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Oliver Rods w/ Larger Diameter Wrist Pins

4K views 15 replies 5 participants last post by  PWORLDSTANG 
#1 ·
I have the opportunity to pick up a set of Oliver Rods at a steal of a price, which is about too good to pass up. They are the F5933MDUL8 rods which are very light (569g) and utilize a larger size wrist pin. A call to Oliver confirmed these will hold my HP goals with room to grow, and some researching across various engine platforms returned great reviews of these rods. My only hesitation on these is the wrist pin size. Stock and all other rod sizing calls for an .866'' pin. These rods use a .927" pin. Are there any concerns I should have with running a larger size wrist pin?

I do realize these could likely result in a heavier pin (depending on wall size), and also custom pistons to fit the larger pins (which could also impede on crown thickness). I don't suspect this to be something the guys at Gibtec couldn't work around, but I would still like any feedback anyone has on these rods requiring larger pins.

https://oliverracingparts.com/catalog/f5933mdul8/
 
#4 · (Edited)
I have the opportunity to pick up a set of Oliver Rods at a steal of a price, which is about too good to pass up. They are the F5933MDUL8 rods which are very light (569g) and utilize a larger size wrist pin. ... My only hesitation on these is the wrist pin size. Stock and all other rod sizing calls for an .866'' pin. These rods use a .927" pin. Are there any concerns I should have with running a larger size wrist pin?

I do realize these could likely result in a heavier pin (depending on wall size), and also custom pistons to fit the larger pins (which could also impede on crown thickness). I don't suspect this to be something the guys at Gibtec couldn't work around, but I would still like any feedback anyone has on these rods requiring larger pins.

https://oliverracingparts.com/catalog/f5933mdul8/
Brandon,

Years ago when I came to the Modmotor from blown alcohol Hemi's the first thing that caught my eye was the diminutive 0.866" pin diameter the engine used. We used taper walled 1.094" diameter tool steel pins with a DLC surface treatment. I immediately began shopping for a rod manufacturer that would build the rod you are currently looking at.

Oliver was one of several candidates for the finished rod. Although the -.927 pin is larger you still need to upgrade the wall thickness to get the strength we need for upper rpm reliability. Weight-wise, depending on pin length, the pins ended up being essentially a push. Suddenly the heavy wall 0.866" diameter pins started looking better.

The larger SBC pin will slightly crowd your ring package because of the increased diameter. The use of oil support rails is wide spread today and will allow the pin bore incursion into the ring land with a fairly high in service reliability. The ability to enter the oil ring land with the oil bore gives back some of the lost ring package spacing. In the end the rod should work as advertised for you. You do end up with custom, one off pistons which substantially reduces their resale.

If I were going to use a custom rod I would use the Ford / Manley Saleen rod with the SBC journals or a set of Carrillo's with the Honda journal. In my personal engine I used the Saleen's because I was after the shorter 5.850" center to center distance and also access to the SBC race bearing alternatives that are essentially over the counter parts today. The race bearings are available for both SBC and Honda journals and that appears to be all. In fact that is the rod I used for my engine. If you do that it will require cutting the rod journals down to the 2.000" SBC dimension and renitriding the crank.

If you feel strongly about the Olivers, they will work. You will just have a less common rotating assembly. One of the nicest rods I have seen recently is the new Manley H-Tuff rod (see pic below)

Font Bicycle part Rim Auto part Composite material


This is probably the most bang for the buck rod you can buy today and it is a natural evolution of an already successful design - but it willl cost you $870 at Jegs or Summit.

Although your Oliver selection will work also, you might want to stay closer to standard components for simplicity. These engine builds can easily get off into the engine design space and the flexibility, availability of parts and cost to build can quickly go out the window if you don't police yourself.

All this other stuff not withstanding, the Olivers will work!

Ed
 
#5 ·
Thanks for the info and reassurance Ed.

I checked back in today to see if the rods were available and they sold. Even though they were a steal, that isn't necessarily a bad thing on my wallet. You are spot on with the cost and complexity quickly escalating when deviating away from the norm. As nice as these rods were, and even comparing them to newer options like the Boostline rods, I think I'll stick with the 'ol faithful Manley/SVT rods that I've had and save some money.

Thank you again!

- Brandon
 
#7 ·
In fairness I have to admit I am prejudiced, Hendri. I like all of Tom Molnar's products. He does an excellent job of conceiving, designing and implementing his products and then he hits price points others for whatever reason choose not to. So, I am a bit biased. Tom's rods are excellent and his supercharged application rod, what he calls the power adder design, is very well thought out and implemented as you might expect from Tom.

Is his power adder rod the biggest baddest rod offering out there - no. Do you need the biggest baddest rod offering out there? Very likely not! If you are like most of us mere mortals and operate your engine below 9000 rpm and 1800 hp you don't necessarily need the double throw down, super elite, touched by only God, $2000 rods from Manley and Carrillo. when the rod pricing gets down to the $1,200 or so price point of the Boostline Wiseco rods it is less a matter of do you need them and more a matter of will the budget stretch a bit farther to put stunning but unneeded overkill in the engine.

