What's up?! Piston higher than the rest.

Got the assembled short block back from the machine shop. Pistons 2-8 all between .002-004 out of the hole. #1 is .012-.013 out. What's up? I will be calling back in the morning.

Did you check piston rock? In the center or towards the outside?

Should have been noticed at the shop IMO.

Yes I did. This is with the piston rock split between high and low and the deck height measured parallel to the pin with a straight edge and feeler gauge. Dial gauge gives similar reading. You can see with your eyes that #1 is higher than the rest. It's that obvious. Arghh...

Rod with bad dimensions? Piston pin on the wrong location?

Custom stuff or shelf parts?

Swap the piston/rod from #4 into #1 and remeasure.

Lem Evans wrote:Swap the piston/rod from #4 into #1 and remeasure.

I was just thinking that, block deck could be slopped too.

OK I remember back when I did my own assembly You'd have to take the pistons from hole to hole to get them to equal out. Try taking the one piston that's giving you the problem and putting it where the lowest piston is and see if you can get them to all equal out. You'd be surprised how much they move around from journal to journal. Then while you have it apart why don't you do a ring gap check to make sure they didn't Fuck that up right away too.
When I file fit my rings I'd mark the hole they where fitted for and the rings where the last thing I put on the pistons after I figures out which hole they wanted to live in. There lots of fitting done to get the short block together right. A little extra time spent now will save you big head ache later on in your build.

Now I'm no expert, but I do remember fucking up the little things and they come back and bite me in the ass hard. The other big measurement is the Piston to valve clearance. Take your time on this one and make sure it's right. Use a dial indicator with light springs and make sure you have enough. I clayed mine one year and it said I had .120 int and .080 exh. When I fired it up it ran for 10 sec. and bent every valve in the heads. Oops .. ya back then Valves where cheap, Now a days there $125.00 a pop x 16 = $2000.00 Booger Job.

But Enough of my horror stories .. take the time now and make sure it's right.



Dan

Pistons were custom ordered from Diamond. Uncle Charlie ordered for me. I had to replace two rods but the whole assembly was properly balanced(I have the paperwork). The shop is very reputable and has done excellent work for me before. I'll call tomorrow before tearing down and swapping holes. Does seem odd that there's only one that's high. Got the block from a forum member here with machine work already done. I asked the machine shop to check the deck height. They said they would "check everything". Wondering what happened?

Thanks for all the replies. Merry Christmas.

About to head out to the mother-in-laws...

I can't imagine that the crank would/could be off that far. The deck or rod would be the #1 suspects.

what head gasket you plan to use? the deck may not be an issue anyway......

I'll decide on a head gasket once the #1 piston is back where it's supposed to be. I'll try and keep the quench in the 40's.

1st update from the shop. Piston to deck:

4. -.001. 8. .000
3. .005. 7. .001
2. .008. 6. .001
1. .012. 5. .001

He doesn't suspect the crank or the pistons. Also, doesn't believe the deck could be off by .013 on one side. Suspect rods. Tear down on 01/02/13. Will know then.

Any more guesses?

damn sure looks like the deck is sloped on the one side, numbers add up......

richter69 wrote:damn sure looks like the deck is sloped on the one side, numbers add up......

X 2 on what Fabio said.

Charlie

X 3...

738drvr wrote:1st update from the shop. Piston to deck:

4. -.001. 8. .000
3. .005. 7. .001
2. .008. 6. .001
1. .012. 5. .001

He doesn't suspect the crank or the pistons. Also, doesn't believe the deck could be off by .013 on one side. Suspect rods. Tear down on 01/02/13. Will know then.

Any more guesses?

Like I said.......swap 1 and 4 piston/rod and a guy would have the answer in less than 10 min.

I'd bet Rob's Freddy Mercury tank top that the deck of the block is an issue.

I feel pretty confident that the shirt is safe. That deck has a taper in it for sure. Take the block back and have them straighten out the mess, even if it means running a little more head gasket thickness.

You are going to have to run a tapered head gasket. Sucks cause they are hard to find.

shop cut the deck ? better for them to get you another block and make it right .

BTW , you don't pay for others mistakes

from the first post he bought the block already machined.

richter69 wrote:from the first post he bought the block already machined.

Like all the others say, it will probably be the block is not decked right. When I did my 514 with a piston and rod in ALL 4 corners of the block to check deck heights before having it decked, I found on one side there was about .011/.012 difference in the deck height. I assume it was that way from the factory???? When I took it to the machine shop, they questioned my measurements. When I picked up the block, they said they checked the deck height off the crank centerline and came up with the same results as me. This was only on one bank that it was off, the other bank was OK.

BM2271 wrote:You are going to have to run a tapered head gasket. Sucks cause they are hard to find.

This ones learning fast !! HeRo in Training.........

BM2271 wrote:You are going to have to run a tapered head gasket. Sucks cause they are hard to find.

And make sure you put em on right or the taper is worse Don't ask how I know

Block was never decked. 95.00 to deck both sides. Free clean and reassembly. All pistons will be .015 out. I will use a .060 MLS Cometic gasket and run it. Should be fine for street/strip use. Don't won't to cut the pistons in case I reuse the rotating assembly in another block.