marlar98

At what point should one consider using aftermarket rods over rebuilt stock rods with ARP bolts? Along with that, what's the matter with the speed pro pistons? Is it the weight that's the issue? What are the advantages for going with Eagle rods with aftermarket pistons BESIDES the speed pros?

I'm asking in reference to a 450-500hp primarily street-driven car not seeing 5500+ RPMs not too often.

Thanks.

covertolds

My 455 has stock rods with ARP bolts and Speed-Pro forged pistons. It dyno'd 498hp/536tq.

Probably about as far as I would go with these parts. Heavy pistons and 40+ year old rods. Shift it at 5600rpm.

Next engine will have Eagle rods and Ross or CP pistons or equivelents.

DeltaPace77

Factory reconditioned forged rods should be fine, for what you're doing, and what I did in my 455. Factory low compression cast pistons and heads are long gone though. Everythings at 10.25 compression now with 0.30 over TRW forged pistons and Dave Smith SS heads, and at the very edge of 93 octane pump gas. This wasn't just a bolt in, as all the assemby's been balanced, ext.

olds 307 and 403

The advantage is lighter weight and thinner ring pack on most modern pistons. A lot of the higher $$$ pistons are 2618 alloy, compared to 4032 in the Speed Pro. The thinner ring pack supposedly wears less plus less friction and heat. Plus the Eagle rod weighs less and are a much harder material. The lighter the parts in a 455, the better. A lot of people seem to have bottom end issues compared to Olds 350's.

cutlassefi

That's the key.
No doubt there is a benefit to both the aftermarket rods and lighter pistons with a better/thinner ring pack.

matt69olds

It depends on how deep your wallet is and how much work you want/need to spend to recondition factory rods. Aftermarket rods are much more available and cheaper than they were a few years ago. If you have to spend a bunch of money to make 40 plus year old rods work for your needs and aftermarket isn't much more Id go aftermarket. Lighter rods and pistons are the key to getting a 455 to stay together at higher engine speeds.

marlar98

Thanks for the insight. Are Eagle rods the only aftermarket rods available for Oldsmobile now? There used to be a company called CAT or something like that. Are they still around?

olds 307 and 403

Rpm Pro Maxx I beams for the 455, $461 on their website. Cat no longer makes those rods, I believe.

VinMichael

I had my factory rods reconditioned with ARP bolts/big ends resized. If I could do it over, I would have went with Eagles. They come with bushed small ends so you can put the pistons on yourself. That right there will save you the $80 or so that you would pay the machinist to press the pistons on for you, so that's an instant savings. Pretty sure you have to clearance the block a bit for the Eagles, but that doesn't seem like a very big deal.