Combustion chamber volumes in stock heads exist within a range, due to casting tolerances. I"ve seen a little over 2cc variance from one end to the other of the same head.. so they're far from perfect to begin with. Which is of course why blueprinting some engines brings more power gain than others. Only way to know for sure is to CC 'em and then average the numbers across all chambers. BTW, over the years, valve jobs can sink the valves and increase chamber volume; conversely, surfacing the gasket surface area will reduce volume....lots of variables. Not to mention that the decks aren't exactly parallel either.. unless of course you spent the cash to get them that way. Usually most folks want to know chamber volume so they can compute CR.. and IMHO, the only accurate way of computing SCR is to quantify all volumes with a large syringe or CC'ing buret. Even the type and heat range of spark plug used has a slight bearing on this equation. When in doubt, go for the high side of the spec....most likely it'll be closer to reality. PS.. there are some thinner head gaskets out there as well and can be well worth the money of the engine is tuned for the increase in CR. And I'm with baddad on the 1.94 valves for milder street based builds since they give slighlty better response and less shrouding on small bore motors.
Ok so the 194 valve heads it is... I just got a quote from a local machine shop... $650 dollars to build my 30 over short block....
very good question above. IMHO, that seems a bit steep if it's purely the cost for the machine work and putting it together. Unless of course it includes plugs/bearings/seals and is nearly fully blueprinted afterwards.. in which case I'd actually be leary of such a low price.
I will get the details when I go see them... so far I know, hot tank the block and clean it up, bore it 30 over and install new pistons and rings... Also new cam and main bearings,freeze plugs....
Am I the only one on this forum that doesn't add the over-bore to the cubic inch displacment? To me...a 302 + 0.030 is still a 302 that had to have the cylinders cleaned up. Now if you stroked the crank...then I can see adding more numbers to the cubic inch displacment. I'm not trying to step on anybody's toes but I'm the guy who doesn't call a Tracion-Loc a Posi or a Rack and Pinion kit a Mustang II front end
Boring the block adds to the cubic inch displacement (however slightly). It's just a fact of life. My engine is a 306, like it or not.
Agreed, go the drag strip and tell them it's a 306 & 99% will know exactly what it is... You guys that are going to the trouble to say it's a 302 punched .030 over, need to hang with a more knowledgeable crowd... BTW River Rouge never cast the first small block
You are the only one. I like telling people I have a 306, some people have no idea...you should see the look on their face.
Well, here's something for you to ponder: I've got Chevy "327" fender emblems gracing either side of my Boss 9 hood scoop. A 331 is simply a .030 over 327. Same stroke, same (std) bore for both. I get very few questions now-a-days regarding the emblems, seems the liter designation has taken hold after 30 years of use. I guess I could just call it a 5.4 Tripower instead of 5.4 Triton
That's not a bad price then, considering a factory reman usually costs more, but does that price include the parts ? Or just the labor ?
