hey Guy's. have a friend that is building a '63 B-body & is wanting to use a 426 max wedge block that he has. the block is bored .060. he's had it honed & checked by machine shop. he didn't have the #'s on hand, but said 7 cylinders were 'O.K.', but 1 was 'LOOSE'. so, would the best option be to order custom pistons to fit the largest hole?(hone the other 7 to that size)
if so, any better piston company than others for this? also will be using orig. cross ram intake & wants aluminum heads with max ports. which heads would work using standard rocker arms? not an all out race car, just a good runner. Thanks, Tom

Need to be a little more specific on "loose",probably better to sleeve it if all the others are OK.

Trick Flow 270 heads are max wedge size and use a standard rocker arm. They are an extended runner design so the intake is moved up a bit from stock. Works fine but you'll need a solid valley plate.

Have the machine shop figure out the piston selection. It will depend on what clearance they want to run and what ring size is available. If it is only a thou or two then you can order the pistons a couple of thou oversize and use file fit rings and it should work fine. Without knowing any numbers we're just guessing at an answer so have the machine shop figure it out.

Before you spend any $$$ on pistons you should have the block sonic checked. I have seen quite a few at .060" crack a wall.

as said find out from them how much clearance/out of round/taper that cyl (actually all of em have). are you thinking cast/hyper or forged?

I have not seen any shelf pistons available in what little I have looked. are their any ? don't really care about cast, forged, etc except for which ever material might be more forgiving as to the wide clearance. I will get the exact cylinder measurements personally this next week.

I don't think anyone has a shelf piston for a 426 Wedge. You'll have to buy a semi-custom piston. They don't cost a ton since the only difference is the bore size.

I have taken street wedge 426 to +.070 over, which is standard 440 bore size
I did have that block sonic tested first and it was good, it was a late 1964 street casting
Have a good shop sonic test his and go from there
The other option already mentioned is to sleeve it, which I like to stay away from unless I have a excellent shop that know exactly how to do one cylinder without distorting the rest of the cylinders on that side
Good luck, let us know what you guys do

70 over street wedge here done close to thirty years ago and still runs just fine, I do not put many miles on it.

Better to hear 'em than to smell 'em.

what would be the ideal or acceptable clearance for say a TRW L2208 .060 piston ?

I agree with having the block sonic tested. You will then know what you are working with and can safely go from there. If it checks out ok and you can go the extra 0.010, do it. There are tons of pistons available in the 440 bore size. Cast, forged or hypereutectic, take your pick.

I don't remember the TRW and speed Pro part numbers for the OEM 415 and 415 HP M.W. 426 pistons so if this is one of them from .0065 to .012 worked for me back in the day, the looser the noisier when cold

what kind of wall thickness #'s am I looking for with the sonic check ?

When I built my old 383 back in the 90's the cylinders were worn some oversize but after honing with a rigid hone they were round. All pistons were to loose as these were stock pistons that run about .0015 to .002 piston to wall clearance. So I had all 8 pistons knurled and ran the .005 over rings and set my end gaps. After the pistons were knurled they were tight in the cylinders so I file fit each one to about .002 piston to wall. Many years ago it used to get done alot and it will still work today. And once you fit the pistons I like that the knurls will hold a little oil in them which helps keep oil on the cyl walls. Its just an option if you use them pistons and one is to loose. I also had a machine shop bore just one cylinder .030 over and run one oversize piston in a 390 Ford eng. Actually the well respected machine shop owner recommended to run just the one oversize piston. I questioned the balance and he said he will get it close enough. It worked fine and had no vibration as it was my dad's 390 truck eng I was rebuilding for him. Ron

^^^ that's what I'd consider, going 30 over & locating a single piston & I believe OS sets are lightened to keep the balance factor the same (or close) as std pistons & if it is heavier (& crosses the line to where it needs balancing adjusting) you can trim the pin as BB pins have more contact area than needed & can easily lose 1/4 off of each end with no compromise to durability. HF has a gram scale for $9.99 or likely get one for free with the coupon with another purchase & they always have SOMETHING that you cant live without!

The OP said the block is already 0.060 oversize. That's why it was suggested he have the block sonic checked and see if there is enough metal to go another 0.010, 440 bore size.

His block is already .060" over.

Depends on how loose the one hole is.

The options are run it or have that piston coated or knurled if it's too sloppy or go with a set of standard 440 pistons. Without an actual measurement there's really no way to give a good recommendation.

If this was a running engine at .060" over and it didn't crack, I don't think I would lose any sleep over an extra .005" on the radius if the easiest solution was a set of standard 440 pistons.

Kevin

keep in mind, we have no pistons at this point. the suggestion to bore another .010 to the 440 bore of 4.320 sounds like an excellent alternative if the block with take it. can someone tell me what the sonic #'s would need to be to be comfortable in doing this ?

What is the casting number of the block he is planning on using?
For a standard stroke and standard length rod engine for occasional race use but mostly street duty we used .150" minimum on the major thrust side as a rule.