Definitely need to rebalance your rotating assembly regardless of piston choice. Don't let anyone tell you it's not necessary. I also agree that spending the extra time and money on making a stout short block is definitely worth it. You already have some expensive parts in your build. Do it once, do it right. You'll forget about the debt on the first burnout!
340p.030 Pistons net about 9.3 with .040 fel pro gasket. .020 off block is about 9.75. Should be enough compression for that cam. Get harmonic balancer rebuilt also. Safe insurance.
Here for the umpteenth time is the DCR article with downloadable calculator. http://www.empirenet.com/pkelley2/DynamicCR.html Here are the engine specs from TA's website. If you want to zero deck any motor, you work with your machine shop. That is their stock and trade, measuring things and precisely cutting milling to your specification. You tell them what compression you want, then they tell you what they have to do to attain it. You tell them that you want to buy a set of customized pistons and you consult with them about compression height to achieve 0 deck, or .005 if you prefer. So lets do a little calculating. Here is your .030 over 350 using a piston that gives you .005 deck height. Our aim here is 9.5:1 SCR. With the TA 212 cam installed at a 106* ICL, that gives you right around 8.0 DCR. Here's an example of a possible engine. Then we figure valve timing, Now, Dynamic Stroke Length, And finally, DCR.
Who rebuilds harmonic balancers? Thanks Larry for all of this. Only wish I knew what it all meant. I'm a engine building novice and don't know all the terms and tricks
Todd, It isn't rocket science. It's just a matter of learning. You have the knowledge of the world at your fingertips. You have a computer. Even just buying the Chassis Manual for your car and reading through it will give you the basic knowledge you need to understand everything else in this thread. I've never built an engine in my life, but if I don't understand something I see, I research it, with Google, and I read up on it, and I ask questions until I do. I typed" rebuild harmonic balancer" into Google and got this, https://www.damperdoctor.com/
Thanks for all you guy do for us lesser informed persons. I did google it and came up with the same results. Didn't know if there was a Buick guy doing it. My dampners rubber section is all cracked up and I do not want to take a chance with it.
Damper dudes I hear are good also. For rebuilding dampers. I would measure everything as TA’s specs that Larry posted have proved to be incorrect. 340p pistons are rated at 1.835 compression height. TA lists piston at 1.875. Most common replacement Pistons for 350 are 1.805 compression height. . So measuring will produce the accuracy you want.
My machine shop will know what this means. I'm guessing it means the 1.805 is worse than 1.835 equaling more combustion areas? I'm trying to learn what all this means....
Yes. The piston will sit lower , or below deck. Stock 70-72 piston seems to sit about.058/.060 below deck. More combustion area , lower static compression ratio.
Compression height is defined as the measurement from the center of the piston pin bore and the top of the piston. A larger compression height means the piston sits higher in the cylinder at the top of the stroke. The desirable situation is for the top of the piston to be level with the block deck when the piston is at the top of it's stroke (zero deck). Stock pistons can be as much as .090 in the hole at the top of the stroke. That is a big reason why the advertised compression ratios don't match up with as measured compression ratios. Getting the piston height right means you don't need to mill a lot off the deck. Once the machine shop measures your block, they will know how much they need to mill the deck just to true it up. They can then tell you what the compression height of the pistons need to be to get you to zero deck. http://www.hotrod.com/articles/hrdp-1212-how-to-calculate-piston-compression-height/
Received a call from engine shop today crankshaft that came with the replacement block is not polishable and needs to be turned or get a new crank kit. 4 Weeks getting cranked turned. So I’m a pull the crank out of my cracked block and have them check that one. Should I also use the rods off of my cracked block ?
Rebuilt long block is back in my hands, primered and ready to start installing the remainder of items needed to get it ready for reinstall. Working on getting engine compartment cleaned up and alittle paint on it. Also need to replace the steering gear box and a few other front end items. So I'm getting closer. Also finally got to installing my big air compressor and running airlines thru out the shop and to my blasting booth. For you guys that have blast booths what media to you prefer for normal around the shop use? I was thinking glass beads would work for what I would use it for. Also have my parts washer awaiting welding of a 1/2" nipple to the bottom for a drain valve. So I can finish getting it back in service. Loads of projects and not enough time to work them all. More to come.
Glass bead is for cleaning soft metals like brass or aluminum at low pressure like under 60PSI. It turns to dust at higher pressures.
