All Small Six 250 Engine Build

[twentyover]

I will not start a 250 fordsix engine project.... I will not start a 250 fordsix engine project.... I will not start a 250 fordsix engine project.... I will not start a 250 fordsix engine project....

Crap. It followed me home

74 Maverick, runs good. So the junyard tag says.

I am an idiot

 

[twentyover]

And the beat goes on... The drum keeps pounding rhythm to the brain....

So a coupla weeks ago i picked up a 250. Struggle in my head about how to build it. Was initially thinking about following Lavron's build, but it appears both he and comet6 found the 2,5 HSC rods longer than published, and comet6 indicates he may have the last full set on the planet. Lavron and comet 6 had different fixes for the long rod, both could work.

So where to go for longer rods? Manley has an H beam rod for a Barra, 6.058 long, problem is pin bore is 0.8671 and the price of $883. Ouch. Scat and Boostline offer similar products for similiar prices. Tomorrow's phone call will ask can the pin bore be, well, bored to 0.912.

Pauter offers an X beam (I guess that's what they call it) rod they identify for use in "STRAIGHT 6, 246-250." It's 6.055 center to center, w/ a 0.912 pin bore. Tomorrow's phone call will be cost and availability (Pauter recently had the forging house they used close it's door, so they are needing to retool forge dies)

Third option is early Ford 300 rods. By the time you put good rod bolts in them, resize, polish beams and shot peen, you're looking at the same kind of money as aftermarket Barra rods

More research ahead

 

[Jmustang_65]

Chevy inline 6 Rods an option?

5.7 fitted with arp bolts $260 a set

194-230-250 Rod Set

Home of the HI-FLOW lump kit. 194, 230, 250, 292 Chevy and 153,181 ,2.5, 3.0 mercury engine. Inline chevy 6 performance, Turbocharging, Custom parts, 12 bolt rebuilding

www.12bolt.com

6.0 - I beam rods $440 a set

6" Connecting Rod 194-230-250 SPA Budget version

Home of the HI-FLOW lump kit. 194, 230, 250, 292 Chevy and 153,181 ,2.5, 3.0 mercury engine. Inline chevy 6 performance, Turbocharging, Custom parts, 12 bolt rebuilding

www.12bolt.com

 

[Invectivus]

I think the issue with the Chevy rods listed are
-The BE width is 1.027", bigger than our .994", needing to be shaved down.

I'm going to eat most of my words, besides the width, and that only because I'm ignorant of how easy/hard it is to narrow rods, and the approximate cost (maybe I'll eat those too, I'm hungry). It looks like pretty much anything you do except the early 300 rods require rod journal resizing, to a standard Chevy 2". And once you play with length, you're probably getting a custom piston anyway that can handle a variety of pin diameters and press/float options.

Will/Kelly's Manley part number looks like 14044 2.125” BE

EDIT: Here it is, quote and link:
"We're using off the shelf aftermarket Manley H-Beam rods for a 4.6L Ford V8. They use a standard .912" wrist pin and are .088" longer than the 250 rod. (pretty sure that's the correct number!) The big end is a little smaller than the 250 rod, so you'll need to machine the rod journal to fit....or offset grind it to gain a few more cubic inches.
Because they're V8 rods, the big end width is less. I don't remember the exact numbers off hand, but it's something like .040" less. So the rod will "travel" fore and aft a bit within the rod journal. We haven't seen any issues with that at all! We've torn down the engine numerous times for other issues or just for maintenance, and have never had a problem with that extra rod room in the journal."

D

Post in thread 'Is there a good forged alternative rod out there for a 250?'

Sep 28, 2016

Just to be clear....our "carnage" wasn't caused by a failed connecting rod! It was caused by a cyl. wall that broke at around 4500rpm or so. The piston rings for that hole then got jammed and then the train wreck started to happen. Hence all of the broke or bend rods!

We spin Kelly's 250 to 6100rpm at the traps. We haven't used stock rods since that grenade engine, but that was more to do with getting the piston closer to a zero deck height.

We're using off the shelf aftermarket Manley H-Beam rods for a 4.6L Ford V8. They use a standard .912" wrist pin and are .088" longer than the 250...

• Does10s

With the 300 rod being 6.210" CtoC, there's a mess of rods that can fit with a custom piston between 5.880"-6.200" and long as you can resize your journal and have a decent ring pack and lands, right?

 

[twentyover]

Currently trying to get the funding together to get a set of used Ford 300 rods w/ Racetech/Autotech pistons. The pistons are a little larger than I prefer (+0.040, rather than my preferred +0.020- twentyover), but for the cost and lead time I'm willing to forgo my desired oversize. For the horsepower and rpm this deal will run (maybe-please 160-170 and <5800 rpm), the incremental weight savings of an aftermarket rod vs the cost put it out of reach

 

[drag-200stang]

It is a rare 250 block that the #1 bore will clean up at .020'' . I have offset bored that cylinder a little to made it work.

 

[powerband]

for reference on 250 cylinder bore and piston applications , the vintage Clifford Machine Shop - TriPower 250 in the '61 has AMC 258 - 3.75" std pistons.
.
Ford 250: bore = 3.68 / comp distance = 1.5 / OEM dish volume = 13cc
AMC 258: bore = 3.75 / comp distance = 1.633 / D-Sump = 21cc's
Forged 258 pistons are available afaik.

Cylinder bore is @ .070 over and the AMC piston compression height is toward the deck .133 . The specs list the pin diameter of the ford at .9122", the AMC's at .9310" and small end of the rod accommodated .
.
AMC 258 piston recess is 21ccs. With the .070" overbore the bore is 3.75", stroke of 3.91, typical head gasket at .050", a zero deck height, chamber volume of 60ccs and a piston recess of 21 ccs, gives a SCR of @ 8.8:1. OEM Shot Peened rods finishes key parts.
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Found engine in Falcon Club magazine classified @ 2003 , was built for a Maverick drag car but mothballed in it's original packing crate much earlier.
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. . . .
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.070 overbore with AMC pistons and stock rods is unusual if not unique but has allowed for redline shifts @ 5500. ( so far )
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. . .
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have fun