Vito's stroker +3mm crank and correct port timing

[Alex m]

Hello everybody.
I installed a Vito's stroker +3mm crank with spacer plate in my dt's engine and I would like to correct port timing myself.
Dt and Blaster engines are almost the same(same bore,same stroke) except some details like power valve etc...

At TDC everything is ok butt at the BDC the piston crown is 3mm lower than the bottom of the port windows.
Should I grind all port windows bottom about 3mm to match up the piston crown at BDC?

here is a photo with the piston at BDC


Uploaded with ImageShack.us

Thanks!

 

[bonzaiking]

normaly you put a degree wheel on with original crank make a map of the ports then put in the +3 crank put on the degree wheel and match up the ports like they were with stock crank you can play a bit with the speacer plate don't forget your squish!!!

 

[Alex m]

Sorry for being late to reply.
I put a degree wheel on , with stroker crank, 1mm thick spacer plate and two gaskets 0,25 mm thick each and I found that the Exhaust port duration is 194 degrees,the Transfer port duration is 127 degrees and Blowdown is 33.5 degrees. My target is about 10.000rpm so I think it's fine.

As you can see from the picture below at BDC the piston is lower than the port windows .Is that a problem?
I would appreciate any help!
Thanks!

 

[StrokedTater244]

that should be a real screamer.. i would drop the ports as you said. what squish and CR you setting it at?

 

[Alex m]

Deck clearance is near 0,head gasket is 0,8mm thick and the squish area had machined 0,4mm deep 12 degrees and 11mm.So squish clearance is 0,8+0,4=1,2mm.

 

[StrokedTater244]

Deck clearance is near 0,head gasket is 0,8mm thick and the squish area had machined 0,4mm deep 12 degrees and 11mm.So squish clearance is 0,8+0,4=1,2mm.

so your saying the squish is going to be 2.4mm? im confused with the commas instead of decimal points.

 

[Alex m]

Im sorry.I said squish is 11mm @ 12 degrees.
Squish clearance is 1.2mm

 

[StrokedTater244]

Im sorry.I said squish is 11mm @ 12 degrees.
Squish clearance is 1.2mm

cool............

 

[Alex m]

Do you think it's going to work well if I grind port windows bottom to much up piston crown at BDC?

 

[StrokedTater244]

Do you think it's going to work well if I grind port windows bottom to much up piston crown at BDC?

yeah i would only take them to the crown though..not the whole way down.. the bigger you make them the more velocity you will loose.. it sounds to me like it will be a really strong runner. have reserched about changing the angles at all?

 

[Alex m]

yeah i would only take them to the crown though..not the whole way down.. .. .

What do you mean not the whole way down?
I have read that piston at BDC should be higher or level with the exhaust port floor to avoid high speed gas flow disruption.
I want to grind all port floors to level with piston at BDC and correct high speed gas disruption.

the bigger you make them the more velocity you will loose

I know butt is it preferable to let the ports as it is?

have reserched about changing the angles at all?

No,since I don't have many experience about porting I would not change the angles.

it sounds to me like it will be a really strong runner

I hope so!
Thanks for helping me.

 

[StrokedTater244]

What do you mean not the whole way down?
I have read that piston at BDC should be higher or level with the exhaust port floor to avoid high speed gas flow disruption.
I want to grind all port floors to level with piston at BDC and correct high speed gas disruption.

I know butt is it preferable to let the ports as it is?

No,since I don't have many experience about porting I would not change the angles.

I hope so!
Thanks for helping me.

pm sent.........

 

[Surfrjag]

pm sent? but we all want to know. well i do...

 

[StrokedTater244]

pm sent? but we all want to know. well i do...

yours is in mr. mears' hands..it will be great!

 

[brandoz28]

yay for tech info! rep for you guys

 

[blasterbumkin]

pm sent.........

bump, anyone know the answer?