16 April 2011

how to correct the timing on your NC w forged crank?

Setting the timing with the motor in the car isnt all that bad depending on your idea of bad. Off the top of my head..here's the process:
-remove battery and tray
-remove airbox and ECU
-remove nose of car and under tray
-unbolt swaybar brackets and let swaybar lower a bit
-remove trans (optional, but makes tightening easier/possible)
-remove plug on side of block and install crank stop pin
-rotate crank CW till it stops on crank stop
-install flywheel vise to lock the crank down at TDC
-loosen crank pulley bolt
-rotate pulley so that alignment hole is at 6 o'clock and insert alignment bolt (M6x1.0 30mm)
-remove valve cover
-using a big wrench rotate cams so that the #1 cyl lobes are at 1:30 (EX) and 10:30(IN) and slots on back of cams are horizontal
-insert a ~9" lenth of barstock into the slots in the cams to hold their position. (i'll update this w the thickness later)
-tighten the main crank bolt to 100Nm + 90deg (or more??) Use the 3 stage method
-reasemble car

Reflections

I did a little un-scientific testing to see if there is a difference w tightening the main pulley bolt in one stage or in 3 stages as proscribed by ARP.
I tightened the bolt to spec, 100Nm + 90deg. I then loosened it and noted the force it took to loosen.
Then with a different bolt, I did the following:
- 100Nm >loosen
-100Nm + 45deg >loosen
-100Nm + 90deg >loosen and observe force

there was definately a difference between the 1 stage and 3 stage force it took to loosen the bolt. While this is un-scientific and I have no empirical evidence, I am certain that it took more effort to loosen the latter method.

What I will do the next time: 
-Start with a new bolt (actually I did this last time, this is just a reminder)
-apply a liberal amount of Loctite high strength
-torque using the 3 stage method
-my final rotation value will be more than 90deg...maybe 135deg or so..that is TBD right now while I look into it a little more.

The main pulley sees much higher loads with the blower than the factory intended, and short of installing a load assist (keyway) I think more torque is the ticket (to a point)

Incedentally, when I fixed my timing I saw boost levels drop. How much i cant be sure as I also went from a 3.0 pully to a 2.8, bit w the 3" the car made ~12psi and w the corrected cam timing and 2.8 pulley i saw 11psi! Talk about breathing better.... 

planning..

heres a price list of various associated parts from MazdaMotorsports.

new long block $3100
loaded head (no cams) $1100
09' valve springs $3.79 each
Valves IN $9.95ea EX $10.29ea
Engine gasket kit $150
09' pistons $72ea
09' ring set $57 set

ughhh..

It's not looking good....


Click here to see the rest.

Going to take it to the machine shop next week to see what they think

Mrrrr...

My car looks like this way too often

06 April 2011

Oh boy....this is getting old

So , I autoxd my car this weekend. Man was it strong. Need to dyno it still but what a huge difference. I placed 3rd overall. Not too shabby w my 235 Starspecs. 
Monday, after a 600mile weekend, on a datalogging run my crank pulley decided go it's own way. The crank pulley bolt loosened up and my cam timing was gone. so here is what the car looks like now.



I have not determined yet if there was any valve to piston contact, though I dont think so as everything looks ok from the top and the motor spins freely. Also I never heard a bang, crunch or otherwise. Hoping (though that is probably too soft a word) that I will just need to put a new pulley bolt in and retime the thing.

The weird thing is that I tightened the main bolt down to spec. 100Nm and then 90deg. Not sure what happened. I talked w Cosworth to see if they had any tips and they said that they use loctite on the bolt but still tighten the bolt to factory spec as I did. Ugghh