What con rods?

S

Sparkz#0535

Member
I know a lot of guys here are running the eagle rods with the arp bolts that come in them. My machinist is trying to push me towards scat rods with upgraded arp bolts and diamond pistons. I was thinking that might be a little overkill for what I want out of the engine.

I was thinking eagle rods with a middle of the road forged piston and 2 bolt mains with arp studs would be fine in the 400hp range. Is my thinking wrong?

stock turbo or possibly a billet 60-1

thanks for any advice or comments
 
autoaddictions

autoaddictions

Active member
Re: What con rods?

Eagle rods have proven to be strong enough to make 800 hp. I wasn't aware scat had off the shelf rods for a 4.3. Oliver used to make them but they haven't produced them in years. They pop up on here occasionally. I had Cunningham make me custom 5.85 length Rods good to 2000 Hp but they cost 4 times the price of the standard length Eagles. I have run Eagles in my last few stock block motors and spun them to 7000 rpm. I've never had a rod failure. The block will give out before the rods.
 
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C

Chevymec

New member
Re: What con rods?

I used a set of Eagle rods when I built my 4.3. Can't give you any feedback on the m though since I haven't run my motor yet.
 
Don W.

Don W.

Stab it and steer it
Re: What con rods?

Go here, just a bit beyond half way down the page. Or do a search for "connecting". Interesting info on I vis H beam rods.

https://540ratblog.wordpress.com/

Supports Dave's observations.

Rod strength in tension is not as important for us for 2 reasons, we don't rev that high and, in theory anyway, at TDC exhaust we still have pressure in our cyls because we have to force exhaust against the resistance of the turbo. For the same reason we don't, or shouldn't, have much valve overlap.

I happen to have Eagles but only because I got a good deal on them and hadn't done any research.
 
syclone3

syclone3

Member
Re: What con rods?

Good article. They key word is material. So many companies claim to use specific metal when making rods. But who really test the actual material. I have used and am using Eagles. Maybe its not a good design. Haven't seen too many break. But the ones that have they broke alright and the rest of the block.
For low rpm and hp like the 4.3 I think they suffice fine. Sure a nice set of I-beams would be great. And so is the cost. Anyone building an engine that sees some serious rpm and loading. Better spend some money on the components in the lower end.
 
S

Sparkz#0535

Member
Re: What con rods?

Is there a way to ID the Romulus rods vs Tonawanda rods or do they look identical ? any markings to looks for?
Are the stock Romulus rods ok to use with heaver forged pistons if I use good bolts?
I'm still on the fence about even putting a baby cam in this engine as I really like the way the stock cam drives so I think 4500 or so will be the max rpm for me.

* im reading the link DonW posted ...
 
Don W.

Don W.

Stab it and steer it
Re: What con rods?

No only because our rod journals/bearings are not the same width. We're narrower.
 
Peter

Peter

my Ty and me 25+ years
Re: What con rods?

For what it's worth, I've run Eagle rods with Diamond pistons to 5600 rpm countless times with no issues.
 
atomicmecha

atomicmecha

I hate rust
Re: What con rods?

DaveP said:
Look at the balance pad on the cap. If it is machined on 5 sides, it is a Romulus rod. If it is only machined on the top surface, and the sides are raw, it is a Tonawanda rod.
Click to expand...

Only picture I have on hand atm, but is this what you mean by being machined on all 5 sides? These would all be Romulus rods correct?
12745691_975843489156723_1485557993750086257_n.jpg
 
S

Sparkz#0535

Member
Re: What con rods?

So its looking like stock Romulus rods with arp bolts and forgies.

Now I'm thinking about a custom cam being that I will have a little more cash for the build
 
Couger1968

Couger1968

Dazed and Confused
Re: What con rods?

I guess I don't know if there is any truth to this, but one of the reasons I didn't just change my bolts was that the rods need to be resized one you put them in because they are probably out of round.
 
Don W.

Don W.

Stab it and steer it
Re: What con rods?

On a good rebuild the rods should magnafluxed, resized, checked for straightness, If floating pins, re-bushed (or checked) but ours are press fit, bolts and nuts replaced (optional IMHO but often done, cheep insurance.), and maybe balanced.
 
Couger1968

Couger1968

Dazed and Confused
Re: What con rods?

I figured that and before I spent all that money on my old rods, new Eagles weren't much more. That is why I put Eagles in.
 
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