Author Topic: OPPY TIMING QUESTION  (Read 10033 times)

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Offline boomboom

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OPPY TIMING QUESTION
« on: August 26, 2015, 11:14:39 pm »
Quick question.....I have a 46ci oppy with billet rods, billet flywheel, precision 212 cam, EC double valve springs, ported to the hilt. Stock appearing carb lol. I have heard and read mixed opinions in the past about where to set the timing along with air gap. Where Im set now is  air gap 15, timing is 5 marks advanced on flywheel. I run a 1/10th mile track and Im around 4000rpm. Very aggressive off the corner but flattens out at end of the straight. Like I mentioned, Im not breaking 4000. Any tips on what timing and air gap with this cam? Thanks in advance!
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Offline redline

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Re: OPPY TIMING QUESTION
« Reply #1 on: August 27, 2015, 08:00:01 am »
By air gap are you meaning valve lash?
If so, and you have it set at .015", thats a whole lot of lash.
Or, do you mean the flywheel to coil air gap?
If so, .015" is not enough, should be .040 minimum I believe. Would have to double check that figure though.
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Offline PJG56

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Re: OPPY TIMING QUESTION
« Reply #2 on: August 27, 2015, 08:51:06 am »
Ed you are correct on air gap .040 min.with billet wheel.

FYI you should be turning that more than 4000 rpm,5500 min.
Paul Guptill  (oppy) #238modX
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Offline boomboom

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Re: OPPY TIMING QUESTION
« Reply #3 on: August 27, 2015, 08:52:40 am »
Yes air gap as in coil to flywheel. My valve lash is set to Mikes specs.
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Offline BIG AL 202

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Re: OPPY TIMING QUESTION
« Reply #4 on: August 27, 2015, 10:00:06 am »
IS IT GEARING THAT IS KEEPING YOU FROM TURNING MORE RPM? YOU REALLY ARE UNDER THE MEAT OF THE POWER BAND.
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Offline redline

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Re: OPPY TIMING QUESTION
« Reply #5 on: August 27, 2015, 10:22:04 am »
He may only be spinning 4000 rpm, but, he is saying it drops power at the end of the straight.
I think that the carb may not be enough, or properly adjusted to get past that. This is based off Paul saying it should turn more with that cam.
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Offline boomboom

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Re: OPPY TIMING QUESTION
« Reply #6 on: August 27, 2015, 10:26:46 am »
BIG AL that was my first thought. I played with gearing first, but whats leading me to timing is that Im a cannon off the corner, but flat at the end of the straight and our straights arent very long. Flat at 4000rpm. Plugs are a nice ash brown color so I believe my mixture is good. I do have a velocity stack and my carb is honed out and opened up. Lots of work to the carb. You guys are great and I know most of you have been there and done that so Im all ears!
REDLINE does it sound like a carb problem to you? I havent ruled that out either. If so Ill go that route in a heartbeat lol. What degree should the timing be?
I should most definetly be turning past 4000rpm with the work done to this mowtor.
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Offline BIG AL 202

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Re: OPPY TIMING QUESTION
« Reply #7 on: August 27, 2015, 10:43:41 am »
I AGREE WITH REDLINE, SOUNDS LIKE IT'S RUNNING OUT OF FUEL.
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Offline chavez

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Re: OPPY TIMING QUESTION
« Reply #8 on: August 27, 2015, 01:09:25 pm »
or possibly cam advanced a tooth...
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Offline BIG AL 202

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Re: OPPY TIMING QUESTION
« Reply #9 on: August 27, 2015, 01:48:21 pm »
THERE'S A THOUGHT
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Offline boomboom

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Re: OPPY TIMING QUESTION
« Reply #10 on: August 27, 2015, 01:53:16 pm »
Didnt even think to check that. Didnt feel like that but anythings possible. Ill pull the side off after work and check. Thanx guys.
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Offline BIG AL 202

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Re: OPPY TIMING QUESTION
« Reply #11 on: August 27, 2015, 03:53:15 pm »
LET US KNOW!
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Offline boomboom

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Re: OPPY TIMING QUESTION
« Reply #12 on: August 27, 2015, 04:02:49 pm »
10-4. Absolutley will do.
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Offline PJG56

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Re: OPPY TIMING QUESTION
« Reply #13 on: August 27, 2015, 05:13:41 pm »
Even if cam is advanced one tooth it should make good power to about 6200rpm.
I ran that same cam advanced one tooth in 2013 and the mower won the ARMA national championship.
As far as timing goes I ran mine 3 lines to the+ side with the cam advanced one tooth(not at shop,so cant tell you how many deg.that was),I think I'd try some more fuel!!!

P.S. mine turned 6200-6500 that year
Paul Guptill  (oppy) #238modX
2012 slmra mowstock champion(builder/owner)

2013 slmra mowdified champion(builder/owner)
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2014 ARMA national champion Mod-X(builder/owner)
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2014All American Champion FXT (engine builder)
2014 All American 2nd place SP(builder/owner)
2015 All American 2nd place BP (builder/owner)
2016 OutlawTriple Crown FXT Champion (engine builder)

Offline boomboom

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Re: OPPY TIMING QUESTION
« Reply #14 on: August 27, 2015, 05:30:08 pm »
Ok its definetly not the cam. Cam is spot on.  :confused: :smashcomputer:
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