How strong or how much abuse can the stock rod bolts take? The engine was rebuilt when I bought the car and it's a basic rebuild with forged trw slugs.

I'm making over 500whp now and concerned that the bottom end isn't going to take it. If the rod bolts are the problem I should be worried about than what is? Thanks in advance..

I think the stock rod bolts are one of two things that are a weak link in the oem engine, the other being the Ford Valves with the aluminized coating. I would definately switch to the standard ARP rod bolts(not the wave loc bolts)for any performance application. I have found these bolts to hold up very well when I raced my Mustang in NHRA Super Stock. The ARP bolts have been tested to 9000 rpms on many occasions in my engines. I broke 2 engines with the Boss 351 rod bolts after the combined number of 6 runs between the 2 engines, so I don't have much faith in the oem bolts. You will need to have the rods rebuilt, if you replace the bolts. Just my opinion but others may have had better luck.

www.lifterboretools.com

do they stress the big ends in a differnt way than ford designed them?

I have not used the wave loc bolts but I have heard of some guys having trouble with them. I have had really good luck with the standard ARP bolts and I do not change something that has worked for me just because it is the latest fad. When you torque down the ARP bolts, you can feel the difference between them and the factory bolts. They tighten up at 45 ft. lbs. and feel so much stronger than the stock bolts and nuts.

www.lifterboretools.com

when I ran stock rods. I changed to an SPS or ARP rod nut and no more problems. Just my personal experience.
Randy

I try not to shift above 6k because of that reason.It's just hard cause thats were most of the power is,higher it revs the more boost the more power!

So there's no way of swaping out the bolts without pulling the engine?I was hoping I can swap them out from below.

The previous owner rebuilt the engine and used the original rod bolts? How do you know, that they are not already a good aftermarket bolt?

Not 100% sure but everything that was done to the engine when I bought the car was done wrong.Stock head bolts were on it and they were torqued incorrectly (60ftlbs),intake was a painted performer with a 600cfm vacuum sec. 2v headers on 4v heads, 2 inch exhaust with stock type mufflers.open rearend 9inch with a 3.90 gear. Multi rib valve locks with valve springs so soft I could compress them with one hand.80lbs on the seat 200lbs at .500(junk)

So my guess the rod bolts are stock.

Pull the pan , change the nuts to some from ARP (available seperately) and rev it up with confidence. BTW, I would never suggest ANYTHING that could injure you or your car/motor just to save a buck. I have done the nut exchange on every stock rod Ford I build and have had ZERO bolt/nut failures
for the last 30 years. It's not because I'm lazy or can't afford it, I believe I found the real cause of my numerous failures long ago.
Randy

Randy what torque setting do you use when you change to arp nuts on the stock bolt, just the ford specs? also do you use a bolt stretch guage now days or just go with torque settings and be done with it.

Thanks
Darren

45ft lbs of torque w/ARP bolt prep moly paste. I only use my stretch gauge on capscrew rod bolts, guess I'm lazy, but it works for me.
Randy

I am a bit confused by this advice. How does changing the nut affect the strength at specified stretch of the bolt? Advising someone to use a new nut on an old bolt doesn't make a bit of sense.

It seems like you are fishing for something...I guess I'll bite.

Can you expound on your observations?

James P.

a problem. I thought that was clear. Several of my failures 30 years ago had 1 thing in common, pulled threads on the OEM Boss 302 rod nuts. These are the same nut for the 351C. I've never broken a rod bolt by the bolt pulling or stretching apart. The problem with rod nuts didn't show up until I began running over 7,800 rpm , about the same rpm
that I had to quit using press pin rods and go to full floaters.
IF YOU DON"T AGREE, that's ok I don't have an ego problem
and it's still a free country. Nobody HAS to listen to the
ramblings of an old geezer like me, but it did work for me or I wouldn't have responded to this post.
Randy

my understanding also from long ago. obviously, we are each the architect of our own Cleveland, we each do what we think is needed(sometimes much more) with the resources available.

all threads are not created equal. i've never researched it but it's possible/probable that the percentage of thread depth in a stock nut is less than in an aftermarket nut, making all the difference.

"Enlightened statesmen will not always be at the helm" ~ James Madison

on budget rebuilds on stock 351c's and other fords, if the rod was ok for size, he threw the stocker nuts in the garbage and installed aftermarket nuts. I don't remember exactly what he said about the stock nuts, either they were made of swiss cheese, or they could be hiding cracks in the threads.

