RotorsRulePistonsDrool

Okay, I know I post on here a lot, but I truely try to only make a thread when I am puzzled. So my engine seems to knock very hard under heavy boost presure. At first it was only a slight knock at the top of 10psi. So I retarded the ignition map according to 10 psi seemed to *help. It still knocks at 10 to 14psi when trying to do a pull. So I further retarded the timing and now its to the point that all of the psi settings of timing change are in the -30's and still knocking... There was a setting for pump 2 timing adv I believe and it was set to positive 5 degrees. That makes me wonder if I should advance the timing from where stock values (all psi only under 10 degrees on the psi map) were to get rid of knocking on a rotary. If all else fails I will try to install water/meth injection to stop it.

I have tried resetting the cas, but maybe I am doing it improperly because the cosmo timing marks on the pulley etc are not the same as everyone's marks on an fd pulley.

Anyone have some tips to my timing/knocking malfunctions?

thanks

Aaron Cake

iTrader: (1)

Start by finding true TDC and verify your pulleys are correct.

What is your setup? Any ignition boxes? ECU?

RotorsRulePistonsDrool

There are many threads on finding tdc but I have found varying results from trying each of them. What do you recommend as the best way to find tdc?

The cosmo pulley doesn't have the same markings on it as the fd one. Should I just buy a used fd one or aftermarket one to get better results?

My setup is stock cosmo 13b engine, stock twins, stock injectors, no wategates (pinned them for free floating turbo setup), greddy bov set to very soft for safety, and microtech lt10s w/ x4 box.

The knock is pretty heavy. I have tried higher octane with no result as well.

Aaron Cake

iTrader: (1)

Position the eccentric so that the front hub keyway is at 9 o'clock. That's TDC.

Shouldn't matter which pulley you have as long as you can mark TDC on it.

flaco

iTrader: (7)

is tunning for sure . just take it to a good tuner

bumpstart

you have timing less than 10 degrees BTDC yet it pings at low boost ?

normally i would say-

you either have plug wires **** about
the engine timed 180 out ( can happen when you add gilmer pullies )

or you have seriously misjudged TDC

but you mentioned the issues came on slowly,, and previously it ran to 10 psi before it had issues
if the problem has got progressively worse,, then i would blame fuel pump or injectors

flaco

iTrader: (7)

is the timing moving on the screen???

RotorsRulePistonsDrool

Aaron your method was perfect. There was a couple things wrong. I pulled thep ulley. moved the shaft till the 9 position. Put the pulley on. put the eshaft in pretty good. Followed microtech's instructions and the pulley moves clockwise when revved. The timing static functions were also on zero.... Fixed that and gave her a test ride. No more knocks at all and a ton more power. Thanks! I'll post up a new thread on my next issue...

Aaron Cake

iTrader: (1)

Did you follow the instructions for safely removing the front hub? Hopefully the torrington bearing is still in place.

RotaryEvolution

iTrader: (30)

assuming the marks didn't line up indicating the hub and pulley weren't matched properly? i'd try to find a match set so that it can be timed better than by eyeball.

RotorsRulePistonsDrool

Well I have no idea what that bearing looks like. I just undid the crank bolt, turned the pulley to make the keyway move then put the pulley on back to the torque spec. HOw will i know if this bearing is out of place or fell out? Can you show me a pic of this mysterious bearing?

Aaron Cake

iTrader: (1)

Measure the end play of the engine. If it is now zero, the bearing has dropped. Also if the main pulley doesn't line up any more with the water pump pulley.

RotaryEvolution

iTrader: (30)

don't forget about the distinct crunching noises.