Scody21
Just send it
- Joined
- Jul 17, 2019
- Messages
- 3,834
- Reaction score
- 4,990
273 Cylinder Bore .004 over spec
- Thread starter Bossanova5
- Start date
-
Go to Line2line.com and look at the coatings.
Figure out how to do the measurements they want and use their form. Fill it out.
Send the pistons to them.
They will send them back to you coated and they will be better than new.
All for less than 350 bucks.
Here is no way I’d bore it for that little bit of oversize.
In fact, before you do anything else, none the bore to get them straight and round. Even if you have to take another .004-.005 out to get them all straight and round and to the same size.
Then do the math and send them in for coating.
It works. No need to bore and hone and buy pistons. This is a better fix anyway.
Figure out how to do the measurements they want and use their form. Fill it out.
Send the pistons to them.
They will send them back to you coated and they will be better than new.
All for less than 350 bucks.
Here is no way I’d bore it for that little bit of oversize.
In fact, before you do anything else, none the bore to get them straight and round. Even if you have to take another .004-.005 out to get them all straight and round and to the same size.
Then do the math and send them in for coating.
It works. No need to bore and hone and buy pistons. This is a better fix anyway.
Bossanova5
Well-Known Member
That is an interesting idea...
I cannot seem to find the standard piston bore dimensions in the factory service manual, only the block bore tolerances.
Does anyone have the dimensions for the pistons or direct me to where the information is?
Thanks
I cannot seem to find the standard piston bore dimensions in the factory service manual, only the block bore tolerances.
Does anyone have the dimensions for the pistons or direct me to where the information is?
Thanks
Last edited:
Lets get real here. Post #27 is on the money. .006 or .007 clearance is not crazy loose. You probably can't even catch a finger nail at .006. Get the bores straight, round and put it back together. I like the idea of coating the piston skirts. I doubt the ring lands are shot. Get a good valve job and run it.
Scody21
Just send it
- Joined
- Jul 17, 2019
- Messages
- 3,834
- Reaction score
- 4,990
Make sure you do the break in correctly as they talk about on L2L site. We have used them a bunch. There is a company in NASCAR land of NC that also coats pistons and bearings.
Are yall SURE you're getting this? The guy is saying it's .004" beyond the MAXIMUM allowed spec. Yall got that, right? And you wanna "save"" the engine with coatings? Yeah. Do that. Yall have fun, ya hear?
Yes, but he is quoting Max as .002 over stock bore, 3.625. Is he using a dial bore gage? I do not know, I can only go by what he says. I know that Chevrolet specs were + .010 as acceptable at one time.
I know exactly what he said.
That’s why I said to coat the pistons. It’s the best fix for the guy.
Plus what are the pistons at? How much coating will it take? Even if you coat everything, the block still has to go to the machine shop to be honed back round and get the taper out. How much is that? Plus the coating? 300 bucks huh? Even if it's 1/8" thick? While coatings have their place, like temperature control, IMO (again, IN MY OPINION) they are NOT for taking up sloppy clearances. What's it cost to hone a block correctly back round (and now way out of spec)? 350-500? So now, what could you have done correctly for 800? Put a little more with it? Look guy, if you already knew you were gonna build a sloppy motor, why did you even ask? To get just THAT ONE person to say "yeah, try this"? Why did the factory even use specs at all? I guess we're all engineers now.
And the next guy?
the way i sees it, this goes to the machine shop. there's no way around spending the dough for block prep, so now it's down to whether that cash is splashed for a band-aid or a proper done job.
And like I said, that poor "next guy" cause there's always a next guy. What if it's a son, daughter, niece or nephew. Or whoever. Buy will they get a pile of crap.
That's it for me. Yall have fun! lol
If you are going to use a coating as a band aid fix for sloppy clearances, why not just use a band aid? They have got to be at least .003 or so. 
Bossanova5
Well-Known Member
For measuring tools, I used a Starret telescoping gauge and a Starret 3-4" .0001 outside micrometer.
I took six total measurements per cylinder. Top / middle / bottom / in line with the crank and 90 degrees out.
The spec shows the standard bore to be between 3.625"-3.6270"
My largest measurement is .0048" out of spec at 3.6314
I know I have to bite the bullet and do it right................
I took six total measurements per cylinder. Top / middle / bottom / in line with the crank and 90 degrees out.
The spec shows the standard bore to be between 3.625"-3.6270"
My largest measurement is .0048" out of spec at 3.6314
I know I have to bite the bullet and do it right................
Last edited:
TT5.9mag
Two atmospheres are better than one
Real? You ever built one (on purpose) at .007 skirt clearance? I have. In fact I just did. I told my machinist to set the skirt clearance at .0075 because of the way the engine will be used. Turbocharged in a boat constantly loaded. He didn’t want to do it said the pistons came (Mahle before you ask) at .005 and that’s where we should run it. I said make it .0075. I’ll tell you this it ain’t no minivan where you turn the key and go jump on the freeway before things get up to temp. You have to warm it up, you have to get the oil hot before putting the coals to it, or you’ll be picking up pieces of piston off the ground. That’s real. No bullshit. His is too damn loose to throw back together and run it. The DLC coating is a good idea and will work. They can coat pretty damn thick and it’s abradable so it will wear in its own running clearance. But other than that, it needs to go to the machine shop.
at what point do economics of the situation turn the worm?
by the time it's done with coating, shipping, rings and a hone job it might'n maybe be within spitting distance of some new pistons and bore job.
granted it wouldn't be real deal "commando" pistons, but it'd still be 10:1 if that's what you wanted.
but as the adage goes, if you want it done exactly your way then it's pay to play.
Bossanova5
Well-Known Member
Where are you getting the wear limit of .005" from?
The FSM spec shows a bore parameter of 3.625-3.6270 which is .002.
The FSM spec shows a bore parameter of 3.625-3.6270 which is .002.
You need to go read up on the coating.
I know exactly how much they can cost and it will have better ring seal than if he bores and hones the block.
The next guy can bore it.
New piston set from EGGE is $700 , why fart around?
Plus rings and a bore and hone. And shipping.
I don’t get the blowback from coating the pistons.
That’s the best, most economical fix.
I see you haven't used this coating.
It works, I had more clearance than necessary on my engine. I sent mine in mostly because my bores got a few scuffs from butted rings.
I run .0015 p/w clearance with forged pistons.
The coating is showing and measured a couple tenths of wear after serious flogging on the Dyno.
Big difference between my engine and the op's engine is my bores are straight and round.
His might have taper but the coating is meant to fit to the bore and it does what they say and works as intended.
Absolutely, that's not cheap. It adds up fast
I'm not questioning the coating.
I'm just a spends now guy rather then later.
It's cheaper to go faster when you spend once doing it right.
SpeedPro file-to-fit ring sets are usually .004"-.005" oversize, if You can get a set for Your bore, get 'em & get the slugs coated & go. As pointed out, the taper should be minimized, if You won't/can't spend the $$$$....this is Your path.
-
Similar threads
