How much can you take off of the chamber to sweep it out for
reduced shrouding of the valves?

I read that you can sweep out to the gasket line - is this correct?

I've got the block bored to +0.028". I think the gasket is +0.166"

Thanks

 

What casting? The factory did that on 2.02" intake valve heads with 64cc chambers. They did not do it to the bigger chamber heads as they were pretty much thin cast open chamber emissions style and it was not needed. You can cut out to the same diameter as the factory but I do not know the dimension at this time, sorry. I would not cut much past the bore and definately not out to the gasket.

-Mark.

 

The heads are aftermarket 2.02 64cc torquers from ProTop line.
They are like the world torquers...

 

with stingr, no need to open chamber larger than bore size - or ur asking for sharp edges, hot spots and problems. In fact i would look for a tighter fitting head gasket to match closer to the bore for the same reason.
I think ur saying u want to unshroud the vlvs and i got this done along with the pocket porting on mine. It's not a major operation if the machine shop is set-up for this. Just a cutting tool that swings on the vlv guide center. Similar to the pocket port tool used. Very little blending by hand needed with the right machines and tools. Well anyways they cut my chambers just out the bore line - but only near vlvs. Head cast for 67cc chambers came out to 68cc-69cc after cutting.
But the big guys (Vizard, Lingenfelter) say its easy enough by hand too. But please use some more hp and carbide cutter rather than a little Dremel tool with stones. And practice on the old heads would help - if u still have them.
The big disision here is cost. As u get close to $1000 dollars its much easier to buy some good Trickflow or Edelbrock aluminum and just bolt on as is.
Good luck and post some pix. cardo0

 

Coat the heads with Dykem Blue and bolt onto block and bring chambers out to bore line, no further. You will have problems keeping a head gasket on if you go to the gasket size (with conventional gaskets and the "fire ring" steel embossed sealing.) You can also radiuus the tops of the cylinder block bores to the gasket edge to unshroud the intake valve but, be careful how far down the bore you go and leave the top piston ring some area above the relief, at least 0.100" (Chevy does this at the factory on some big block motors check one out for an example of how far to go down the bores.) The reason you can go to the gasket outline on the cylinder block and not risk gasket failure is because it will remain protected by the cylinder head but, if you bring the combustion chamber out to the gasket BIG PROBLEMS will happen to the head gaskets, don't ask me how I found this out, it is a long story.) The combustion chamber wall on the sparkplug side can give some big returns if it is the "305" style or cylinder head. The process of unshrouding the combustion chamber is easilly done with a Sunnen VGS style cylinder head machine and will be consistant to the point you wont have to check the final volume of you combustion chambers and equalize them again (a long a boring job if you have ever done it like I have.) Some people wonder why my 355 cu/in Chevy makes 373RWHP on a Dyno-Jet and I'm giving you some of the reasons why here, HAVE FUN!