![]() I think you might have a stack-up of variables all conspiring to wreck your idle. I was pausing here because Jim from Air-Cooled Ranch had mentioned that he did not think the "Torque Special" was actually a very radical cam.īut, I do NOT want to put everything back together and wish I hadn't! 050 between piston and cylinder edge, cylinders torqued down to about 20 ft/lbs with nuts and washers on each head stud corner. It is nice, of course, to get the piston further out towards the edge of the cylinder. But, I do not acutally know your combustion chamber volumes. 028 sealing rings (if your flycut will allow you to) will give you a 7.5:1 compression ratio, which is perfectly acceptable. If you have the deep 15cc dished pistons, then deleting the. The need for a cylinder head sealing ring may have been caused by the usual bugaboo, too deep of a flycut. ![]() you are spot-on with a 7.3:1 compression ratio. Would these deck heights, with the additional clearance of the shim, result in too much deck height?Īssumption I : you have 7mm shallow dish pistonsĪssumption II : you have 52cc combustion chambersĪssumption III: you have that. I don't know if that would indicate that these heads have ever been flycut or not. I have not cc'd the heads yet, but on both heads, the cylinder mating surface is approx. I bolted the cylinders down and took measurements between the top of the cylinder and the top of the piston right at the outer edge of the piston, at 12, 3, 6, and 9 o'clock positions. I pulled the heads tonight, and measured the deck height of each piston as best I could with my digital caliper. I like to pop them out put a nice finish on the aluminum surface then pop them back in and take the prechambers down as close as i can to the aluminum surface without touching it with that wheel.Vwlover77 wrote:Jim at the Air-Cooled Ranch suggested that too much deck height might be the reason why the CB Performance Torque Special camshaft in my engine idles so poorly. When milling the cutter reacts differently to the harder material and screws up your finish, especially if your auto feeding, when grinding you should be using a different wheel for the aluminum than the steel. I must enjoy the breeze from my zipper being down but have had no problems and had engine with my machined head go 300k and still climbing! Also as for machining with them in, frankly i wouldn't let you near my tools or machines! Iconel or stainless machine differently than aluminum. 0005 or less not flush but slightly protruding. Quote from: BigVWman on October 18, 2011, 09:36:14 am When i say they should protrude slightly i am thinking order of. Here is my hand abrasion setup, a bit crude, but fully functional and calibrated with newspaper to remove natural sag in 3 sheets of plate glass on bench: Machine minimal, but enough to allow contact round the cylinders, and not as I did as I watched the symetrical abrasion patterns emerging. Much warpage is in the surface, where it has turned to jelly and reset. Leave the manifolds on and tight if possible. Only when released from the block and removed from the intake and exhaust manifold does further shape changing take place. But my own opinion, is that with a failed head gasket, whilst still on the engine the warpage is in the interface and not carried through to the cam carriers. ![]() My hand-abraded head is clearly done with skilled arms, Dewarping a head is a complex issue. There can be no better holder of a precup that a purpose built aluminium home. If the tool is knocking them out then job is being rushed. Removing intact precups is just shoddy work skills that are inviting trouble. A head bolt or even stud is not capable of extruding the gasket in the metal regions. How can it seal on the stepped interface for either fiber or metal. Protruding precups are like walking around with your flies undone.
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