Measure Measure Measure!! Piston Woes!!

[Turbo Archie]

You said the shop bored it, you need to hone it to size after you bore it.
I assume the shop bored and honed it? Which doesn't make sense.
..

 

[HackersDna]

I’ll go slower.. the shop bored it past the size of the pistons by .0045 on the positive side.

Normally that is not how it works. Normally a machine shop would bore and hone if they physically had the pistons. This shop did not have the pistons. They were given a number with the instructions to stay under that by .002 so I could physically hone it myself. So now if I touched it with a hone I would only be removing more metal off something that’s already too big. Kinda like beating a dead horse.

I made mistakes during all this by being a control freak but it is my crap. I assumed that people could follow instructions. Guess I thought I was back in the 80’s again. Now ya want to come over and have a beer and see if This is salvageable?

 

[Gene Van Horn]

Talk to earlbrown,he makes pistons i believe. Perhaps he can find some for your bore. Dont quit on it yet.

 

[750H.P.V6]

Running .0045 to .005" side clearance on a set of JE pistons is fine. If this is the actual measurement file fit the rings and press on.

Neal

 

[Reapersgbodys]

Either have Earl make you a set of pistons to fit your bore size, or like Neal said, file fit rings and roll!!! Back in the day, my father used to build short track race engines, not that they were Buick V6’s, but he would run some pretty loose tolerances and had a damn good failure rate. I have heard some that you thought were gonna fall apart, but lasted the season, lol
To quote the old man, “She’s gonna go or blow” lol
Hope you get it figured out and get back to the asphalt!!!!!!

 

[earlbrown]

If you're already at 4 1/2 thou with an unhoned bore, those slugs won't work with that block. By the time you knock off a couple more thou to get the finish right, the pistons would be flopping around in the bore. Not only would that potentially trigger the knock sensor, it'll cause the rings to rock up on their sides and the leak down rate will be pretty horrible.

 

[BEATAV8]

My new Diamonds call for .0065" on the low side up to .0085" loose. Every piston design is different.

 

[HackersDna]

Thanks for chiming in Beatav8. All the main guys are saying I should be fine. I will do a leakdown test after I get her fired up and re-torqued. Get both a cold & hot percentage.

 

[earlbrown]

I guess that means I don't qualify as a 'main guy'.

Just one more question, and I'll opt on out... Are you going to put those pistons in bored cylinders without honing them?

 

[BEATAV8]

I guess that means I don't qualify as a 'main guy'.

Just one more question, and I'll opt on out... Are you going to put those pistons in bored cylinders without honing them?

You're always a main guy in my book Earl

 

[750H.P.V6]

I'm a bit confused, is the block honed or not? Can you post a pic of the bores as they are right now?

Neal

 

[earlbrown]

You're always a main guy in my book Earl

We're not talking about main caps, this is about cylinders.

 

[earlbrown]

I'm a bit confused, is the block honed or not? Can you post a pic of the bores as they are right now?

Neal

From what I've read the OP wanted a bore job performed by a shop and he was going to hand hone the block to size at home. Then the boring operation took the block out too far to use the OPs pistons correctly. So instead of making it 'worse' by honing, it appears he'd been advised by main guys to run 'a little looser than spec'.



Personally I'm VERY curious how long it will last. I really don't know if the timeframe will be measured in seconds or minutes. Odds are it's the romantic in me, but I'll take destruction testing over CAD/CAM any day of the week. (as long as it's not my stuff, that is).

 

[750H.P.V6]

Personally I've never seen someone have a block bored by a machine shop just to hone it by themselves by hand. It's an odd notion and counter intuitive. If this is what's being proposed please stop now and take your parts to a competent engine builder.

 

[HackersDna]

Ouch... Of course Earl your a “Main” guy, but u hadn’t chimed in until... So I was going off by those who did contact me before you had. The Machine shop did hone it and I’m now being told it was with a plate.. and that is the reason my measurements are proud compared to his.
And as far as a competent builder I believe I more than qualify but that doesn’t mean I know everything hence why I come to you all who have already been there and done that. Bottom line is my wallet gave instructions that wasn’t followed which is very aggravating and can be expensive.
And ya know it very well might go “Boom”.
I hope it doesn’t for sure. I’ll get u a pic of the cylinders.

 

[HackersDna]

 

[750H.P.V6]

It looks like we've sorted out the misinformation in the thread and the block is honed not just bored. Back to my previous statement, if the side clearance is .0045 to .005 it will be fine.

 

[HackersDna]

And 750hp.. I’ve already said I have a bit of a control issue. And although It’s not an uncommon practice to let a machine shop do the whole thing to the final end it’s also not uncommon for individuals to do a final hone as well if said person is competent and has the tools needed.
Don’t tell anyone but I also set up my own cylinder heads. Holy hell this thing is going to go up in great fashion. But I’ll guarantee the vendors will like it when it does.

 

[750H.P.V6]

I get where you're coming from, I build all my own stuff and have done for a long time. I trust my machinist but I always check his work. Recently I started doing my own heads since one of my co-workers has been a cylinder head guy for about 35 years and has all the tooling.

Neal

 

[ek02]

I agree with 750HPV6. Since it is honed, you will be fine at.0045-.005. That is what JE recommends on their forged pistons and what I have always set them up at (assuming they are forged pistons).