2.3L Connecting Rods

This is from a book by SA Design called "How to Rebuild the Small-Block Ford." Page 54-56, published 2005. Bear with it, it's long, but all applicable. If you want to see just the good stuff, stop after paragraph two.

Ford small-block engines have been blessed with rock-solid bottom ends from the factory for more than 40 years. The 221-, 260-, 289-, and 302-ci engines have strong forged-steel connecting rods that have undergone very few engineering changes throughout their production life. The 289 High Performance connecting rod, for example, differs little from the standard rod except for a larger 3/8-inch bolt pressed into a broached seat. Because connecting rod bolts are the single greatest reason for rod failure at high revs, the larger 3/8-inch bolt is a great deterrent to failure.

There are two basic small-block Ford connecting rods for 289/302 engines. The 221, 260, and 289 rod (5.1535 to 5.1565 inches center to center) is numbered "C3AE" while the 302 rod (5.0885 to 5.0915 inches center to center) is numbered "C8AE." The 302 connecting rod is actually shorted than the 221/260/289 rod. What may surprise you is the Boss 302 rod number "C2AE-D" is exactly the same rod forging as the C3AE with 3/8-inch bolts for structural integrity at high revs. When we closely examine the Boss 302 rod, the large end of this rod appears to be a bit beefier than its 289/302 counterpart, but the Boss 302 rod is basically nothing more than the 289 High Performance rod. The 221, 260, 289, and Boss 302 connecting rod later found its way into the 2.3L OHC turbo 4-cylinders used in the T-Bird Turbo Coupe, Cougar XR-7 Turbo, Mustang GT Turbo, and the Capri RS Turbo available during the 1980s. There are a lot of them floating around out there.

Because the 302 has an entirely different bottom end dimensionally, it has the C8AE connecting rod forging married to its 2M crankshaft. This rod is not interchangeable with the 221/260/289 and Boss 302 engines just mentioned because it is shorter. The C8AE rod is common to all the 302ci (5.0L) engines. Aside from subtle improvements to this rod that came with the power increases of the 1980s, this rod is virtually the same and quite interchangeable. It's always wise to match a set of rods, which means a set of rods that are identical in appearance and forging numbers. One modification is upgrading the 302 rod bolt from 5/16 to 3/8 inch. this gives the 302 rod the durability of the 289 Hi-Po/Boss 302 rod mentioned earlier. One drawback here is rod integrity because although larger bolts are stronger, we tend to weaken the rod when we take away some material to fit the larger bolt. The 351W engine was equipped with one basic connecting rod, the C90Z unit with 3/8-inch bolts, regardless of the application. This rod remained unchanged throughout the life of the 351W (and 5.8L).

The standard 351C-2V and 4V engines were fitted with the D0AZ-A rod forging. The Boss 351, not to mention the 351C High Output and CJ, were equipped with the D1ZX-AA connecting rod, which was Magnafluxed and shot-peened for added strength. This is a good thing to do with any small-block Ford connecting rod you intend to use. The 400M has a D1AZ-A rod that served with this engine throughout its entire production life.

Connecting rod selection boils down to how you intend to use your engine. If you're going to lean on it periodically or are building a weekend cruiser, forged I-beam (stock) connecting rods are adequate. This means you can recondition your stock connecting rods, fit them with new ARP bolts, and be ahead of the game. You may also step up to larger 3/8-inch rod bolts for your 289/302 and have the integrity of the Boss 302 or 289 Hi-Po rod. Just remember to have the rod forgings shotpeened for added strength.

If you're going to blow squeeze at your 289/302/351, forged I-beam or H-beam rods become mandatory due to the loading they will see - even on a limited basis. The same can be said for supercharging or racing where the rods will be hammered hard on a regular basis.

Some drag racers use aluminum connecting rods, which are fine for drag racing but bad for road racing or street use. Aluminum rods weigh considerably less than their steel counterparts. This means they will consume less power. However, aluminum rods are appropriate only for the fast-quick blast of drag racing."

try to put a 289 rod in your 2.3 or vice verse and you will find out the guy that wrote that doesn't know what he is talking about.

a 289 rod is 5.155" long and a 2.3 rod is 5.205". the rod journal diameter is different too but i don't have those dimensions saved in my noggin. i suppose they could be forged from the same dies and machined to different dimensions but i doubt it.....the rod caps look different. 289 rods have a ribbed cap and 2.3's look more like a 302/5.0 rod cap. they are definitely not interchangeable.


he's wrong on 351w rods too. there are 2 different 351w connecting rods made from the same forging. passenger car and high performance/truck. the passenger car rod has a broached rod bolt seat and the truck rod has a spot faced seat. the spot faced rod is the desireable one because less material is removed from that critical area during the machining process. the spot faced rod uses a bolt with a "football" shaped head and the broached rod uses a square headed rod bolt.

however, he is correct in writing that putting 3/8" rod bolts in 289/302 rods weakens the rod. it is better to install high strength 5/16" bolts.

one other thing to add. i have built plenty of 5.0's with 289 rods. you have to machine about .045"-.050" off the top of the piston to bring it back down to "zero deck", but it is worth the extra effort. i have even ran one of these combo's with the piston .010" above the deck with no issues.

2.3 conn rod journal diameter 2.0465 - 2.0472"

Length, center to center 5.2031 - 5.2063"

yeah, i think 289/5.0 rod journal is 2.123".

Pretty amazing the amount of incorrect info in that short section of the book. I guess that's why it's necessary to check the factory manual and just use those books loosely as a guide and for the pictures. Tthanks for clearing that up and hopefully this topic will be of good reference use to others in the future. At least we cleared up the fact that they are indeed forged, not cast.

so all 2.3 turbo or non turbo are the same rod??? just change to arp bolts and ur good for 450-500 hp???????????????

Not so sure I would just put in better bolts and call it good.
My #4 connecting rod broke at the big end doing approx. 6800rpms and 33 psi from the Holset (around 420-430rwhp). The stock rod bolts were undamaged.
My tune was good so I am leaning toward metal fatigue as the primary cause of failure. My stock shortblock had 245k miles at the time.
Anything over 400rwhp and I would swap to a better rod. It just isn't worth taking a chance on destroying a perfectly good turbo block.

i'm with boosted chicken on this. people think putting in ARP bolts makes the rods virtually indestructable. while it is a recommended upgrade, i have not seen a pattern of broken OEM ford rod bolts in all my years of racing.

Twenty some odd years ago we raced the 2300 on the oval track. As things go in roundy round sometimes the engine may go from 7000 or above rpm to zero. We learned early on that if you had a sudden stop of the engine from high RPM that it was a must to pull the engine down and replace what were at that point stretched rod bolts. I was a Ford parts manager at the time and we just used factory bolts. Also we always used new bolts because you don't know what that engine has been through.
Now I'm gonna scare you. When the 2300 first came out they had no oil hole in the rods to lubricate the cylinder walls. This caused piston scuff and Ford had a huge campaign (unforced recall). We replaced the pistons, rods, rings and bearings on virtually every 2300 built up to that time free to the customer. Here's the scary part. We looked for the old style rods without the oil hole because they were stronger. We ground them down and lightened them taking a huge amount of weight off them. We never had a rod fail that you could blame on the rod and we never had piston scuff. Of course you tore the engine down once or twice a season anyway. The cars that actually had piston scuff usually had better than 40,000 miles on them and I can't remember ever having to have one bored to clean it up. They were honed and put back together