Gen2 Head milling inquiry...

[WESTCOAST JASON]

A 98 that is stock with 11k miles started mixing water/oil and smoking. After removing the heads, the gaskets SEEM like they did not blow. Putting a straight edge along the heads does show that they may be warped. The passenger side head bolts were substantially less torqued than the driver side (noticed during removal) The question is can a stock head be milled a little without drastically affecting the compression or the alignment of the intake during the re-install? Thanks

 

[Greg Good Cylinder Heads]

You can mill up to .025" without incurring manifold to head fit problems.

It takes .007" stock removal to lose 1 cc on a Viper head. Let's say you milled the heads .021". That would reduce your chamber volume from 75cc's down to 72cc's and raise your compression from 9.54 to 9.82. Still fine for pump gas.

 

[WESTCOAST JASON]

Greg, thank you for the info. Are the head gaskets re-usable? thanks

 

[Greg Good Cylinder Heads]

I would get a new set of gaskets. I don't of anyone re-using the stock units but I would like to see it tried. The stock gaskets are of a 3 layer embossed steel construction similar to the new Cometic brand of gaskets on the market. I know guys that re-use the Cometics.

 

[WESTCOAST JASON]

Thanks again Greg. I was unsure but figured in theory that they could be used again if not damaged. A new set is present for the re-install though....

 

[Dyno Dave]

Check the cylinder liners in the block to make sure they haven't sunk. They should be flush with the deck.

 

[WESTCOAST JASON]

Thanks for that tip. I will. The heads should be back from the shop on Monday. As a point of curiosity - can these headgaskets be stacked to reduce compression?

 

[GR8_ASP]

In general no. That is the cylinder head and block bending that occurs in order to produce adequate fire ring (or stopper for MLS) pressure would be doubled. That is generally not good for valve seat distortion, etc. A better way is to add an additional inactive layer on the flat side of the center layer (stopper). The stopper is the folded over or slightly thicker portion directly around the bore diameter.

Note this is coming from a general knowledge of MLS gaskets and not Viper specific.

 

[WESTCOAST JASON]

Thanks for the reply on that. Other than the factory gasket, does anyone make aftermarket gaskets of different thickness?

 

[Greg Good Cylinder Heads]

Jason, in my opinion, if you need to reduce the compression ratio it would be best to make the combustion chambers larger, not stack gaskets. I don't think stacking multilayers steel gaskets would even work.

Figure out what compression ratio you want and we'll figure out what chamber volume you need and you can have a reputable head porter in the area do the work.

 

[WESTCOAST JASON]

Thanks Greg! It was actually just a theoretical question I never had answered way back in the early days of doing Turbo's on my car.

I appreciate the offer of assistance! That is what this club is all about.

 

[Vipermed 97.01]

Jason, Greg is absolutely right,I opened mine to about 77cc which will bring you to about 8.5:1.Thicker gaskets will lower compression,I dont believe that i would try stacking OEM gaskets.But the proper and most reliable way would be your combustion chambers