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I have never seen a carb on a oval port without the plastic tops.
ive seen just one of the 1992 engines and that had plastic tops, if that had been a recall I have no idea.
its like not all of the oval had VRO, some just came with the vro style fuel pump and pre-mixing, mainly commercial/safety applications I think.

I also dont understand why on nearly all the older omc engines there were different jets available for different altitude, but nothing listed for the plastic top carbs.

when looking at the parts for the carbs on this chart the jet sizes seem to be a bit weird, why would the 50hp have a larger top jet than the 60 for example ?
look at the sizes of numbers 14 and 22 for all three models.

http://www.marineengine.com/parts/johns ... C+60%2C+70

This appears to be the non plastic top carb.
http://www.ebay.com/itm/Johnson-Evinrud ... LD&vxp=mtr

Here is the other plastic top. Same seller has both for sale
http://www.ebay.com/itm/Johnson-Evinrud ... SwpDdU5NOW


I can't answer your question as to why the manufacturer does certain things.
The threads purpose is to help T850 racers building an oval port nothing else.

I dont think any of the oval ports came with those carbs.
they may be for old stock engines made just before oval port came out.
just like some of the oval ports being sold as 2004 engines.

they are also smaller bore at the back as in the pictures show by another seller of these carbs.

http://www.ebay.ca/itm/0433237-0436664- ... 5d6078c51f

looking at the back of the carbs its easy to see they arethe smaller 1.1/4 bore at rear.

from info I have managed to get the oval port carbs all start with numbers 437????

somebody somewhere has a lot of info that we could all do with knowing.
need someone who worked at the factory during the 90's.

thought I had solved it, then found loads of carbs for different years .
But all fitted to bridgeports.
1991 60hp Bridgeport was fitted with omc 0433237, same year 70hp fitted with omc 0434160.

1992 early production 0433237 Carb 60hp and 0434160 Carb 70hp .......

1992 late production
0435385 Carburetor 70hp needle valve with 8-32 threads ..
0435911 Carburetor 70hp needle valve with 8-56 threads

???
http://www.ebay.com/itm/437633-0437633- ... 7675.l2557

this is the sort of thing I was seeing advertised over here as 70hp carb, yet they are real tiny 50hp things.
and when you talk to a lot of dealers (even omc dealers ) they try telling you they are all the same.

its crazy.

its a shame that omc just didn't stamp 60 or 70 or whatever on the bodys.

We know that there were 1.5 bore carbs for the oval port. You have a set, Mike had a set and Craig has a set. It appears from the part numbers and EBAY pictures that the smaller 1.25 bore started in 1995. I found a dealer who has 1 only NOS non plastic cap carb with the correct part number [0434160] for the 70 hp. I will e-mail him to measure the bore size.
http://www.marineengine.com/newparts/pa ... OMC0434160

if it aint got a plastic top its not from an oval port, it would be from one of the last bridgeports.

none of the oval port engines came with non plastic tops.
I think the mix up is because the oval port was around at the same time as the last bridgeports, and in 1993 both engines were
still coming out of the factory, probably left over stock.
I think the oval port was advertised as the new 1993 model. but was available in late 92 like most thing boat and car wise.


would be good to compare 1 particular engine/boat with a true set of 70 oval and a set of 70 Bridgeport carbs and get results.

339172 is the carb body part number and like Don said the carb body was shared across the various 2 and 3 cylinder motors of the time with different jetting depending on the motor. OMC kept refining the carbs over the years in order to get the motors to idle better and burn cleaner. It was always about the idle as that was how the average consumer judged a good running motor. If you compare the early 80's version of the carb against the last version of the carb on the same motor the idle difference is quite noticeable. You will not see any top end differences between the various carbs with prop jetting.

The oval port did come with non-plastic carbs, it was the new "plastic top" carb that was not introduced til the later part of 1992, not the block, the plastic top carbs showed up in 1992 on the 2 and 3 cylinders at the same time.

so when do you say the 56 cu in oval port engine was released ?