Connecting rods

[Anonymous]

Should I go for new forged connecting rods or try to re-use my existing cast rods? 1967 Mustang I6. Since I am going to spin this to about 7500, I am leaning towards new connecting rods, but since the throw is so short, maybe the cast will work? Any insight? Horror storries?

Thanks

Hank

 

[Anlushac11]

8)

According to my article from Ak Miller, all ford 200's have forged rods til 1973.

So I would take your rods and shot peen, have them polished, and put in some HD ARP rod bolts.

BTW for 7500rpm forged pistons are required.

 

[Anonymous]

I've turned my 144 cu in motor over 8600 rpms in my hydroplane with stock rods with no failures. However, they were drilled and fitted with 3/8 396 Chevy rod bolts. Balancing, forged pistons and proper clearences are a must. No short cuts or you waste your time and money.

 

[Thad]

OH, no Mister Bill not the polish.

Polish, anneal, then shot peen, if shot peened first, polishing would remove. The purpose of shot peening is to compress the "skin" layer on the rod. For a rod to break after being properly polished and shot peened the rod will have to bend enough that the compressed "skin" on the outside of the bend area is stretched until there is no compression in the metal before a tear can start.

Rod bolts, HRM some year ago did an article on engine part failures, Rod bolts stretch and/ or failure was the #1 cause of rod failure. Rod bolts yield, big end goes out of round, squeezes the bearing, grabs the crank, rod can not rotate so beam bends until it breaks.

 

[Anlushac11]

:roll:


My bad...What Thad said. My point was that your stock rods should be fine with some proper modifications.

 

[Anonymous]

thanks all...just what I was thinking!!

 

[Anlushac11]

8)

Not that I have been around the racing scene that muchbut rods seem to be pretty strong. I have seen several rods almost straight go through side of block and I have seen bent rods but I have never personally seen a broken rod. I have seen pictures of bent rods but have never come in contact with one.

 

[Thad]

Ok, Ted,
Pls tell us what were you doing or had you done to scatter the 250 to such an extreme.
Sounds like a '49 Ford flathead that we grenaded in hi- school. Simple, nitromethane, methanol and hydrazine, a dense head (mine not the Ford's), a heavy foot and God's own grace that the three of us did not get hurt.
: : : :roll:

 

[Anonymous]

I'm gonna dredge this topic back up cuz I got a question. The older rods are forged, well forged what? Forged steel, forged alluminum?

Then they went to cast, cast iron? Cast steel(i'm not even sure if such a thing exists), cast aluminum?

Then they went back to forged something in the newest Falcon sixes, of the early eighties.

So what type of rod is each?

I can't find the answer in any of the manuals I have, and I'm curious.

 

[MustangSix]

Forged Steel, Cast Nodular Iron, no aluminum, no titanium, no unobtanium. Nodular iron is a high strength alloy.

Not sure when the cutoff was on a 200, but on a 250 the first rods are forged steel and have a C9 casting number and a forged part line. Later rods have a D8 casting number and are a nodular iron with a thin casting part line. The later rods are thicker, heavier, and weaker, but entirely adequate for a stock 250.

The 200 rods probably switched in the early to mid 70's. You can tell a forging from a casting by looking at the part line along the beam. A forging will have a wider (about 1/8" to 3/16") line that looks almost like a machined edge. A casting will have a thin line where the mould parted.