Re: Piston Dome Volume Determination

Posted by dr.sportster on November 20, 2006 at 17:51:56 from (67.72.98.85):

In Reply to: Piston Dome Volume Determination posted by Aaron Ford on November 20, 2006 at 16:17:27:

The only way to cc the comp ratio accuratly is to use the piston installed.Place a degree wheel on the motor.Use the positive stop method to zero degree wheel.put modeling clay as a ring seal with piston at TDC [rings on].then fill comb chamber all the way[noting exact amount from cc tube].Then bring piston to BDC[take off head and check sealing of modeling clay and fill the comb.chamber and cylinder[noting that amount].If you measure the cyl volume then fill the head off the motor you are not taking into account the squish area at TDC.I have found that trying to calculate squish area gives innacurate results.It doesnt take many ccs to give a half a point of compression inaccuracy.The trick thats the hardest is to get the spark plug hole to be the highst point of filling.The thinner the fluid the faster it will drain from your cc tube but then you risk leakage around rings if its too thin.I use tranny fluid and some parts cleaner to help it along.Then save it in a container marked cc fluid.I have tried to measure the piston domes alone using mdoel clay in a candy tin and when you pull it out of the clay it gives a little causing innacuracy.If you use the method Ive stated you will get the real deal.If you measure it as separate parts youll be close within maybe half a point of the real ratio.On some motors its very hard to get the spark plug hole as the highest point without it laying down and alot of wood shims etc.

Replies:

• Re: Piston Dome Volume Determination dr.sportster 18:17:50 11/20/06 (0)

Add a Reply Name: E-Mail: Subject: Comments: Optional Link URL: Link Title: Optional Image URL: Email Notification: If you check this box, email will be sent to you whenever someone replies to this message. Your email address must be entered above to receive notification. This notification will be cancelled automatically after 2 weeks.

TRACTOR PARTS	TRACTOR MANUALS

We sell tractor parts!  We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today. [ About Us ]