Pistons for 250's

[Anonymous]

I had a little time to kill today, so I searched Silvolite's site for possible replacement pistons. Here is a list that I created:

Ford 250/4.1 Silvolite P/N 1120
Bore 3.68/93.5mm
Comp Height 1.5
Pin Dia 0.9122 Offset

Ford 260 Silvolite P/N 1106
Bore 3.8/96.5mm
Comp Height 1.58
Pin Dia 0.9122 Offset

Ford L4 140/2.3L Silvolite P/N 1163
Bore 3.7795/96mm
Comp Height 1.578
Pin Dia 0.9122 Offset

Ford 232/3.8L Silvolite P/N 1183
Bore 3.811/96.8mm
Comp Height 1.584
Pin Dia 0.9122 Offset

Ford 255/4.2L Silvolite P/N 1176
Bore 3.68/93.5mm
Comp Height 1.585
Pin Dia 0.9122 Offset

Chevy 265/4.3L and 305/5L Silvolite P/N 1482h
Bore 3.736/94.9mm
Comp Height 1.54
Pin Dia 0.9273

Now for the block work.
Ken

 

[80Stang]

Ford 260 Silvolite P/N 1106
Bore 3.8/96.5mm
Comp Height 1.58
Pin Dia 0.9122 Offset

Ford L4 140/2.3L Silvolite P/N 1163
Bore 3.7795/96mm
Comp Height 1.578
Pin Dia 0.9122 Offset

Ford 232/3.8L Silvolite P/N 1183
Bore 3.811/96.8mm
Comp Height 1.584
Pin Dia 0.9122 Offset

These are too big / too much overbore.

But these would work:

Ford L 4 141 / 2.3L 1983-94 P/N 1185 (the 2.3 HSC piston)

Ford L 4 153 / 2.5L 1986-91 P/N 1192 (the 2.5 HSC piston)

From Chevy pistons also most others listed with 3.736 (in) bore. Variations concern dish size & shape and if there is valve reliefs or not.

AMC/Jeep/Eagle L 6 258 / 4.2L 1971-78 P/N 2226

and maybe the

AMC/Jeep/Eagle L 6 258 / 4.2L 1971-78 P/N 2227

if the block has an untouched deck. This piston last piston has .130 more compression distance than 250 stock piston so actually it would pretty much make the decking unnecessary and you could preserve thick deck on your block. And even if the block was already decked some, it might make sense to shave the pistons and preserve the deck.

As discussed by skilled members here at the forum, .070 overbore already is risky making the use of Chevy and AMC pistons more or less undesirable.

 

[Anonymous]

Thanks 80Stang,
I knew the bore was a little radical, but I am looking for options. My next 250's power band will be around 5500rpm. After I get my info together, I plan to talk to my engine builder. I am interested in finding out about sleeving a block. I have no idea how much this machining process will cost.
Thanks,
Ken

 

[80Stang]

Yep, X here

http://fordsix.com/forum/viewtopic.php?t=37952

introduced good view on sleeving options. If you'd like to put in a bigger sleeve to make room for bigger pistons - well, worth investigating. Would it affect water passages too much etc.

This got me into thinking about a sleeve for the AMC 258 pistons. X said, that engines producing 1.5hp per ci with 11:1CR should have .180 wall thickness. 1.5hp/ci is pretty much, makes an 388hp engine out of 259cid. Naturally aspirated, most probably we are not going to see that hp and the .180 will be plenty, but a good goal for insurance.

I talked to my machinist just minutes ago. Sleeving will cost here about 55EUR per hole, making it around 330EUR job (415USD), plus the sleeves.
Now, where are we going to get suitable sleeves (around 4.1" od), as he said those are the hard part. Sleeves that big will meet each other between the cylinders, so this seem not too easy...

 

[addo]

I can see where this will lead you! A CHI alloy block with siamesed bores and true SBF bell pattern.

 

[Anonymous]

Chevrolet 262 = 3.671" bore (vee eight)