Jhucks03

What would be the “limits” for a stock ‘68 Toro rod (assuming ARP hardware)? Power and/or RPM values

coppercutlass

I can tell you 7k rpm on a stock rod ain't good lol. 6k would be safe . I built a big block last year and let's just say we forgot to set the rev limiter and 7k comes up fast with a 4.56 gear in the burnout box.

OLDSter Ralph

Why did you run it to 7,000 in the burnout box ? ARP bolts are good and you are good to 6,000. 455's have a long stroke,so they shouldn't rev to 7,000 unless you have a lot done to the rotating mass.

matt69olds

This is the 17th year on the short block in my car. Heavy forged Speed Pro pistons, stock roads with ARP bolts. I shift it at 5400 rpm, go thru the traps at 5800.

The heavier and more rpm, the lower the safe limit. Unfortunately, Olds connecting rods leave much to be desired. Aftermarket rods have gotten pretty affordable, unless your building a mild engine stock rods aren’t the best choice.

coppercutlass

I actually didn't rev it to 7k that was my co pilot. In the burnout box he is used to pegging it to the rev limiter on his race car . We never set it and he was waiting for the RPM to bounce as the indicator to let off and roll out. I don't run a rev limiter and I usually run an SBO and usually keep the rpm under 6k in the burnout box but shift at 7k but between the sbo and bbo the weak link is the heavy bob weight. . we didn't intend the engine to live long and it was a joint venture for fun we had one shot to get it to the track . We did and made plenty of runs. Despite the fact we hurt the engine on run # 2

OLDSter Ralph

X 2 Except I went through the traps@ 6,200 RPM's with 5.00 rear gears on 10.50 X 15 M&H Racemasters. I never lost a rod,but I did break a factory piston. The new, affordable "H beam" rods are better. Stock rods can be improved but won't ever be as good as the "H beam" rods.

You don't have to turn over 5,000 to clean and heat up the tires. I believe I read in a thread you shifted one gear at 6,500 and the other gear at 6,700 so it shifted by 7,000 ?

coppercutlass

On my 350 I shift at 6700 to make up for range of motion . In the burnout box it's a la carte drivers choice on how to clean the tires and heat them up. Some guys keep it down. Stick shift guys will usually just hang the RPM up and not shift. So really it's all about application and taste.

OLDSter Ralph

So, you are actually shifting at 6,500 to 6,700 RPM's and not 7,000. Burnout RPM's over the tire spin you need to clean and heat up the tires is just "show boatin".

coppercutlass

I shift at 6700 and by the time frame it takes me to react to the light and shift it hits at 7k. I confirmed this with a timer and go pro. As far as the burnout goes. It don't take much to spin an engine that hight and smoke the tires. My mickey thompson smoke up even from a roll on the street if I smash the throttle . Rule of thumb spin them until you see a little smoke and roll them out.
My shift points are on my sbo. A bbo with proper work even in stock rods should handle 6000 rpm

pettrix

I think it was Trovato who said that factory 455 rods only belong in one place, in the garbage. Maybe I am paraphrasing but the point is stock rods were marginal at best with stock HP levels.

Eagle makes forged H-Beam rods for around $500. Well worth the investment. Put a lighter piston on it and you are doing very well for longevity.

coppercutlass

I would agree with you on that but for decades guys ran stock rods with no issues on HP set ups . Now that there is parts yeah use new but if all you do is run a stock rod then it will work but to a certain degree

pettrix

I am not sure about running stock rods with "no issues" on HP set ups. Most of the guys I knew that ran stock rods back in the 90's, 2000's and even early 2010's, pretty much all eventually had a rod bearing failure or the engine had to be torn down after a few seasons of racing. Bill Trovato stated that even on fully reconditioned factory rods with ARP bolts, after a few runs, the big end was no longer true when pulled apart and checked. This would put the rod bearing into accelerated wear or end up spinning a rod bearing or worse case scenario, throwing a rod out the block.

