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Skimming the head of a late style 56cu in ?

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 PostPosted: January 16th, 2016, 9:57 am   
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anything from 1992 is oval port apart from sst60.
so you have from 1992 to 2001 50hp 60hp and 70hp engines to choose a powerhead from.


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 PostPosted: February 2nd, 2016, 12:25 am   
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OVAL PORT?
http://www.kijiji.ca/v-boat-parts-trail ... nFlag=true


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 PostPosted: February 2nd, 2016, 9:40 am   
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Nice but lets say you were only looking for a power head cause you're going to change the crank to a 4 spline and the electronics to earlier style after all it's going on a short foot right? She's going to become a very expensive motor with lots of spare parts.


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 PostPosted: February 2nd, 2016, 11:00 am   
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We do not see a lot of running oval port motors come up for sale. If this motor still has the 145 compression it would be good for a T guy wanting an oval port. Used parts for oval ports motors sell. The oval port gear case, power trim, crank shaft and electrics all have value and can be sold. For a T guy with a 49 OMC short shaft this can be a good option. He can use the crank, plastic reeds and electrics from his 49, use the base plate and tuner off the oval port. I would re ring the oval point just to be safe. Put some larger jets in the oval port carbs. Overall the finally cost is less than doing an older bridge port when you consider the cost of new pistons, machine work etc.

Currently EBAY is a good place to sell. 70 cent Canadian Dollar.


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 PostPosted: February 2nd, 2016, 7:58 pm   
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Very true


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 PostPosted: February 3rd, 2016, 9:14 pm   
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what are the larger jets in the oval port carbs ?
the true 70hp oval port carbs have black top, the large 1 1/2 inch bore and jets are 52d down at the bottom and 60D up in the black plastic top.
I cant see any information anywhere as to bigger jets for these carbs ?,

I ould like to know about this if there are other sizes for the 70hp carbs.


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 PostPosted: February 4th, 2016, 7:41 am   
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phillnjack wrote:
what are the larger jets in the oval port carbs ?
the true 70hp oval port carbs have black top, the large 1 1/2 inch bore and jets are 52d down at the bottom and 60D up in the black plastic top.
I cant see any information anywhere as to bigger jets for these carbs ?,

I ould like to know about this if there are other sizes for the 70hp carbs.


The motor for sale is a 60 hp so it would need to be up graded to the 70 hp jets. I have not seen the motor but the carb bore size is likely the same as the 70 hp. If not you would need to use complete 70 hp carbs. Since you are not making any internal changes to the powerhead the stock jets would be fine.
If you did need larger jets there is an OMC parts list showing all the D jet sizes. Many T racers have the list. I do not.


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 PostPosted: February 6th, 2016, 7:45 pm   
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Here is a picture of the 2 sets of carbs I have, the top is 70hp bottom set is 60hp.
Both these sets of carbs are from the later oval port 56 cu in engines from 1993 onwards and both sets have the plastic tops.
looking at this pic you can see the inlet manifold side, there is a 1/4 inch difference in size across the bore. 60hp =1 1/4 inch & 70hp =1 1/2 inch diameter.
this makes the 70hp carbs have a surface area 43% more than the 60hp, that's a huge difference.
notice the top left carb v bottom left carb hole sizes ?

Image

this pic below shows the restriction inside the bore of the 60hp carbs from a front view. ( much smaller throttle plate)
the outer bore size at the front of both 60 and 70 is the same, this often makes people think the carbs are the same.
its not until you look inside and at the back that difference is realy noticed.

Image

.


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 PostPosted: February 7th, 2016, 12:13 am   
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Thanks for posting the two pictures. The oval port motors we saw in T in 2014 were all running the large bridge port carbs. Many T racers have asked about the carbs. Now thanks to your pictures they now know there are large bore carbs. I hope a racer finds a set and runs them.


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 PostPosted: February 7th, 2016, 8:50 pm   
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the oval port 70hp carbs are the way to go on the oval 56, they let through more juice than the Bridgeport carbs.
I spoke to a few people who had tried the Bridgeport large bore and they were better than the 60hp oval port, but NOT as
good as the 70hp plastic top carbs from the proper 70 oval port.

i hope to have a good run with mine in the next few weeks and will report my findings with these bigger carbs.
what i am hoping for is about an extra 400to 500 rpm top end with more punch in the lower and mid-range using the same prop
that i was running with the 60hp carbs for testing.

.


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