Cast or Forged Rods?

[tomking]

I am trying to identify which are cast and which are forged. I know the hump at the squirter means forged but are some of the other rods also forged but without humps? I believe, well I hope that only the last picture is a cast rod on left side of the picture. What do you think?

[opeldean]

I think you are correct, the cast is on the left of your last photo. It is thicker looking and more rounded.

Enclosed is a picture from my rebuild that RB identified for me, in my rebuild thread.

when compared, the forged look thinner ,sharper angles and less beefy.

[RallyBob]

Originally Posted by tomking I am trying to identify which are cast and which are forged. I know the hump at the squirter means forged but are some of the other rods also forged but without humps? I believe, well I hope that only the last picture is a cast rod on left side of the picture. What do you think?

Correct, last pic...left side rod is cast (brand new judging by the coating!). The rest are forged.

[tomking]

Thanks for your help guys. Yes the cast one is new. I had been searching for the comparison photos but hadnt found them.

[neuropel]

Well, I thought I had this issue straight, but now I'm second-guessing myself. Pictured in the first photo below (on the left) is one of a set of newly reconditioned forged rods. The rod beside it (still with piston) was pulled from the block I'm having bored for a 2.2. It looks to be forged as well, but appears to be a bit more beefy (plus, it has a funny hump near the oil hole). Can someone confirm that both of these are forged rods? Pictured in the second photo is a rod/piston assembly I pulled from my '74 Manta, which was supposedly a stock engine. Is this also forged? If so, is it typical for a '74? I thought most Opel engines had cast rods. The reason I'm second guessing myself is that every Opel engine I pull from my parts stash seems to have forged rods, and I'm wondering if this is really the case.

Are the rods in the first photo of equal strength?

Todd

[neuropel]

Well, after looking through this thread and others, it sure looks to me like the clean rod in the first photo is actually a cast rod, not forged - also the rod in the second photo looks cast.

[RallyBob]

Originally Posted by neuropel Well, I thought I had this issue straight, but now I'm second-guessing myself. Pictured in the first photo below (on the left) is one of a set of newly reconditioned forged rods. The rod beside it (still with piston) was pulled from the block I'm having bored for a 2.2. It looks to be forged as well, but appears to be a bit more beefy (plus, it has a funny hump near the oil hole). Can someone confirm that both of these are forged rods? Pictured in the second photo is a rod/piston assembly I pulled from my '74 Manta, which was supposedly a stock engine. Is this also forged? If so, is it typical for a '74? I thought most Opel engines had cast rods. The reason I'm second guessing myself is that every Opel engine I pull from my parts stash seems to have forged rods, and I'm wondering if this is really the case. Are the rods in the first photo of equal strength? Todd

Todd, the left-hand photo shows a cast rod on the left, forged rod on the right. The right-hand photo shows a cast rod as well.

HTH,
Bob

[neuropel]

Thanks for confirmation Bob. I think what was confusing me was that the rods were sold to me as forged rods, when in fact they are cast.

[kwilford]

Originally Posted by neuropel Pictured in the second photo is a rod/piston assembly I pulled from my '74 Manta, which was supposedly a stock engine. Is this also forged? If so, is it typical for a '74? I thought most Opel engines had cast rods. The reason I'm second guessing myself is that every Opel engine I pull from my parts stash seems to have forged rods, and I'm wondering if this is really the case.

I agree with Bob, the "reconditioned" rod on the left is cast, as is the rod in the photo of the one rod/piston. AFAIK, only 1974 and 1975 (maybe late 1973) engines had cast rods, all the earlier ones were forged. It is fairly easy to tell them apart, as the cast rods have a thicker web at the base where the beam connects to the big end.

Originally Posted by neuropel Are the rods in the first photo of equal strength?

The forged rods are stronger, but I don't believe that the cast rods are actually "weak". That is, I would use a forged rod for an engine that I was building up, but by the same token, I wouldn't hesitate to use a cast rod for a street engine, unless I had a set of forged rods that were in equal condition.

JM2CW

[guyopel]

The cast rods were the only replacement from the Dealers
and all 4 rods had to be replaced even if you need only one. The '75 FI engs. all had cast rods from the factory .
HTH
John