Plus the power levels guys are putting out on their 455's today is vastly more than what they were running back in the 80's, 90's and 2000's.

Maybe some are more daring than me but I wouldn't trust a factory 455 rod with a modified engine and high RPM. I am not a gambling man

therobski

What are the HP limits on stock rods 425-455?

therobski

Early 400E's? for got to mention this bad boy

matt69olds

My burnout procedure is to pull the the edge of the water, set the line loc (2 step is set at 4800 if I remember correctly) leave the trans in drive, snap the throttle open fast (spinning tires on the 1-2 shift will kill the intermediate sprag!) as soon as the tires warm and start to drag the engine speed down, I let off the line loc. Don’t let up on the throttle, come out of the water box under power. Letting off the throttle and letting the tires grab can kill the sprag in the converter.

John force style burnouts overheat the tires, abd really don’t do anything other than look impressive.

coppercutlass

It does not take much for the m/it's to smoke up.inuwuqlly don't sit in the burnout box much longer than a few seconds. I usually do a 2-3 burnout. This th350 I have now has been around the block a few times and surprisingly still holding up very well.

Andy

Good post, lots of differing opinions. Been contemplating this very question on a 455 rebuild. Basically putting together the factory numbers matching block on my 70 w30. I have zero plans for drag racing it, however I want to do it once..only thing I don’t like about the h beams is you have to grind cylinder wall on the bottom of the cylinder for rod beam clearance..is there an I beam forged aftermarket rod?

pettrix

The Scat 455 rods don't have to be notched. Good luck finding them. Notching the block for Eagle rods isn't that bad of a procedure.

Running factory rods beyond their limits, they will permanenently notch your block by exiting out the side of it

pettrix

Its not only HP but heavy pistons and RPM that will stress factory rods. Plus detonation. I think anything over 400HP is entering dangerous territory but you will probably hear from others who ran 450HP + with stock rods.

Andy

Are you talking Scat H beam rods don’t have to be notched? Thats the only rod scat makes I believe..

matt69olds

I had my car tuned on a chassis dyno last year, after my buddy was all done tuning the final numbers were almost 430 hp to tires. Using the common 20% drivetrain lose correction factory, that’s over 500 flywheel.

cutlassefi

Eagle, Scat and Speedmaster make big block (6.735) H beam rods. I’ve used all three. Eagles and Scats are fine, Speedmasters are junk. They’ll come in almost .001 OVER the high spec.
Eagles you have to clearance for cuz they’re wider than the Scats.
I wouldn’t use a stock rod in anything. It doesn’t makes sense. The H beams are not only much stronger but actually lighter than the stock ones. And by the time you pay to press pistons on and off, recon with new bolts, you’re 3/4 of the way to a set of new ones anyway.

Hope this helps.
Mark

OLDSter Ralph

Thanks Mark.

therobski

Great information. Thanks.

67OAI

Gotta agree with Mark! Even with lighter pistons, the stock Olds rods in my E block would always be out of round when I tore it down. I used to spin it to 6200 with the stock original pistons and about the same RPM after using lightened TRW pistons.

Andy

Mark, sent you an email..
Andy

coppercutlass

I'm just playing devil's advocate on my part. Has it been done yes. Does it have its limits yes. If you wanna build something reliable then new rods are obviously the way to go. I been spinning stock sbo rods to 7k for 3 years now. Now it's apples to oranges since the sbo does not have all that massive bob weight ., but most of my engines usually see 3 or so seasons of racing then I change it up. Next engine will be stroker crank alnew rods Pistons and thats simply because I need something close to bullet proof since the older I get the less time I have and the more I have learned the more selective I have become. So in short yeah you can run stock rods but as mentioned it's borrowed time. My. Buddy has a 550 hp 455 on stock rods with close to 300 runs on it. No issues hasn't been apart at all . As mentioned rods probably are all out of spec but it still works.

matt69olds

I have ZERO doubt the rods in my engine are out of round. Until the engine comes apart, I ain’t going to worry.