As I've stated in the past, I appreciate your input to the forum. You have more experience than most people on this board combined. But, you suggested something that is unorthadox, and deserving a little more discussion. Didn't mean to offend, I hoped to convey some humor in my post.

If we were standing around in anyone's shop talking about engines, and you mentioned changing the rod nuts only, you would have to expect some questions. Do you think all the factory rod nuts were softer than the bolts, or do you think just some runs were bad?

Best,
James P.

Like I said you've got to do what makes you comfortable. I won't waste a nickle on something that is of no benefit even if it means I'm not in the "in crowd". The stock rod nuts are indeed soft or of lesser material than the bolts. As Mr. Wydendorf said the Boss 351 bolt is better but uses the same lousy nut, go figure. The stock Cleveland rod with it's strap style,
non ribbed cap, should be replaced in any race Cleveland IMHO. Be honest with yourself, if it's a high performance street car that might go to the track once or twice keep the stock rod. For more race than street, spend the money on aftermarket rods. For race only buy the best you can afford. ARP nuts are offered in 6 point and 12 point and I don't remember the part # sorry. As always if you don't agree with me do it your way, it's your money.
Randy

But I prefer to work on engine standing up, while it's bolted to an engine stand. not rolling round under a car.....

Darren and randy thanks.

Hey would you happen to have the part number for a set of replacement conn rod nuts ? Thanks

I would not run any stock bolt in that application. A stock bolt is good up to maybe 6K and IMHO that's pushing it. I have used the ARP wave locs and have no trouble with them. Also, After using a rod bolt stretch gauge, I would NOT use any stock torque spec anymore and ONLY use the stretch gauge. The first thing a good stretch gauge shows you is how bogus torque specs can be when you talk about fastener stretch.

1967 Falcon 4 door 351C-4V
1970 Mustang 351C-2V
http://raceabilene.com/kelly/hotrod
Owner built, owner abused.

On the bench when you assemble them, to get some mic readings, you need a bloody special tool to get them apart. I wonder how you get the caps off, when you tear the engine down for freshening?
I think the way the WaveLoc is set up for a ridiculous amount of interference fit, Ford made the rods and didn't intend for them to fit this way! JMHO
If you have any info or links, why a stock rod should use wavelocs, post away.

The Mustang engine is full of them. Careful work gets the caps off. I use upgraded bolts on all engines, I got a good price on the wave locs when I did this one. Even got a spare on the shelf. When the old 4V engine dropped a valve, two cylinders broke everything except the rods and caps. The other 6 rods went into the 2V engine in the Mustang, that was about 3000 rounds of racing ago. It came down for a refresh 2 winters ago - everything looked good, no problems with disassembly.

1967 Falcon 4 door 351C-4V
1970 Mustang 351C-2V
http://raceabilene.com/kelly/hotrod
Owner built, owner abused.

"We don't buy H bream rods anymore in our blown engines, stock rods with ARP WaveLoc bolts do the job!" Blown Chevy Small Block Magazine.

"10,000 runs and 20 years later, the rods are still perfectly round with ARP Wave Loc rod bolts!" Bracket Gomer Racing Magazine.

if your not making power/RPM, hardware store bolts will do in a stock rod. believe what you read but carry a broom & shovel. speedy dry is a good idea also

I realize the engines are different, but my last 302 build I replaced the stock bolts and had the rods resized, then I bought a decent set of forged pistons. The pistons were lighter than the stock TRWs, so the crank had to be rebalanced.

I added it up and figured out I could have bought a stroker kit for not much more money. Like I said, the Cleveland is not a 302 and stroker kits for Clevos cost more. I just recommend you add up all the little costs so you aren't surprised.

There is a big diference between a boss 351 stock bolt and a stock cleveland . A Boss 351 bolt is a lot stronger than a Cleveland bolt but like Randy said the nuts are garbage.

Yeah. I thought my post made sense but you're free to disagree.

with a 302 stroker, which is not a cleveland. Ok, now it all makes sense!

1916 rounds, shift point 6000 RPM - teardown showed all bearings, including rod bearings, to be in great condition with very little wear. Meaning the big ends appear to be still round. Replaced bearings anyway, now about 1500 more rounds on the engine. I'm a bracket Gomer and I approved this message.

