Technical 292 Y-Block pistons size problem

Hi everyone
I have a problem with finding correct size of pistons for my first engine rebuild. It's a 292 Ford Y-block, I need .020" oversize set of pistons and rings, but I found that there is only 0.30" on ebay , and .macsautoparts.com is the only place with .020" but they are very pricey! Could anyone let me know if there is somewhere .020" available? or should I overbore my block to .030"?

thank you in advance

Mariusz .

 

I am not a y block guy but my thought is what size bore will give you 312". That would be a stock size bore.

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Why are you so set on .020" pistons? If the block has to be bored any ways, go with the cheapest, available piston.. .030" is a more common oversize. That's why the availability/cost difference

If your block is already .020". Then find a shop that has a Ck-10 or CV-616 Sunnen or equivalent honing machine.. A decent shop, will then only charge for a hone job.

 

312 bore is 3.8 or .050 over 292 Ford changed the rod lenght to account for the add stroke. MY experance it almost always takes more to clean it up than you first thought go with the .030 pistons.

 

I've learned something new.
Thank you

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030 is the normal first overbore. And sometimes you need to bore the block first to see what size it needs....I did a 235 chevy that was standard size, and needed to go .060 to clean it up!

 

That's what happened with my 235. The pistons had been knurled and even though it it had never been bored they had to punch it .060 to get everything squared up.

 

Thank you all for detailed comments, my block has 3.75" bore, it's a factory size, mechanicans told me that 0.020" should be enough, and this is why I am looking for this size. My block is not overbored yet, it's waiting in the line, until I get the proper pistons. I can talk to them and said that 0.030 should be ok.

 

Most common American engine oversizes are .030", .040" and .060". There have been a few odd rare occasions through the years that a .020" oversize piston was common for certain engines, but not all of them. Just because the block can clean up quickly at a .010" or .020" oversize, doesn't mean that a piston can be obtained for it unless you go custom.

 

If .020 is the minimum it needs to clean it up, you will have him bore it .030" simply because that's what size pistons you can buy. This is totally normal procedure.

If you're worried about future overbores....don't....it won't get driven enough to wear it out so much that it ever needs another overbore.

 

They probably only have .030 and larger pistons but take a look at Northern Auto. A .030 overbore was the usual remedy if oversize rings and knurling wouldn't stop the Y block smokescreen. Back in the 60s, if you had a 272, it got punched out to accept 292 pistons.

 

Boring a block is kind of a catch22 You need to bore it to find what over size but you need the pistons because of the variance between pistons in a set. A customer brought a set of name brand 400 pistons that varied .005

 

bore it to the standard oversize that will clean up, buy the pistons, then hone it to final size to fit the pistons.

 

I found out the Northern auto Parts have in stock standard size, and .030" only, but in a Ford 292 1955-1964 Block Kit you can choose .020", it's strange, I would buy a whole kit If I knew it before, but I already bought a gasket set :/ , I am confused
But most of you told me to buy .030", so I think I will stick with this size.

 

Northern will adjust will adjust price and leave out the gaskets. I have used their kits all name brand parts.

 

Yes, I buy many kits from them. They can build about any reasonable variation on kits.

 

I worked in a rebuild shop for years (early 60's). Don't risk buying .020 pistons & rings. Go with .030.
Cylinders often have a taper wear pattern. .020 might or might not clean up all the cylinders.
Forbes is right. Final honing (which MUST be done) will achieve correct piston fit.

 

adjust sounds great for me

 

you guys are great, I wasn't expected so many important comments within few hours! I have never received so many and so fast on facebook's car forums or ebay, thanks a lot for help!

 

wow, early 60's, you must be right!

 

Rock auto has .030 pistons. 32 bucks each for the 292

 

When I overhauled my 292, it had enough wear in the bores that any machine shop would tell me it needed to be rebored. But I know that with somewhere around .005" wear in the bores, I could just replace the rings, and the engine would work fine, and last probably 20,000 to 40,000 miles before beginning to use oil, lose compression, etc. So, I just honed it and put in new standard size rings. I put about 5,000 miles on the car before I sold it, and I really doubt it will get another 5,000 miles use in it's lifetime (no one seems to drive old cars any more). Surprisingly, it would take over 3,000 miles to use a quart of oil, which is excellent for a 57 year old engine!

So...think about whether or not you really need to rebore the engine and get new pistons.

 

Two of my pistons are damaged, and all of the rings are already broken, in one skirt you can feel concave upon your finger, so I think it has to be rebored.

 

Yes, it probably does. Now we know.

 

I am about to buy 292 engine rebuild kit from Northern Auto Parts, I found out that they have .020" and .030" pistons available, I know you all told me to buy .030", but I need a final advice from all of you please

 

If the machinist is confident it will clean up at .020 and the price is similar, then I guess it is up to you.

 

I'd go .030 just to be sure it will clean up.

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292s had thick walls If you bore .030 and need to rebuild again theres .060 then you can go oversize 312 pistons. I ran a 292 that was .150 over to use 318 poly pistons It was a late block and sonic tested.

 

also old blocks don't always have the bores perfectly perpendicular to the deck, and if the boring machine locates off the deck surface, it might miss the end of the bore. There are several reasons why the normal first overbore is .030 instead of .020

 

I am almost sure of .030", any more comments from others?