Last year I have a HUGE dumbass attack, I accidentally slide the floor jack under the car just a little too far. The jack saddle caved in the oil pan. I tried for several hours to remove the 8 quart pan with the engine still in the car, it wasn’t going to happen! I reluctantly pulled the engine. My neighbor came over to see what was going on, he asked if I was going to pull some main/rod caps to inspect the bearings. I told him absolutely not!! If I saw something I didn’t like, I knew the car would be down the rest of the summer. I knew if I saw something I didn’t like, I would either baby the car, or worry anytime I took it out for a drive. I figure the oil filter is always clean, the oil pressure hasn’t changed in ten years, if it ain’t broke don’t fix it!!!

coppercutlass

You could have used a stud welder and a little leverage bar to pull the dent from the pan. I have actually done this on an engine that I needed to run before I tore it apart. , But I'm a body man so I have those tools lol.

VORTECPRO

What MPH does your car run at the track at what weight?

matt69olds

Little over 4000 with a “dangerously underweight” (&#128527 driver and almost 115mph. My best 60ft has been a 1.54, best eight mile is 7.42.

This is one of my time slips from Drag Week from a few years ago. I put a progressive nitrous controller in the car a few weeks before the event, and played around with settings to get as close to a 11.50 as possible. Since I refuse to put a cage in the car, 11.50 is as fast as I can go as per the rules.


If I remember correctly, it took a few seconds of the nitrous at around 20% to hit the 11.50-11.55 number. My 5 day average was 11.62, good enough for quickest Olds.

VORTECPRO

115 mph @ 4050 = 474 hp

grannys442

As a footnote: For anyone building a 400G, the aftermarket rods (at least Eagle) are too wide to fit into the ridiculously small bore UNLESS the block is bored to at least 4.000" . To clarify, I'm not talking about hitting the block after they're installed...I'm talking that they won't physically drop down into the bore when trying to insert the rod/piston combo into the bore. There may be some high end rods that will fit a <4.00" bore but to my knowledge none of the affordable H beam rods will drop down into the < 4.00" bore. Yet another hurdle for the 400G but I expect most of the G's are built for restoration projects where a reconditioned stock rod would be appropriate.

VinMichael

ARP bolts with stock rods are more than fine for a mild build. With an auto trans your not going to be shifting past 5,000 RPM anyway so who cares. Mild 455 is still a ton of low end power you won’t find in many other engine platforms.

And Trovato wrote a book called “Maximum Power Oldsmobile” or something which says stock rods are junk. This book was about building Oldsmobile racing engines. By now Trovato is running LS engines and has been for years.

Olds 455 is not a good choice for a racing engine. It is an awesome choice for effortless torque on the street under 5,000 RPM. Don’t overthink it.

VinMichael

Trovato has been running a late model Camaro and LS engines for OVER a DECADE.

He’s been running late model Camaro’s and LS engines so long his late model Camaro race car grille looks dated compared to Camaro front-end face lifts for the last 5 years.

cutlassefi

Curious as to what the trans has to do with when you’re going to shift. Wouldn’t it be the engine combination?
I’m being nice here. The trans being used has absolutely nothing to do with when you shift. Not sure why you would say that.
And the ARP bolts are a waste of money. The issue is the stock rods don’t repeat. In other words after they’re reconditioned, and pulled apart and remeasured, they change. Ford FE rods typically have a similar problem.

VinMichael

From a stop put the car in D and take off. The 1 and 2 shift will occur below 5,000 on a th350 or th400 with stock governor.

With average gear ratio and tire size, at what MPH do we care about RPM above 5,000 I final drive gear 3rd?

cutlassefi

So you can’t shift it yourself, really?.
Its the engine combination that matters, not the transmission.

VinMichael

The th350 in my car is built to be operated in D. It shifts at 4,800 when floored.

The radials will bark on 1st and 2nd shift in D when floored with a 2,500 stall.

cutlassefi

Again what does this have to do with anything. You’re smarter than this. Think about it for a second.