Thread: 355 build HP and Torque?

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Originally Posted by rollie715

So now what do I do to balance them if needed?, or is that close enough?
Do I match the larger ones and remove 1cc material from the 2 smaller chambers? I read about "sinking a valve" on another racing site. Should I have my machinest grind the exhaust seats a little on those 2 chambers to make them even? Actually I'm wondering if my measurements could have been off just enough, to not worry about it and assume they are all pretty close as they stand.

For a street driver motor, I wouldn't worry about the 1cc difference. The only reason I'm expanding on this is because of your eagerness to learn.

What I would do is to sit the heads on a flat and level surface with the chambers down and stand up the edge of a straightedge on the top of the valve stems to make sure that none of the valves are installed shorter or taller than the other ones. If the valves are reasonably the same height from the deck, then measure from the bottom of the straightedge to the surface where the heads are sitting to see if they run downhill or uphill from one end of the head to the other. This will require that you use a buddy to hold the straightedge while you place a standard under the straightedge at each end of the head, right up against the head and measure the difference between the top of your standard and the bottom of the straightedge with feeler gauges. I'm trying to explain this so that most anyone reading it can do it without the use of precision tools which they may not have. The standard can be anything that is flat on the bottom and offers an area on the top where you can insert a gauge blade between the standard and the bottom of the straightedge. When I was a young man with few tools, I used an upside-down drinking glass from the kitchen. Use the same glass on each end of the rule of course and measure at the same place on the glass bottom. You might mark a spot where you will measure with a Magic Marker or Sharpie. Of course, to do this properly, you should measure all valve lengths with a 6" dial caliper or other suitable tool. If you don't have one and can't buy one, have a buddy measure them or go down to the machine shop and pay 'em their shop fee to measure them for you. You will want to measure the margins also and see that you have a matched set of valves. As good as it could get is that the two small chambers could have the valves closer to the deck than the other valves in the other chambers. Then you could cut the seats a little to equalize the distance from the deck to the seats on all valves. Then you'd equalize valve stem heights and you'd have a set of blueprinted heads.

I've read that the L31 design was reached only after GM engineers tweaked for six months on their best Corvette LT1 chamber design. THEREFORE; RESIST ANY NOTION YOU MAY DEVELOP THAT INVOLVES GRINDING IN THE CHAMBERS BY YOU OR ANYONE WHO DOES NOT HAVE A DOCTORATE IN FLUID DYNAMICS.

Originally Posted by rollie715

At this point I am assuming the heads don't need a valve job, although I do plan to do a simple fine lap job on the seats, after they check out on the magnaflux and then pin the studs and install the beehive springs.

Check carefully what the angles and the dimensions are on the seats and valves. I've read from more than one source that the valve job from the Chevrolet assembly line is about as good as it gets and contributes greatly to the flow of the heads, so, you don't want to fix it if it ain't broke. If they held the fluid for you to do the cc procedure and didn't leak into the port, then leave 'em alone, assuming they're low-mileage heads. Number the valve faces upon removal so you can keep everything in order upon reassembly.

Originally Posted by rollie715

Using 65.5cc and 18cc dish pistons, and a .040 quench, I calculate an 8.90 SCR and 8.08 DCR with my new cam calc of 29 IVC at 0.050.

Wow!, Look at all those numbers I'm throwing around, that I had no clue about a few months ago.

LOL, funny stuff. Reminds me again that I should have been a teacher. Not all is lost though, I'm able to contribute in my own way.

Originally Posted by rollie715

I think my next step is to finish stripping the block, taking it to the machinest, verify the bore size and order the pistons.

Sounds ok to me.
In my opinion, you'll be better off in the long run if you can save the cam bearings by not using a caustic cleaner on the block. The shop will want to replace them because that's how they make their money. You, on the other hand, should be making your decisions by what you can afford to do that will still offer a good service life. I got tired of all that expense of changing cam bearings on street motors and the fact that usually, the replacements were slightly small or slightly large or slightly narrow or whatever. The ones that the factory put in will work fine for a long time and I would only replace them if there was excessive play between the cam journals and the bearings. There are more than likely fellows on here and other places who will tell you to change the cam bearings every time. If they make more sense to you, then follow their advice. I just know what works for cheap for me.