it runs 34 degrees i think (will check) at certain points, i will definately take a touch out. It is all in the ECU so that is easy enough.

Its the inlet valve side of both piston 3 and 4 that has the scraping marks up the sides. they are rooted!

Exhaust valves look to of got quite hot, thats why the damage would be on the rear of the piston, I would put it down to timing over advanceing.
How do you alter your advance, through distributor or computer? I know that about 36 degrees is that max total spark you'd want to run in any datsun motor regardless of compression fuel or initial timing settings.

I milled 80 thou (2mm) off the head a while ago, seems to be the same amount that BigE milled off my super duper head, so i'm assuming its not too bad. not sure on comp tho.

pulled the bottom end apart and found that both piston 3 AND 4 had the marks similar to the pic that benny posted on the previous page.
the scraping damage is up the inside of each piston as in the bit that faces the other so the thin part of the bore. why would it do it on this side only? no pinging evidence on no. 4 piston.

will take bits to cylinder head guy to get checked over tomorrow hopefully

Is it possible for inj to be blocked or not firing as it should?
It wouldnt help with heaps of comp either, not to mention fuel quality.

a little too much comp perhaps?? there heaps milled off that head...

thanks for your condolences fellas, made me shed a tear ;)

interesting yours benny, my piston i think will look similar. It has scored the bore up towards the firewall end, bottom end is still together been flat out this weekend. here are some pics. i'm going to get the injectors flowed and tested but i suspect it was a bit too much timing for the old girl.

interested to know if anyone can read anything out of the colour of the valves. There is a big carbon buildup on the pistons which can't have helped and heaps of carbon on the back of the valves.










pic of the manifolds installed, no relevance to buggered engine, just looks cool :)

Sorry to hear the bad news, but i guess any excuse for a displacement increase is a good one. Cant wait to hear how the a15 wil go! good luck

it wasent running lean on that piston???
cherping could of been air leak on that piston???head gasket leak??
my show up rich at senser, because its the mix of all four
need to check exhaust temps,make shure all temps are even
no good to here,NEXT.
thinking about tods 1000

Thats a bit of bad luck Leigh, The car got you home though, didn't it? So technically it hasn't let you down yet haha.

I managed to cook the #4 piston on my track car several years ago, as a result of high RPM lean out. Since running A-series for a lot of years now, I have taken note that they typically run hottest in number 4 and progressively cooler in the adjacent cylinders towards the front. I would interested to know what happened to you engine. In your case I doubt its fuel lean out, as you running efi, but excessive heat and ign timing maybe the contributing factors.

Was the head gasket a quality item? I guess time will tell with your investigations.

For a bit of comedy value, this is a pic of the piston I killed in my A-series.




cheers
benny

The wideband a/f meter is a kit i bought years ago from a place called techedge. its a data logging kit with an led display but i just use the led guage display. i'm yet to use the data logging feature.

the wheels were cahnged for the trailer camping trip :)

I've been aiming to be in the high 12's under load so 12.5s should have been real safe. I'm going to get my injectors flowed and cleaned as number 3 cylinder is shot with detonation. thats one area i can rule out easily, im a bit puzzled as to why it would happen and without me hearing any of it! maybe the induction bark is too loud!

so far cyl 3 is detonated to buggery, the piston is stuffed but the head looks to be ok. It also blew the head gasket between cyl's 3 and 4.

i'll get some picks up when i get back home on sunday.