Back to the mere mortal world and our options I believe the new Manley H-Tuff rods, the Molnar Power Adder and similar options that are available today from others are all excellent choices that you would be hard pressed to select a bald alternative from, if that were possible at all. In the end we are blessed with a multitude of excellent choices and the beauty really lies in the eyes of the beholder. The one consideration I would give to Tom's rods is that they are 100% designed and manufactured here in the US..

With the current Covid-19 Pandemic investigation beginning to look for the bad guy who screwed up in letting it out, China is the leading candidate to wear the badge of dishonor. Whether intentional or otherwise, US manufacturing supply chains and for that matter worldwide supply chains are going to be systematically removed from China very rapidly. Most of (not all) the rod manufacturers have some level of Chinese participation from basic forgings to finished goods associated with their product. When that dries up, the music stops, so to speak.

The only connecting rod provider, today, that is 100.00% designed and manufactured in the USA is Tom Molnar. Pretty good argument right there for Tom's stuff! Are there stronger rods available, very likely. Do you need them (for other than bragging rights) - very likely not. Tom is a good guy with good products at a very nice price point and all Made in the USA - that is an almost impossible combination to come up with.

Ed
 
#8 ·
Ed,

I will challenge you that Molnars stuff is made in the USA. The forgings on his rod and cranks are done in China. If you would like to verify, call him and I am sure he will tell you. Bottom line, it's still good stuff.
 
#9 · (Edited)
When I last spoke with Tom, about 6 months ago, just before he started offering cranks as I recall, in the course of our discussion he had indicated to me the engineering, design and manufacturing for his products was domestic. Although it is certainly possible that could have changed since, I have no information to indicate it has.

I suspect that anyone who currently sources products in any stage of completion from the Chinese will minimally rethink their sourcing decisions going forward. The Chinese economy and their ability to service ongoing commitments will change in the post covid-19 world economy. The worldwide predisposition to remove the various supply chain dependencies that currently run through the Chinese economy will be impressive to say the least. I think we are about to see a reshuffling of both the economic and trade playing card decks for all goods and services sourced from or through the Chinese.

That said I still think very highly of Tom's connecting rods and other product offerings.


Ed
 
#10 ·
Ed,

Out of curiosity, what's the story with the Ford/Saleen rods? This is the first I've heard of them from what I can recall.

They're shorter and have a smaller journal size, but our crank is 2.086" so I'm unsure of the need for the size reduction there. Using a smaller journal diameter - and thus bearing size - surely has the benefit of less frictional losses. But the difference between 2.086" and 2.000" is negligible.

Are the performance benefits of such a minute reduction tangible, or is there another purpose for the size reduction that I am missing?
 
#11 · (Edited)
The Saleen package used a 5 liter version of the Modmotor. Ford has had several ways to achieve what they call a 5 liter Modmotor. One of the earliest was the FR500C road race Mustang engines. Those cars used a purpose built aluminum block with a 3.700" bore and a 3.543" stroke for an actual displacement of 304.8 cubic inches. In the FWIW bucket 5 litres is 305.12 (actually 305.118) cubic inches. Of all the 5 Litre variants FORD brought to life the race only FR500C came closest to the 5.0 litre mark. The car and engine were untouchable in class while Ford offered the car. This is a pic of what the block looked like;

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Notice the very high valley floor between the cylinder banks. This was coupled to the crankcase to mitigate pumping losses associated with the pistons going up and down the cylinder bores. The high floor also meant that there was no room for the OEM intercooler Ford used on the Terminators. Additionally the large 3.700" bore, actually 94mm, only left less than a quarter inch of gasket sealing surface between bores. The actual dimension was 0.24 inches. This was marginally OK for a n/a engine and in general a bad idea for a s/c engine - unless you o-ringed the heads with a figure 8 style o-ring.

This is a pic of a normal 4.6 Aluminum block and you can easily see the difference in the valley floor between this block and the FR500C block.

Vehicle Auto part Font Metal Fashion accessory


The Saleen option came with a 5 litre engine. They engineered a 3.750" crank stroke instead of a 3.542" stroke to get to its 5 Litre displacement. The intellectual and emotional problem was that crank only produced 297.3 cubic inches of displacement. Of course the righteous truth sayers of automotive virtue would have no part of a 297 inch motor masquerading around as a 305 inch motor - where are the missing 8 cubic inches?

Somewhere some particularly disturbed individual stretched the 3.750' stroke crank to 3.800' to righteously produce yet another 5 Litre engine that yet again fell short of the 305 inch gold standard. The 3.800" stroke crank only came up to 301.2 cubic inches.

Both the 3.750" and 3.800" crank 5 Litre solutions had a special problem. Using the 5.933 stock length rod would either compress the ring package so tightly it impaired its operation or if you went to a significantly shorter rod to regain ring package space, the piston would hit the counterweights. The compromise solution was a 5.850" rod length for the Saleen project that over the years has become known as the stroker rod. It is available even today in Manley's catalog.