1967 Falcon 4 door 351C-4V
1970 Mustang 351C-2V
http://raceabilene.com/kelly/hotrod
Owner built, owner abused.

TIGHT ! gotta use a cap buster to break them apart while out , if dissasembling the engine I've had to grab the balance pad in vise grips and wrestle the devils out .

Is that how wave lock's do you ? cause I've had enough of that .

I hope this pict posts. This is a rod failure at about 6,000rpm in a stock rod 351C. Factory bolts and nuts. I went out to the shed this morning to have a look and try to take a pic for show and tell. Had to stand on one foot, lean over bunch of crap, and stretch my arm to the limit, but the picture came out OK.

After this discussion on stock bolts and nuts, wanted to have a fresh look at the failure. There are two rods in the pic, one intact, one not so intact. I have numbered the rod bolts 1-4. At first blush, it looks like a rod bolt broke but the nut was OK(bolt 1). If you look at bolt 2, you can see that it looks flush with the end of the threads in comparison to intact bolts 3 and 4. So, the nut theory is looking pretty good. Maybe #2 started pulling threads and caused excessive clearance, then all hell broke loose?

Any other thoughts?

James P.


Edit: I permanently hosted the picture. Tom C.

I see no bearing? Did the bearing burn up first?

but I remember finding the bearing in the pan. The crank isn't blued and there was no metal transfer. One gouge about a 1/4" long on the crank throw where it whacked the rod. It all happened instantly at the top of 1st gear during a smoky burnout. My Dad built this engine and never was happy with the way it ran. He couldn't get it to rev to 6000. He was relying on the factory ribbon tach, which I found out later reads about 350 rpms low at the high end. So it finally went bang. The piston pin bore is cracked too, and part of the piston skirt was also busted. I don't know which came first, they were 2377 TRWs.

I tried many times to get him to let me build a new engine but he just let the car sit for several years. I finally bought the car from him and had it shipped to North Carolina from Arkansas. If interested, I will try to get better pics.

James thanks for the pictures.That convinces me that something must be upgraded.I'm not really sure how much power it's making but it's alot.

I down shift to second (c4) at 45mph and it spins my hoosiers all the way til I shift.Soon as the track opens will see..

The first thought by most is those lousy rod bolts! Look
they tore apart! The closer inspection shows less thread showing on the end of both nuts. The rod is not blue because the bearing didn't weld itself to the crank from lack of oil. The nuts allowed the cap to seperate and hammer the bolt apart. This is what I saw too many times 30+ years ago. If you find the bearing , the surface will look pretty good but it will be folded up. No evidence of spinning. The longer stroke of the Cleveland makes this happen at lower rpm levels than the 302's I ran back then.
Thank you again this should show everyone what I've been talking about.
Randy

since they probably used pneumatic tooling to put em together . or maybe they were designed to torque to yield ONE TIME and after that,,, no damn good ?

my sk rods have a fastener that requires a special socket and the bolt is 7/16 , like trans-am rods this may be an admission that the stock package was good but not over-engineered .

if anybody else is holding pics show em please !

James, great picture, but it doesn't show the other end of the bolt...I'm curious what the head looked like? I've heard that the Boss rod bolts had a 180,000 psi rating....the bolt head looks like a football. I have a 72 351 CJ...some of these came with the Boss bolt...the previous ower rebuilt the motor, balanced it and I was concerned with the rod bolts had not been changed...but when I saw they appear to be the Boss bolt I wasn't worried. I want to make sure I don't replicate your picture...but if these bolts will live at 6000-6500 then I don't want to have to resize and rebalance the bottom end.

I tried to upload a picture of my rod bolts...not sure if you can see it.

What I gathered from this thread was that the bolts were all good, it was just the nuts that could be suspect. So if you want insurance, just change the nuts. Don't know where you would find the right nuts though. Maybe someone will chime in.

Good luck,
James P.

stock style hex, 200-8604 by the 'each', 200-8624 is a 2-pack, or 200-8634 is a 10-pack

12 point flanged nut, 300-8371 each, 300-8381 2-pack or 300-8391 10-pack



"Enlightened statesmen will not always be at the helm" ~ James Madison

Thanks for posting the info on the ARP nuts. Any idea if the weight of the ARP nut is any different than the stock nut? Not sure if that slight a difference would cause issues with a balanced rotating assembly?

Although different nut weight can have an influence on the stride of a XY homonid, in your case the differences in the weight of the rod nuts will have absolutely no effect. It is within the "guesstimate" tolerances of calculating the weight of the oil for balancing purposes.

James P.