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Old 08-26-2019, 10:40 AM
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Default Raptor Con Rod Question

I'm still looking into a better con rod for my flathead so I can remove the governor safely, but I've also noticed that there are some Briggs Raptor racing rods on Ebay for about 1/3 the price of an ARC rod(see pics)

The first one is a 555179 part number, and the second one is a 555208.

Could either of these work with the stock piston, or do I need a Raptor piston as well?
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Old 08-26-2019, 10:45 AM
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1st choice: ARC ROD
2nd choice: rod with the dipper built into it
3rd choice: rod with the bolt on dipper

3rd choice will fatigue the oil dipper and it can snap off
2nd choice will not have the strength and oiling capability of the arc rod. Most con rod breaks happen because journal is starved of oil during high rpm
1st choice is stronger and has better oiling capabilities. I would rather spend a few bucks more and do it right the first time.

You dont need the raptor piston, but it is a significant weight reduction. In my flathead i run the stock length ARC rod and the stock piston.
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Old 08-26-2019, 11:08 AM
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Sooo, would the Raptor rod work with the stock piston?

And also, I want as many people who know what they're talking about to chime in on this.

Obviously the the integrated dipper is better, but I would imagine the safety margin is still significantly higher than a stock rod.
I don't expect this engine to redline much(if at all), with most of the high rpms coming from straightaways while racing at a parking lot (that I have permission to use).
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Old 08-26-2019, 12:35 PM
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Well i mean id just save for the arc one lol
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Old 08-26-2019, 12:39 PM
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Well, I mean some of the Raptor ones are literally less than $20, which is less than some STOCK rods.
Grant, it's not totally clear, but can I use a Raptor rod with the existing piston in the engine?
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Old 08-26-2019, 01:11 PM
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You won't be going crazy enough to have a problem with the raptor rod. Just check the numbers to make sure you are getting standard length and not an over/under rod.
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Old 08-26-2019, 01:27 PM
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Will the bolt on dipper rods present a problem?
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Old 08-26-2019, 02:26 PM
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I have seen pics of them failing. The 1st gen raptor rods had bolt on dippers. If you have $15 You can get a nos rod that is .001 short from Ebay right now.

---------- Post added at 02:26 PM ---------- Previous post was at 01:59 PM ----------

My advice is not to worry about it. You are not building a racing engine. I would suggest you save up and look around for a block first. All the other parts are easier to find. You need to have cash in hand so you can get a block when it comes available.
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Old 08-26-2019, 02:29 PM
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Or leave the kart how it is and save for a road legal vehicle. Which you'll need in acouple years.
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Old 08-26-2019, 04:26 PM
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He needs to get a license first before the vehicle...Hes got a few years on that still....
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Old 08-26-2019, 04:45 PM
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Quote:
Originally Posted by mckutzy View Post
He needs to get a license first before the vehicle...Hes got a few years on that still....
And I have a license and no vehicle......
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Old 08-26-2019, 05:21 PM
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With the 0.001 rod, it says it measures 3.128 from inside to inside.
I know the stock con rods are 3.875 center to center, so are the pistons "taller"?
Or is the 0.001 rod going to work?
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Old 09-03-2019, 12:16 PM
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I ran WKA stock rules 20 plus years ago. The best bolt on dippers are the black hardened ones they used many years ago. And we cut the dipper even shorter. I would not use either from ebay if I was going to thrash it. I have seen the built in dippers break off due to oil drag and deflection at high rpm. The secret to keeping a stock style rod together is the rod to crank pin clearance to less than .003 thousands. It takes a lot of rods and time with a micrometer to find the perfect fit. Just as soon as they let us go to Horstman rods we did. ARC was just getting into the rod business. But will it bolt in yes.
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Old 09-03-2019, 03:50 PM
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Any by bolt in, you mean compatible with the stock piston, yes?
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Old 09-03-2019, 04:46 PM
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Yes.
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Old 09-03-2019, 05:50 PM
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Thanks for the info! I went ahead and bought a Raptor rod with built in dipper that's 0.001" short.
Only $14!
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Old 09-04-2019, 04:31 PM
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Sweet. Good luck.
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