I think I understood the value of the hardblock epoxy as mentioned in your previous message for cylinder walls >0.100", and I was planning to follow your advice. Thanks also for the detail regarding muratic acid cleaning:TU: However, you also mentioned a build that had leak-down issues in the cylinder with 0.090" wall thickness. My 425 will have a cyl with wall @ 0.093" after going 0.040", so using your information suggests that this could be a problem. Unless the bad cylinders are sleeved, as some have suggested. Thanks
Partially my fault. Didn't mention that after adding the epoxy leak-down issues were solved. That's because at least the bottom of the cylinder walls were now more stable. Even before your block was bored it was marginal when new. Just like the majority of 425's. Even 401's from the factory are marginal, but better than 425's in most cases.
Good news! The worst cylinders cleaned-up with 0.035" Machinist is going to 0.040" but does not have a Nailhead torque plate to simulate flex in the block from the cylinder heads. Torque plate or no torque plate on final bore hone? Are these available for loan from a reasonable source? Thx,
Personally, I would not worry about the torque plate deal,,,,, I have built a lot of engines that never had that done to them and they held up just fine... unless you are looking for absolute perfection and the last oz. of power that is not necessary .....
The "Hillbilly" shortcut for a torque plate is to put a stack of hardened washers on hardware store Grade 8 bolts and thread 'em into the head bolt holes, being sure they go into the block EXACTLY as far as the regular head bolts will. Torque the bolts, hone the block. This is not as good as using a torque plate; but produces similar cylinder distortion.
Deck height for this block is now 9.992" because it needed 0.015" clean-up to get rid of the abuse. This will lead to CR of 10.45:1 with 0.015" gasket and 9.96:1 with 0.036 gasket assumption. Will the intake still fit, or do i have to fly cut that as well? (heads will have to be surfaced too, but not sure how much yet.) CR calculation numbers: Push-rod length = 6.220" Crank extension = 1.820" (stroke 3.64"/2) Piston height = 1.91" (Egge cast pistons 2.25 - 0.34" dome) dome volume = 46cc chamber volume = 126cc bore = 4.3525" Piston depth from deck = 0.042" I wanted 9.5:1 CR, but might be able to handle 10:1 driving at 5300'
Any comments from the experts? I had to assume chamber and dome volumes, because i have not measured these yet.
I'm sure you meant con-rod length at 6.220". You didn't figure in the volume for the valve reliefs. You will more than likely be at around 9.5 with steel gaskets. The intake should fit with no alignment problems.
You are right - meant con-rod, but wrote "push-rod" ou: What dome volume do you assume after valve relief? Thx
