85hp carbs:1 3/16 or 1 5/16?

[John Bett]

Hello, Could someone help me with a problem that I have with my '70 85hp evin outboard. I want to put the bigger 1 5/16 carbs on to get a little more power whereas I should have the smaller 1 3/16 on there now, but after totally inspecting the carburators on my bench, the only number besides a casting number on the bowls is a single '5' on the front of the carb where the air box bolts up. I took a micrometer and the bore where the carb bolts to the manifold is approximatly 1.375 . does the 5 denote 1 5/16? Thanks.

 

[jimmbo]

Re: 85hp carbs:1 3/16 or 1 5/16?

Unless you change the porting of the block all your going to do is create a bog off ilde and poorer acceleration if you instsll the bigger carbs.

 

[John Bett]

Re: 85hp carbs:1 3/16 or 1 5/16?

Thanks, jimbo, but since I cant seem to identify the carbs on this motor as I described above I would like to know if someone can measure either a 1 3/16 or a 1 5/16 carb port where it bolts up to the manifold so I may see If someone may have put the bigger carbs on my motor and it is causing it to run poorly. mine measured approximatly 1.375 at the port side.<br />Thanks for advice!

 

[jimmbo]

Re: 85hp carbs:1 3/16 or 1 5/16?

Simple measure the diameter of the throttle bore, of course you have to take the carb off the motor

 

[Hooty]

Re: 85hp carbs:1 3/16 or 1 5/16?

The bigger bore carbs will give you a little more on the top end but you'll pay for it coming outa the hole.<br /><br />c/6<br />Hooty

 

[ledgefinder]

Re: 85hp carbs:1 3/16 or 1 5/16?

You have to measure the size of the venturi. That is, the smallest cross-section, where the throttle plates are.

 

[John Bett]

Re: 85hp carbs:1 3/16 or 1 5/16?

Thanks for the information!

 

[jimmbo]

Re: 85hp carbs:1 3/16 or 1 5/16?

Actually the measurements that refer to the different carbs is of the bore size not venturi size