reviews	KA: Decked head changed cam timing I have a n/a s13 ka bored . 5 over, 10k miles on the rebuild. I was having some problems with it and turned out to be the head gasket, so i changed that and had the head decked before it was put back together. Did a compression test after it was done and was 160 across, i feel it should be more than that. Right now It runs real rich,but it has a brand new fpr, fuel filter, and pump. I had the fuel pressure checked and apparently was 2psi over stock, but you can see some black smoke out of the exhaust and it fouls plugs like crazy. Voltage to the fuel pump checks out and all the vaccum leaks were fixed with the aid of a smoke machine. Also, the egr and all the components were removed. I've tried multiple maf's and ecu's, replaced the rotor and the cap is good. I tried another external coil thing. Someone told me that since the head has been decked 2 times it could have changed my cam timing, so that my valves are opening differently causing me not to have enough vacuum? And to fix this i would need adjustable cam gears?Could this be why my compression seems low?

01-19-2011, 02:09 PM	#2
blo0d Zilvia Member Join Date: Jan 2011 Location: JAMAICA Posts: 206 Trader Rating: (1) Feedback Score: 1 reviews	1) how are u checking the fpr psi? maybe youre doing it incorrectly 2) also how much material was removed from the head? skimming/decking the head twice may not have a significant effect on cam timing if minimal material was removed in both cases 3) are you absolutely sure the cam timing is correct? incorrect cam timing can lead to strange motor behaviour

01-19-2011, 02:13 PM	#3
sidewaysil80 Nissanaholic! Join Date: Jun 2008 Location: NoVA Age: 38 Posts: 1,711 Trader Rating: (23) Feedback Score: 23 reviews	i have had the same problem and thats exactly what it was. i needed adjustable cam gears because the head/block were bother decked 2x a piece. but i am not sure if that is your problem. if you are 100% timing is correct then that is def. a possibility.