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[69shovelsled]

So I have a 04 screaming Eagle 103 and I bought weisco dome 103 .060 pistons. Will that dome work with those heads? Or am I going to have to mill the dome off?  I read somewhere they won’t work with those heads because of the chamber shape. And also what lift can the springs handle?

Thanks in advance

[johnsachs]

Will NOT WORK. SE 103" heads have a round chamber shape. Standard RPO 103"  heads, have a bath tub shape. Before you start removeing the dome, you better check the thickness of the piston in that area,( top of dome to under side of the piston ). What cam set/grind are going to run ? You can mill your SE heads up to .060", without needing to remove material from the intake pads.
RE VALVE SPRINGS: What cams are you planning to use ?  IIRC, your 103" SE Cams, CVO 253, have a max lift of .530". If you are NOT going to use cams with more than .530" lift, the SE springs will work. And DON"T believe the NONSENSE, that the SE Springs are " bad/junk/too much tension ". I've built an untold amount CVO engines, with those springs, and NEVER had an issue.
John

[69shovelsled]

The cam is 598 mackie. We got springs for it. Kibble white.
    What is the reason the dome pistons won’t work? Too much compression? I don’t see them having any head interference? That mackie cam needs ALOT of compression because it bleeds so much off. Thanks for the reply


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[johnsachs]

The cam is 598 mackie. We got springs for it. Kibble white.
    What is the reason the dome pistons won’t work? Too much compression? I don’t see them having any head interference? That mackie cam needs ALOT of compression because it bleeds so much off. Thanks for the reply


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From what you posted, it sounds like you have dome pistons for the "Bath Tub" style chambers. You need "Hemi" style pistons for the round style CVO heads chambers.
Post a picture of the piston and the combustion chamber.
John

[69shovelsled]

You are correct, i machined the dome off of them. They are good to go now.


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[johnsachs]

What compression did you end up with ?

[HD Street Performance]

I have milled the heads further which forms a perimeter squish band which required intake flange faces to be cut on the heads. These engines had about 8.3:1 compression with a flat top piston from the factory. On other builds I have used Arias pistons that can be purchased from CP that fit the chamber and even regular domes for the bathtub and they work as long as checked for clearance to gain compression. On a few occasions I have even welded the chamber sides and made kidney shaped chamber similar to the water cooled heads on the 2015 models. Respect to John Sachs, he is a good builder and knows these engines well also.

[69shovelsled]

How much could I take off the head to get around 10:1 compression? Thanks I was going to just run the pistons but he acted like they wouldn’t work. Honestly I’m over this build it’s been plagued from the start. I’m probably going to just bolt it together I really don’t give a chit anymore.


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[69shovelsled]

I think I’m going to take .060 off the head like John said because the cam I’m running needs compression. Needs 10-10.5 somewhere in there. I have .030 head gaskets and the piston isn’t quite flush with the cylinder.


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[HD Street Performance]

Have patience and act logically. These engines actually have good potential. Sometimes a little help from a shop is smart to help these projects win.

[69shovelsled]

Playing with a compression calculator I will need a chamber volume of 85 ccs to get 10:1 compression. I don’t know how accurate this is. Stock is 95cc correct? But my question is if I take .060 off the heads what will that make my chamber volume? I appreciate the help. I apologize for getting flustered. I can mill the throttle body but I don’t really want to. I just need to get the compression up for this cam.


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[HD Street Performance]

In the ballpark but the only way to do this properly is by fluid checking and creep up to the desired volume. Consider a .027 head gasket to help a little if your pistons are below the deck at TDC. Measure that for accurate calculations.

[69shovelsled]

I think I can get it close to 10:1 pistons are .016 down in the cylinders. I’m just looking for an apparatus to figure out the chamber volume. A burret would be my best bet. 

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[johnsachs]

If you have any interest, I have a set of 103" (stock bore) Screamin Eagle pop up pistons for the heads(HEMI) on your SE 103". If you have had boring, or head milling done, they WON'T work. I can send pictures.
John

[69shovelsled]

Yea they have been bored .060 over to make it a 107. I got it sorted out. Had .058 milled off the heads to achieve a 81 cc combustion chamber. We’re at about 10.5:1 so I think that cam will be happy.  Once I get it together I will share the results. But I’m a lot happier with the results now.


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