Orifice question for '79 Evinrude 140 I am rebuilding

[Chris's CVX16]

So I am deep in the process of rebuilding a '79 Evinrude 140 and found out a few interesting things. Basically besides needing an overbore I am need a real big overbore since it was previously knocked out to 3.540. So with it being 3.564 now I am curious if I should also change the main orifice plugs in both carburetors. Right now they are #65C's. The previous rebuild ended up with piston ring damage and since I picked it up not working I assume that it might also be running real lean on the top end. I also don't know about the idle plugs but that isn't as big a deal until I get her put back together and actually make some noise.

My question is should I drop in say #68C's or something even larger? It's not inexpensive so I'd like to do it right one time.

 

[Faztbullet]

68's should be close.....make sure the deflectors,t-stats and poppets are up to par. Make sure exhaust ports are chamfered since sleeve are so thin now

 

[Chris's CVX16]

Thanks for the fast reply. Most of those parts will be replaced with new. I'll be chamfering the ports when I get the block back. What are these deflectors you speak of? Any other carburetor changes recommended?

 

[Faztbullet]

deflectors are the rubber tube between cylinder to direct water flow

 

[racerone]

I would look for another block .------Just so you can go to 0.020" O/S on that.------At 0.064" sleeves will be thin

 

[Chris's CVX16]

It was already out to 0.040 over with wear. Comparing it to my 88 SPL's block the sleeves aren't really any thinner. My only issue tight now is how to chamfer.

 

[emdsapmgr]

The factory says no change to jetting on overbores up to .030 over. Since yours is going to be so much larger it's best to jet up the mains. Maybe two jets sizes for starters. The flow will increase significantly each jet size you go up, base on the (larger) circle area formula. Just on that large bore cyl.