Author Topic: OPPOSED TWIN BILLET RODS  (Read 15572 times)

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Offline boomboom

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OPPOSED TWIN BILLET RODS
« on: February 27, 2015, 04:13:30 pm »
Ok all 3 of you oppy lovers  :lol: I have a question. I have a 46ci oppy. I went ahead and had a cam ground for it and ordered a set of ARC Billet rods. Heres the dilemma. I wont mention the name of the guy who ground the cam, though he is well known. He sent me a set of 42ci billet rods (#6302). When I called to tell him they were wrong, he said the 42 and 46 are the same size. I know their not, Ive been running oppys for a few years now. Anyway I looked them up and saw 42's are 4.96 and the 46 are 4.87. Didnt think it was a big difference. Well my piston is sitting 1/2 inch above the deck. Put a call in to the "engine guy" and havent heard back. Is there a certain piston I have to run with these? Does the model 28 piston have a different wristpin height than a stock piston? Im a little on the frustrated side right now so I do apologize. Im very disappointed in this guy. After spending a decent chunk of change, I would hope to get the right combination.....not just sell me parts. Any help would be very appreciated. Thanks all!
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Offline Jim Knutson

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Re: OPPOSED TWIN BILLET RODS
« Reply #1 on: February 27, 2015, 04:42:53 pm »
first off, which model number on that oppy? Second of all, are you usimg the stock oppy piston, or the newer AVS style?
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Offline boomboom

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Re: OPPOSED TWIN BILLET RODS
« Reply #2 on: February 27, 2015, 04:48:44 pm »
461707, and no I have stock pistons. Im kind of guessing stock wont work. Lol. Am I looking for a certain wristpin height?
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Offline Jim Knutson

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Re: OPPOSED TWIN BILLET RODS
« Reply #3 on: February 27, 2015, 04:58:11 pm »
You have a long stroke, std oppy bore (3.44") engine,  and you need the 46 ARC rod. Then, the ARC rod is made for the AVS pistons, which have the wrist pin located higher in the piston. Together, the wrong rods, and stock piston would account for the piston being 1/2" out of the hole. Have you made any full revolutions with the rods and cam in place? The 46 rod has the rod cap on an angle, compared to the 42 rods which are straigh to the beam....the 42 rod wont clear the cam when combined with a long stroke crank.
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Offline boomboom

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Re: OPPOSED TWIN BILLET RODS
« Reply #4 on: February 27, 2015, 05:39:27 pm »
That is pretty much exactly the confirmation I needed. Thank you. I did not put the cam in yet, and I did notice the rods were not angled and the top rod cap just barely cleared the block. I had a strong feeling wristpin height needed to be different. Thanks again bud I really appreciate the help.
These rods will be shipped back out tomorrow in exchange for the 46 rods. If I can get this guy on the phone. Pistons will be ordered tonight. The 31AVS pistons are for the same bore correct? Their not oversized?
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Offline BIG AL 202

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Re: OPPOSED TWIN BILLET RODS
« Reply #5 on: February 27, 2015, 05:53:53 pm »
31 pistons are 3.56, stock oppy bore is 3.44. the block HAS to be bored and sleeved to install 31 pistons. when you assemble the engine roll ti over slow and check clearances between cam and rods and block, just to make sure. It is cheaper and easier to fix it now!
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Offline boomboom

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Re: OPPOSED TWIN BILLET RODS
« Reply #6 on: February 27, 2015, 05:57:04 pm »
Would the model 28 pistons work then? Im not sleeving this thing unless I absolutley have to. Are the wristpin heights the same on the model 28 and 31AVS?
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Offline BIG AL 202

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Re: OPPOSED TWIN BILLET RODS
« Reply #7 on: February 27, 2015, 06:00:20 pm »
YES the OHV pistons have the thin rings and will work.
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Offline boomboom

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Re: OPPOSED TWIN BILLET RODS
« Reply #8 on: February 27, 2015, 06:02:09 pm »
Your a life saver BIG AL. I really appreciate it thank you.  :wavey: :wavey: :twothumbsup:
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Offline Jim Knutson

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Re: OPPOSED TWIN BILLET RODS
« Reply #9 on: February 27, 2015, 06:28:30 pm »
Dont be confused on the pistons....you can get AVS or old style pistons in 3.44" bore (std oppy, and 28 cid singles) however you want to order and use the new AVS style pistons (3.44" for 28cid singles) with the ARC rods. Again, do not use the old oppy pistons.
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Offline boomboom

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Re: OPPOSED TWIN BILLET RODS
« Reply #10 on: February 27, 2015, 06:54:39 pm »
Jim thanks for your help bud. Really. I just ordered the pistons. Should be good to go so long as this guy makes good on the rods. Should be an even swap. I hope. Our first race is April and I found an old Montgomery Ward that I decided to build for this year. So the clock is ticking lol. If I don't hear back I'll just order the right rods and work it out somehow. Thanks again guys. You really saved this redneck Yankees day!!
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Offline THawley08

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Re: OPPOSED TWIN BILLET RODS
« Reply #11 on: March 09, 2015, 11:11:26 am »
I will say....IF and IF you sleeve it to fit the 31ci pistons it wakes that engine up. My last year of racing we had an engine built by Rooster and it was a rocket in the CP class. Sadly, we only got one season out of it due to valve guide failure.
Tommy Hawley
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Offline rotten ron

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Re: OPPOSED TWIN BILLET RODS
« Reply #12 on: March 09, 2015, 05:40:55 pm »
Tommy,has your father had any more fires? That was exciting :woo:

Offline boomboom

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Re: OPPOSED TWIN BILLET RODS
« Reply #13 on: March 17, 2015, 06:53:50 pm »
Ok. Heres the latest. Engine guy finally sends out the billet rods for my 46ci oppy. Only problem, again, is they are for a pressure lube. I have a splash lube. Has anyone ever attempted to convert a billet rod to a splash lube by drilling it? Im getting a little desperate here. First race is in 3 weeks and I cant afford to send these back AGAIN and wait GOD knows how long for him to send them back to me wrong AGAIN.  Opinions are greatly appreciated!
PS: I did get the model 28 pistons n wristpins, measured them out with these rods and it will work out perfectly so Thank You all for the input!
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Offline BIG AL 202

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Re: OPPOSED TWIN BILLET RODS
« Reply #14 on: March 17, 2015, 08:30:54 pm »
DON"T USE THEM!!! Call ARC and talk to them, you are probably not the first and won't be the last!
ALWAYS VOTE FOR ED!   FONGS BROTHER FROM ANOTHER MOTHER!