I took the crank to the shop today (different shop ), looks like it will take another .020" on the crank pin and another .010" on the mains to get it right. Have not ordered bearings yet, although I did talk to Mike T. today. I assembled the rod and rod caps and torqued them accordingly, I then measured the I.D without bearings. It's not easy to get good measurements so I took (4) measurements of each assembly to get a good average. I used a combination of a telescoping gage (shown in picture) and micrometers. #1 = 2.3850" (spun), #2 = 2.3739", #3 = 2.3740", #4 = 2.3738", #5 = 2.3739", #6 = 2.3737, #7 = 2.3740", #8 = 2.3743" Mains are next..... Almost forgot, 4 of 8 pistons were on backwards!
Craig, You don't plan to get the crank ground before you get the bearings and measure them installed do you? With the variation in new parts today you cannot count on the consistancy. You'll definately need to get the bearings, install and torque them, take your measurements then have your crank ground to your requirements, its likely that you'll be calling out different dimensions for many of the surfaces.
You say that 4 pistons were on backwards, are you sure? Piston pins will be offset a little, this offset will be on the same side of the motor on each side due to the rotation, some of the foward facing marks will actually face to the rear on one bank. It can be confusing. Check the pin offset.
I'll be ordering the bearings today, I just had to get the shop to mic the crank to see if I needed .020" or .030" bearings. I did consider moving the bearings around to get the right clearances but I'll ask them to wait til I get the bearings and rods to the shop to fine tune the fit for each. They will also check the rods and bolts to make sure they are good. I'll double check the piston orientation. From memory the bump on the rod and cap should face towards the rear on odd cylinders and to the front on even cylinders, right? Is there another way to confirm? I ask because a white dot was added to each rod, half of the dots are on the bump (side) and half are opposite the the bump side of the rod.
The bump on the cap goes on the same side as the dot on the rod, these will face each other on shared crankpin, this will point the oil spurt holes toward the cam. As far as the pistons, that why you see pistons with 4 valve reliefs in them becuuse they face different directions depending on which bank there in. Front does not mean front of car it means front on side of engine bank. Four will face to the front and four will face rearward.
Excuse me? 4 will face forward and 4 will face rearward? I think not. The reason those pistons have 4 valve notches is so that the piston can go on either side of the engine. In other words, if you take a piston with the "F" facing forward say for cylinder number 1 , you will be using one set of valve notches, if you take the same piston, leave it oriented the same forward direction and move to the other side of the engine, cylinder number 2, you will be using the other set of notches. Jim Burek
My bad, that "damn shop" had the rods and pistons turned the correct way. Tim the bumps facing each other was a good way to say it, and I was with you, until the piston part The painted, dots that someone added, on the rods, is what threw me, why would someone do that? It just adds to the confusion! If I screw up (when) please point it out (damn it). I can't fathom another tear down, I must cruise this summer!
My machinist put the rods and pistons in a box with a big "F" on one end and a big "B" on the other, with F being the front and B being the back. I guess this is a common mistake, don't feel bad. But in my case it sure made popping the pistons and con rods in the right way easy! I can't see the issue, really, because I constantly hear that God loves an idiot, so I must be covered:laugh:
Ok Jim I see where your coming from on the notches, little brain fade going on. About the piston question, don't the offset on the piston pin all go to the same side.??, such as the piston pin would be offset to the drive side on both banks(not sure what side it really is) on my motor I do have one set of pistons facing rearward (pass side i think) when i questioned the shop thats what i was told- these people build aircraft engines BTW. Does any of this sound right........thanks. Check the piston pin offset Craig and see what you fine...which side is it on.....let us know..
Checking your rod's ID with a telescoping gauge is OK, but it will only be as accurate as the user. I am a machinist and I know for a fact that will only get you in a few thousandths. Checking it properly, you need to use a dial bore indicator. this is a very accurate way to check it and you can take many reading to ensure have a a round bore.
I agree about using telescoping gages. We just confirmed the measurments this morning with the dial bore gage at the shop. All were very close to my measurments except one (.0013" off). All the rods looked good, except the #1 that spun. The #1 was also twisted ~.050", I don't know if this was already there with last assembly or not.
