Was helping Mart the other day to prep the block he is going to use for his new build and we found out something very interesting. Just for sh!7s and giggles we torqued a head on the bare block we just mapped out the cylinders on with a .0001" bore gauge and the cylinders were within .0001" of what we measured from the bottom of the bores with the head torqued on as it was without the head on from the top! Looks like to me that the sbb 350 doesn't need to be torque plate honed after all and would be a waste of time, effort and $$$ to do so. Mart found this older article some how of a Jim Burek build; https://streettechmag.com/2015/08/04/buick-350-engine-build/#prettyPhoto "We sent the block to Jim Burek at Performance Automotive Engines in El Paso, TX. Jim has been building high-performance Buicks for over 20 years and is considered by many to be one of the best. Jim had the block machined at a local shop to his specs. The Buick 350 does not require a torque plate for boring as all of the head bolts are blind, meaning they do not hit the water jackets, so the cylinder does not tweak when the head is bolted down." Even though its a Jim Burek build, the guy that fudged his dyno numbers by changing the atmospheric settings as if he was dynoing that engine in the eye of a typhoon, it does confirm the results we got when we actually measured the bore with and without a head torqued on a sbb 350 block. Lots of other good info in the article as well for a JB build.
Yes, but have you ever figured out why before now or measured the bores with and without a head torqued on to know why?
Guess my 350 Torque Plate is now worthless - Thanks. I figured BHJ was probably happy to get rid of it 25 years ago. Seriously though, seems like further evidence that the Buick 350 is a pretty stout Block. Seemingly with a billet crank and good rods, they should be pretty indestructible up to a pretty decent HP #. Is there a consensus on where a girdle is necessary? I know Sean has one and Gary Paine had a couple left and while I'm a ways off from an all out 350 build, I was considering buying one, but then I figured if the heads really do what we hope and these engines finally get the respect they deserve and that limit is reached where the girdles are necessary (i.e. we start seeing some blocks go), that they'll be readily available.
Are not like some other GM motors the head bolts on the 350 cast into head deck and not attached to the Bore , as this is what makes for so little deformities in the top of the Bore.
Not that I know of. I would be curious to see the results if someone did. Plus, just because that article mentioned "blind head bolt holes" doesn't mean every engine with those wouldn't benefit from torque plate honing. It depends on where those are and how the bolt bosses are attached to and how the fasteners pull on the cylinder walls.
I have a 455. It was torque plate honed, using TA's rented plate. I used my .0001" dial bore gauge to double check the machinist once I got the block home. None of the cylinders matched the others, there was taper top to bottom, and out of round as you go around the clock dial. Then i thought "I don't have the torque plate, I'm wasting my time". So i stopped. That was my experience.
You could of torqued a head on with an old gasket and bore gauged it from the bottom like we did, you didn't need the torque plate to check it. Is it together yet? The description of how the bores you measured doesn't sound so good! I hope the taper and out of round wasn't too excessive?
I didn't think of that lol, plus the heads are still out being ported. The pistons are in it and I'm too lazy to take it apart and put a head on it
You would only need to take 1 piston out for that test. If the bore you measure straitens out then you'll have the piece of mind that your bores are good. If the readings are still out of round and tapered then you might want to have that corrected BEFORE you start it! Dealers choice though.
