Murphys Romance Racing

[pro70z28]

Good to see them stand behind the products. Goota' news.

[Lippy]

You'll get it Murff!!

[Murff]

Well, we're back in the game (he said optimistically).

Pistons re-re-re-arrived yesterday. Took them to the machinist straight away and lo & behold they actually fit the chambers. Of course the vendor neglected to inform me just how much of the dome they carved away in CC's so at this stage I have no idea of actual CR.

I had machinist shave .020 off of the heads so I pick up a little uder 3 CC's there, then when everything comes back from the balancer (2 - 3 weeks) I will CC the domes to to determine where I'm at. If the .020 off the heads turns out to be too close I figure I can fudge my gaskets a bit.

What's the best (easiest?) method for CCing the domes? I've done chambers before but not pistons. Modeling clay over the dome and then fill & measure the depression? 700 laser beam digitizer? Ask my dog?

Help?

Murff

[draglist]

Good luck, Murff. bp

[greenracing]

Get your handy dandy dial indicator and set it up on the top of the piston. Put the piston at top dead center. Rotate the crank and watch the dial indicator until the piston has moved down an inch.

Put some grease around the piston - just enough to seal it up so the oil doesn't run down the hole. (a little tiny phillips screw driver works good to push the grease down around the piston and seal it up)

Put your CC plate on the deck and fill it up.

Now take the measurement and subtract the volume of 1" of cylinder and you'll have your dome measurement. This will give you 0 for a flat top, a negative number for a dome, and a positive number for a dish.

Of course you have to convert things to centimeters and all that - here's the formula:

CCdome = CCmeasured - (((bore x 2.54) x (bore x 2.54)) x PI x 2.54) / 4


Then the overall C/R:

Vup = CCchamber + CCgasket + CCdome

Vdown = Vup + (((bore x 2.54) x (bore x 2.54)) x PI x stroke x 2.54) / 4

CR = Vdown / Vup

[Murff]

Thanks Perry, I think I can muddle my way through that. Good instructions, the muddling part will be my contribution.

How goes your crank search? Sure wish I could help but I just don't know anyone with hemi stuff laying around.

Our 'freshen ups' seem to have some similarities tho', don't they?

Thanks again.

Murff

[greenracing]

Yeah - surely some similarities - on the frustration level anyway

I'm taking the crank over to another shop this afternoon - this shop is better known for higher end drag stuff - we'll see what they can do. (teach me for trying to take the fast/cheaper route eh?)

[Murff]

Call from Speed Shop today, it is all done and ready to pick up. Saturday morning we grab the truck and go bring it all back home again. Been so long I had about given up.

Machinist found more discrepncies from the last machine shop I used and they're the types of things that can cause trouble trying to tune. Pretty sure I was leaving a lot of power on the table. Like Perry the quick & cheap route has ended up costing more in the long run.

The plan is to get everything home, sorted out, order up some gaskets and such, and then take a weeks vacation to fit and assemble with no distractions.

Might just be able to make some noise here in a month or so.

Murff

[draglist]

Good luck, Murff... bp

[jim sanders]