Limited Modified Rod choice?

"J'-remy

Member
Had a discussion with an engine builder who claimed that the Briggs World Formula rod was a better choice than an ARC long rod because of bottom end issues. was curious if running this rod was popular and why it would be better than a longer rod with bearing inserts. thanks for any info.
 
I've used both and prefer the ARC 6249 beefy rod if I'm sticking to the stock length rod. I've also used the 6248 long rod without any issues. I like being able to swap out bearings. Last time I bought a WF rod is was more expensive than an ARC rod.
 
I've used both and prefer the ARC 6249 beefy rod if I'm sticking to the stock length rod. I've also used the 6248 long rod without any issues. I like being able to swap out bearings. Last time I bought a WF rod is was more expensive than an ARC rod.
I also like to be able to swap out bearings. I make it part of my routine maintenance every 8 to 10 races. I have put an ungodly number of races on a few engines without having to send them out for rebuilds. New piston and rings 16-20 races, re-lap the valves 8 -10 races, new valve springs 16 - 20 races, and a rod bearing 8-10 races. Good as new!
 
Any choice will work as long as you do regular oil changes/keep clean air filters on the motor/regular internal maintenance as already mentioned, to include replacing/re-torqueing rod bolts somewhat regularly...and not turning the engine 9000+ on a regular basis...😁
 
I've used both and prefer the ARC 6249 beefy rod if I'm sticking to the stock length rod. I've also used the 6248 long rod without any issues. I like being able to swap out bearings. Last time I bought a WF rod is was more expensive than an ARC rod.
interesting this fellow stated he would not stand behind the engine if the arc rod was used. said I would need to rebuild the bottom end every two races.
 
interesting this fellow stated he would not stand behind the engine if the arc rod was used. said I would need to rebuild the bottom end every two races.
Some early ARC rods were problematic in the animal engine (talking 15 years ago or so now.) Maybe your guy is a bit stubborn and still gun-shy from that experience.
We've all had our share of the light weight rods come apart back in the day. Since that issue, ARC developed their "beefy" rod and we've not seen any problems with these rods at all. The WF rods are alright, but I'm like these other guys - I like to be able to replace bearings and re-use the rod if I can.
For a limited, use a long rod and aftermarket piston -- no reason to be stuck with stock length stuff.


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🏁Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cutz
www.CarlsonMotorsports.com
Carlson Motorsports on Facebook
33 years of service to the karting industry ~ 1Cor 9:24
Linden, IN
765-339-4407
bcarlson@CarlsonMotorsports.com
 
talked to ARC after talking to another engine builder. they both agreed to toss the rod after about 5 or so races or half the season depending on what we turn it, laps, practices etc. I then asked why does it have replaceable bearings?
soooo what's the life expectancy of a billet rod? in a limited or a stock flathead????
horstman would shot peen the surface and not carve in logos (stress risers) they also had a much larger oiling hole. did the older ones last longer ?? I sure wish they forged them.
 
"I then asked why does it have replaceable bearings?"
What did they say?

The bearing provides a better surface in my opinion, they ingest dirt and contaminants better than raw aluminum, makes a buffer for heat transfer, and it's also softer material so it provides some cushion for the explosion that happens 10,000 X per minute in a limited.

We replace bearings and rod bolts after 2-3 races in a limited, and replace the rod at 5-6 races, depending on laps and how hard it was run. Pretty standard deal.

Stock length rods can last several seasons in a stocker (flathead or animal.) Just replace bearings at each rebuild. Life expectancy? Minimum 30 race days. Maximum? I've got some engines with rods that are 10 years old in them still!
 
What did they say?

The bearing provides a better surface in my opinion, they ingest dirt and contaminants better than raw aluminum, makes a buffer for heat transfer, and it's also softer material so it provides some cushion for the explosion that happens 10,000 X per minute in a limited.
you turn limiteds 20,000 rpm?
 
Ok, I now understand how I was wrong in my criticism, sorry. IMO the main stress of the bearing and rod is the many more times it stops and starts moving in the opposite direction.
Just think of the old flathead limited 4.670 rods with that tiny 5/16" wrist pin hammering an oval whole in the aluminum piston bazillion times per lap. They were my favorite.
 
The ARC bearing insert is more forgiving, doesn't stick as often!
 
I h
talked to ARC after talking to another engine builder. they both agreed to toss the rod after about 5 or so races or half the season depending on what we turn it, laps, practices etc. I then asked why does it have replaceable bearings?
soooo what's the life expectancy of a billet rod? in a limited or a stock flathead????
horstman would shot peen the surface and not carve in logos (stress risers) they also had a much larger oiling hole. did the older ones last longer ?? I sure wish they forged them.
I have rods in flatheads that's been run for years like Mr Carlson said, I have S/A animals and small block opens, with the same rods for 3 years now, just change the bearings every 6-8 races, I guess it depends on oil and how often you change it also.
 
I am sure he would if he could Raging Bull Engines but you should understand that 10,000 explosive events per minute is equal to 10,000 RPMs.
Lol, Don't try to school me. On a 2 stroke 10,000 firing events is 10,000 rpm. On a 4 cycle it would be 20,000 rpm with 10,000 firing events per minute.
 
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