Hi all

l recently built a y block with mummerts advise and expertise these yblocks are pretty good and very high reving engines
forged pistons mummert suppled rods cam heads manifold 750cfm dp holley c4 conversion and a 9inch LSD and l have to say lm
impressed and they sound better than any other V8 out there

YB Billy: re the intake side milling. I got confused on that one also. Re read his post. Ted said to apply the 1.4 ratio cut "after" 0.030, not on the total cut.. However, your method comes out about the same..  


Paul

We've been going at the static compression ratio thing, Babor.  As you likely know, your engine's dynamic compression ratio really determines the maximum static compression ratio you can get away with for the fuel you plan to use.

One of the references that has been previously suggested here to use as you contemplate your build is the dynamic compression ratio calculator at

http://www.wallaceracing.com/dynamic-cr.php

Dynamic compression ratio is a measurement of the swept volume of the cylinder and combustion chamber area when the actual compression of the air-fuel mixture commences when the intake valve closes after bottom dead center on the compression stroke compared to the volume of the area above the piston when it is at top dead center in the cylinder.

NOTE:  the volume above the piston in the cylinder when it is at top dead center includes:

-    the recess of the piston in the cylinder bore below the block deck

-    the cylinder head’s combustion chamber volume

-    the volume of the area bounded by cylinder head gasket thickness

It has been amazing to me how WHEN the intake valve closes after BDC so significantly affects how high a static compression ratio my engine will tolerate.  With the information I've previously gotten from Ted Eaton, for my purposes (street and highway) and with 91 octane pump gas, I look to stay at 8.0:1 dynamic compression maximum for reliability purposes (no detonation) due to the quality of gas in my area.

Regards,

NoShortcuts
a.k.a. Charlie Brown
near Syracuse, New York

Ted, 1.4 times .050" = .070"
.54 X .050" = .027 I thought it was somewhere around there.

55 Vicky & customline

58 Rack Dump, 55 F350 yard truck, 57 F100

59 & 61 P 400's, 58 F100 custom cab, 69 F100, 79 F150, 82 F600 ramp truck, 90 mustang conv 7 up, 94 Mustang, Should I continue?

Before attempting to mill any Y cylinder head, be sure to measure the pads at the outer edge under the spark plugs.  These are typically 1.000” as delivered from the factory and anything measured that’s less than this will be a good indication of the amount that those particular heads had being previously milled.

Lorena, Texas (South of Waco)

I just milled a pair of G heads .030  They cc'd out at 63. 

The first 0.030 that’s milled off of the heads will not require any milling to compensate for intake manifold fit assuming that composition head gaskets (recommended) are being used.  After 0.030” of head or deck mill, then mill the intake side of the head 1.4 times whatever is taken off of the deck surface of the heads after 0.030”.  For example, if the heads are being milled a total of 0.050”, then mill the intake side of the heads 0.028”.  Any milling of the decks also counts into all of this.

Lorena, Texas (South of Waco)

Cool! Thanks Billy! I was wondering about that because we are likely going to mill the heads but haven't completely decided yet as it could later wind up with a blower or twin turdblows. More than likely N/A or Blown though as I think I am going to run ZOOMIES! 

Charlie, Babor, You can have the heads milled on the intake surfaces instead of having the intake milled, that way any intake will fit, can't remember the exact figure but I thinks its .64 or .54 of whatever the head surfaces are milled, maybe John or Ted knows this figure off the top of their heads.

55 Vicky & customline

58 Rack Dump, 55 F350 yard truck, 57 F100

59 & 61 P 400's, 58 F100 custom cab, 69 F100, 79 F150, 82 F600 ramp truck, 90 mustang conv 7 up, 94 Mustang, Should I continue?

That is AWESOME news! Thank you for your response! I think I will likely just do some cleanup work after reading this and researching a little. Probably just have him do the basic bowl blend and de-burr the ports and finish with a medium grit polish for atomization as well as setting up a spring set for the camshaft. I really need to find another transmission now as this will be a street/strip rig with a little more weight than a rail. Any cost efficient ideas???