:::RHMT::: Real Home Made Turbo
General Category => Hybrid/Tech => Topic started by: 92CXyD on April 24, 2025, 01:44:37 PM
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I'm worried my math maybe wrong:
d15b2 block has crower rods and vitara pistons and block decked 0.080" (about 2mm) so block is 205mm tall.
Head surfaced 0.010" or 0.254mm
Delta 272-2 cam is y8 based cam.
Looking at https://www.d-series.org/threads/y8-cam-w-z6-sprocket-z6-cam-w-y8-sprocket.41363/
(https://www.d-series.org/cdn-cgi/image/format=auto,onerror=redirect,width=1920,height=1920,fit=scale-down/https://www.d-series.org/attachments/1745514578153-png.148659/)
I advance cam 4.5 deg
Looking at https://www.d-series.org/threads/ignition-timing-cam-gear-timing-timing-belt.14790/ post #11
(https://www.d-series.org/cdn-cgi/image/format=auto,onerror=redirect,width=1920,height=1920,fit=scale-down/https://www.d-series.org/attachments/1745514520330-png.148658/)
I advance cam 5 to 8 degs
I'm using y8 crank pulley and a z6 based adjustable cam gear.
I also adjust cam gear to y8 zero since vtec head on d15 block use a y8 cam gear to correct.
Eye balled using a y8 gear over the adj gear with cam gear center bolt out to line up keyway.
Then I mad the above adjustments, and the engine still cranks and no start.
So now I'm questioning my degree math.
Valve lash has been checked
I'm getting spark, fuel and compression but the timing events seems slightly off.
I was seeing a low vac reading from map at -4" hg, but advance the cam in 10deg territory and was seeing -9" hg now.
This is a fresh engine never been ran
So is my math for timing off?
Anybody got ideas?
Oh and another thing these posts talking about advancing and retarding is always in degrees on adjustable gear. As in 1 tic mar is 1 deg or do they mean 1 tic mark is 2 degs?
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i believe each tick is actually a few degrees, let me see if i can find a thread i used to make a degree wheel and figure it all out.
https://www.d-series.org/threads/diy-degree-your-cam.108399/ (https://www.d-series.org/threads/diy-degree-your-cam.108399/)
you can print a degree wheel stick it to card board and figure it all out. might not be the answer you were looking for cause i know people used to just know use this cam with this block etc but i remember just learning how to figure out the whole event.
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i believe each tick is actually a few degrees, let me see if i can find a thread i used to make a degree wheel and figure it all out.
https://www.d-series.org/threads/diy-degree-your-cam.108399/ (https://www.d-series.org/threads/diy-degree-your-cam.108399/)
you can print a degree wheel stick it to card board and figure it all out. might not be the answer you were looking for cause i know people used to just know use this cam with this block etc but i remember just learning how to figure out the whole event.
Perfect I can do that in my car.
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Got it fingered out, had to advance cam 12tic marks or 24 deg crank.
She runs but wastegate exit to close to oil pan for comfort.
Got to do some more fab work, and I may have this pig street tuned by end of month.