On your stock type pistons and some of the lesser expensive replacements, the pin is indeed off set to one side slightly. The reason for doing this was to reduce piston rocking in the bore and decrease cylinder wall loading on factory engines. In the old days, guys used to flip the pistons around and put them in backwards, they claimed it made a little more horsepower that way, engine life was reduced. It was not a big difference in power from what I understand, something along the lines of 8 to 10 horsepower. My understanding is that if the pistons are marked with a forwardor front mark, then it uses the offset pin. Your more expensive pistons, typically do not use the offset pins, they are centered. These pistons are not necessarily designed for quiet operation. Jim Burek
Craig, hang in there, some would have given up by now. Sometime a trip down a rocky path makes it sweeter in the end. I'm sure when your done you will be able to enjoy it for many years.......
Next, cam bearings. The cam bearings still look good so I am not removing them. Now to check the cam bearing clearances. I measured the installed cam bearing inside diameter in two places and averaged them, this is not so easy. I measured the cam journals the same way (average of 2 measurments 90 deg. apart). The calculation looks like this: Average installed cam bearing I.D. minus average cam journal O.D. divided by 2 to get a clearance value. #1(front) -->.0012" example: 1.7879-1.7855=.0024, .0024/2=.0012" #2 -------->.0012" #3 -------->.0014" #4 -------->.0013" #5(rear) --->.0010" My book says the "journal clearance in bearings" is: .005"-.0025" (#1) and .005"-.0035" (#2, #3, #4 and #5) I'm using TA grooved cam bearings with dry film coating and a TA-413 cam. Clearances look o.k. to me, anyone think I need to adjust the #5 cam journal? I know these clearance measurments do not take into account the alignment of the cam bearings in the block so a little extra might be a good idea. I have noticed the cam rotates a lot easier than when I first installed the bearings, this was some 60 easy miles ago Maybe one was slightly cocked o No:
Clearance values are always specifed as the difference between the bearing bore and the journal. No need to divide.. You can think of it as 1/2 on one side, and 1/2 on the other, but is that reality?.. Prolly not.. And yes, they are a little on the tight side, but should be ok ... how did the cam bearings look? Coating should be worn off on the bottom, on the surface of the bearing. And yes, if they are ok, leave them alone.. they made it thru breakin, and should be good to go now, JW
Thanks Jim, I spelled out the calculation because I wasn't positive about the term "clearance". Cam bearings looked just as you described, only wear a little on the bottom. :TU:
I just want to say to hang in there to. I worked in a engine machine shop until forced to stop working for health reasons. I learned alot of lessons on the 455 through the years. It is very rewarding to put one together and have it work the way it is supost to. The very first 455 I did had chevy main bearing clearences and hammered at idle like the 6.2 diesel in my suburban. I went from running 14.90s to 11.50s doing my own work along with the help of good people like the ones on this board. Problem now is I need to spend money on the 12 bolt to hold all the torque :laugh: PS, How do you guys get such nice clear pictures of stuff on here? Do I need a digital camera? Tom
O.K., time for cylinder bore measurments. These measurements were taken ~.5" below the ring line. The measured vertical bore was larger then the horizontal bore on each. Is this typical? #1 - 4.3438"-- 4.3429" #2 ------37" ------23" #3 ------31" ------24" #4 ------30" ------27" #5 ------31" ------25" #6 ------35" ------29 #7 ------39" ------21" #8 ------39" ------23" Obviously these numbers are not ideal, but are they o.k.? #7 has the widest variaion (.0018") ouch. What is a acceptable range, or maybe I should say workable range? I'm planning on honing the cylinders lightly by hand with a drill. My friend has the correct stone for the rings.
O.K., time for cylinder bore measurments. These measurements were taken ~.5" below the ring line. The measured vertical bore was larger then the horizontal bore on each. Is this typical? #1 - 4.3438"-- 4.3429" #2 ------37" ------23" #3 ------31" ------24" #4 ------30" ------27" #5 ------31" ------25" #6 ------35" ------29 #7 ------39" ------21" #8 ------39" ------23" Obviously these numbers are not ideal, but are they o.k.? #7 has the widest variaion (.0018") ouch. What is a acceptable range, or maybe I should say workable range? I'm planning on honing the cylinders lightly by hand with a drill. My friend has the correct stone for the rings.
Craig, what kind/make pistons are you using and what kind of piston to wall clearance are you going for..????also what type rings and end gap specs......?? sorry if I missed some info from previous posts.
