Author Topic: Full 46ci pressure lube oppy build thread- now with billet goodies  (Read 436 times)

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Offline Wheelinhorse

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Look, I know oppys are now dinosaurs for you racers, but for us offroad tractor guys its a cheap, torquey option that works very well for what we do.
Been acquiring parts and will be starting a build soon. Complete 46CI pressure lube vertical engine, a horizontal cam cover, pump, sump, etc..  and recently scored an ARC wheel, rods, AVS pistons, and Precision 212alt cam. Yes it will be flipped horizontal. Intake is an early 2 piece, massaged, 1" tall adapter and a 27hp Kohler command 'pumper' carb on top, and 2:1 header, all are currently on the stock internal 18hp powering it right now. They both work very well- the carb made a day and night difference in power.
Since im much more concerned with low/midrange grunt than a top end screamer, how do you feel about this cam versus the stock 46ci? I have the ability to knock some base circle off the stocker, as well as all the equipment necessary to play with porting, decking/milling, valves, seats and angles, etc...
How about trading a bit of airflow for a boost in compression, a big oppy no no....
Come on, most of these things arent even raced anymore, you guys can give me some direction without giving away secrets cant ya? Ha.

Offline BIG AL 202

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Re: Full 46ci pressure lube oppy build thread- now with billet goodies
« Reply #1 on: January 06, 2022, 02:45:07 pm »
You never mentioned boring to fit 31ci pistons. There is no substation for cubic inches. I believe it will make about 50ci. The cam grinder to use it Tim Isky. He's been grinding oppy cams for a long time. You are on the right track.
ALWAYS VOTE FOR ED!   FONGS BROTHER FROM ANOTHER MOTHER!


Offline Wheelinhorse

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Re: Full 46ci pressure lube oppy build thread- now with billet goodies
« Reply #2 on: January 07, 2022, 06:29:19 am »
Had no idea these blocks could be taken out that far, if at all. Is there enough meat?

Offline BIG AL 202

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Re: Full 46ci pressure lube oppy build thread- now with billet goodies
« Reply #3 on: January 07, 2022, 05:27:06 pm »
YES!
ALWAYS VOTE FOR ED!   FONGS BROTHER FROM ANOTHER MOTHER!

Offline Wheelinhorse

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Re: Full 46ci pressure lube oppy build thread- now with billet goodies
« Reply #4 on: January 10, 2022, 07:53:07 am »
Uh oh. I have a Kwik Way boring bar and sunnen hone in the back room, some stuff I never got rid of when I closed the speed shop. This could get silly!

Offline BIG AL 202

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Re: Full 46ci pressure lube oppy build thread- now with billet goodies
« Reply #5 on: January 11, 2022, 08:27:13 pm »
NOW THAT"S WHAT WE LIKE TO HEAR!!
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Offline Wheelinhorse

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Re: Full 46ci pressure lube oppy build thread- now with billet goodies
« Reply #6 on: January 20, 2022, 09:47:45 am »
I built a crude but functional flowbench and am learning a lot. Although I cannot get actual flow numbers, I can measure gains and losses and am pretty surprised at some of the findings so far.

Offline PJG56

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Had no idea these blocks could be taken out that far, if at all. Is there enough meat?
In order to go to 31ci bore(3.5625") youll have to sleeve the block.
Paul Guptill  (oppy) #238modX
2012 slmra mowstock champion(builder/owner)

2013 slmra mowdified champion(builder/owner)
2013 ARMA national champion Mod-X(builder/owner)
2014 ARMA national champion Mod-X(builder/owner)
2014 All American Champion Mod-X/CP(builder/owner)
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)