Once we had broken the glass, so to speak, on the use of a non-standard rod length, why stop there? You are already in custom country so lets tweak a bit more. Back before Honda journals became all the rage in NASCAR the über desirable journal diameter was the 2.000" SBC journal. Not only was it the go to journal for crank manufacturers, it was the go to journal for all the rod bearing manufacturers, who made their most advanced bearing technology offerings available only in SBC journal size. Even today there are specialty bearings only available in SBC dimensions (and now Honda also) that can not be obtained for any other journal size.

Surprise, surprise the Saleen rods were manufactured for use and sale in a Ford vehicle using SBC journal dimensions.

So why did I use them in my engine and not talk very much about it? I didn't want to start a lot of emotional flame thrower sessions about the "optimum" rod for our engines. I like the 5.850 rod because it allows me to use a generous ring placement on the piston w/o the wrist pin entering the oil land - for me this is a personal big deal. The other benefit is I gain access to a rich variety of otherwise unavailable (over the counter) custom race bearings. This in aggregate puts yet another smile on my face.

There is no reason anyone else could not use these rods if they wanted to do the pushups to make them work. It is worth while noting that when you cut the rods 0.010" undersize many cranks will relax and kick the mains out of alignment mandating you also cut the mains 0.010" under size. When you get done then you need to renitride the entire crank. The nitriding is about $300 and the journal work is probably around another $300 or so which means you are into the crank for an additional $600+. That's the bad news.

The good news today is that you can usually pick up a crank with a spun bearing for $100 to $150. Add $600 to it for the trip to the beauty shop and you come out in a worst case scenario as a push with a pristine used crank or more likely $250+ cheaper than a new aftermarket crank. Pistons are a wash because you were going new anyhow.

Ed
 
#12 ·
Thanks for the history lesson Ed - great info! I do remember the FR500 Cammer engine. I also do remember that the 3.800" stroker crank has been on the market for years, although it isn't the commonly used choice for stroker cranks. I actually remember a thread from a gentlemen years ago I believe on SVTP who used the 3.800" crank. After assembly and driving the car, he learned that his pistons were coming in contact with his crank at BDC. That was obviously a costly mistake for him.

I'm also glad you spoke about the use of non-traditional parts, rod bearings in this particular case. Custom parts or ones not readily available can obviously add unnecessary costs to a build, but I feel it's these minute details that separate a common 'stock' engine rebuild for added strength, from a more unique build that presents other benefits, as you mentioned. Our engine platform has been around so long that it's rare that you find someone doing a build that hasn't already been done. But I can certainly appreciate those that deviate from the norm.
 
#13 ·
Actually a couple of the other nice "benefits" that accrue to those using the SBC journal diameter is the easy over the counter access to the trick higher tech race bearings, Brandon. Another nice benefit, aside from just being available, is that many of them come in at SBC pricing instead of the normally higher "other brand" pricing. :)


Ed
 
#14 ·
That is a great benefit. No sense in paying a brand tax if at all avoidable! Which of these are some of your favorite high(er) tech bearings Ed?

With so many bearing options available, it's hard to narrow down what would simply work as a bearing should, and what would work while providing additional benefits.

Also, what do you think about DLC coatings for the rods and mains? Depending on what bearings I end up purchasing, I am strongly considering sending my rod and main bearings to Calico for to be DLC treated.

https://www.calicocoatings.com/coating-data-sheets/calico-diamond-like-carbon-dlc-coating/
 
#15 · (Edited)
The Diamond Like Carbon (DLC) coatings are very attractive in sustained high temperature / high load environments, Brandon. It does not hurt in other environments but there is little benefit over more common less expensive friction reducing treatments. My favorite that I have spoken about many times on the site is ProLong. The Prolong treatment needs about 12 oz per oil change (depending on oil pan size) and is one of the very best things you can do for OHC engines. Here is a link to the additive on Amazon click here => ProLong 12 oz costs $15 and 128 oz costs $63. Do the math.

Just because something is available does not mean it is necessary for all users. Specialized products are created for specialized applications. Will bad things happen to your engine if you use DLC coated components - absolutely not! But, bad things will happen to your build budget and your wallet. The budget will go up and the size of your wallet funding for your build will go down. There are more than enough expensive must haves that should be bought first. Save your money.

I would not worry too much about all the trick tech bearings for the SBC journal size. There are specialized materials, coatings, bearing undersizes and modified clearance specs for asymmetric bearings. Just like the DLC coatings -save your money. Buy a babbit bearing with standard clearances and enjoy the low price. Babbit is the absolute best bearing material for supercharged engines because of its embedability and importantly its ability to absorb shock loads - especially important in detonation sensitive gasoline engines. If you have a billet crank buy a narrowed version of the same bearing that is designed to clear the full radius journals used on the rods and mains of billet cranks.

Ed
 
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