Rod Bolts

[Dark Allison]

We disassembled my 225 Promax and the rod bolts had the letters( FC )on them. 260 hi-po's have the letters ( SPS) on them do these bolts have the same tensile strength? What Rpm's are the FC's good to?

Thanks

James:cool:

[T-REX]

Tha 225 PM rod bolts are tha same az 200 bolts...nutt'in special about them...I would use them 3 times, IF U know they have never been streched...and that can only be dun if U have torqued them yourself!!!...

[us1]

The FCs are not as strong. I don’t like to run them over 7000 RPM but I have run them up to 8000 before. The SPS bolts are a much safer bet. There is a post on here by DaveR with all the tech. info.

[Dark Allison]

Does anyone have the sps rod bolt part numbers for the small rods?:D

[us1]

Small 2.5 or 2.4?

[O/B Dude]

The SPS rod bolts are $18 each and you need 12. Also, your rods will need to be machined to fit the wider head of the sps bolt. I asked everyone I could think of about bolt choices because I was in the same "boat" as you are. I decided to go with Pro Marine replacement bolts. What I was told is that the Pro Marine bolts for fishing motors are stronger than the stock merc fishing motor bolts, but not nearly as strong as the SPS bolts. I wasn't sure how strong until I talked to Greg Moss and T-Rex. Both told me they would be just fine beyond the 8500 rpm range I wanted to run. My opinion from the info I gathered is the stock 200 rods and new $3 Pro Marine bolts will be just fine. I revved my stock merc fishing motor bolts and rods to 8250 rpm regularly and had no failure. Opinions vary, just my 2 cents. :)

[us1]

I am asuming they are 2.5 top guided small rods. The part number is 848475. You dont have to maching to rods if you simply grind down the out side of a 3/8 12 point scocket so it fits over the bolt.

[O/B Dude]

US1...interesting info on the socket grinding deal.

[Dark Allison]

Thanks guys!

[T-REX]

I use tha pro marine replacement rod bolts in my 2.0 with 2.5 top guide rods..I have run it at every race except one this past yeer, plus several local bouts, and 1/8th mile races...tha motor has turned over 9g ever time out and wit a 24" wheel, it will show ya 10.7 on tha recall...When properly torqued, they will hold thier own...I've only had one rod bolt failure in my O/B deel'inz, and it wuz a SPS bolt!!!...REX:cool:

[Tom D.]

Watched a show called "Two Dudes (Guys) Garage" You know Dave & Sam. Well they had a guy from ARP show them how to use a bolt streacher rather than a tourque wrench on there rod bolts for a small block chevy they were building. Anybody ever hear or try/use this method.

Tom

[Superdave]

Is the ONLY way to torque. :D
Go here (http://www.carrilloind.com/install.html)

Buy here (http://www.carshopinc.com/product_info.php/products_id/59234/CSRBSG)

Dave:cool:

[T-REX]

I would thank that torque'in iz tha only way ta know how much strech ya putt'in on a bolt:rolleyes: :rolleyes: ...unless ya do tha merc thang and go ta set torque and pull 90*...an I juss don't like dat ****!!!...I've used torque wrenches fer 40 yeerz, why change now:confused: ...REX:cool:

[NEECAPR]

Just a quick answer now, T-Rex, 'cause gotta run. Merc's tightening method absolutely maximizes preload(right at yield) to minimize cyclic loads and their stresses. Cyclics and fatigue are what break these bolts and the increase in life, even while the base stress level is very high, is really amazing. The Merc method is widely used on aircraft engines to combat variability in torque vs. preload.
The method you're using is as successful as anyone would need by most counts. It's just a matter of risk. In principle, the highest preload will be the best method, but, there aren't enough failure problems to justify a new bolt every time for everyone.:)

[ken medendorp]

I use to work at performance engineering where they did alot of boat and big inch chevy pull truck engines .drag car stuff and what they did was torgue the rod bolt with a torque wrench until you got .003-.004 rod bolt stretch,checking it with a special fixture and indicator,once you got to that point you would look at the setting on your torque wrench and that would be the setting you would use when you assemble your motor.That was on new ARP rod bolts

[Propelled Marine]

Pro Marine rod bolts for top and bottom guided.

set of 12 bolts- $27.00

[NEECAPR]

Ken, when you found the 'stretch torques' at Performance Engrg., did you measure every bolt and nut combo. or just one sample for a lot quantity? :)

[ken medendorp]

It was just one bolt&nut

[Superdave]

Prevent Rod Failure (http://www.carrilloind.com/pdfs/10777_eprint.pdf)
Dave

[Tom D.]

Interesting read Dave. Thanks!

Tom

[Rickracer]

http://rickracers.com/index.php?cPath=21_26_143

:cool:

[Propelled Marine]

Kevin at Pro Marine says their bolts have been tested 3 different ways, and they have been found superior to stock Mercury bolts.
Torque to 32lb's with no extra 90* turn.

set of 12 bolts $27.00

[Rickracer]

:eek: :D :cool: